Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Taxa

  • abundant taxa
  • additional taxa
  • algal taxa
  • american taxa
  • animal taxa
  • arthropod taxa
  • bacterial taxa
  • basal taxa
  • common taxa
  • derived taxa
  • different taxa
  • distinct taxa
  • diverse taxa
  • dominant taxa
  • endemic taxa
  • european taxa
  • extant taxa
  • extinct taxa
  • few taxa
  • fish taxa
  • fossil taxa
  • fungal taxa
  • host taxa
  • indicator taxa
  • individual taxa
  • infraspecific taxa
  • ingroup taxa
  • insect taxa
  • intraspecific taxa
  • invertebrate taxa
  • investigated taxa
  • larger taxa
  • macroinvertebrate taxa
  • major taxa
  • mammalian taxa
  • many taxa
  • marine taxa
  • multiple taxa
  • native taxa
  • new taxa
  • of taxa
  • other taxa
  • outgroup taxa
  • parental taxa
  • phytoplankton taxa
  • plant taxa
  • pollen taxa
  • pollinator taxa
  • prey taxa
  • primate taxa
  • rare taxa
  • recent taxa
  • relate taxa
  • remaining taxa
  • same taxa
  • several taxa
  • similar taxa
  • sister taxa
  • species-level taxa
  • studied taxa
  • sympatric taxa
  • terminal taxa
  • terrestrial taxa
  • variety of taxa
  • various taxa
  • vertebrate taxa
  • zooplankton taxa

  • Terms modified by Taxa

  • taxa belonging
  • taxa richness

  • Selected Abstracts


    EVOLUTION, Issue 2 2000
    Peter J. Wagner
    Abstract., Frequencies of new character state derivations are analyzed for 56 fossil taxa. The hypothesis that new character states are added continuously throughout clade history can be rejected for 48 of theses clades. Two alternative explanations are considered: finite states and ordered states. The former hypothesizes a limited number of states available to each character and is tested using rarefaction equations. The latter hypothesizes that there are limited possible descendant morphologies for any state, even if the character has infinite potential states. This is tested using power functions. The finite states hypothesis explains states: steps relationships significantly better than does the ordered states hypothesis in 14 cases; the converse is true for 14 other cases. Under either hypothesis, trilobite clades show appreciably more homoplasy after the same numbers of steps than do molluscs, echinoderms, or vertebrates. The prevalence of the exhaustion pattern among different taxonomic groups implies that worker biases are not to blame and instead implicates biological explanations such as intrinsic constraints or persistent selective trends. Regardless of the source of increased homoplasy, clades appear to exhaust their available character spaces. Nearly all examined taxa show significant increases in proportions of incompatible character pairs (i.e., those necessarily implying homoplasy) as progressively younger taxa are added to character matrices. Thus, a deterioration of hierarchical structure accompanies character state exhaustion. Exhaustion has several implications: (1) the basic premise of cladistic analyses (i.e., that maximum congruence reflects homology rather than homoplasy) becomes increasingly less sound as clades age; (2) sampling high proportions of taxa probably is needed for congruence to discern homoplasy from homology; (3) stratigraphic data might be necessary to discern congruent homoplasy from congruent homology; and (4) in many cases, character states appear to have evolved in ordered patterns. [source]


    JOURNAL OF PHYCOLOGY, Issue 5 2009
    Maja Blume
    Charophytes produce a thick-walled zygote, the so-called oospore, the characters of which (size, shape, and structure) are used as taxonomic determination criteria. In the present study, the variation of length, width, length-to-width ratio, and number of striae of oospores collected both from the field and after cross-fertilization experiments was compared within and among taxa, populations, and individuals belonging to the Chara baltica Bruzelius "species complex." Although the oospore characteristics differed significantly among the taxa, the variations among populations belonging to the same taxon and even among individuals belonging to the same population were still higher. Oospores developed by means of allogamy were not significantly different from oospores developed by autogamy. Oospores were 5% shorter and 27% narrower when measured dry compared with wet material. Information about this treatment is unfortunately lacking in charophyte monographs and oospore determination keys. We concluded that oospore descriptions of different charophyte taxa should be based on a larger amount of data material collected from different populations and individuals and accompanied by a detailed method description, and that a determination of closely related taxa by means of oospores should be interpreted carefully. Ecological aspects of oospore size variation are discussed. [source]

    Naturalization and invasion of alien plants: concepts and definitions

    David M. Richardson
    Abstract., Much confusion exists in the English-language literature on plant invasions concerning the terms ,naturalized' and ,invasive' and their associated concepts. Several authors have used these terms in proposing schemes for conceptualizing the sequence of events from introduction to invasion, but often imprecisely, erroneously or in contradictory ways. This greatly complicates the formulation of robust generalizations in invasion ecology. Based on an extensive and critical survey of the literature we defined a minimum set of key terms related to a graphic scheme which conceptualizes the naturalization/invasion process. Introduction means that the plant (or its propagule) has been transported by humans across a major geographical barrier. Naturalization starts when abiotic and biotic barriers to survival are surmounted and when various barriers to regular reproduction are overcome. Invasion further requires that introduced plants produce reproductive offspring in areas distant from sites of introduction (approximate scales: > 100 m over < 50 years for taxa spreading by seeds and other propagules; > 6 m/3 years for taxa spreading by roots, rhizomes, stolons or creeping stems). Taxa that can cope with the abiotic environment and biota in the general area may invade disturbed, seminatural communities. Invasion of successionally mature, undisturbed communities usually requires that the alien taxon overcomes a different category of barriers. We propose that the term ,invasive' should be used without any inference to environmental or economic impact. Terms like ,pests' and ,weeds' are suitable labels for the 50,80% of invaders that have harmful effects. About 10% of invasive plants that change the character, condition, form, or nature of ecosystems over substantial areas may be termed ,transformers'. [source]

    Trading off the ability to exploit rich versus poor food quality

    ECOLOGY LETTERS, Issue 5 2002
    Alan J. Tessier
    Abstract Lakes differ in the quality of food for planktonic grazers, but whether grazers adapt to this resource heterogeneity is poorly studied. We test for evidence of specialization to resource environment within a guild of suspension feeding daphniids inhabiting lakes that differ in food web structure. Using bioassays, we demonstrate that food quality for grazers increases from deep to shallow to temporary lakes, which also represents a gradient of increasing predation risk. We compare growth rates and reproductive performance of daphniid taxa specific to each of the three lake types and find they differ greatly in minimum resource requirements, and in sensitivity to the resource gradient. These differences express a trade-off in ability to exploit rich vs. poor resources. Taxa from deep lakes, poor in resources, have low minimal needs, but they do relatively poorly in rich resource environments. We conclude that grazer distribution is consistent with an adaptive match of exploitation ability to resource environments. [source]

    Response of zooplankton communities to liquid creosote in freshwater microcosms

    Paul K. Sibley
    Abstract In this study, the response of zooplankton communities to single applications of liquid creosote in model aquatic ecosystems (microcosms) was evaluated. Liquid creosote was applied to 14 microcosms at concentrations ranging from 0.06 to 109 mg/L. Two microcosms served as controls. Zooplankton samples were collected from each microcosm on days 7 and 1 before treatment and on days 2, 5, 7, 14, 21, 28, 43, 55, and 83 following treatment. Temporal changes (response-recovery) in composition of the zooplankton community were assessed using principal response curves (PRC). Creosote induced a rapid, concentrationdependent reduction in zooplankton abundance and number of taxa, with maximum response (50,100% reduction in population densities) occurring between 5 and 7 d after treatment. Taxa that dominated at the time of treatment experienced the greatest impact, as indicated by large, positive species weight values (>1) from the PRC analysis. Many of these taxa recovered to pretreatment or control levels during the posttreatment period, with the degree and duration of recovery being strongly dependent on concentration. Creosote had little effect on species composition at less than 1.1 mg/L, because changes in the types and relative proportion of species contributed from Cladocera, Rotifera, and Copepoda were comparable to those observed in control microcosms. However, a significant shift in species composition was observed at concentrations greater than 1.1 mg/L; these microcosms were generally dominated by low numbers of rotifers, some of which had not been collected before treatment. Community-level effect concentrations (EC50s) were 44.6 and 46.6 ,g/L at 5 and 7 d, respectively, based on nominal creosote. Corresponding no-effect concentrations were 13.9 and 5.6 ,g/L. The results of this field study indicate that creosote may pose a significant risk to zooplankton communities at environmental concentrations potentially encountered during spills and/or leaching events. [source]

    Evolution and development of the primate limb skeleton

    Chi-Hua Chiu
    Abstract The order Primates is composed of many closely related lineages, each having a relatively well established phylogeny supported by both the fossil record and molecular data.1 Primate evolution is characterized by a series of adaptive radiations beginning early in the Cenozoic era. Studies of these radiations have uncovered two major trends. One is that substantial amounts of morphological diversity have been produced over short periods of evolutionary time.2 The other is that consistent and repeated patterns (variational tendencies3) are detected. Taxa within clades, such as the strepsirrhines of Madagascar and the platyrrhines of the Neotropics, have diversified in body size, substrate preference, and diet.2, 4,6 The diversification of adaptive strategies within such clades is accompanied by repeated patterns of change in cheiridial proportions7, 8 (Fig. 1) and tooth-cusp morphology.9 There are obvious adaptive, natural-selection based explanations for these patterns. The hands and feet are in direct contact with a substrate, so their form would be expected to reflect substrate preference, whereas tooth shape is related directly to the functional demands of masticating foods having different mechanical properties. What remains unclear, however, is the role of developmental and genetic processes that underlie the evolutionary diversity of the primate body plan. Are variational tendencies a signature of constraints in developmental pathways? What is the genetic basis for similar morphological transformations among closely related species? These are a sampling of the types of questions we believe can be addressed by future research integrating evidence from paleontology, comparative morphology, and developmental genetics. [source]

    Relationships in Taraxacum section Arctica s.l. (Asteraceae, Cichorieae) and allies based on nrITS

    FEDDES REPERTORIUM, Issue 1-2 2009
    I. Uhlemann
    nrITS sequences of 19 Taraxacum -species as well as four outgroups of Asteraceae-Cichorieae were analysed using Bayesian and parsimony analyses in order to establish their systematics. The Arctica s.l. clade together with T. bessarabicum is sister to all derived European and South American taxa. The division of Arctica s.l. into smaller units (sections: Antarctica, Arctica s. str., Australasica) is supported. Within the remaining taxa, Taraxacum farellonicum, a species from the Chilean Andes which is described as new, is supposed to be a hybrid of T. gilliesii and an introduced Ruderalia -species. Section Erythrosperma is well separated and supported. With the exception of T. patagonicum and T. bracteatum which are sister to the other representatives of the European taxa two groups are distinguished: first the Ruderalia/Hamata alliance (including T. tenebricans with some exceptional characters) of predominantly ruderal species and second an assemblage of the sections Celtica, Fontana, Macrodonta, Palustria and Taraxacum prefering a lesser ruderal habitate. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Molekulare Systematik der Gattung Taraxacum Sektion Arctica s.l. (Asteraceae, Cichorieae) und verwandter Arten auf der Basis von nuklearer ribosomaler DNA (nrITS) Die Verwandtschaftsverhältnisse von 19 Arten der Gattung Taraxacum und vier Außengruppen aus den Asteraceae-Cichorieae wurden mit Bayesischen und Parsimonieanalysen der nrITS Sequenzen rekonstruiert. Die Sektion Arctica s.l. bildet zusammen mit T. bessarabicum die Schwestergruppe zu den abgeleiteten europäischen und südamerikanischen Taxa. Die Klassifizierung der Arctica s.l. in die Sektionen Antarctica, Arctica s.str. und Australasica wird von den Analysen unterstützt. Die in dieser Studie neu beschriebene Art, Taraxacum farellonicum, aus den chilenischen Anden ist wahrscheinlich ein Hybrid aus T. gilliesii und einer neophytischen Art der Sektion Ruderalia. Die Sektion Erythrosperma erscheint als gut gestützte Gruppe. Mit Ausnahme von T. patagonicum und T. bracteatum, die Schwestergruppen zu den anderen Vertretern europäischer Taxa bilden, können zwei größere Komplexe unterschieden werden: erstens die Ruderalia/Hamata -Gruppe (einschließlich T. tenebricans mit einigen besonderen Merkmalen), welche vorwiegend Arten der ruderalen Standorte umfasst und zweitens ein Verwandtschaftskreis aus den Sektionen Celtica, Fontana, Macrodonta, Palustria und Taraxacum, die an weniger stark ruderalisierten Standorten vorkommen. [source]

    The identity of Paeonia corsica Sieber ex Tausch (Paeoniaceae), with special reference to its relationship with P. mascula (L.) Mill.

    FEDDES REPERTORIUM, Issue 1-2 2006
    Hong De-Yuan
    The taxonomy of the genus Paeonia in central Mediterranean islands has been controversial, with number of recognized taxa changing greatly from one species without infraspecific division to three species or five infraspecific taxa in one species, and with the number of synonyms as great as 30. In the present work, the taxonomic history is thoroughly reviewed and a taxonomic revision is made based on extensive field work, chromosome observation, population sampling, examination of a large amount of herbarium specimens, and subsequent statistic analysis. As a result of the studies P. corsica Sieber ex Tausch, an ignored specific name, is restored at specific rank, and the species is found distinct from all the three subspecies of P. mascula in this region in having mostly nine (vs , 10) leaflets/segments, shorter hairs (1.5 mm vs 3 mm long) on carpels, rather densely holosericeous (vs glabrous or very sparsely hirsute) on the lower surface of leaves. It is a diploid, confined to Corsica France), Sardinia (Italy), Ionian Islands and Akarnania Province of Greece, whereas P. mascula is a tetraploid, widely distributed from Spain to Turkey and Iraq, but not in Corsica, Sardinia and W Greece. In addition, type specimens of four taxa are designated, and 29 botanic names are listed as synonyms of P. corsica in this paper. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Die Identität von Paeonia corsica Sieber ex Tausch (Paeoniaceae), mit besonderem Bezug auf ihre Verwandtschaft mit P. mascula (L.) Mill. Die Taxonomie der Gattung Paeonia auf den zentralen Mittelmeerinseln ist stets kontrovers gewesen. Die Anzahl der Taxa wechselte zwischen einer Art ohne infraspezifische Differenzierung bis zu drei oder fünf infraspezifische Taxa innerhalb einer Art. Die Anzahl der Synonyme beträgt bis zu 30 Taxa. In vorliegender Arbeit wird die Geschichte der Taxonomie sorgfältig betrachtet und eine taxonomische Revision auf der Basis extensiver Feldstudien, Chromosomen-Bewertung, Sammlungen von Populationen, der Untersuchung zahlreicher Herbarproben und abschließender statistischer Analysen vorgenommen. Im Ergebnis dieser Untersuchungen wird Paeonia corsica Sieber ex Tausch, ein bislang unbeachteter Artname, erneut in den Rang einer Art erhoben. Diese in dieser Region gefundene Spezies wurde als verschieden von den drei Unterarten von Paeonia mascula befunden. Sie hat meist neun (, 10) Blättchen, kürzere Haare (1.5 mm vs 3 mm lang) auf dem Karpell dichtere holoserios (vs glabrous oder selten hirsut) auf der Blattunterseite. Paeoniacorsica ist diploid auf Korsika (Frankreich), Sardinien (Italien), den Ionischen Inseln und der Provinz Akarnania in Griechenland, während Paeonia mascula tetraploid ist und weit verbreitet von Spanien bis in die Türkei und den Irak, fehlt aber auf Korsika, Sardinien und in Westgriechenland. Außerdem werden Typspecimen für 4 Taxa festgelegt. Als Synonyme von P. corsica wurden 29 Namen aufgelistet. [source]

    Basidiomycetes and larger Ascomycetes from Yemen

    FEDDES REPERTORIUM, Issue 7-8 2004
    H. Kreisel Prof. Dr.
    From the territory of Yemen 39 taxa of larger fungi (macromycetes: 36 Basidiomycetes and three Ascomycetes), including former records in literature, are enumerated and annotated. 22 taxa have been collected in recent times; 16 of them are first records from Yemen. Actually eight taxa are known from the highlands, 16 taxa from the coastal lowland, and 15 taxa (only very old records) from the island Socotra. Constituents of the macromycete flora of Yemen are species of south-temperate to mediterranean distribution (mainly represented in the highlands), species of subtropical to tropical distribution (mainly represented in the lowlands) and nearly cosmopolitic elements. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Basidiomyceten und größere Ascomyceten aus Jemen Aus dem Territorium des Jemen werden, unter Einbeziehung früher publizierter Funde, 39 Taxa von Großpilzen (36 Basidiomycetes und drei Ascomycetes) aufgezählt. 22 Taxa wurden in neuerer Zeit gesammelt; 16 werden hier erstmalig für Jemen angezeigt. Aus dem Hochland sind nunmehr acht Taxa, aus dem Küstentiefland 16 Taxa und von der Insel Socotra (von hier nur sehr alte Angaben) 15 Taxa Macromyceten bekannt. Bestandteile der Pilzflora des Jemen sind südlich-temperate (vorwiegend im Hochland nachgewiesene), subtropisch-tropische (im Küstentiefland nachgewiesene) und annähernd kosmopolitische Arten. [source]

    Orobanche benkertii sp. nova (Orobanchaceae Vent.) und weitere Orobanche -Sippen aus dem Nordwest-Kaukasus

    FEDDES REPERTORIUM, Issue 1-2 2004
    St. Rätzel
    Im Verlaufe von zwei Exkursionen des Erstautors in den Nordwest-Kaukasus (Republik Adygeja) in den Jahren 2001 und 2002 konnte reichhaltiges Material der Gattung Orobanche L. gesammelt werden. Im Ergebnis der Durchsicht der Belege wurden weitere Erkenntnisse insbesondere zu den weniger bekannten Endemiten Orobanche gamosepala, O. grossheimii und O.inulae gewonnen sowie sechs neue Taxa (Orobanche benkertii sp. nova, O. laxissima sp. nova, O. alba subsp. xanthostigma subsp. nova, O. alba subsp. xanthostigma f. sineglandulosa f. nova, O. grossheimii f. pallescens f. nova, O. flava subsp. cicerbitae subsp. nova) werden beschrieben. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Orobanche benkertii sp. nova (Orobanchaceae Vent.) and further Orobanche species from the Northwest Caucasus mountains During two excursions of the first author to the northwest Caucasian area (Republic Adygeja) in 2001 and 2002 rich material of genus Orobanche L. has been collected. As a result of the determination of these specimens better knowledges especially about the lesser known and endemic species Orobanche gamosepala, O.grossheimii and O.inulae could be received and , besides , six new taxa (Orobanche benkertii sp. nova, O. laxissima sp. nova, O. alba subsp. xanthostigma subsp. nova, O. alba subsp. xanthostigma f. sineglandulosa f. nova, O. grossheimii f. pallescens f. nova, O. flava subsp. cicerbitae subsp. nova) are described. [source]

    The hairs of Plantago reniformisBeck, section EremopsylliumPilg. (Plantaginaceae)

    FEDDES REPERTORIUM, Issue 3-4 2003
    E. Andrzejewska-Golec Dr. habil
    The paper is a continuation of the investigations on the hairs in representatives of family Plantaginaceae. It regards monotypic section EremopsylliumPilg. separated by Pilger from sectio LamprosanthaDecne. According to Rahn and Rønsted it is incorrect. In Plantago reniformis headed hairs typical of the family Plantaginaceae are present. They are plesiomorphic hairs with one celled stalk and head divided vertically into two cells. Headless hairs also are similar to hairs in subgenus Plantago sensu Rahn. Die Haare von Plantago reniformisBeck, Sektion EremopsylliumPilg. (Plantaginaceae) Dieser Beitrag ist eine Fortsetzung der Untersuchungen von Haaren an Vertretern der Plantaginaceae. Der vorliegende Artikel betrifft die monotypische Sektion EremopsylliumPilg. Pilger löste die Sektion Eremopsyllium aus der Sektion Lamprosantha heraus. Nach Rahn und Rønsted ist dies nicht berechtigt. Bei Plantago reniformis treten nur für die Familie Plantaginaceae typische Köpfchenhaare auf. Diese plesiomorphen Haare haben einzellige Stiele und die Köpfchen sind vertikal in zwei Zellen geteilt. Die Art besitzt auch ähnliche kopflose Haare wie die Taxa des Subgenus Plantago sensu Rahn. [source]

    Effects of increased flow in the main stem of the River Rhine on the invertebrate communities of its tributaries

    FRESHWATER BIOLOGY, Issue 1 2005
    Melanie C. Beckmann
    Summary 1. We hypothesised that increased flow in the main stem of the River Rhine would influence the invertebrate communities of its tributaries and therefore investigated the invertebrate fauna of six tributaries over 2 years. 2. We collected quantitative invertebrate samples at three sites in each tributary: in the tributary mouth (influenced by Rhine water whenever flow in the Rhine exceeded mean annual level), in the zone reached by average floods (return period 1.5 years) in the Rhine (average flood level sites), and immediately upstream of the range of extreme Rhine floods (reference sites). Samples were taken in spring, summer and autumn of each year, at different flow levels of the Rhine. We also compared substratum composition at the three sites. 3. Tributary mouth sites had the finest substratum, the lowest total invertebrate density and the lowest taxon richness. At average flood level and reference sites, these three parameters were similar. 4. Taxa known to prefer larger rivers were mostly confined to the tributary mouth sites, and species preferring upland streams dominated at the average flood level and reference sites. 5. Multivariate analyses confirmed the influence of the Rhine on the tributary mouth sites. Invasive invertebrate species, which usually appear only in the Rhine itself, were found at the tributary mouth sites but not further up in the tributaries. 6. Our study shows that increased flow in the main stem of the Rhine influenced substratum composition and invertebrate communities at the tributary mouth sites. These results imply that the relationship between the main stem of a river and its tributaries is not one-way (from tributary to main stem), but rather a two-way interaction. [source]

    ORIGINAL ARTICLE: Coalescent analyses support multiple mainland-to-island dispersals in the evolution of Malagasy Triaenops bats (Chiroptera: Hipposideridae)

    Amy L. Russell
    Abstract Aim, We investigate the directionality of mainland-to-island dispersals, focusing on a case study of an African-Malagasy bat genus, Triaenops (Hipposideridae). Taxa include T. persicus from east Africa and three Triaenops species from Madagascar (T. auritus, T. furculus, and T. rufus). The evolution of this bat family considerably post-dated the tectonic division of Madagascar from Africa, excluding vicariance as a viable hypothesis. Therefore, we consider three biogeographical scenarios to explain these species' current ranges: (A) a single dispersal from Africa to Madagascar with subsequent speciation of the Malagasy species; (B) multiple, unidirectional dispersals from Africa to Madagascar resulting in multiple, independent Malagasy lineages; or (C) early dispersal of a proto-species from Africa to Madagascar, with later back-dispersal of a descendant Malagasy taxon to Africa. Location, East Africa, Madagascar, and the Mozambique Channel. Methods, We compare the utility of phylogenetic and coalescent methodologies to address the question of directionality in a mainland-to-island dispersal event for recently diverged taxa. We also emphasize the application of biologically explicit demographic systems, such as the non-equilibrium isolation-with-migration model. Here, these methods are applied to a four-species haploid genetic data set, with simulation analyses being applied to validate this approach. Results, Coalescent simulations favour scenario B: multiple, unidirectional dispersals from Africa to Madagascar resulting in multiple, independent Malagasy bat lineages. From coalescent dating, we estimate that the genus Triaenops was still a single taxon approximately 2.25 Ma. The most recent Africa to Madagascar dispersal occurred much more recently (c. 660 ka), and led to the formation of the extant Malagasy species, T. rufus. Main conclusions, Haploid genetic data from four species of Triaenops are statistically most consistent with multiple, unidirectional dispersals from mainland Africa to Madagascar during the late Pleistocene. [source]

    Analysis of the Italian Dutch Elm Disease Fungal Population

    A. Santini
    Abstract Sixty-two Ophiostoma ulmi sensu lato strains have been collected from symptomatic trees in seven areas of Central Italy. Isolates were compared with 10 reference strains, belonging to the species O. ulmi and to the two subspecies of O. novo-ulmi, in order to establish the genetic variability within the Italian population of this fungal pathogen. The structure of the population has been analysed by means of morpho-physiological features and of the direct amplification of minisatellite-region DNA polymerase chain reaction (DAMD-PCR) by using the M13 core sequence. The DNA profiles have been compared with taxonomic parameters (growth rate, culture aspect and fertility barriers). Taxa could thus be well separated. None of the isolates collected was recognized as O. ulmi. Isolates assigned to the two subspecies of O. novo-ulmi (novo ulmi and americana) by means of the fertility test, showed short genetic distances with the respective reference strains and they constituted subgroups according to their geographical origin. The high level of variation detected indicates a postepidemic situation in Italy. Some inconsistency was found within the subspecies clusters. Several isolates, assigned to subspecies americana using fertility test, were in the novo-ulmi cluster and vice versa. A possible explanation is that these isolates are americana,novo-ulmi hybrids. [source]

    Mating behaviour of the ,cosmopolitan' species Phyllognathopus viguieri (Copepoda: Harpacticoida) and its systematical significance

    D. Königshoff
    Abstract The mating behaviour was studied and recorded on video with individuals of four cultures of Phyllognathopus viguieri from different populations obtained from the interstitial water of a slow sand filter near the river Ruhr (Germany) (Ruhr population), from a compost heap in Bethesda (Maryland, USA) (Maryland population), from a rain gauge in Windsor Campbell farm (Jamaica) (Jamaica population), and a tree trunk with moss in a forest in the municipality of Rio de Janeiro (Brazil) (Brazil population). The mating behaviour was divided into the well-known initial phase, copula phase and postcopulatory mate guarding phase. An additional phase prior to the initial phase serves to recognize the female, the recognition phase. The mating behaviour is identical in the males of the Jamaica and Brazil populations of P. viguieri. A postcopulatory mate guarding phase is not found in these two groups. Here, we refute the hypothesis, that a postcopulatory mate guarding phase is found in taxa in which only adult males grasp adult females. The males of the Ruhr and Maryland populations differ from each other in their mating behaviour. Generally, the males of all four populations do not mate with fertilized females which are equally unattractive to the males, i.e., females mate only once in their lifetime to produce offspring. These results corroborate the view that the different populations of P. viguieri do not belong to a single cosmopolitan species. Zusammenfassung Das Kopulationsverhalten wurde an Vertretern aus vier Populationen von Phyllognathopus viguieri mit unterschiedlicher geographischer Herkunft mit Videoaufzeichnung untersucht. Die Tiere stammen aus dem Grundwasser der Ruhr (Langsamsandfilter) Deutschland (Ruhr-Population), aus Moospolstern im städtischen Wald von Rio de Janeiro, Brasilien (Brazil-Population), aus einem Komposthaufen in Bethesda, Maryland, USA (Maryland-Population) und aus einer Zisterne der Windsor Campbell farm, Jamaika (Jamaica-Population). Das Kopulationsverhalten kann in wie bereits bekannt Initialphase, Kopulaphase und Postkopulaphase eingeteilt werden. Während der Initialphase findet keine Balz statt. Als zusätzliche Phase findet vor der Initialphase eine Prüfphase statt, die dem Erkennen des Weibchens dient. Es konnte festgestellt werden, daß die Vertreter der vier Populationen sich in Bezug auf ihr Kopulationsverhalten voneinander unterscheiden. Das Kopulationsverhalten der Tiere aus Jamaika und Brasilien war identisch, sowohl die Dauer der einzelnen Phasen, als auch das Verhalten der einzelnen Versuchsindividuen. Bei ihnen trat keine Postkopulaphase auf. Bei den Tieren der Ruhr- und der Marylandpopulation trat eine Postkopulaphase von unterschiedlicher Dauer auf. Auch das Fortpflanzungsverhalten der Männchen war unterschiedlich. Die in der Literatur vertretene Hypothese, dass bei Taxa, in denen die Männchen nur adulte Weibchen greifen, eine Postkopulaphase vorkommt, wird in dieser Studie widerlegt. Die Weibchen kopulieren nur einmal in ihrem Leben, was für ihre gesamte Reproduktion ausreichend ist. Männchen kopulieren in der Regel nicht mit bereits begatteten Weibchen. Bereits begattete Weibchen zeigen ein Abwehrverhalten, um die Männchen an der Anheftung der Spermatophore zu hindern. Die Spermatophore wird ohne Hilfe der Schwimmbeine übertragen. Die Befestigung der Spermatophore am Genitalfeld des Weibchens geschieht mit einer Kittsubstanz, die vom Männchen abgegeben wird. Die Individuen der Ruhr- und der Marylandpopulation zeigen trotz einer bei beiden vorkommenden Postkopulaphase unterschiedliches Fortpflanzungsverhalten. Wir schließen daraus, dass sie unterschiedlichen biologischen Arten angehören. Die Individuen der Jamaika- und Brazil-Populationen sind einer Art zuzuordnen, die sich von diesen beiden Arten unterscheidet. Die in dieser Arbeit gemachten Beobachtungen sind eine Bestätigung dafür, dass P. viguieri keine kosmopolitische Art ist, sondern dass es sich tatsächlich um eine Gruppe kryptischer valider Arten handelt. [source]

    The role of character loss in phylogenetic reconstruction as exemplified for the Annelida

    C. Bleidorn
    Abstract Annelid relationships are controversial, and molecular and morphological analyses provide incongruent estimates. Character loss is identified as a major confounding factor for phylogenetic analyses based on morphological data. A direct approach and an indirect approach for the identification of character loss are discussed. Character loss can frequently be found within annelids and examples of the loss of typical annelid characters, like chaetae, nuchal organs, coelomic cavities and other features, are given. A loss of segmentation is suggested for Sipuncula and Echiura; both are supported as annelid ingroups in molecular phylogenetic analyses. Moreover, character loss can be caused by some modes of heterochronic evolution (paedomorphosis) and, as shown for orbiniid and arenicolid polychaetes, paedomorphic taxa might be misplaced in phylogenies derived from morphology. Different approaches for dealing with character loss in cladistic analyses are discussed. Application of asymmetrical character state transformation costs or usage of a dynamic homology framework represents promising approaches. Identifying character loss prior to a phylogenetic analysis will help to refine morphological data matrices and improve phylogenetic analyses of annelid relationships. Zusammenfassung Die Phylogenie der Annelida wird nach wie vor kontrovers diskutiert und morphologische und molekulare Analysen liefern hierbei unterschiedliche Ergebnisse. Merkmalsverluste können phylogenetische Analysen morphologischer Daten in die Irre führen. In der vorliegenden Arbeit werden ein direkter und ein indirekter Ansatz zur Erkennung von Merkmalsverlusten vorgestellt. Es wird gezeigt, dass Merkmalsverlust innerhalb der Anneliden häufig auftritt und das hiervon auch typische Annelidenmerkmale, wie z.B Borsten, Nuchalorgane oder Coelomräume betroffen seien können. Molekularphylogenetische Analysen unterstützen eine Stellung der Echiura und Sipuncula innerhalb der Anneliden und somit ist für diese Taxa ein Verlust der Segmentierung anzunehmen. Es wird demonstriert, dass Merkmalsverlust durch herterochrone Evolution verursacht werden kann. Am Beispiel von Orbiniiden und Arenicoliden wird gezeigt, wie paedomorphe Taxa in kladistischen Analysen morphologischer Daten falsch platziert werden. Verschiedene Ansätze zum Umgang mit Merkmalsverlust in morphologischen Datensätzen werden präsentiert und diskutiert. Hierbei stellen die Verwendung asymmetrischer Merkmalstransformationskosten oder die Verwendung dynamischer Homologiehypothesen aussichtsreiche Ansätze dar. Jedoch werden für alle Ansätze Phylogeniehypothesen benötigt, die in einer Analyse unabhängiger Daten (bspw. Moleküle) erstellt wurden, um Merkmalsverluste sicher zu identifizieren. [source]

    Towards a phylogenetic classification of dendrocoelid freshwater planarians (Platyhelminthes): a morphological and eclectic approach

    R. Sluys
    Abstract We explore and review the taxonomic distribution of morphological features that may be used as supporting apomorphies for the monophyletic status of various taxa in future, more comprehensive phylogenetic analyses of the dendrocoelid freshwater planarians and their close relatives. Characters examined are: (i) musculature of the pharynx; (ii) anatomy of the eye; (iii) distribution of testis follicles along the longitudinal axis of the body; (iv) epidermis of the body wall; (v) musculature of the ventral body wall; (vi) presence or absence of a penis papilla; (vii) position of the mouth opening; and (viii) anterior adhesive organ. A phylogenetic hypothesis, in the form of a character state tree, is developed. This hypothesis suggests that the Kenkiidae should be resurrected as a separate family, sharing a sistergroup relationship with the Dendrocoelidae. This sistergroup relationship is supported by the shared presence of an apomorphic anterior adhesive organ. Although the shape of the anterior adhesive organ, both within and between kenkiids and dendrocoelids, may differ considerably between species, they are all constructed according to the same principles. The monophyly of the Kenkiidae is supported by the presence of an apomorphic thickening of the marginal zone of the epidermis and presumably also by the presence of prepharyngeal testes. Within the Kenkiidae, the genus Macrocotyla should be considered as a junior synonym of Kenkia, which is characterized by the presence of an apomorphic ,planariid pharynx-type 2'. The monophyly of the Dendrocoelidae is suggested by the presence of a dendrocoelid type of pharynx. It is shown that multicellular eye cups with numerous photoreceptor cells are not restricted to the Dugesiidae and the Terricola but are also characteristic for the Dendrocoelidae; the phylogenetic implications of this character state distribution are discussed. It is pointed out that in planarians there may be a relationship between: (i) body size, the size of an eye cup and the number of its constituent pigment cells; and (ii) the size of an eye cup and the number of photoreceptor cells that it contains. Some tentative phylogenetic groups are suggested on the basis of the following presumed apomorphic characters: presence of transverse fibres in the ventral subepidermal musculature, presence of an extra longitudinal muscle layer in the outer pharynx musculature, a mouth opening that has shifted anteriad. It is suggested that the presumed monophyly of the genus Bdellocephala is supported by the apomorphic absence of a penis papilla, combined with a penial lumen provided with many plicae. Zusammenfassung Wir untersuchen und begutachten die taxonomische Verbreitung morphologischer Merkmale, die man als Apomorphien für die Monophylie verschiedener Taxa in einer zukünftigen umfangreicheren phylogenetischen Analyse der Dendrocoeliden und ihrer nächsten Verwandten heranziehen könnte. Zu diesen untersuchten Merkmalen gehören die Pharynxmuskulatur, die Augen-Anatomie, die Anordnung der Hodenfollikel entlang der Längsachse des Körpers, die Epidermis, die Muskulatur der ventralen Körperwand, das Vorhandensein oder Fehlen einer Penispapille, die Lage der Mundöffnung sowie des vorderen Hartorgans. Eine phylogenetische Hypothese wurde als character state-Stammbaum entwickelt. Hierin wird vorgeschlagen, die Kenkiidae wieder als eigenständige Familie und als Schwestergruppe der Dendrocoelidae zu betrachten. Dieses Schwestergruppen-Verhältnis wird durch den gemeinsamen Besitz eines apomorphen vorderen Haftorgans gestützt. Obwohl sich die Form dieses Organs sowohl innerhalb als auch zwischen Kenkiiden und Dendrocoeliden beträchtlich zwischen den Arten unterscheiden kann, ist es grundsätzlich gleich aufgebaut. Die Monophylie der Kenkiidae wird durch eine als apomorph betrachtete Verdickung des Epidermisrandes und durch das Auftreten praepharyngealer Hoden gestützt. Innerhalb der Kenkiidae sollte die Gattung Macrocotyla als Juniorsynonym von Kenkia angesehen werden, die durch den apomorphen Planarien-Pharynx-Typ 2 charakterisiert ist. Als Beleg für die Monophylie der Dendrocoelidae wird der Dendrocoeliden-Pharynx-Typ vorgeschlagen. Es wird gezeigt, dass vielzellige Augenbecher mit zahlreichen Photorezeptorzellen nicht auf die Dugesiidae und die Terricola beschränkt, sondern auch für die Dendrocoelidae charakteristisch sind; die phylogenetische Bedeutung dieser Merkmalsverteilung wird diskutiert. Es wird hervorgehoben, dass es in den Planarien wahrscheinlich eine Beziehung zwischen (i) Körpergröße, Größe der Augenbecher und Zahl der Photorezeptorzellen ebenso wie (ii) der Größe eines Augenbechers und der Zahl seiner Photorezeptorzellen gibt. Versuchsweise werden einige phylogenetische Gruppierungen auf der Basis der folgenden vermutlich apomorphen Merkmale vorgeschlagen: Vorhandensein transversaler Fasern in der ventralen subepidermalen Muskulatur, Auftreten einer zusätzlichen Längsmuskelschicht in der äußeren Pharynxmuskulatur und eine nach vorn verschobene Mundöffnung. Es wird weiterhin vorgeschlagen, die vermutete Monophylie der Gattung Bdellocephala durch das Fehlen einer Penispapille als Autapomorphie zu stützen, zusammen mit dem Merkmal eines durch viele Falten gekennzeichneten Penislumens. [source]

    Molecular phylogeny and biogeography of Honey-buzzards (genera Pernis and Henicopernis)

    A. Gamauf
    Abstract A partial sequence of the cytb gene (382 bp) was amplified and sequenced from 35 individuals (mainly museum specimens) of the genus Pernis representing all valid taxa (10) and two taxa (P. p. gurneyi, P. p. japonicus) with questionable validity as well as representatives of the Old World Perninae, namely Henicopernis and Aviceda, to assess their relationships to the genus Pernis. Furthermore, Gypaetus barbatus, Neophron percnopterus, and Buteo buteo were included as outgroup taxa. In the trees derived from the sequence data, Aviceda represents the sister group of the genus Pernis. The genus Henicopernis and the Old World vultures Gypaetus andNeophron appear rather distantly related to Pernis. Within the genus Pernis, two of the described species (Pernis apivorus, Pernis ptilorhyncus) form monophyletic groups, whereas the relationships of the two clades representing three subspecies of Pernis celebensis are still uncertain. Although this study is based on comparatively short DNA-sections, the trees deduced from these sequences can be considered as a first approach for inferring the phylogenetic relationships of the genus Pernis and related genera and for addressing questions concerning the evolutionary history, biogeography, and systematics of this group. Zusammenfassung Eine Teilsequenz des Cytochrom b Gens (382 bp) wurde von 35 Individuen (hauptsächlich Museumsmaterial) der Gattung Pernis amplifiziert und sequenziert. Inkludiert wurden alle validen Taxa (10) und zwei weitere (P.p. gurneyi, P. p. japonicus) mit zweifelhaftem taxonomischen Status. Weiters wurden die übrigen Vertreter der altweltlichen Perninae (Henicopernis, Aviceda) untersucht, um deren Verwandtschaft zum Genus Pernis festzustellen. Als Außengruppen-Taxa wurden Bartgeier Gypaetus barbatus, Schmutzgeier Neophron percnopterus und Mäusebussard Buteo buteo verwendet. In den aus den Sequenzen errechneten Bäumen stellt Aviceda die Schwestergruppe der Gattung Pernis dar. Die Gattungen, Henicopernis und die Altweltgeier Gypaetus und Neophron erscheinen mit der Gattung Pernis nur entfernt verwandt. Innerhalb der Gattung Pernis formen zwei der beschriebenen Arten (P. apivorus, P. ptilorhyncus) eine monophyletische Gruppe, die Verwandtschaftsverhältnisse der beiden anderen Clades, welche die drei Unterarten von P. celebensis repräsentieren, können jedoch auf der Basis dieser Sequenz nicht eindeutig geklärt werden. Obwohl diese Analyse auf relativ kurzen DNA-Abschnitten basiert, können die aus den Sequenzen abgeleiteten Stammbäume als erster Versuch angesehen werden, die Phylogenie der Wespenbussard-Gattung Pernis und verwandter Genera mittels molekularer Methoden und unter Berücksichtigung evolutionsbiologischer, biogeographischer und systematischer Aspekte darzustellen. [source]

    Phylogenetic signal and the utility of 12S and 16S mtDNA in frog phylogeny

    S. Hertwig
    Abstract Genes selected for a phylogenetic study need to contain conserved information that reflects the phylogenetic history at the specific taxonomic level of interest. Mitochondrial ribosomal genes have been used for a wide range of phylogenetic questions in general and in anuran systematics in particular. We checked the plausibility of phylogenetic reconstructions in anurans that were built from commonly used 12S and 16S rRNA gene sequences. For up to 27 species arranged in taxon sets of graded inclusiveness, we inferred phylogenetic hypotheses based on different a priori decisions, i.e. choice of alignment method and alignment parameters, including/excluding variable sites, choice of reconstruction algorithm and models of evolution. Alignment methods and parameters, as well as taxon sampling all had notable effects on the results leading to a large number of conflicting topologies. Very few nodes were supported in all of the analyses. Data sets in which fast evolving and ambiguously aligned sites had been excluded performed worse than the complete data sets. There was moderate support for the monophyly of the Discoglossidae, Pelobatoidea, Pelobatidae and Pipidae. The clade Neobatrachia was robustly supported and the intrageneric relationships within Bombina and Discoglossus were well resolved indicating the usefulness of the genes for relatively recent phylogenetic events. Although 12S and 16S rRNA genes seem to carry some phylogenetic signal of deep (Mesozoic) splitting events the signal was not strong enough to resolve consistently the inter-relationships of major clades within the Anura under varied methods and parameter settings. Zusammenfassung Zur Anwendung in einer phylogenetische Analyse müssen die ausgewählten Gene konservierte und detektierbare Information zum untersuchten phylogenetischen Niveau enthalten. Ribosomale Gene des Mitochondriums wurden für ein breites Spektrum phylogenetischer Fragestellungen bei verschiedenen Gruppen und insbesondere bei Froschlurchen eingesetzt. Wir untersuchten die Frage, ob Rekonstruktionen der Anuren-Phylogenie, basierend auf 12S und 16S rRNA Gensequenzen, plausibel sind. An einer Auswahl von 27 Arten, arrangiert in Taxa-Gruppen abgestufter Hierarchie, rekonstruierten wir phylogenetische Hypothesen unter verschiedenen, a priori festgelegten Bedingungen. Dazu gehörten die Auswahl verschiedener Alinierungsmethoden und,parameter, der Umgang mit variabel alinierten Positionen, die Auswahl der Algorithmen zur Baumkonstruktion sowie die Auswahl alternativer Modelle der Sequenzevolution. Die Methoden und Parameter der Alinierung und der Rekonstruktion, sowie die Auswahl der Taxa, hatten bedeutenden Einfluss auf die Resultate. Daraus resultierte eine große Anzahl alternativer Topologien, in denen nur sehr wenige Knoten in allen Analysen Unterstützung fanden. Ausschluss variabel alinierter Positionen ergaben Topologien mit niedrigem Grad der Auflösung. Die Sequenzen enthielten ein gewisses Signal für die Monophylie von Discoglossidae, Pelobatoidea, Pelobatidae und Pipidae. Der Knoten Neobatrachia wurde deutlich unterstützt. Die robuste Auflösung intragenerischer Phylogenien von Bombina und Discoglossus weisen auf eine besondere Eignung der Gene für die Untersuchung junger Aufspaltungsereignisse hin. Obwohl 12S und 16S rRNA-Gene eine heterogene Unterstützung für wenige frühe (mesozoische) phylogenetische Ereignisse zeigten, war das Signal nicht geeignet, um die Beziehungen der Taxa höherer Ordnung der Anura unter variierten Parametern und Analysemethoden konsistent aufzulösen. [source]

    The phylogeny of the Praomys complex (Rodentia: Muridae) and its phylogeographic implications

    Among the African Murinae (Rodentia, Muridae), the Praomys complex, whose systematics has been studied by different approaches, has raised numerous taxonomic problems. Different taxa, namely Praomys, Mastomys, Myomys and Hylomyscus have been considered either as separate genera or subgenera of Praomys. In order to understand the relationships within the Praomys complex and to test the monophyly of the genus Praomys, a cladistic analysis was conducted, based on morpho-anatomical factors involving different species of Praomys, Mastomys, Myomys and Hylomyscus. The results indicate that the Praomys complex is monophyletic, as are the genera Hylomyscus, Mastomys and Myomys, whereas the genus Praomys appears paraphyletic. Indeed, a group of species including Praomys jacksoni was found to be more closely related to the genera Mastomys and Myomys than to a Praomys tullbergi -group. The biotopes and the distribution areas of the species were mapped on the phylogeny. It appears that the different clades each present a relative ecological cohesion and are arranged according to a gradient from closed to open habitats. From there, an evolutionary scenario is proposed for the emergence of the different clades and species of the genus Praomys sensu stricto. Phylogénie du complexe Praomys (Rodentia: Muridae) et ses implications biogéographiques Au sein des Murinae africains (Rodentia, Muridae), le complexe Praomys, dont la systématique a étéétudiée par différentes approches, a soulevé de nombreux problèmes taxinomiques. Les différents taxons Praomys, Mastomys, Myomys et Hylomyscus ont été considérés tour à tour comme des genres séparés ou des sous-genres de Praomys. Afin d'appréhender les relations de parentéà l'intérieur du complexe Praomys ainsi que pour tester la monophylie du genre Praomys, nous avons conduit une étude cladistique basée sur la morpho-anatomie, incluant différentes espèces de Praomys, Mastomys, Myomys et Hylomyscus. Les résultats indiquent que le complexe Praomys est monophylétique, comme le sont les genres Hylomyscus, Mastomys et Myomys, alors que le genre Praomys est paraphylétique. En effet un groupe d'espèce incluant P. jacksoni se trouve être plus proche des genres Mastomys et Myomys que du groupe incluant Praomys tullbergi. Les biotopes et les aires de distributions des espèces ont été plaquées sur la phylogénie. Il apparaît alors que les différents clades présentent chacun une relative unitéécologique et sont agencés suivant un gradient des milieux fermés vers les milieux ouverts. A partir de ces résultats, un scénario évolutif, basé sur les oscillations climatiques quaternaires, est proposé pour les différents clades et espèces du genre Praomys sensu stricto. Die Stammesgeschichte des Praomys-Komplexes (Rodentia: Muridae) und deren phylogeographischen Konsequenzen Unter den Afrikanischen Murinen (Rodentia, Muridae) ergaben sich beim Komplex der Gattung Praomys, der bereits in verschiedener Weise untersucht worden war, zahlreiche taxonomische Probleme. Die verschiedenen Taxa Praomys, Mastomys, Myomys und Hylomyscus wurden entweder als verschiedene Gattungen oder als Untergattungen von Praomys angesehen. Um die Verwandtschaftsbeziehungen zwischen den Taxa des Praomys- Komplexes besser verstehen zu lernen und die Frage der Monophylie der Gattung Praomys zu testen, führten wir eine kladistische Analyse unter Verwendung morpho-anatomischer Parameter von verschiedenen Arten von Praomys, Mastomys, Myomys und Hylomyscus durch. Die Ergebnisse zeigen, daß der Praomys- Komplex monophyletisch ist, wenn man die Gattungen Mastomys, Myomys und Hylomyscus betrachtet, während die Gattung Praomys paraphyletisch zu sein scheint. Allerdings erweisen sich einige Arten, Praomys jacksoni eingeschlossen, näher verwandt zu den Gattungen Mastomys und Myomys als zur Praomys tullbergi -Gruppe. Die Biotope und die Verbreitungsgebiete der Arten wurden mit Bezug auf die Phylogenie kartiert. Es zeigt sich, daß jede der verschiedenen Kladen eine relative ökologische Zusammengehörigkeit und einen gegliederten Gradienten von geschlossenen zu offenen Habitaten erkennen läßt. Davon ausgehend wird ein evolutionstisches Szenario für die Entstehung der verschiedenen Kladen und der Arten der Gattung Praomys sensu strictu vorgeschlagen. [source]

    Cryptic speciation and patterns of phenotypic variation of a highly variable acanthocephalan parasite

    MOLECULAR ECOLOGY, Issue 19 2007
    Abstract An investigation of a parasite species that is broadly host- and habitat-specific and exhibits alternative transmission strategies was undertaken to examine intraspecific variability and if it can be attributed to cryptic speciation or environmentally induced plasticity. Specimens of an acanthocephalan parasite, Leptorhynchoides thecatus, collected throughout North America were analysed phylogenetically using sequences of the cytochrome oxidase I gene and the internal transcribed spacer region. Variation in host use, habitat use, and transmission were examined in a phylogenetic context to determine if they were more likely phylogenetically based or due to environmental influences. Results indicated that most of the variation detected can be explained by the presence of cryptic species. The majority of these species have narrow host and microhabitat specificities although one species, which also may comprise a complex of species, exhibits broad host and habitat specificity. Alternate transmission pathways only occurred in two of the cryptic species and correlate with host use patterns. Taxa that mature in piscivorous piscine hosts use a paratenic fish host to bridge the trophic gap between their amphipod intermediate host and piscivorous definitive host. One potential example of environmentally induced variation was identified in three populations of these parasites, which differ on their abilities to infect different host species. [source]

    Molecular phylogenetics of the Macaronesian-endemic genus Bystropogon (Lamiaceae): palaeo-islands, ecological shifts and interisland colonizations

    MOLECULAR ECOLOGY, Issue 4 2005
    Abstract A molecular phylogenetic study of Bystropogon L'Hèr. (Lamiaceae) is presented. We performed a cladistic analysis of nucleotide sequences of the internal transcribed spacers (ITS), of the nuclear ribosomal DNA, and of the trnL gene and trnL-trnF intergenic spacer of the chloroplast DNA. Bystropogon odoratissimus is the only species endemic to the Canary Islands that occurs in the three palaeo-islands of Tenerife. This species is not part of an early diverging lineage of Bystropogon and we suggest that it has a recent origin. This phylogenetic pattern is followed by most of the species endemic to the palaeo-islands of Tenerife. The two sections currently recognized in Bystropogon form two monophyletic groups. Taxa belonging to the section Bystropogon clade show interisland colonization limited to the Canary Islands with ecological shifts among three ecological zones. Taxa from the section Canariense clade show interisland colonization both within the Canary Islands and between the Canary Islands and Madeira. Speciation events within this clade are mostly limited to the laurel forest. The genus has followed a colonization route from the Canaries towards Madeira. This route has also been followed by at least five other plant genera with species endemic to Macaronesia. Major incongruences were found between the current infrasectional classification and the molecular phylogeny, because the varieties of Bystropogon origanifolius and Bystropogon canariensis do not form two monophyletic groups. The widespread B. origanifolius appears as progenitor of the other species in section Bystropogon with a more restricted distribution. [source]


    PALAEONTOLOGY, Issue 4 2008
    Abstract:, A new terebratulid brachiopod species, Rhenorensselaeria jansenii, has been identified in the Merzâ-Akhsaï Formation of the Dra Valley, Morocco, and the Grauwacke de Montguyon of the Amorican Massif, France. It is compared with the other known species of Rhenorensselaeria from Europe, Rh. strigiceps and Rh. demerathia, as well as with Rh. macgerriglei from North America, from which it differs in being larger and having coarser costae. Its possible life habit in clusters and its fossil community are compared with those of Rh. strigiceps from the Rheinisches Schiefergebirge (,Rhenish Slate Mountains'), Germany, which it most resembles. A new phylogeny of the subfamily Rhenorensselaerinae is constructed. The close phylogenetic relationship between Rh. jansenii and Rh. strigiceps confirms close palaeobiogeographical relationships between North Africa, France and the Rheinisches Schiefergebirge as well as a wider relationship between Central Europe and Gaspé, eastern Canada, during the Early Devonian. Taxa of Rhenorensselaeria are mainly restricted to the Middle and Upper Siegenian, although rare individuals have been found in the Lower Emsian of Central Europe and North America. Because of their abundance in the Dra Valley and Rheinisches Schiefergebirge and their short life span, rhenorensselaerid taxa can be regarded as important stratigraphical markers of Middle,Late Siegenian and Early Emsian sediments in North Africa and Central Europe. [source]

    Molecular Phylogeny of Caryophyllidae s.l. Based on MatK Sequences with Special Emphasis on Carnivorous Taxa

    PLANT BIOLOGY, Issue 2 2000
    H. Meimberg
    Abstract: Despite intensive morphological, chemical and cladistic studies on Caryophyllidae, the circumscription of this subclass and the interfamilial relationships are still under discussion. Using comparative sequencing of the chloroplast matK gene, hypotheses of relationships between the carnivorous Droseraceae, Nepenthaceae and Dioncophyllaceae and ten other families of the Caryophyllidae s.l. were tested and compared with previously published cladograms based on rbcL, 18S rDNA and ORF2280 sequences. Parsimony analyses indicate two well-differentiated clades. One strongly supported clade comprises the carnivorous families Droseraceae and Nepenthaceae, along with its close relatives Dioncophyllaceae and Ancistrocladaceae. The second clade is restricted to the Polygonaceae, Plumbaginaceae, Tamaricaceae and Frankeniaceae. The Simmondsiaceae are more closely related to Caryophyllales and are at the base of the remaining taxa. Results of this analysis suggest that carnivory within Caryophyllidae s.l. has a monophyletic origin and, with the exception of Triphyophyllum, this syndrome was lost in the taxa of Dioncophyllaceae and Ancistrocladaceae. The exclusion of Drosophyllum from Droseraceae suggests no close relationship with this family. Finally, the data support a sister group relationship between the Plumbaginaceae and Polygonaceae and the Frankeniaceae and Tamaricaceae. An extensive survey of the rpl2 intron via PCR amplification indicates that the intron is absent from chloroplast genomes of Droseraceae and all taxa of Caryophyllales, but is present in Drosophyllum. Consequently, there is evidence for a multiple loss of the intron and strong support that Drosophyllum has affinities outside the Droseraceae. Our sequence data corroborate many aspects of recent cladistic analyses based predominantly on rbcL sequences. This study shows that matK sequences are useful for'phylogenetic inference among closely related members of Caryophyllidae. [source]

    From the Editors: Describing New Taxa of Unicellular Protists


    Seed plants of Fiji: an ecological analysis

    An annotated list of indigenous Fijian seed plant genera is presented and comprises 484 genera and 1315 species in 137 families. The relative diversity of the largest families and genera in Fiji is indicated and compared with floras in New Caledonia and the Upper Watut Valley, Papua New Guinea. Differences and similarities appear to be due to biogeographical/phylogenetic factors rather than ecological differences or means of dispersal. Generic diversity for the seed plants as a whole is greatest between 0,100 m and decreases monotonically with altitude. However, in the largest family, Orchidaceae, maximum diversity occurs between 200,400 m. Fifty percent of the families are recorded from shore habitat. Twenty-seven percent of the families and 80 species occur in or around mangrove, where the most diverse families are Orchidaceae, Rubiaceae, and the legumes. Some of the mangrove-associate species are pantropical or Indo-Pacific but most are locally or regionally endemic. Fifty-six percent of the Fijian families are recorded on limestone. Twenty-nine species are restricted to limestone and 12 species usually occur on limestone. The importance of calcium in reducing the effects of salinity is emphasized and 39 species are recorded from both mangrove and limestone. A plagiotropic habit occurs in 38 species which occur on limestone or around beaches, and 20 of these are Pacific endemics. Genera restricted to higher altitudes include many present elsewhere in Melanesia but absent from Australia despite suitable habitat there, again indicating the importance of biogeographical and historical factors. Altitudinal anomalies in Fiji taxa are cited and include 7 anomalously high records from northern Viti Levu, a site of major uplift, and 22 anomalously low altitudinal records in the Lau Group, a site of subsidence. It is suggested that the Fijian flora has not been derived from immigrants from Asia, but has evolved more or less in situ. Taxa would have survived as metapopulations on the individually ephemeral volcanic islands always found at oceanic subduction zones and hot spots, and the atolls which characterize areas of subsidence. The complex geology of Fiji is determined by its position between two subduction zones of opposite polarity, the Vanuatu and Tonga Trenches, in what is currently a region of transform faulting. The large islands comprise fragments of island arcs that have amalgamated and welded together. There has been considerable uplift as well as subsidence in the islands and it is suggested that both these processes have had drastic effects on the altitudinal range of the taxa. Limestone and mangrove floras could have provided a widespread, diverse ancestral species pool from which freshwater swamp forest, lowland rainforest, dry forest, secondary forest, thickets, and montane forest have been derived during phases of uplift. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 407,431. [source]

    New Taxa of Chrysomelidae (Insecta: Coleoptera) from Rovno Amber, Late Eocene

    Konstantin NADEIN
    Abstract: Leaf beetles Chrysomelidae of Rovno amber, from the Late Eocene, are recorded and described. Chrysomelidae of Rovno amber are represented by three subfamilies: Galerucinae (Alticini), Chrysomelinae, and Eumolpinae. Two new genera and three new species of Alticini: Manobiomorpha Nadein, gen. nov. (type species Manobiomorpha eocenica Nadein, sp. nov.), Psyllototus Nadein, gen. nov. (type species Psyllototus progenitor Nadein, sp. nov.), and Crepidodera decolorata Nadein et Perkovsky, sp. nov. are described. A new chrysomeline genus and species Paleophaedon minutus Nadein gen. nov. et sp. nov. is described. Probable trophic association of Crepidodera decolorata sp. nov., the taxonomic positions of Manobiomorpha gen. nov. and Psyllototus gen. nov., and the composition of leaf beetle faunas of Middle and Late Eocene of Europe are discussed. [source]

    Paleogeographical Distribution of Mesozoic Palaeontinidae (Insecta, Hemiptera) in China with Description of New Taxa

    Bo WANG
    Abstract: Until now, all Chinese palaeontinids have come from northern China and are more diverse than any other hemipterous insects in the Mesozoic. Most palaeontinids have been discovered from the area encompassing northern Hebei, the Ningcheng area of Inner Mongolia and western Liaoning. The difference in ubiquity of fossil records between northern and southern China is probably related to taphonomical and collecting bias. Records of Early and Late Jurassic palaeontinids are very scarce. The highest diversity of palaeontinid species occurs in the Middle Jurassic of Daohugou Lagerstätte. Early Cretaceous palaeontinids of China are restricted to the typical distribution of Jehol Biota. Palaeontinodes sp. is described from the Lower Cretaceous Yixian Formation of Yangshuwanzi, Inner Mongolia and is the only Palaeontinodes specimen from the Cretaceous. Plachutella exculpta Zhang, 1997 from the Lower Jurassic Badaowan Formation of Karamai, Xinjiang is re-described and some previously reported species of this genus are discussed. [source]

    Phylogenetic Comparative Methods Strengthen Evidence for Reduced Genetic Diversity among Endangered Tetrapods

    evolución de la historia de vida; extinción; heterocigosidad de proteínas; regresión filogenética; tamaño poblacional efectivo Abstract:,The fitness of species with little genetic diversity is expected to be affected by inbreeding and an inability to respond to environmental change. Conservation theory suggests that endangered species will generally demonstrate lower genetic diversity than taxa that are not threatened. This hypothesis has been challenged because the time frame of anthropogenic extinction may be too fast to expect genetic factors to significantly contribute. I conducted a meta-analysis to examine how genetic diversity in 894 tetrapods correlates with extinction threat level. Because species are not evolutionarily independent, I used a phylogenetic regression framework to address this issue. Mean genetic diversity of tetrapods, as assessed by protein heterozygosity, was 29.7,31.5% lower on average in threatened species than in their nonthreatened relatives, a highly significant reduction. Within amphibians as diversity decreased extinction risk increased in phylogenetic models, but not in nonphylogenetic regressions. The effects of threatened status on diversity also remained significant after accounting for body size in mammals. These results support the hypothesis that genetic effects on population fitness are important in the extinction process. Resumen:,Se espera que la adaptabilidad de una especie con poca diversidad genética sea afectada por la endogamia y una incapacidad para responder a cambios ambientales. La teoría de la conservación sugiere que las especies en peligro generalmente muestran menor diversidad genética que taxa que no están amenazados. Esta hipótesis ha sido cuestionada porque el período de tiempo de la extinción antropogénica puede ser muy rápido para esperar que los factores genéticos contribuyan significativamente. Realice un meta-análisis para examinar cómo se correlaciona la diversidad genética de 894 tetrápodos con el nivel de amenaza de extinción. Debido a que las especies no son independientes evolutivamente, utilice un marco de regresión filogenética para abordar este tema. La media de la diversidad genética de tetrápodos, medida como la heterocigosidad de proteínas, fue 29.7,31.5% menor en las especies amenazadas que en sus parientes no amenazados, una reducción altamente significativa. En anfibios, a medida que disminuía la diversidad el riesgo de extinción incrementaba en los modelos filogenéticos, pero no en las regresiones no filogenéticas. El efecto del estatus de amenaza sobre la biodiversidad también permaneció significativo después de considerar el tamaño corporal de mamíferos. Estos resultados dan soporte a la hipótesis de que los efectos genéticos sobre la adaptabilidad de la población son importantes en el proceso de extinción. [source]

    Quantifying Plant Population Persistence in Human-Dominated Landscapes

    Base de Datos de la Diversidad Natural de California; conservación de plantas; crecimiento de la población; especies en peligro; paisajes urbanos Abstract:,We assessed population performance of rare plants across a gradient from rural to urban landscapes and evaluated 2 hypotheses central to strategic conservation planning: (1) population performance declines with increasing human dominance and (2) small populations perform poorly relative to larger ones. Assessing these hypotheses is critical to strategic conservation planning. The current conservation paradigm adheres to the well-established ecology theory that small isolated populations, particularly those in human-dominated landscapes, are the least likely to succeed over the long term. Consequently, conservation planning has strongly favored large, remote targets for protection. This shift in conservation toward ecosystem-based programs and protection of populations within large, remote systems has been at the expense of protection of the rarest of the rare species, the dominant paradigm for conservation driven by the endangered species act. Yet, avoiding conservation of small populations appears to be based more on theoretical understanding and expert opinion than empiricism. We used Natural Heritage data from California in an assessment of population performance of rare plants across a landscape with an urban-rural gradient. Population performance did not decrease in urban settings or for populations that were initially small. Our results are consistent with a pattern of few species extinctions within these landscapes over the past several decades. We conclude that these populations within compromised landscapes can contribute to overall biodiversity conservation. We further argue that conservation planning for biodiversity preservation should allocate relatively more resources to protecting urban-associated plant taxa because they may provide conservation benefit beyond simply protecting isolated populations; they may be useful in building social interest in conservation. Resumen:,Evaluamos el funcionamiento de la población de plantas raras a lo largo de un gradiente de paisajes rurales a urbanos y evaluamos 2 hipótesis centrales para la planificación estratégica de la conservación: (1) declinaciones en el funcionamiento poblacional con el incremento de la dominancia humana y (2) las poblaciones pequeñas funcionan pobremente en relación con las grandes. La evaluación de estas hipótesis es crítica para la planificación estratégica de la conservación. El paradigma actual de la conservación se adhiere a la teoría ecológica bien establecida que propone que las poblaciones pequeñas aisladas, particularmente en paisajes dominados por humanos, tienen menor probabilidad de sobrevivir a largo plazo. Consecuentemente, la planificación de la conservación ha favorecido objetivos grandes y remotos. Este cambio hacia programas de conservación basados en ecosistemas y la protección de poblaciones en sistemas extensos y remotos ha sido a costa de la protección de las especies más raras entre las raras, el paradigma dominante en la conservación conducida por el acta de especies en peligro. No obstante, la evasión de la conservación de poblaciones pequeñas parece estar basada más en entendimiento teórico y en la opinión de expertos que en el empirismo. Utilizamos datos del Patrimonio Natural de California en una evaluación del funcionamiento de plantas raras en un paisaje con un gradiente urbano a rural. El funcionamiento de la población no decreció en sitios urbanos o en poblaciones que eran pequeñas inicialmente. Nuestros resultados son consistentes con un patrón de extinción de especies en estos paisajes en las últimas décadas. Concluimos que estas poblaciones en paisajes comprometidos pueden contribuir a la conservación de la biodiversidad en general. También argumentamos que la planificación de la conservación para la preservación de la biodiversidad debería asignar más recursos para la protección de taxa de plantas asociadas a ambientes urbanos porque pueden proporcionar beneficios de conservación más allá de simplemente proteger poblaciones aisladas; pueden ser útiles para construir el interés social por la conservación. [source]