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Evolutionary Lineages (evolutionary + lineage)
Kinds of Evolutionary Lineages Selected AbstractsEdaphic niche differentiation among Polybotrya ferns in western Amazonia: implications for coexistence and speciationECOGRAPHY, Issue 3 2006Hanna TuomistoArticle first published online: 22 FEB 200 To study the degree of edaphic specialization in Amazonian plants, the distribution patterns of seven species of Polybotrya ferns were studied in 109 sites in a climatically uniform area of northwestern Amazonia (Colombia, Ecuador and northern Peru). The two most abundant species of Polybotrya were found in about two-thirds of the sites with almost 7000 individuals each, the rarest species occurred in just one site with 40 individuals. Each of the seven species appeared to have a unique realised niche, when niche dimensions were defined by gradients in soil texture, soil cation content, and inundation. The species also differed in how broadly or narrowly they were distributed along each gradient. Some species were practically never found in the same sites, whereas others co-occurred with a high frequency, in spite of showing clearly different abundance patterns among sites. A single site only contains a small part of the edaphic variation present in the landscape, and a small proportion of any species' niche space, so broad-scale studies are needed to adequately describe and compare species' niches and to assess to what degree niche differences promote species coexistence. The distribution patterns in Polybotrya are consistent with, but do not prove, that ecological speciation may have been important in the radiation of the genus. If such a pattern is found to be common in other Amazonian plants, this would indicate that each evolutionary lineage has adapted to the available habitats largely independently of the others. [source] SOME PROBLEMS WITH ASSESSING COPE'S RULEEVOLUTION, Issue 8 2008Andrew R. Solow Cope's Rule states that the size of species tends to increase along an evolutionary lineage. A basic statistical framework is elucidated for testing Cope's Rule and some surprising complications are pointed out. If Cope's Rule is formulated in terms of mean size, then it is not invariant to the way in which size is measured. If Cope's Rule is formulated in terms of median size, then it is not invariant to the degree of separation between ancestral and descendant species. Some practical problems in assessing Cope's Rule are also described. These results have implications for the empirical assessment of Cope's Rule. [source] Patchy distribution of flexible genetic elements in bacterial populations mediates robustness to environmental uncertaintyFEMS MICROBIOLOGY ECOLOGY, Issue 3 2008Holger Heuer Abstract The generation and maintenance of genetic variation seems to be a general ecological strategy of bacterial populations. Thereby they gain robustness to irregular environmental change, which is primarily the result of the dynamic evolution of biotic interactions. A benefit of maintaining population heterogeneity is that only a fraction of the population has to bear the cost of not (yet) beneficial deviation. On evolutionary time frames, an added value of the underlying mechanisms is evolvability, i.e. the heritable ability of an evolutionary lineage to generate and maintain genetic variants that are potentially adaptive in the course of evolution. Horizontal gene transfer is an important mechanism that can lead to differences between individuals within bacterial populations. Broad host-range plasmids foster this heterogeneity because they are typically present in only a fraction of the population and provide individual cells with genetic modules newly acquired from other populations or species. We postulate that the benefit of robustness on population level could balance the cost of transfer and replication functions that plasmids impose on their hosts. Consequently, mechanisms that make a subpopulation conducive to specific conjugative plasmids may have evolved, which could explain the persistence of even cryptic plasmids that do not encode any traits. [source] ON THE IDENTITY OF KARLODINIUM VENEFICUM AND DESCRIPTION OF KARLODINIUM ARMIGER SP.JOURNAL OF PHYCOLOGY, Issue 1 2006AND PIGMENT COMPOSITION, BASED ON LIGHT AND ELECTRON MICROSCOPY, NOV. (DINOPHYCEAE), NUCLEAR-ENCODED LSU RDNA An undescribed species of the dinoflagellate genus Karlodinium J. Larsen (viz. K. armiger sp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species of Karlodinium (K. micrum (Leadbeater et Dodge) J. Larsen) by lacking rows of amphiesmal plugs, a feature presently considered to be a characteristic of Karlodinium. In K. armiger, an outer membrane is underlain by a complex system of cisternae and vacuoles. The pigment profile of K. armiger revealed the presence of chlorophylls a and c, with fucoxanthin as the major carotenoid. Phylogenetic analysis confirmed K. armiger to be related to other species of Karlodinium; thus forming a monophyletic genus, which, in the LSU tree, occupies a sister group position to Takayama de Salas, Bolch, Botes et Hallegraeff. The culture used by Ballantine to describe Gymnodinium veneficum Ballantine (Plymouth 103) was examined by light and electron microscopy and by partial LSU rDNA. Ultrastructurally, it proved identical to K. micrum (cultures Plymouth 207 and K. Tangen KT-77D, the latter also known as K-0522), and in LSU sequence, differed in only 0.3% of 1438 bp. We consider the two taxa to belong to the same species. This necessitates a change of name for the most widely found species, K. micrum, to K. veneficum. The three genera Karlodinium, Takayama, and Karenia constitute a separate evolutionary lineage, for which the new family Kareniaceae fam. nov. is suggested. [source] Population structure and history of southern African scrub hares, Lepus saxatilisJOURNAL OF ZOOLOGY, Issue 2 2004U. Kryger Abstract Genetic differentiation among populations of the South African scrub hare Lepus saxatilis was examined using hypervariable mitochondrial DNA control region I (CR-I) sequences. Neighbour-joining analysis revealed a pattern that did not correspond to the current subspecies delineations. The CR-I sequence data delimit scrub hares into three major maternal lineages. The three phylogenetic assemblages exhibited different geographical distributions. AMOVA analyses and exact tests for population differentiation confirmed this phylogeographic partitioning. One lineage (SW) was confined to the south-western Cape, the second lineage (N) was exclusively found in the northern part of South Africa and in the neighbouring countries, and the third lineage (C) was predominant in the central parts of South Africa. This spatial distribution did not coincide with the ranges of the 10 described subspecies covered by our sampling regime. The lineages C and N overlapped in an area including eastern parts of South Africa and southern Namibia. The presence of both lineages in that area of overlap was interpreted as the result of secondary contact due to recent range expansions after the two lineages had undergone a population restriction approximately 18 000 years ago. Analyses of contemporary gene flow disclosed an exchange of migrants between N and C, which was biased towards a movement from C to N. The SW group represents a very distinct evolutionary lineage that has been isolated for more than 45 000 years. It does not exchange female migrants with the other two groups. Mismatch distribution analyses indicated sudden population size expansions in the history of all three populations. [source] Evolutionary genetics and biogeographic structure of Rhizobium gallicum sensu lato, a widely distributed bacterial symbiont of diverse legumesMOLECULAR ECOLOGY, Issue 13 2005CLAUDIA SILVA Abstract We used phylogenetic and population genetics approaches to evaluate the importance of the evolutionary forces on shaping the genetic structure of Rhizobium gallicum and related species. We analysed 54 strains from several populations distributed in the Northern Hemisphere, using nucleotide sequences of three ,core' chromosomal genes (rrs, glnII and atpD) and two ,auxiliary' symbiotic genes (nifH and nodB) to elucidate the biogeographic history of the species and symbiotic ecotypes (biovarieties) within species. The analyses revealed that strains classified as Rhizobium mongolense and Rhizobium yanglingense belong to the chromosomal evolutionary lineage of R. gallicum and harbour symbiotic genes corresponding to a new biovar; we propose their reclassification as R. gallicum bv. orientale. The comparison of the chromosomal and symbiotic genes revealed evidence of lateral transfer of symbiotic information within and across species. Genetic differentiation analyses based on the chromosomal protein-coding genes revealed a biogeographic pattern with three main populations, whereas the 16S rDNA sequences did not resolve that biogeographic pattern. Both the phylogenetic and population genetic analyses showed evidence of recombination at the rrs locus. We discuss our results in the light of the contrasting views of bacterial species expressed by microbial taxonomist and evolutionary biologists. [source] Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitatsPLANT CELL & ENVIRONMENT, Issue 12 2001J. Cavender-Bares Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source] Gene trees: A powerful tool for exploring the evolutionary biology of species and speciationPLANT SPECIES BIOLOGY, Issue 3 2000Alan R. Templeton Abstract Evolutionary trees can be constructed from the haplotypes observed with molecular surveys of sequence or restriction site variation. Such gene trees can be constructed regardless of whether or not all of the individual specimens came from one or many species. Hence, these gene trees can straddle the species/population interface, thereby providing a powerful tool for studying the meaning of species and the process of speciation. We illustrate how historical approaches using gene trees can be used to separate the effects of population structure from population history, in order to rigorously test the species status of a group, and to test hypotheses about the process of speciation. A worked example of species status in the Piriqueta caroliniana complex is presented. Species status is evaluated under the cohesion species concept that defines a species as an evolutionary lineage with boundaries arising from the forces that create reproductive communities. Such forces are collectively called cohesion mechanisms and consist of two main subtypes: (i) genetic exchangeability, and (ii) ecological interchangeability. To make this definition operational, populations that behave as separate evolutionary lineages are first identified. A method is reviewed for inferring lineages using explicit statistical criteria from geographic overlays upon gene trees. Once lineages have been identified, the next step is to use the cohesion mechanisms to identify candidate traits that should contribute to genetic exchangeability and/or ecological interchangeability. The cohesion species are then identified by performing overlays upon gene trees in order to identify significant transitions in the candidate traits. Cohesion species are recognized only when statistically significant reproductive/ecological transitions occur that are concordant with the lineages defined earlier. This data-rich method of recognizing species automatically generates much information about the biogeography, population structure, historical events, and ecology and/or reproductive biology of the group under study. In turn, this information provides much insight into the process of speciation. It also makes the criteria, data, methods of analysis and degree of support for the species inference completely explicit, thereby avoiding confusion, inconsistency and artificial controversies that plague much of the literature on species concepts. [source] A STATISTICAL TEST OF UNBIASED EVOLUTION OF BODY SIZE IN BIRDSEVOLUTION, Issue 12 2002Folmer Bokma Abstract., Of the approximately 9500 bird species, the vast majority is small-bodied. That is a general feature of evolutionary lineages, also observed for instance in mammals and plants. The avian interspecific body size distribution is right-skewed even on a logarithmic scale. That has previously been interpreted as evidence that body size evolution has been biased. However, a procedure to test for unbiased evolution from the shape of body size distributions was lacking. In the present paper unbiased body size evolution is defined precisely, and a statistical test is developed based on Monte Carlo simulation of unbiased evolution. Application of the test to birds suggests that it is highly unlikely that avian body size evolution has been unbiased as defined. Several possible explanations for this result are discussed. A plausible explanation is that the general model of unbiased evolution assumes that population size and generation time do not affect the evolutionary variability of body size; that is, that micro- and macroevolution are decoupled, which theory suggests is not likely to be the case. [source] Characterization of the Hox gene cluster in the malaria vector mosquito, Anopheles gambiaeEVOLUTION AND DEVELOPMENT, Issue 6 2000Martin P. Devenport SUMMARY The Hox genes play a central role in regulating development and are involved in the specification of cell fates along the anteroposterior axis. In insects and vertebrates, these genes are clustered and organized in an arrangement that is largely conserved across evolutionary lineages. By exploiting the sequence conservation of the homeobox, orthologues of the Hox genes Sex combs reduced (Scr ,), fushi tarazu (ftz,), Antennapedia (Antp), Ultrabithorax (Ubx,), and abdominal-A (abd-A) have been isolated from the malaria vector mosquito, Anopheles gambiae. These genes were first identified in Drosophila, where they achieve a high level of functional complexity, in part, by the use of alternative promoters, polyadenylation sites, and splicing to generate different protein isoforms. Preliminary analyses of the Anopheles Hox genes suggest that they do not achieve their functional complexity in the same manner. Using a combination of in situ hybridization to polytene chromosomes and chromosome walking, the Anopheles Hox genes have been localized to a single cluster in the region 19D,E on chromosome 2R, a situation distinct from that of Drosophila where the Hox complex is split into two clusters. This study, therefore, provides a framework for future comparative analyses of the structure, organization, and expression of developmental regulatory genes between the lower and higher Diptera. Moreover, the genes that have been isolated enhance the genetic and physical maps of chromosome 2R in this medically important mosquito species. [source] Shuffling genes around in hot environments: the unique DNA transporter of Thermus thermophilusFEMS MICROBIOLOGY REVIEWS, Issue 3 2009Beate Averhoff Abstract Natural transformation permits the transport of DNA through bacterial membranes and represents a dominant mode for the transfer of genetic information between bacteria and between microorganisms of distant evolutionary lineages and even between members of different domains. This phenomenon, known as horizontal, or lateral, gene transfer, has been a major force for genome plasticity over evolutionary history, and is largely responsible for the spread of fitness-enhancing traits, including antibiotic resistance and virulence factors. In particular, for adaptation of prokaryotes to extreme environments, lateral gene transfer seems to have played a crucial role. Here, we present a survey of the natural transformation machinery of the thermophile Thermus thermophilus HB27. A tentative model of the transformation machinery comprising of components similar to proteins of type IV pili and type II secretion systems is presented. A comparative discussion of the subunits and the structure of the DNA translocator and the underlying mechanism of transfer of free DNA in T. thermophilus highlights conserved and unique features of the DNA translocator in T. thermophilus. We hypothesize that the extraordinary broad substrate specificity and the high efficiency of the T. thermophilus DNA uptake system is of major importance for thermoadaptation and interdomain DNA transfer in hot environments. [source] Molecular phylogenetic analysis of the white-crowned forktail Enicurus leschenaulti in BorneoJOURNAL OF AVIAN BIOLOGY, Issue 2 2005Robert G. Moyle Comparison of 1017 nucleotides of mitochondrial ND2 and ND3 DNA sequences of 26 individuals of white-crowned forktail Enicurus leschenaulti from SE Asia revealed multiple evolutionary lineages within Borneo. Montane birds were genetically homogeneous across localities, but diverged by more than 4.3% from all other samples. Lowland birds formed two distinct clades, one consisting of individuals from northern Borneo, and the other including individuals from western Borneo, as well as Sumatra and Malaya. Relationships among the subspecies were not well resolved. These findings indicate another example of montane and north Bornean endemicity, support the separation of the montane and lowland species, and define areas of conservation interest. [source] Phylogeography of Pulsatilla vernalis (L.) Mill. (Ranunculaceae): chloroplast DNA reveals two evolutionary lineages across central Europe and ScandinaviaJOURNAL OF BIOGEOGRAPHY, Issue 9 2008Micha, Ronikier Abstract Aim, The aim of this study was to test hypotheses regarding some of the main phylogeographical patterns proposed for European plants, in particular the locations of glacial refugia, the post-glacial colonization routes, and genetic affinities between southern (alpine) and northern (boreal) populations. Location, The mountains of Europe (Alps, Balkans, Carpathians, Central Massif, Pyrenees, Scandinavian chain, Sudetes), and central European/southern Scandinavian lowlands. Methods, As our model system we used Pulsatilla vernalis, a widely distributed European herbaceous plant occurring both in the high-mountain environments of the Alps and other European ranges and in lowlands north of these ranges up to Scandinavia. Based on a distribution-wide sampling of 61 populations, we estimated chloroplast DNA (cpDNA) variation along six regions using polymerase chain reaction,restriction fragment-length polymorphisms (PCR,RFLPs) (trnH,trnK, trnK,trnK, trnC,trnD, psbC,trnS, psaA,trnS, trnL,trnF) and further sequencing of trnL,trnF and trnH,psbA. In addition, 11 samples of other European species of Pulsatilla were sequenced to survey the genus-scale cpDNA variation. Results, Eleven PCR,RFLP polymorphisms were detected in P. vernalis, revealing seven haplotypes. They formed two distinct genetic groups. Three haplotypes representing both groups dominated and were widely distributed across Europe, whereas the others were restricted to localized regions (central Alps, Tatras/Sudetes mountains) or single populations. Sequencing analysis confirmed the reliability of PCR,RFLPs and homology of haplotypes across their distribution. The chloroplast DNA variation across the section Pulsatilla was low, but P. vernalis did not share haplotypes with other species. Main conclusions, The genetic distinctiveness of P. vernalis populations from the south-western Alps with respect to other Alpine populations, as well as the affinities between the former populations and those from the eastern Pyrenees, is demonstrated, thus providing support for the conclusions of previous studies. Glacial refugia in the Dolomites are also suggested. Isolation is inferred for the high-mountain populations from the Tatras and Sudetes; this is in contrast to the case for the Balkans, which harboured the common haplotype. Specific microsatellite variation indicates the occurrence of periglacial lowland refugia north of the Alps, acting as a source for the post-glacial colonization of Scandinavia. The presence of different fixed haplotypes in eastern and western Scandinavia, however, suggests independent post-glacial colonization of these two areas, with possible founder effects. [source] Remarkably low mtDNA control-region diversity and shallow population structure in Pacific cod Gadus macrocephalusJOURNAL OF FISH BIOLOGY, Issue 5 2010M. Liu To investigate the genetic diversity and describe the population structure in Gadus macrocephalus, a 452 base pair (bp) fragment of the mitochondrial DNA control region was analysed in 259 individuals. The results showed remarkably low nucleotide diversity and a lack of genealogical structure. Small but significant genetic differentiations, however, were detected among north-western Pacific populations, but no large-scale regional differences were detected. These results indicate that populations of G. macrocephalus in the north-western Pacific are genetically subdivided and represent evolutionary lineages that should be managed individually. [source] Polymorphisms in the sequences of Marteilia internal transcribed spacer region of the ribosomal RNA genes (ITS-1) in Spain: genetic types are not related with bivalve hostsJOURNAL OF FISH DISEASES, Issue 6 2005B Novoa Abstract Marteilia refringens is a protozoan parasite causing a disease notifiable to the Office International des Epizooties (OIE) and its distribution has implications for the transfer of live animals. The internal transcribed spacer-1 (ITS-1) from Marteilia clones contains polymorphism. Digestion with HhaI reveals two different restriction profiles, previously referred as ,O' (Marteilia from oyster or Marteilia refringens) and ,M' (Marteilia from mussels or Marteilia maurini). The aim of the present work was to determine whether the two previously described Marteilia molecular types (O and M) exist in the Iberian Peninsula and the strictness of the association with their bivalve host species. The sequence variability in the ITS-1 of Marteilia species was studied in mussels, Mytilus galloprovincialis, and flat oysters, Ostrea edulis, from different geographical locations in Spain, to establish the existence and the distribution of different species or molecular types. Although there were two distinct evolutionary lineages that corresponded more or less strictly with the ,M' and ,O' types, it was evident from the estimated phylogeny that some ,O' types have switched to ,M' type, and vice versa. Moreover, ,O' types were found in mussels and ,M' types were found in oysters, which suggests that there have been several cross-species transmissions of Marteilia between mussels and oysters. [source] UNIVERSAL PRIMERS AMPLIFY A 23S rDNA PLASTID MARKER IN EUKARYOTIC ALGAE AND CYANOBACTERIA,JOURNAL OF PHYCOLOGY, Issue 3 2007Alison R. Sherwood The challenge in the development of universal algal primers lies in the genetic diversity contained within the vast array of evolutionary lineages present in this informally named group of organisms. A comparative genomics approach was used previously to identify conserved primers flanking a region of the plastid genome. Our present research illustrates the feasibility of amplifying and sequencing this marker across multiple algal lineages. We present a preliminary framework of 107 novel sequences of this region from 62 red algae, 19 green algae, 14 brown algae, 8 cyanobacteria, 2 diatoms, 1 xanthophyte, and 1 euglenoid, and illustrate levels of divergence of the marker for well-represented groups in a neighbor-joining analysis. This ,410 nt region distinguishes most species included in the analysis. The remarkable universality of these primers suggests potential for their use in assays of environmental samples in which they could be used to simultaneously detect a number of different algal lineages. [source] 145 Preliminary Results of Cytoskeletal Components in Various Red Algae Using Confocal Laser Scanning MicroscopyJOURNAL OF PHYCOLOGY, Issue 2003W. E. Schmidt Data concerning the cytoskeletal components of red algae are scant. The goal of this ongoing comparative survey is to develop a more complete characterization of the red algal cytoskeleton, and subsequent elucidation of its function, using representative taxa belonging to major evolutionary lineages within the Rhodophyta. Preliminary data were obtained using enzyme digestion of cell walls and detergent rinses with direct (phalloidin) and indirect (monoclonal antibodies) labeling methods for microfilaments and tubulin, respectively. Samples were viewed using confocal laser scanning microscopy. Results will be discussed in light of the more thoroughly understood cytoskeletal system reported for green algae. [source] Geographical patterns of mitochondrial DNA variation in Apis mellifera iberiensis (Hymenoptera: Apidae)JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1 2008F. Cánovas Abstract An extensive survey of mitochondrial haplotypes in honeybee colonies from the Iberian Peninsula has corroborated previous hypotheses about the existence of a joint clinal variation of African (A) and west European (M) evolutionary lineages. It has been found that the Iberian Peninsula is the European region with the highest haplotype diversity (12 haplotypes detected of the M lineage and 10 of the A lineage). The frequency of A haplotypes decreases in a SW-NE trend, while that of M haplotypes increases. These results are discussed in relation to hypotheses about the African origin of Apis mellifera and an early colonization of west Europe during intermediate Pleistocene glaciation events, followed by a regional differentiation. The extant pattern of haplotype frequency and distribution seems to be influenced at a regional scale by adaptation to local climatic conditions and the mobile beekeeping that has become a large-scale practice during the last decades. Other previous anthropogenic influences (Greek, Roman and Arab colonizations) are thought to be of minor importance in present day populations. Resumen Un extenso estudio de los haplotipos mitocondriales en colonias de la abeja doméstica de la Péninsula Ibérica ha corroborado las hipótesis previas acerca de la existencia de una variación clinal conjunta de los linajes evolutivos africano (A) y europeo occidental (M). Se ha encontrado que la Peninsula Ibérica es la región europea con la mayor diversidad (12 haplotipos detectados pertenecientes al linaje M y 10 al linaje A). La frecuencia de los haplotipos africanos disminuye en la orientación SW-NE, al tiempo que aumenta proporcionalmente la de los M. Estos resultados se analizan en relación a las hipótesis recientes que ubican el origen de Apis mellifera en África, junto con otras que postulan una colonización temprana de esta especie en Europa occidental, seguida de una diferenciación durante el Pleistoceno. El patrón geográfico actual de haplotipos y frecuencias a escala regional, parece estar influido por la adaptación a las condiciones climáticas locales y la trashumancia, práctica que ha adquirido grandes proporciones en las últimas décadas. Otras influencias antrópicas acontecidas como las colonizaciones de griegos, romanos y árabes han tenido posiblemente poca influencia sobre las poblaciones ibéricas actuales. [source] A geometric morphometric analysis of the shape of the first upper molar in mice of the genus Mus (Muridae, Rodentia)JOURNAL OF ZOOLOGY, Issue 4 2006M. Macholán Abstract Phenotypic variation in the shape of the first upper molar among 595 mice, representing nine extant and three extinct taxa of the genus Mus, was studied with thin-plate spline analysis. The reliability of classification of individual specimens into known groups based on their molars varied from 75 to 100%, depending on group and method used. Including 13 sliding semilandmarks to the analysis improved the detection of different kinds of size and shape variation as well as visualization of shape differences between studied groups. Correlation between phylogenetic and morphometric distances suggested about 80% contribution of phylogenetic inertia to the molar shape variation; moreover, the importance of localized versus global shape changes was similar in the detection of phylogenetic signals. Finally, shape changes along individual evolutionary lineages were revealed, suggesting a few cases of reversals, convergence and/or retention of ancestral shape. The evolution of mouse molars has thus been driven by random effects of drift together with stabilizing selection and convergence. [source] The species delimitation problem in the Simulium damnosum complex, blackfly vectors of onchocerciasisMEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2009R. MORALES-HOJAS Abstract. The Simulium damnosum Theobald complex (Diptera: Simuliidae) comprises 57 cytoforms grouped into six subcomplexes. Previous phylogenetic studies using gene sequences have not completely resolved the evolutionary relationships of the cytoforms. The present study investigated the systematics of the complex using a phylogeographic approach. The differentiation between eastern and western forms observed in the phylogenetic studies is confirmed in the estimated haplotype networks. However, haplotypes tend to group in geographical clades and not according to cytoforms. Spatial analyses of the molecular variance also resulted in optimal groupings of sequences that did not correspond to cytoform boundaries. Moreover, Mantel tests showed significant correlations, although not strong, between genetic and geographical distances. This suggests an isolation-by-distance model of differentiation. Furthermore, there are instances in which genetic differentiation between cytoforms is low and not significant. These results indicate a lack of clear genetic differentiation between the cytoforms, which may be explained either by a separation of the taxa recent enough to allow the accumulation of few genetic differences or by recombination between the genomes of the cytoforms, which may be the result of hybridization with introgression or of non-independent evolutionary lineages. The results also emphasize the need for further sampling and for the use of more variable markers in order to clarify the evolutionary history of the group. [source] The divergence of two independent lineages of an endemic Chinese gecko, Gekko swinhonis, launched by the Qinling orogenic beltMOLECULAR ECOLOGY, Issue 12 2010JIE YAN Abstract The genetic structure and demographic history of an endemic Chinese gecko, Gekko swinhonis, were investigated by analysing the mitochondrial cytochrome b gene and 10 microsatellite loci for samples collected from 27 localities. Mitochondrial DNA data provided a detailed distribution of two highly divergent evolutionary lineages, between which the average pairwise distance achieved was 0.14. The geographic division of the two lineages coincided with a plate boundary consisting of the Qinling and Taihang Mts, suggesting a historical vicariant pattern. The orogeny of the Qinling Mts, a dispersal and major climatic barrier of the region, may have launched the independent lineage divergence. Both lineages have experienced recent expansion, and the current sympatric localities comprised the region of contact between the lineages. Individual-based phylogenetic analyses of nucDNA and Bayesian-clustering approaches revealed a deep genetic structure analogous to mtDNA. Incongruence between nucDNA and mtDNA at the individual level at localities outside of the contact region can be explained by the different inheritance patterns and male-biased dispersal in this species. High genetic divergence, long-term isolation and ecological adaptation, as well as the morphological differences, suggest the presence of a cryptic species. [source] Phylogenetic similarity and structure of Agaricomycotina communities across a forested landscapeMOLECULAR ECOLOGY, Issue 7 2010IVAN P. EDWARDS Abstract The Agaricomycotina are a phylogenetically diverse group of fungi that includes both saprotrophic and mycorrhizal species, and that form species , rich communities in forest ecosystems. Most species are infrequently observed, and this hampers assessment of the role that environmental heterogeneity plays in determining local community composition and in driving ,-diversity. We used a combination of phenetic (TRFLP) and phylogenetic approaches [Unifrac and Net Relatedness Index (NRI)] to examine the compositional and phylogenetic similarity of Agaricomycotina communities in forest floor and surface soil of three widely distributed temperate upland forest ecosystems (one, xeric oak , dominated and two, mesic sugar maple dominated). Generally, forest floor and soil communities had similar phylogenetic diversity, but there was little overlap of species or evolutionary lineages between these two horizons. Forest floor communities were dominated by saprotrophic species, and were compositionally and phylogenetically similar in all three ecosystems. Mycorrhizal species represented 30% to 90% of soil community diversity, and these communities differed compositionally and phylogenetically between ecosystems. Estimates of NRI revealed significant phylogenetic clustering in both the forest floor and soil communities of only the xeric oak-dominated forest ecosystem, and may indicate that this ecosystem acts as a habitat filter. Our results suggest that environmental heterogeneity strongly influences the phylogenetic ,-diversity of soil inhabiting Agaricomycotina communities, but has only a small influence on forest floor ,-diversity. Moreover, our results suggest that the strength of community assembly processes, such as habitat filtering, may differ between temperate forest ecosystems. [source] Evolutionary history of lamprey paired species Lampetra fluviatilis (L.) and Lampetra planeri (Bloch) as inferred from mitochondrial DNA variationMOLECULAR ECOLOGY, Issue 9 2007RUTE ESPANHOL Abstract A remarkable trend in the evolution of lampreys is the occurrence in most genera of ,paired species', in which the parasitic anadromous lampreys are believed to have given rise to nonparasitic freshwater resident populations. The present work examines the phylogeography of the European paired species Lampetra fluviatilis and Lampetra planeri, in an attempt to elucidate species pair evolutionary history. We studied sequence variation in cytochrome b and ATPase 6, 8 mitochondrial genes in 63 individuals from 21 localities of the paired species throughout their distribution range. Results from the phylogenetic and nested clade analyses were largely consistent, suggesting the existence of three major evolutionary lineages: lineage I and possibly lineage II are widespread throughout Europe, while the most ancestral lineage III is apparently restricted to the Iberian Peninsula. The high genetic diversity observed in the Iberian Peninsula is probably the result of refugial persistence and subsequent accumulation of variation over several ice ages, whereas the low levels of genetic diversity observed in central and northern Europe should reflect a rapid postglacial colonization. Results suggest that L. planeri originated within at least two distinct evolutionary lineages, rejecting the single origin hypothesis. The observed lack of taxa monophyly within lineage I may be the result of ongoing gene flow if the two taxa are alternate life-history forms of a single species. However, structure within lineage I is also consistent with the hypothesis of divergence of taxa after postglacial dispersion (around 2000 generations ago) with incomplete lineage sorting. Further testing of the alternative hypotheses is warranted. [source] Evolutionary history of the European whitefish Coregonus lavaretus (L.) species complex as inferred from mtDNA phylogeography and gill-raker numbersMOLECULAR ECOLOGY, Issue 14 2005K. ØSTBYE Abstract We compared mitochondrial DNA and gill-raker number variation in populations of the European whitefish Coregonus lavaretus (L.) species complex to illuminate their evolutionary history, and discuss mechanisms behind diversification. Using single-strand conformation polymorphism (SSCP) and sequencing 528 bp of combined parts of the cytochrome oxidase b (cyt b) and NADH dehydrogenase subunit 3 (ND3) mithochondrial DNA (mtDNA) regions, we documented phylogeographic relationships among populations and phylogeny of mtDNA haplotypes. Demographic events behind geographical distribution of haplotypes were inferred using nested clade analysis (NCA) and mismatch distribution. Concordance between operational taxonomical groups, based on gill-raker numbers, and mtDNA patterns was tested. Three major mtDNA clades were resolved in Europe: a North European clade from northwest Russia to Denmark, a Siberian clade from the Arctic Sea to southwest Norway, and a South European clade from Denmark to the European Alps, reflecting occupation in different glacial refugia. Demographic events inferred from NCA were isolation by distance, range expansion, and fragmentation. Mismatch analysis suggested that clades which colonized Fennoscandia and the Alps expanded in population size 24 500,5800 years before present, with minute female effective population sizes, implying small founder populations during colonization. Gill-raker counts did not commensurate with hierarchical mtDNA clades, and poorly with haplotypes, suggesting recent origin of gill-raker variation. Whitefish designations based on gill-raker numbers were not associated with ancient clades. Lack of congruence in morphology and evolutionary lineages implies that the taxonomy of this species complex should be reconsidered. [source] Mitochondrial gene diversity in the common vole Microtus arvalis shaped by historical divergence and local adaptationsMOLECULAR ECOLOGY, Issue 11 2004SABINE FINK Abstract The phylogeography of the common vole (Microtus arvalis) was examined by analysing mitochondrial DNA (mtDNA) sequence variation in 1044 base pairs (bp) of the cytochrome b (cytb) gene and in 322 bp of the control region (ctr) among 106 individuals from 58 locations. The geographical distribution of four previously recognized cytb evolutionary lineages in Europe was refined and a new lineage was found in southern Germany. All lineages were distributed allopatrically, except in one sample that was probably located in a contact zone. The occurrence of several lineages in the Alps is in keeping with their recent recolonization from distinct sources. The translation of 84 cytb DNA sequences produced 33 distinct proteins with relationships that differed from those of the DNA haplotypes, suggesting that the mtDNA lineages did not diverge in response to selection. In comparison with M. agrestis, a neutrality test detected no overall evidence for selection in the cytb gene, but a closer examination of a structural model showed that evolutionarily conserved and functionally important positions were often affected. A new phylogeographical test of random accumulation of nonsynonymous mutations generated significant results in three lineages. We therefore conclude that the molecular diversity of cytb in M. arvalis is overall the result of the demographic history of the populations, but that there have been several episodes of local adaptation to peculiar environments. [source] Five hundred and fifty microsatellite markers for the study of the honeybee (Apis mellifera L.) genomeMOLECULAR ECOLOGY RESOURCES, Issue 2 2003Michel Solignac Summary Microsatellites are currently considered the most useful genetic markers with wide applications in genomics, quantitative and population genetics. We present here the structure of the core sequence of 552 microsatellites, together with the sequences of the primers and the length of the sequenced allele. These microsatellites were isolated from several libraries constructed from either fractions of total genomic DNA or from clones of a bacterial artificial chromosome (BAC) library. All 552 loci are polymorphic in the honeybee. Many of them were also successfully amplified in three other species of Apis: A. cerana (58%), A. dorsata (59%) and A. florea (38%). A summary of the variability of 36 loci in the three main evolutionary lineages of A. mellifera is given. [source] Evolutionary consequences of autopolyploidyNEW PHYTOLOGIST, Issue 1 2010Christian Parisod Summary Autopolyploidy is more common in plants than traditionally assumed, but has received little attention compared with allopolyploidy. Hence, the advantages and disadvantages of genome doubling per se compared with genome doubling coupled with hybridizations in allopolyploids remain unclear. Autopolyploids are characterized by genomic redundancy and polysomic inheritance, increasing effective population size. To shed light on the evolutionary consequences of autopolyploidy, we review a broad range of studies focusing on both synthetic and natural autopolyploids encompassing levels of biological organization from genes to evolutionary lineages. The limited evidence currently available suggests that autopolyploids neither experience strong genome restructuring nor wide reorganization of gene expression during the first generations following genome doubling, but that these processes may become more important in the longer term. Biogeographic and ecological surveys point to an association between the formation of autopolyploid lineages and environmental change. We thus hypothesize that polysomic inheritance may provide a short-term evolutionary advantage for autopolyploids compared to diploid relatives when environmental change enforces range shifts. In addition, autopolyploids should possess increased genome flexibility, allowing them to adapt and persist across heterogeneous landscapes in the long run. [source] Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitatsPLANT CELL & ENVIRONMENT, Issue 12 2001J. Cavender-Bares Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source] Gene trees: A powerful tool for exploring the evolutionary biology of species and speciationPLANT SPECIES BIOLOGY, Issue 3 2000Alan R. Templeton Abstract Evolutionary trees can be constructed from the haplotypes observed with molecular surveys of sequence or restriction site variation. Such gene trees can be constructed regardless of whether or not all of the individual specimens came from one or many species. Hence, these gene trees can straddle the species/population interface, thereby providing a powerful tool for studying the meaning of species and the process of speciation. We illustrate how historical approaches using gene trees can be used to separate the effects of population structure from population history, in order to rigorously test the species status of a group, and to test hypotheses about the process of speciation. A worked example of species status in the Piriqueta caroliniana complex is presented. Species status is evaluated under the cohesion species concept that defines a species as an evolutionary lineage with boundaries arising from the forces that create reproductive communities. Such forces are collectively called cohesion mechanisms and consist of two main subtypes: (i) genetic exchangeability, and (ii) ecological interchangeability. To make this definition operational, populations that behave as separate evolutionary lineages are first identified. A method is reviewed for inferring lineages using explicit statistical criteria from geographic overlays upon gene trees. Once lineages have been identified, the next step is to use the cohesion mechanisms to identify candidate traits that should contribute to genetic exchangeability and/or ecological interchangeability. The cohesion species are then identified by performing overlays upon gene trees in order to identify significant transitions in the candidate traits. Cohesion species are recognized only when statistically significant reproductive/ecological transitions occur that are concordant with the lineages defined earlier. This data-rich method of recognizing species automatically generates much information about the biogeography, population structure, historical events, and ecology and/or reproductive biology of the group under study. In turn, this information provides much insight into the process of speciation. It also makes the criteria, data, methods of analysis and degree of support for the species inference completely explicit, thereby avoiding confusion, inconsistency and artificial controversies that plague much of the literature on species concepts. [source] Correlates of body mass evolution in primatesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2006Christophe Soligo Abstract Body mass is undoubtedly central to the overall adaptive profile of any organism. Despite this, very little is known of what forces drive evolutionary changes in body mass and, consequently, shape patterns of body mass distribution exhibited by animal radiations. The search for factors that may influence evolutionary processes in general frequently focuses on environmental parameters such as climate change or interspecific competition. With respect to body mass, there is also the suggestion that evolutionary lineages may follow an inherent trend toward increased body mass, known as Cope's rule. The present paper investigates whether overall directional trends of body mass change, or correlations between patterns of body mass evolution and environmental factors have influenced the evolution of body mass in plesiadapiforms and primates. Analyses of the global fossil record of plesiadapiforms and primates suggest that the former did indeed follow an overall trend toward increased body mass compatible with the predictions of Cope's rule. In contrast, neither primates as a whole, nor a number of individual primate radiations (Adapiformes, Omomyiformes, and Anthropoidea), show any indication of overall directional patterns of body mass change. No correlations of primate body mass change with either the latitudinal distribution of fossil species, or with estimates of global temperature trends, were found. There is evidence, however, that direct competition between omomyiforms and adapiforms (the two main primate radiations known from the Paleogene) influenced processes of body mass evolution in omomyiforms. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source] |