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Character States (character + states)
Kinds of Character States Selected AbstractsEXHAUSTION OF MORPHOLOGIC CHARACTER STATES AMONG FOSSIL TAXAEVOLUTION, Issue 2 2000Peter 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] Notes on two species of the subgenus Lyrothorax Chaudoir (Coleoptera: Carabidae; genus Pterostichus), Pterostichus amagisanus Tanaka and Ishida and Pterostichus fujitai Tanaka and IshidaENTOMOLOGICAL SCIENCE, Issue 2 2009Kôji SASAKAWA Abstract Two species of the subgenus Lyrothorax Chaudoir (Coleoptera: Carabidae; genus Pterostichus), Pterostichus amagisanus Tanaka and Ishida and Pterostichus fujitai Tanaka and Ishida, were revised based on the male endophallus (inner sac everted from aedeagus). P. amagisanus was newly recorded based on a single male from Kyushu, southwest Japan, far from its known distribution (Honshu; the Fuji-Hakone-Izu volcano area), although additional materials are necessary to confirm this record. Despite a highly disjunct distribution, no conspicuous difference was recognized in either external or genital characters between the materials from Honshu and Kyushu. The nominal species P. fujitai was separated into two species, P. fujitai (Honshu) and Pterostichus eoyoritomus sp. nov. (Shikoku; type locality: Mount Jingayama); these two species have some significant differences in the endophallic structures. Character states in male genitalia suggest a sister relationship between P. eoyoritomus sp. nov. and Pterostichus yoritomus Bates. [source] Spermiogenesis and spermatozoal ultrastructure in Trichomycteridae (Teleostei: Ostariophysi: Siluriformes)ACTA ZOOLOGICA, Issue 4 2010Maria Angélica Spadella Abstract Spadella, M.A., Oliveira, C. and Quagio-Grassiotto, I. 2009. Spermiogenesis and spermatozoal ultrastructure in Trichomycteridae (Teleostei: Ostariophysi: Siluriformes). ,Acta Zoologica (Stockholm) 91: 373,389. Siluriformes comprises the most diverse and widely distributed ostariophysan group, a fish assemblage that includes about three quarters of the freshwater fish of the world. In this study, the ultrastructural characterization of spermiogenesis and spermatozoa in specimens of Copionodontinae (the sister group to all other trichomycterids), Trichomycterinae (a derived trichomycterid group), and Ituglanis (a genus not assigned to any trichomycterid subfamily) is presented. The comparative analyses of the data show that trichomycterid species share six of seven analyzed spermiogenesis characters, reinforcing the monophyly of the group. Analyses of trichomycterid sperm ultrastructure showed that the species studied share the same character states for nine of seventeen characters analyzed. Copionodon orthiocarinatus and Ituglanis amazonicus each share more ultrastructural characters with species of Trichomycterus than with one another. Regarding the families of Loricarioidea, the species of Trichomycteridae share more characters of spermatogenesis, spermiogenesis, and sperm with representatives of the families Callichthyidae, Loricariidae, and Scoloplacidae than with Nematogenyidae, its hypothesized sister group. With the exception of the family Nematogenyidae, the character similarities observed reinforce the monophyly of the superfamily Loricarioidea. [source] An investigation of the cranial evolution of Asian pitvipers (Serpentes: Crotalinae), with comments on the phylogenetic position of Peltopelor macrolepisACTA ZOOLOGICA, Issue 4 2010Peng Guo Abstract Guo, P., Jadin, R.C., Malhotra, A. and Li, C. 2009. An investigation of the cranial evolution of Asian pitvipers (Serpentes: Crotalinae), with comments on the phylogenetic position of Peltopelor macrolepis,Acta Zoologica (Stockholm) 91: 402,407. We investigated the evolution of 12 cranial characters of 31 species of Asian pitvipers by examining the character state changes on a consensus tree modified from broadly consistent molecular results. We found that these characters appear stable with only one intraspecific polymorphism. Nine of the 12 characters form useful synapomorphies, whereas three are ambiguous and evolutionarily plastic. Clades that are supported with numerous apomorphies are the Trimeresurus group [consisting of the recently defined genera Trimeresurus sensuMalhotra and Thorpe (2004), Parias, Popeia, Viridovipera, Himalayophis, and Cryptelytrops] and the genera Protobothrops, Parias, and Viridovipera. Two species previously considered as congeners but now known to be distantly related, Ovophis monticola and ,Ovophis'okinavensis, have nearly identical character states, demonstrating substantial convergence in cranial characters. Finally, we attempt to infer the phylogenetic position of Peltopelor macrolepis by comparing its cranial features with that of other pitvipers. [source] The braincase of the chondrichthyan Doliodus from the Lower Devonian Campbellton Formation of New Brunswick, CanadaACTA ZOOLOGICA, Issue 2009John Maisey Abstract The braincase of the late Lower Devonian (Emsian) chondrichthyan Doliodus is described for the first time. Its postorbital process is extended ventrally and probably enclosed part of the infraorbital sensory canal, as in some placoderms. Doliodus has a shark-like dentition, but its upper anterior tooth files were supported by the internasal cartilage of the braincase, not by the palatoquadrates. Modern selachian jaws and dentitions are not representative of primitive crown-group gnathostomes because they display a mixture of conserved and derived character states. Separation of the palatoquadrates by the internasal cartilage is probably a primitive condition for crown-group gnathostomes. Continuity of the upper dental arcade across the ethmoid region may represent a synapomorphy of chondrichthyans and some acanthodians (the condition is not found in placoderms or osteichthyans). Exclusion of the arcade from the ethmoid region is probably apomorphic within elasmobranchs. Doliodus has curious bar-like, paired subcranial ridges ending posteriorly at the hyomandibular articulation. These superficially resemble visceral arch infrapharyngohyals fused to the floor of the braincase, adding circumstantial palaeontological support to the old proposal that parts of visceral arches may be incorporated into the gnathostome braincase, although it seems more plausible that they formed in the lateral margins of the embryonic parachordal or hypotic lamina. [source] External Features of the First Instar Larva of Damaster (Coptolabrus) jankowskii jankowskii (Coleoptera; Carabidae)ENTOMOLOGICAL RESEARCH, Issue 2 2002Jung Lark KIM ABSTRACT Larval features of the carabid beetle, Damaster (Coptolabrus) jankowskii jankowskii (Oberthür) were investigated for the first time. For accomplishing the purpose, the adult beetles were collected by pitfall traps in the deciduous forest of Mt. Palgongsan, southern Korea. They have been reared under the laboratory condition of 16L: 8D at 20°C. The first instar larvae were obtained by isolating eggs after oviposition and were kept at the same condition. In the present study, external morphology of the first instar larva of this subspecies are described and its important character states and comparisons with the kin species are also discussed. [source] REPLICATED EVOLUTION OF INTEGRATED PLASTIC RESPONSES DURING EARLY ADAPTIVE DIVERGENCEEVOLUTION, Issue 4 2006Kevin J. Parsons Abstract Colonization of a novel environment is expected to result in adaptive divergence from the ancestral population when selection favors a new phenotypic optimum. Local adaptation in the new environment occurs through the accumulation and integration of character states that positively affect fitness. The role played by plastic traits in adaptation to a novel environment has generally been ignored, except for variable environments. We propose that if conditions in a relatively stable but novel environment induce phenotypically plastic responses in many traits, and if genetic variation exists in the form of those responses, then selection may initially favor the accumulation and integration of functionally useful plastic responses. Early divergence between ancestral and colonist forms will then occur with respect to their plastic responses across the gradient bounded by ancestral and novel environmental conditions. To test this, we compared the magnitude, integration, and pattern of plastic character responses in external body form induced by shallow versus open water conditions between two sunfish ecomorphs that coexist in four postglacial lakes. The novel sunfish ecomorph is present in the deeper open water habitat, whereas the ancestral ecomorph inhabits the shallow waters along the lake margin. Plastic responses by open water ecomorphs were more correlated than those of their local shallow water ecomorph in two of the populations, whereas equal levels of correlated plastic character responses occurred between ecomorphs in the other two populations. Small but persistent differences occurred between ecomorph pairs in the pattern of their character responses, suggesting a recent divergence. Open water ecomorphs shared some similarities in the covariance among plastic responses to rearing environment. Replication in the form of correlated plastic responses among populations of open water ecomorphs suggests that plastic character states may evolve under selection. Variation between ecomorphs and among lake populations in the covariance of plastic responses suggests the presence of genetic variation in plastic character responses. In three populations, open water ecomorphs also exhibited larger plastic responses to the environmental gradient than the local shallow water ecomorph. This could account for the greater integration of plastic responses in open water ecomorphs in two of the populations. This suggests that the plastic responses of local sunfish ecomorphs can diverge through changes in the magnitude and coordination of plastic responses. Although these results require further investigation, they suggest that early adaptive evolution in a novel environment can include changes to plastic character states. The genetic assimilation of coordinated plastic responses could result in the further, and possibly rapid, divergence of such populations and could also account for the evolution of genes of major effect that contribute to suites of phenotypic differences between divergent populations. [source] EVOLUTION OF MOUTHBROODING AND LIFE-HISTORY CORRELATES IN THE FIGHTING FISH GENUS BETTAEVOLUTION, Issue 4 2004Lukas Rüber Abstract The origin of and evolutionary transitions among the extraordinary diverse forms of parental care in teleost fish remain largely unknown. The "safe harbor" hypothesis predicts that the evolution from a "guarding" to a "brooding" form of care in teleost fish is associated with shifts in reproductive and life-history features such as reduced fecundity, and increased egg volume with higher parental investment. Robust phylogenetic hypotheses may help to identify evolutionary changes in key traits associated with differences in the form of parental care. Here, we used reconstruction of ancestral character states to study the evolution of the two forms of parental care, bubble nesting and mouthbrooding in the fighting fish genus Betta. We also applied a comparative analysis using the phylogenetic generalized least-squares method to test the "safe harbor" hypothesis by evaluating differences between the two forms of parental care in standard length, life-history traits, and three habitat variables. Evolutionary hypotheses were derived from the first molecular phylogeny (nuclear and mitochondrial DNA sequence data; 4448 bp) of this speciose group. Ancestral character state reconstructions of the evolution of the form of parental care in the genus Betta, using the methods of unweighted parsimony and maximum likelihood, are uncertain and further indicate a high rate of evolutionary transitions. Applying different weights for the suspected directionality of changes, based on the consistent phenotypic and behavioral differences found between bubble nesters and mouthbrooders, recurrent origin of mouthbrooding in the genus Betta is favored using parsimony. Our comparative analyses further demonstrate that bubble nesters and mouthbrooders do not have a consistent set of life-history correlates. The form of parental care in Betta is correlated only with offspring size, with mouthbrooders having significantly bigger offspring than bubble nesters, but is not correlated with egg volume, clutch size, and broodcare duration, nor with any of the three habitat variables tested. Our results thus challenge the general predictions of the "safe harbor" hypothesis for the evolution of alternative brood care forms in the fighting fish genus Betta. [source] RECONSTRUCTING PLUMAGE EVOLUTION IN ORIOLES (ICTERUS): REPEATED CONVERGENCE AND REVERSAL IN PATTERNSEVOLUTION, Issue 6 2000Kevin E. Omland Abstract. Several empirical studies suggest that sexually selected characters, including bird plumage, may evolve rapidly and show high levels of convergence and other forms of homoplasy. However, the processes that might generate such convergence have not been explored theoretically. Furthermore, no studies have rigorously addressed this issue using a robust phylogeny and a large number of signal characters. We scored the appearance of 44 adult male plumage characters that varied across New World orioles (Icterus). We mapped the plumage characters onto a molecular phylogeny based on two mitochondrial genes. Reconstructing the evolution of these characters revealed evidence of convergence or reversal in 42 of the 44 plumage characters. No plumage character states are restricted to any groups of species higher than superspecies in the oriole phylogeny. The high frequency of convergence and reversal is reflected in the low overall retention index (RI = 0.66) and the low overall consistency index (CI = 0.28). We found similar results when we mapped plumage changes onto a total evidence tree. Our findings reveal that plumage patterns and colors are highly labile between species of orioles, but highly conserved within the oriole genus. Furthermore, there are at least two overall plumage types that have convergently evolved repeatedly in the three oriole clades. This overall convergence leads to significant conflict between the molecular and plumage data. It is not clear what evolutionary processes lead to this homoplasy in individual characters or convergence in overall pattern. However, evolutionary constraints such as developmental limitations and genetic correlations between characters are likely to play a role. Our results are consistent with the belief that avian plumage and other sexually selected characters may evolve rapidly and may exhibit high homoplasy. The overall convergence in oriole plumage patterns is an interesting evolutionary phenomenon, but it cautions against heavy reliance on plumage characters for constructing phylogenies. [source] EXHAUSTION OF MORPHOLOGIC CHARACTER STATES AMONG FOSSIL TAXAEVOLUTION, Issue 2 2000Peter 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] Deuterostome evolution: early development in the enteropneust hemichordate, Ptychodera flavaEVOLUTION AND DEVELOPMENT, Issue 6 2001Jonathan Q. Henry SUMMARY Molecular and morphological comparisons indicate that the Echinodermata and Hemichordata represent closely related sister-phyla within the Deuterostomia. Much less is known about the development of the hemichordates compared to other deuterostomes. For the first time, cell lineage analyses have been carried out for an indirect-developing representative of the enteropneust hemichordates, Pty- chodera flava. Single blastomeres were iontophoretically labeled with DiI at the 2- through 16-cell stages, and their fates followed through development to the tornaria larval stage. The early cleavage pattern of P. flava is similar to that of the direct-developing hemichordate, Saccoglossus kowalevskii, as well as that displayed by indirect-developing echinoids. The 16-celled embryo contains eight animal "mesomeres," four slightly larger "macromeres," and four somewhat smaller vegetal "micromeres." The first cleavage plane was not found to bear one specific relationship relative to the larval dorsoventral axis. Although individual blastomeres generate discrete clones of cells, the appearance and exact locations of these clones are variable with respect to the embryonic dorsoventral and bilateral axes. The eight animal mesomeres generate anterior (animal) ectoderm of the larva, which includes the apical organ; however, contributions to the apical organ were found to be variable as only a subset of the animal blastomeres end up contributing to its formation and this varies from embryo to embryo. The macromeres generate posterior larval ectoderm, and the vegetal micromeres form all the internal, endomesodermal tissues. These blastomere contributions are similar to those found during development of the only other hemichordate studied, the direct-developing enteropneust, S. kowalevskii. Finally, isolated blastomeres prepared at either the two- or the four-cell stage are capable of forming normal-appearing, miniature tornaria larvae. These findings indicate that the fates of these cells and embryonic dorsoventral axial properties are not committed at these early stages of development. Comparisons with the developmental programs of other deuterostome phyla allow one to speculate on the conservation of some key developmental events/mechanisms and propose basal character states shared by the ancestor of echinoderms and hemichordates. [source] Phylogenetic analyses of marine sponges within the order Verongida: a comparison of morphological and molecular dataINVERTEBRATE BIOLOGY, Issue 3 2007Patrick M. Erwin Abstract. Because the taxonomy of marine sponges is based primarily on morphological characters that can display a high degree of phenotypic plasticity, current classifications may not always reflect evolutionary relationships. To assess phylogenetic relationships among sponges in the order Verongida, we examined 11 verongid species, representing six genera and four families. We compared the utility of morphological and molecular data in verongid sponge systematics by comparing a phylogeny constructed from a morphological character matrix with a phylogeny based on nuclear ribosomal DNA sequences. The morphological phylogeny was not well resolved below the ordinal level, likely hindered by the paucity of characters available for analysis, and the potential plasticity of these characters. The molecular phylogeny was well resolved and robust from the ordinal to the species level. We also examined the morphology of spongin fibers to assess their reliability in verongid sponge taxonomy. Fiber diameter and pith content were highly variable within and among species. Despite this variability, spongin fiber comparisons were useful at lower taxonomic levels (i.e., among congeneric species); however, these characters are potentially homoplasic at higher taxonomic levels (i.e., between families). Our molecular data provide good support for the current classification of verongid sponges, but suggest a re-examination and potential reclassification of the genera Aiolochroia and Pseudoceratina. The placements of these genera highlight two current issues in morphology-based sponge taxonomy: intermediate character states and undetermined character polarity. [source] Cladistic analysis of Medusozoa and cnidarian evolutionINVERTEBRATE BIOLOGY, Issue 1 2004Antonio C. Marques Abstract. A cladistic analysis of 87 morphological and life history characters of medusozoan cnidarians, rooted with Anthozoa, results in the phylogenetic hypothesis (Anthozoa (Hydrozoa (Scyphozoa (Staurozoa, Cubozoa)))). Staurozoa is a new class of Cnidaria consisting of Stauromedusae and the fossil group Conulatae. Scyphozoa is redefined as including those medusozoans characterized by strobilation and ephyrae (Coronatae, Semaeostomeae, and Rhizostomeae). Within Hydrozoa, Limnomedusae is identified as either the earliest diverging hydrozoan lineage or as the basal group of either Trachylina (Actinulida (Trachymedusae (Narcomedusae, Laingiomedusae))) or Hydroidolina (Leptothecata (Siphonophorae, Anthoathecata)). Cladistic results are highly congruent with recently published phylogenetic analyses based on 18S molecular characters. We propose a phylogenetic classification of Medusozoa that is consistent with phylogenetic hypotheses based on our cladistic results, as well as those derived from 18S analyses. Optimization of the characters presented in this analysis are used to discuss evolutionary scenarios. The ancestral cnidarian probably had a sessile biradial polyp as an adult form. The medusa is inferred to be a synapomorphy of Medusozoa. However, the ancestral process (metamorphosis of the apical region of the polyp or lateral budding involving an entocodon) could not be inferred unequivocally. Similarly, character states for sense organs and nervous systems could not be inferred for the ancestral medusoid of Medusozoa. [source] The standard of neutrality: still flapping in the breeze?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 7 2010S. R. PROULX Abstract Neutrality plays an important role as a null model in evolutionary biology. Recent theoretical advances suggest that neutrality is not a unitary concept, and we identify three distinct forms of neutrality. Eu-neutrality means that types do not differ in any measurable way and is thus the idealized form of neutrality. However, individuals or species that do differ in important ways can behave neutrally under some circumstances, both broadening and complicating the applicability of the concept of neutrality. Our second two types of neutrality address two quite different forms of context-dependent neutrality. Circum-neutrality means that two character states have the same direct effect on fitness but do not evolve neutrally because of differences in their circumstances. Iso-neutrality means that two types are equivalent in some population or ecological contexts but not in others, producing an isocline. Confounding of these different definitions has created significant confusion about which models are truly neutral, why some models behave neutrally even when there are large differences in reproductive outputs, and what these different views of neutrality mean to practicing biologists. These complications call into question the acceptance of neutral models as null models and suggest that a better approach is to compare the predictions of models that differ in sources of stochasticity and degree of selection. [source] Parallel evolution of larval morphology and habitat in the snail-killing fly genus TetanoceraJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2006E. G. CHAPMAN Abstract In this study, we sequenced one nuclear and three mitochondrial DNA loci to construct a robust estimate of phylogeny for all available species of Tetanocera. Character optimizations suggested that aquatic habitat was the ancestral condition for Tetanocera larvae, and that there were at least three parallel transitions to terrestrial habitat, with one reversal. Maximum likelihood analyses of character state transformations showed significant correlations between habitat transitions and changes in four larval morphological characteristics (cuticular pigmentation and three characters associated with the posterior spiracular disc). We provide evidence that phylogenetic niche conservatism has been responsible for the maintenance of aquatic-associated larval morphological character states, and that concerted convergence and/or gene linkage was responsible for parallel morphological changes that were derived in conjunction with habitat transitions. These habitat,morphology associations were consistent with the action of natural selection in facilitating the morphological changes that occurred during parallel aquatic to terrestrial habitat transitions in Tetanocera. [source] Reconstructing asymmetrical reproductive character displacement in a periodical cicada contact zoneJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2006JOHN R. COOLEY Abstract Selection against costly reproductive interactions can lead to reproductive character displacement (RCD). We use information from patterns of displacement and inferences about predisplacement character states to investigate causes of RCD in periodical cicadas. The 13-year periodical cicada Magicicada neotredecim exhibits RCD and strong reproductive isolation in sympatry with a closely related 13-year species, Magicicada tredecim. Displacement is asymmetrical, because no corresponding pattern of character displacement exists within M. tredecim. Results from playback and hybridization experiments strongly suggest that sexual interactions between members of these species were possible at initial contact. Given these patterns, we evaluate potential sources of selection for displacement. One possible source is ,acoustical interference', or mate-location inefficiencies caused by the presence of heterospecifics. Acoustical interference combined with the species-specificity of song pitch and preference appears to predict the observed asymmetrical pattern of RCD in Magicicada. However, acoustical interference does not appear to be a complete explanation for displacement in Magicicada, because our experiments suggest a significant potential for direct sexual interactions between these species before displacement. Another possible source of selection for displacement is hybrid failure. We evaluate the attractiveness of inferred hybrid mating signals, and we examine the viability of hybrid eggs. Neither of these shows strong evidence of hybrid inferiority. We conclude by presenting a model of hybrid failure related to life cycle differences in Magicicada. [source] CONFUSING CONVERGENT MORPHOLOGIES: DIVERSITY AND DIFFICULTIES IN NEW ZEALAND ERYTHROPELTIDALES AND BANGIALESJOURNAL OF PHYCOLOGY, Issue 2000W.A. Nelson An examination of New Zealand species of Porphyra and Bangia has led to the discovery of unexpectedly high diversity. In excess of 30 species of Porphyra and 5 species of Bangia can be distinguished, based on 18S rDNA sequence data. It is possible to develop a workable taxonomic framework to distinguish species of Porphyra found within this geographic region using a range of characters (morphological, anatomical, biochemical, physiological, life history characteristics). However, the taxonomic distinctions do not necessarily reflect phylogenetic relationships revealed by sequence analyses: convergence in character states is obscuring relationships. In the course of our work we have discovered that four species, originally described on the basis of traditional morphological and anatomical characters as Porphyra or Bangia, are more closely related to members of the order Erythropeltidales than to the Bangiales. These results are challenging us to consider new ways of describing and defining these organisms. We are finding convergence in character states, not only within Porphyra sens. lat. But spanning both the Bangiales and Erythropeltidales, which confounds both taxonomic distinctions and also phylogenetic hypotheses based on morphology and anatomy. This confusion could be countered effectively by the inclusion of molecular sequence data based on vouchered or type material in descriptions of taxa in the orders Bangiales and Erythropeltidales. This would allow conclusive identification of collected material by appropriate molecular tests, which are quicker and more direct identification tools than, for example, using characters drawn from the growth of these organisms under controlled culture conditions. [source] A phylogeny of anisopterous dragonflies (Insecta, Odonata) using mtRNA genes and mixed nucleotide/doublet modelsJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 4 2008G. Fleck Abstract The application of mixed nucleotide/doublet substitution models has recently received attention in RNA-based phylogenetics. Within a Bayesian approach, it was shown that mixed models outperformed analyses relying on simple nucleotide models. We analysed an mt RNA data set of dragonflies representing all major lineages of Anisoptera plus outgroups, using a mixed model in a Bayesian and parsimony (MP) approach. We used a published mt 16S rRNA secondary consensus structure model and inferred consensus models for the mt 12S rRNA and tRNA valine. Secondary structure information was used to set data partitions for paired and unpaired sites on which doublet or nucleotide models were applied, respectively. Several different doublet models are currently available of which we chose the most appropriate one by a Bayes factor test. The MP reconstructions relied on recoded data for paired sites in order to account for character covariance and an application of the ratchet strategy to find most parsimonious trees. Bayesian and parsimony reconstructions are partly differently resolved, indicating sensitivity of the reconstructions to model specification. Our analyses depict a tree in which the damselfly family Lestidae is sister group to a monophyletic clade Epiophlebia + Anisoptera, contradicting recent morphological and molecular work. In Bayesian analyses, we found a deep split between Libelluloidea and a clade ,Aeshnoidea' within Anisoptera largely congruent with Tillyard's early ideas of anisopteran evolution, which had been based on evidently plesiomorphic character states. However, parsimony analysis did not support a clade ,Aeshnoidea', but instead, placed Gomphidae as sister taxon to Libelluloidea. Monophyly of Libelluloidea is only modestly supported, and many inter-family relationships within Libelluloidea do not receive substantial support in Bayesian and parsimony analyses. We checked whether high Bayesian node support was inflated owing to either: (i) wrong secondary consensus structures; (ii) under-sampling of the MCMC process, thereby missing other local maxima; or (iii) unrealistic prior assumptions on topologies or branch lengths. We found that different consensus structure models exert strong influence on the reconstruction, which demonstrates the importance of taxon-specific realistic secondary structure models in RNA phylogenetics. [source] Phylogeny of the Eurasian freshwater turtles of the genus Mauremys Gray 1869 (Testudines), with special reference to a close affinity of Mauremys japonica with Chinemys reevesiiJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 4 2002M. Honda Phylogenetic relationships of the freshwater turtles of the genus Mauremys and representatives of several other batagurid genera were inferred from variations in 863 base positions of mitochondrial 12S and 16S rRNA genes. Results strongly suggested the non-monophyly of Mauremys by indicating the closest affinity of Mauremys japonica with Chinemys reevesii, the type species of the genus Chinemys. Recent morphological analyses of the batagurid genera suggested that Mauremys is a basal stock of the subfamily Geoemydinae, whereas Chinemys is a member of the subfamily Batagurinae as supported by several putative synapomorphs with other batagurine genera. It is thus probable that the morphological character states used to define Mauremys actually represent symplesiomorphy, and that morphological character states shared between Chinemys and other batagurine genera have resulted from convergence. Also, our results did not support a sister-group relationship between Mauremys annamensis and Mauremys mutica, which has been implicitly or explicitly assumed by a number of previous authors on the basis of morphological data. Instead, M. annamensis was indicated to be closest to Mauremys iversoni, a species assumed to be most divergent among the East Asian Mauremys by previous authors. Phylogenie der eurasischen Su¨ßwasserschildkro¨ten der Gattung Mauremys Gray 1869 (Testudines), mit besonderem Hinweis auf eine enge A¨hnlichkeit von Mauremys japonica mit Chinemys reevesii. Die phylogenetischen Beziehungen zwischen den Süßwasserschildkröten der Gattung Mauremys und Vertretern einiger anderer bataguriner Gattungen wurde aus den Unterschieden an 863 Positionen der 12S-und der 16S-rRNA-Gene des Mitochondriengenoms ermittelt. Die Ergebnisse weisen sehr stark darauf hin, daß die Gattung Mauremys wegen der starken Ähnlichkeit zwischen M. japonica und Chinemys reevesii nicht monophyletisch sein kann. Neue morphologische Analysen der batagiurinen Gattungen ließen vermuten, daß Mauremys einen basalen Ast der Unterfamilie Geomydinae darstellt, während Chinemys zur Unterfamile Batagurinae gehört, was aus den anzunehmenden Synapomorphien mit anderen batagurinen Gattungen gestützt wird. Es ist daher auch wahrscheinlich, daß die zur Beschreibung von Mauremys verwendeten morphologischen Merkmalszustände eher Plesiomorphien darstellen und daß die morphologischen Merkmalsausprägungen, die Chinemys und anderen batagurinen Gattungen gemeinsam sind, auf Konvergenz beruhen. Unsere Ergebnisse unterstützen auch nicht eine Schwestergruppen-Beziehung zwischen M. anamensis und M. mutica, was direkt oder indirekt von einer Zahl von früheren Untersuchern auf Grund morphologischer Daten angenommen wurde. Statt dessen erwies sich M. anamensis am engsten verwandt mit M. iversoni, einer Art, die von früheren Autoren als am stärksten divergent zu den ostasiatischen Mauremys-Arten angesehen wurde. [source] Release vocalizations in neotropical toads (Bufo): ecological constraints and phylogenetic implicationsJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1-2 2001Di Tada The release vocalizations of four nominal neotropical toad taxa (Bufo achalensis, Bufo limensis, Bufo spinulosus, Bufo arenarum) which compose three sympatric species pairs, were quantitatively analysed and homologous call types statistically compared. The first three taxa are closely related members of the mainly Andean Bufo spinulosus species group in which advertisement calls are absent. The specific vocal repertoire consisted of a uniform, unpulsed release call and one (in B. arenarum, two) pulsed release trill(s) which were given either singly or in series of up to three single calls. The uniform call was similar in structure and dominant (= basic) frequency in all taxa and probably represents an unspecific acoustic signal which is used to avoid heterospecific amplexus between sympatric toads. The release trills significantly differed in most call features among the taxa and, using discriminant analyses, even single calls were correctly assigned to sympatric pairs of species. In contrast, calls of allopatric pairs of species were confounded at rates of up to 36% indicating that selection towards species-specific signals increases when different species live in sympatry. The release trills of two allopatric populations (Perú, Argentina) assigned to B. spinulosus were similar in structure, but nevertheless features of pulse train permitted an unequivocal distinction, suggesting a long-lasting independent evolution. The taxonomic significance of this finding remains to be evaluated in further investigations. The complex vocal repertoire also offered the opportunity to assess phylogenetic relationships among the taxa. The extra-Andean B. achalensis seems to be closer related to the Andean B. spinulosus than this species is to the widely sympatric B. limensis– a species with several primitive character states indicating an early separation from the ancestral stock. Befreiungsrufe neotropischer Kröten (Bufo): Ökologische Einflüsse und phylogenetische Bedeutung Die Befreiungsrufe vier nomineller neotropischer Krötentaxa (Bufo achalensis, Bufo limensis, Bufo spinulosus, Bufo arenarum), die drei sympatrisch lebende Paare bilden, wurden quantitativ untersucht und homologe Ruftypen statistisch verglichen. Die drei erstgenannten Taxa sind nahverwandte Mitglieder der hauptsächlich andinen Bufo spinulosus Artengruppe, die keinen Paarungsruf besitzt. Das artspezifische Rufrepertoire umfaßte einen gleichförmigen, nicht-gepulsten Befreiungsruf und einen (bei B. arenarum zwei) aus Impulsen bestehenden Befreiungstriller. Diese Rufe werden entweder einzeln oder als Rufserien mit bis zu drei Einzelrufen abgegeben. Der gleichförmige Ruf war bei allen Taxa strukturell ähnlich und ist wahrscheinlich ein nichtartspezifischer Teil des Kommunikationssytems, der zur Vermeidung heterospezifischer Amplexus zwischen sympatrischen Kröten dient. Die Triller unterschieden sich in den meisten Merkmalen signifikant zwischen den Arten und auch Einzelrufe wurden bei sympatrischen Arten mittels Diskriminanzanlyse korrekt klassifiziert. Hingegen betrugen bei allopatrischen Arten die Fehlklassifikationen bis zu 36%. Dies weist auf einen starken Selektionsdruck zu artspezifischen Signalen bei Sympatrie hin. Die Triller zweier allopatrischer Populationen (Perú, Argentina) von B. spinulosusähnelten sich zwar strukturell, liessen sich aber ohne Fehlklassifikation voneinander unterscheiden, wahrscheinlich ein Hinweis auf eine längere unabhängige Evolution. Zur Klärung der taxonomischen Bedeutung dieses Befundes sind jedoch weitere Untersuchungen nötig. Der komplexe Aufbau der Rufe eröffnete auch die Möglichkeit, mittels bioakustischer Merkmale die phylogenetischen Beziehungen zwischen den Taxa abzuleiten. Die extraandine B. achalensis scheint mit der andinen B. spinulosus näher verwandt zu sein als diese Art mit der weitgehend sympatrischen B. limensis. Letztere Art zeigt eine Reihe primitiver Merkmale, die auf eine frühe Trennung vom der ancestralen Evolutionlinie hinweisen. [source] Species identification of Alnus (Betulaceae) using nrDNA and cpDNA genetic markersMOLECULAR ECOLOGY RESOURCES, Issue 4 2010BAO-QING REN Abstract One nuclear and three chloroplast DNA regions (ITS, rbcL, matK and trnH-psbA) were used to identify the species of Alnus (Betulaceae). The results showed that 23 out of all 26 Alnus species in the world, represented by 131 samples, had their own specific molecular character states, especially for three morphologically confused species (Alnus formosana, Alnus japonica and Alnus maritima). The discriminating power of the four markers at the species level was 10% (rbcL), 31.25% (matK), 63.6% (trnH-psbA) and 76.9% (ITS). For ITS, the mean value of genetic distance between species was more than 10 times the intraspecific distance (0.009%), and 13 species had unique character states that differentiated them from other species of Alnus. The trnH-psbA region had higher mean values of genetic distance between and within species (2.1% and 0.68% respectively) than any other region tested. Using the trnH-psbA region, 13 species are distinguished from 22 species, and seven species have a single diagnostic site. The combination of two regions, ITS and trnH-psbA, is the best choice for DNA identification of Alnus species, as an improvement and supplement for morphologically based taxonomy. This study illustrates the potential for certain DNA regions to be used as novel internet biological information carrier through combining DNA sequences with existing morphological character and suggests a relatively reliable and open taxonomic system based on the linked DNA and morphological data. [source] DNA barcodes for globally threatened marine turtles: a registry approach to documenting biodiversityMOLECULAR ECOLOGY RESOURCES, Issue 2 2010EUGENIA NARO-MACIEL Abstract DNA barcoding is a global initiative that provides a standardized and efficient tool to catalogue and inventory biodiversity, with significant conservation applications. Despite progress across taxonomic realms, globally threatened marine turtles remain underrepresented in this effort. To obtain DNA barcodes of marine turtles, we sequenced a segment of the cytochrome c oxidase subunit I (COI) gene from all seven species in the Atlantic and Pacific Ocean basins (815 bp; n = 80). To further investigate intraspecific variation, we sequenced green turtles (Chelonia mydas) from nine additional Atlantic/Mediterranean nesting areas (n = 164) and from the Eastern Pacific (n = 5). We established character-based DNA barcodes for each species using unique combinations of character states at 76 nucleotide positions. We found that no haplotypes were shared among species and the mean of interspecific variation ranged from 1.68% to 13.0%, and the mean of intraspecific variability was relatively low (0,0.90%). The Eastern Pacific green turtle sequence was identical to an Australian haplotype, suggesting that this marker is not appropriate for identifying these phenotypically distinguishable populations. Analysis of COI revealed a north,south gradient in green turtles of Western Atlantic/Mediterranean nesting areas, supporting a hypothesis of recent dispersal from near equatorial glacial refugia. DNA barcoding of marine turtles is a powerful tool for species identification and wildlife forensics, which also provides complementary data for conservation genetic research. [source] A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922PALAEONTOLOGY, Issue 5 2010MICHELLE R. STOCKER Abstract:,Leptosuchus Case, 1922 (Reptilia: Phytosauria) from the Late Triassic of the American West is represented by many specimens. Here, I present complete morphological descriptions of the skull material of a new taxon from the Sonsela Member (Chinle Formation) of Petrified Forest National Park, Arizona, with the first rigorous phylogenetic analysis focused on the interrelationships of Leptosuchus. The new taxon is recovered as the sister taxon to Pseudopalatinae. It possesses one unambiguous synapomorphy (the ,septomaxillae' form part of the lateral borders of the nares) and shares the presence of a subsidiary opisthotic process with Pseudopalatinae. The new taxon does not fall within the restricted clade Leptosuchus. In my analysis, the previously proposed, but undemonstrated, sister taxon relationship between Angistorhinus and Rutiodon is not supported, Paleorhinus is recovered as paraphyletic, and a subset of taxa traditionally included within Leptosuchus are found to be more closely related to Pseudopalatinae, rendering Leptosuchus paraphyletic. ,Leptosuchus'adamanensis emerges as sister taxon to Smilosuchus gregorii and is here referred to as Smilosuchus adamanensis nov. comb., and ,Machaeroprosopus'lithodendrorum is also transferred to Smilosuchus lithodendrorum nov. comb. Documentation of the variation present within Phytosauria, and specifically within Leptosuchus sensu lato, demonstrates higher diversity within Phytosauria than previously appreciated and places the character states previously proposed for Pseudopalatinae into a broader context of shared characters. [source] THE GENUS GIGANTASPIS HEINTZ, 1962 (VERTEBRATA, HETEROSTRACI) FROM THE LOWER DEVONIAN OF SPITSBERGENPALAEONTOLOGY, Issue 2 2007VINCENT PERNEGRE Abstract:, Material collected in 1969 by the CNRS-MNHN expedition to Spitsbergen includes a new species of Gigantaspis, G. minima, which is the smallest known species of this genus. The revision of Gigantaspis leads to the inclusion of Zascinaspis laticephala Blieck and Goujet in this genus. The phylogenetic analysis presented herein suggests that Gigantaspis is close to Zascinaspis, as suggested by Blieck. Moreover, it is also close to generalized representatives of the Protaspididae. Their shared character states allow the definition of a possible ancestral morphotype for the Protaspididae. [source] The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaurPALAEONTOLOGY, Issue 6 2002Paul Upchurch A relatively well,preserved specimen of Cetiosaurus oxoniensis, from the Middle Jurassic (Bajocian) of Rutland, United Kingdom, is described in detail. The material includes a nearly complete cervical series, representative dorsal vertebrae, a fragment of sacrum, anterior caudals, the right femur, and numerous rib and limb fragments. Contrary to previous suggestions that this specimen possesses 14 cervical and ten dorsal vertebrae, it seems more probable that there were at most 13 cervicals and at least 12 dorsals. The vertebral column displays several autapomorphic features which supplement the generic diagnosis of Cetiosaurus, including: (1) a stout, anteriorly directed process located at the top of the neural spine of the twelfth (?) cervical vertebra; and (2) the presence of lateral pits, separated by a thin midline septum, below the transverse processes of middle dorsal vertebrae. Cladistic analysis indicates that Cetiosaurus is probably the sister,taxon to the advanced neosauropod clade. This relationship affects the distribution of particular character states that have played an important role in determining sauropod phylogeny. [source] Evolution of centric diatoms inferred from patterns of oogenesis and spermatogenesisPHYCOLOGICAL RESEARCH, Issue 3 2008Makoto Mizuno SUMMARY Centric diatoms have three patterns of oogenesis and four patterns of spermatogenesis, yielding a combination of seven patterns. The evolution of these combinations was inferred from differences in character states of the meiotic patterns observed in oogenesis and spermatogenesis. Furthermore, we have inferred the evolutionary relationships among centric diatoms based on the evolution of these combinations, the data on occurrence of combinations and a molecular phylogenetic tree. Our results suggested that the last common ancestor of extant diatoms was a bipolar or multipolar centric diatom with the most primitive among extant oogenetic/spermatogenic combinations. Our results also suggested that ancestors of the radial centrics and pennates would have diverged, in that order, from a bipolar or multipolar centric diatom with the most primitive among extant oogenetic/spermatogenic combinations. [source] The evolution of brachiation in ateline primates, ancestral character states and historyAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2008Andrea L. Jones Abstract This study examines how brachiation locomotion evolved in ateline primates using recently-developed molecular phylogenies and character reconstruction algorithms, and a newly-collected dataset including the fossils Protopithecus, Caipora, and Cebupithecia. Fossils are added to two platyrrhine molecular phylogenies to create several phylogenetic scenarios. A generalized least squares algorithm reconstructs ateline and atelin ancestral character states for 17 characters that differentiate between ateline brachiators and nonbrachiators. Histories of these characters are mapped out on these phylogenies, producing two scenarios of ateline brachiation evolution that have four commonalities: First, many characters change towards the Ateles condition on the ateline stem lineage before Alouatta splits off from the atelins, suggesting that an ateline energy-maximizing strategy began before the atelines diversified. Second, the ateline last common ancestor is always reconstructed as an agile quadruped, usually with suspensory abilities. It is never exactly like Alouatta and many characters reverse and change towards the Alouatta condition after Alouatta separates from the atelins. Third, most characters undergo homoplastic change in all ateline lineages, especially on the Ateles and Brachyteles terminal branches. Fourth, ateline character evolution probably went through a hindlimb suspension with tail-bracing phase. The atelines most likely diversified via a quick adaptive radiation, with bursts of punctuated change occurring in their postcranial skeletons, due to changing climatic conditions, which may have caused competition among the atelines and between atelines and pitheciines. Am J Phys Anthropol, 2008. © 2008 Wiley-Liss, Inc. [source] Unique ramus anatomy for Neandertals?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2005Milford H. Wolpoff Abstract The ramus of Neandertal mandibles is said to show a suite of uniquely Neandertal character states that demonstrate the independent course of Neandertal evolution. This is the latest of numerous attempts to define cranial and mandibular autapomorphies for Neandertals. We examine variation in the four presumably autapomorphic ramal features and show they are neither monomorhic within Neandertals (to the contrary Neandertals are at least as variable as other human samples) nor unique to Neandertals, since they regularly appear in populations predating and postdating them. Neandertals differ from other human populations, both contemporary and recent, but the question of whether this fact reflects a divergent evolutionary trajectory must be addressed by the pattern of differences. In this case, as in the other attempts to establish Neandertal autapomorphies, rather than showing restricted variation and increased specialization, the Neandertal sample shows that the range of human variation in the recent past encompasses, and in some cases exceeds, human variation today, even in the very features claimed to be autapomorphic. Am J Phys Anthropol, 2005. © 2005 Wiley-Liss, Inc. [source] Revision of the genus Chalcasthenes Arrow (Coleoptera: Scarabaeidae: Dynastinae: Oryctoderini) from the Solomon IslandsAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 2 2009Mary Liz Jameson Abstract The genus Chalcasthenes Arrow (Dynastinae: Oryctoderini), a scarab beetle genus endemic to the Solomon Islands, is reviewed. Based on examination of type specimens, the genus Strehlia Frey (Rutelinae: Rutelini: Parastasiina) is a new junior synonym of Chalcasthenes. The historical classification of these genera (either in the subfamily Dynastinae or Rutelinae) and character-based criteria for assigning the taxa to the Dynastinae are provided. We discuss character states that support the monophyly of members of the genus Chalcasthenes, comment on the distribution and biogeography of species in the genus and provide a key to species. The genus includes four species: Chalcasthenes divinus Endrödi, Chalcasthenes pulcher Arrow, Chalcasthenes squamigerus Frey new combination and Chalcasthenes styracoceros Jameson and Ratcliffe n. sp. Species hypotheses are corroborated based on evidence from Pleistocene geological reconstructions of the Solomon Islands, geographic variation of bird species in the region and development in scarab beetles. [source] Review of the spider genus Yoroa Baert (Araneae: Theridiidae: Hadrotarsinae)AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 2 2000Mark S Harvey Abstract A new species of Yoroa Baert, Yoroa taylori sp. n., is described from northern Queensland, and the type species, Yoroa clypeoglandularis Baert from Papua New Guinea, is redescribed. The previously unknown females of Y. clypeoglandularis possess identical clypeal openings to those of the males, and possess two pairs of spermathecae and a dorsoventrally flattened pedipalpal claw. These are character states that are apomorphic for the Hadrotarsinae. [source] | ||||||||||||||||||||||||||||||||||