Browsing by Subject "Systematics"

Now showing 1 - 4 of 4
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    Anatomy, Systematics, and Evolution of Catarrhines from the Late Oligocene and Early Miocene of Eastern Africa
    (2019-10) Jansma, Rutger
    The early Miocene catarrhines are key taxa for elucidating the evolutionary history of the Hominoidea and Cercopithecoidea because they are temporally and morphologically intermediate between more primitive Oligocene faunas and modern primate communities. However, insight into the adaptive processes that led to the living catarrhine clades is obscured because of confusion over both taxonomic diversity and systematic affinities within key early Miocene groups. The research presented in this dissertation takes advantage of the increase in new, more complete fossils and taxa to overcome these limitations. The small catarrhines and nyanzapithecines are revised following a comprehensive review, resulting in the description of two new genera (Gen. nov. A and Gen. nov. B), a new species of Dendropithecus, and transfer of Nyanzapithecus harrisoni to Turkanapithecus. This revision provides evidence for increased geographic and ecological differentiation among sympatric small catarrhines, nyanzapithecines, and large-bodied hominoids during the early Miocene. A new phylogenetic analysis using maximum parsimony includes 64 taxa and 243 characters, and recovered a well-resolved consensus tree (MPTs = 18, 901 steps long) that supports monophyly of Cercopithecoidea and Hominoidea. Within Hominoidea, the Pliopithecidae, Dendropithecidae, and Proconsulidae are identified as successively more derived monophyletic clades. A monophyletic Oreopithecidae clade containing Oreopithecus and the nyanzapithecines is also well supported within Hominoidea. However, the positions of Pliopithecidae and Oreopithecidae are strongly influenced by the morphology preserved within single species in these clades. This demonstrates both the importance of comprehensive taxonomic sampling and the impact of missing data on phylogenetic results. The analysis also reveals that suspensory adaptations documented in living apes appeared independently in four hominoid clades (Pliopithecidae, Oreopithecidae, Hylobatidae, and Hominidae). This result is realized through the large taxon sampling in the analysis and demonstrate that the homoplastic character states in these taxa are expressed differently among clades. Finally, a general perspective on catarrhine evolution emphasizes that the appearance of the ancestral hominin cannot be properly interpreted without making reference to the entire Miocene ape radiation.
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    Assessing the prevalence of common patterns and unique events in the formation of biotas: a study of fish taxa of the North American central highlands
    (2011-09) Halas, Dominik
    The Central Highlands fish fauna is a complex assemblage of hundreds of species, many showing a high degree of endemicity. This diversity has traditionally been explained by invoking relatively simple vicariance and dispersal scenarios. In my study, I assembled all existing phylogenies of fishes from the Central Highlands to conduct a Phylogenetic Analysis for the Comparison of Trees, which revealed that vicariance and dispersal events have both played a role in the formation of the Central Highlands ichthyofaunas. Evidence of co-ordinated dispersal and area reticulation was also discovered. The fauna of some regions, in particular the Tennessee River basin, is shown to have accumulated due to multiple vicariance and dispersal events. One mitochondrial and seven nuclear loci were sequenced for the members of the Etheostoma zonale species group. A high degree of geographical structure was found, with twelve reciprocally monophyletic mitochondrial clades in E. zonale, and nine in E. lynceum. Species tree analysis demonstrated the monophyly of both species. One clade found in the Upper Tennessee River basin was found to have undergone introgression with a second clade. One mitochondrial and three nuclear loci were sequenced for the members of the Luxilus zonatus species group. Four mitochondrial introgression events were found in the group, involving all three members of the L. zonatus group as well as two other species of Luxilus. The geographical extent of the introgression events varies, as does their time of occurrence. A Hierarchical Approximate Bayesian Computation was performed on a set of sister clades of three taxa found in the Ozark and Ouachita Mountains: two clades of Etheostoma zonale, two clades of E. blennioides, and Luxilus cardinalis and L. pilsbryi. All taxon pairs share the same geographical split; the analysis showed that two of these divergences did not happen at the same time as the third, and are thus pseudocongruent. The results of this study show that the Central Highlands ichthyofauna has a more complex history than has been believed, and suggest methods of reconstructing such complex histories which should prove useful in biogeographical studies of similarly complex systems.
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    Systematic studies of the indo-Australian crowned weevils (Coleoptera: Curculionidae: Cryptorhynchinae)
    (2009-08) Setliff, Gregory Peter
    This dissertation focuses on the systematics of weevils (Coleoptera: Curculionidae) from the Indo-Australian tropics. Special consideration is given to a novel group of seven genera of Cryptorhynchinae that comprise the crowned weevil group, so named for the crown-like carina or glabrous semicircular bulge on the vertex on the head of these weevils, which is one of the more salient features shared by these genera. Herein, the phylogeny of the largest crowned weevil genus, Asytesta Pascoe, is reconstructed with parsimony and Bayesian analyses based on a data set of 82 adult morphological characters (187 states) for 40 ingroup taxa. One species of Cyamobolus Schönherr and three species of Cyamotrox Heller are used as outgroups and all six genera and 14 species of the crowned weevil group as redefined here ( Cyamomistus Heller, Eudyasmus Pascoe, Glochinorhinus Waterhouse, Nothotragopus Zimmerman, Panopides Pascoe, and Zygara Pascoe), are used to test the monophyly of Asytesta. The results did not support the monophyly of the Asytesta due to the nesting of monotypic Zygara within an apical subclade of Asytesta. Accordingly, Zygara becomes a new junior synonym of Asytesta and Zygara doriae (Kirsch) is returned to its original combination with Asytesta; A. doriae Kirsch status revised. With the inclusion of Zygara, Asytesta as redefined here is monophyletic. Resolution within Asytesta was poor; however, three subclades with strong support were recovered and are formally recognized as species groups. The analyses also recovered monophyletic Nothotragopus, Panopides, and Glochinorhinus. Relationships among the genera were not resolved. The monophyly of Eudyasmus was not supported. In a strict consensus of all trees recovered, Eudyasmus collapsed into a polytomy with Glochinorhinus. A revision of Asytesta is also presented. Of the 41 species recognized here, 23 are previously described and 18 are new: A. alexanderiae, A. alexriedeli, A. allisoni, A. biakana, A. cheesmanae, A. concolora, A. emarginata, A. fayae, A. frontalis, A. gressitti, A. julieae, A. marginalis, A. morobeana, A. sedlaceki, A. thompsoni, A. tuberculata, A. vivienae, and A. woodlarkiana, new species. Asytesta bidentata Voss new status, is elevated to species status from a subspecies of A. lugubris Heller. Four Asytesta species are synonymized: A. circulifera Lea, 1928 = A. rata Heller, 1910, A. definita Faust, 1898 = A. humeralis Pascoe, 1865, A. granulifera Lea, 1928 = A. aucta Faust, 1898, and A. setipes Lea, 1928 = A. lugubris Heller, 1895 new synonyms. Two previously described species were misplaced in Asytesta and are transferred to other genera as follows: A. maura Pascoe to Microporopterus Lea and A. ypsilon Heller to Meroleptus Faust, new combinations. Three species groups, the doriae, dorsalis, and emarginata groups are newly recognized based on the phylogenetic results and are described. Lectotypes are designated for 18 species. A checklist and key for all crowned weevil genera, key to species groups and species of Asytesta, adult habitus illustrations, distribution maps, and line drawings of diagnostic characters are provided.
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    Systematics, Gill Raker Morphology, and Pharyngeal Arch Development of Suckers (Cypriniformes: Catostomidae)
    (2015-06) Hirt, Michael
    Morphological diversity is shaped by past evolutionary history, function, and ontogeny. Evolutionary history plays an important role in shaping morphological diversity and morphology itself can affect the future evolutionary trajectory of taxa. Morphology is shaped by function through selection and function can be constrained by morphology. Differences among taxa in their morphology arise due to changes in the pattern of development in those taxa. Therefore, a full understanding of morphological diversity requires knowledge about evolutionary history, morphological function, and ontogeny. Suckers, family Catostomidae, are a group of freshwater fish with interesting trophic morphology and feeding habits. I used molecular sequence data and fossil calibrations to reconstruct the phylogeny and divergence times of the families of Cypriniformes, including Catostomidae. I found evidence that gene choice, base compositional heterogeneity, and rate heterogeneity provide challenges to reconstructing the evolutionary history of the order and I found that body size is correlated with the rate of molecular evolution not only in Cypriniformes but in many groups of fishes. Suckers, like most fish, have gill rakers which are complex, repetitive, finger-like projections in the interior of the branchial arches that are important in feeding and vary among species. I quantified and compared gill raker morphology among sucker species and found that multiple aspects of gill raker morphology interact to predict function. Gill rakers are just one component of the complex trophic apparatus of suckers. I described and compared the sequence of chondrification and ossification of the paired elements of the pharyngeal arches and the histological development of the palatal organ, chewing pad, and pharyngeal teeth in five species of suckers and found several examples where heterochrony has shaped the trophic morphology of suckers.