Thomas Near
Yale University, Ecology and Evolutionary Biology, Faculty Member
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Research Interests: Evolutionary Biology, Genetics, Molecular Evolution, Biology, Ecology, and 15 moreBiodiversity, Medicine, DNA, Adaptive Radiation, Mitochondrial DNA, Discriminant Analysis, Habitat, Haplotypes, Animals, Fauna, Molecular Phylogenetics and Evolution, Perciformes, Ecosystem, Invertebrate, and nadh dehydrogenase
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The emergence of a new phylogeny of ray-finned fishes at the turn of the twenty-first century marked a paradigm shift in understanding the evolutionary history of half of living vertebrates. We review how the new ray-finned fish phylogeny... more
The emergence of a new phylogeny of ray-finned fishes at the turn of the twenty-first century marked a paradigm shift in understanding the evolutionary history of half of living vertebrates. We review how the new ray-finned fish phylogeny radically departs from classical expectations based on morphology. We focus on evolutionary relationships that span the backbone of ray-finned fish phylogeny, from the earliest divergences among teleosts and nonteleosts to the resolution of major lineages of Percomorpha. Throughout, we feature advances gained by the new phylogeny toward a broader understanding of ray-finned fish evolutionary history and the implications for topics that span from the genetics of human health to reconsidering the concept of living fossils. Additionally, we discuss conceptual challenges that involve reconciling taxonomic classification with phylogenetic relationships and propose an alternate higher-level classification for Percomorpha. Our review highlights remaining areas of phylogenetic uncertainty and opportunities for comparative investigations empowered by this new phylogenetic perspective on ray-finned fishes.
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Results of a phylogenetic analysis of the complete mitochondrial cytochrome b gene (1140 base pairs) for all species of Catonotus are presented along with a synthesis and phylogenetic analysis of published morphological data. The two... more
Results of a phylogenetic analysis of the complete mitochondrial cytochrome b gene (1140 base pairs) for all species of Catonotus are presented along with a synthesis and phylogenetic analysis of published morphological data. The two datasets are combined in a total evidence analysis, and results from the molecular, morphological, and total evidence datasets are compared with each other and with previously published hypotheses. Phylogenetic relationships suggested by morphological data are similar to those from ...
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North America exhibits the most diverse freshwater fish fauna among temperate regions of the world. Species diversity is concentrated in the Central Highlands, drained by the Mississippi, Gulf Slope and Atlantic Slope river systems.... more
North America exhibits the most diverse freshwater fish fauna among temperate regions of the world. Species diversity is concentrated in the Central Highlands, drained by the Mississippi, Gulf Slope and Atlantic Slope river systems. Previous investigations of Central Highlands biogeography have led to conflicting hypotheses involving dispersal and vicariance to explain the diversity and distribution of the freshwater fish fauna. In this investigation predictions of the Central Highlands pre‐Pleistocene vicariance hypothesis are tested with a phylogeographic analysis of the percid species Percina evides, which is widely distributed in several disjunct areas of the Central Highlands. Phylogenetic analysis of complete gene sequences of mitochondrially encoded cytochrome b recover three phylogroups, with very low levels of sequence polymorphism within groups. The two western phylogroups are monophyletic with respect to the eastern phylogroup. The recovery of two monophyletic lineages with an eastern and western distribution in the disjunct highland areas is a pattern expected from vicariance, but is not predicted by the Central Highlands pre‐Pleistocene vicariance hypothesis. The recovery of very limited mitochondrial DNA polymorphism and lack of phylogeographic structuring across the entire range of the eastern clade, very shallow polymorphism between the disjunct Missouri River and upper Mississippi River populations, and lack of sequence polymorphism in the upper Mississippi River populations, support a hypothesis of dispersal during or following the Pleistocene. The present distribution of P. evides is best explained by both vicariant and dispersal events.
Research Interests: Polymorphism, Phylogeography, Biology, Ecology, Biogeography, and 15 moreMedicine, Historical Biogeography, Molecular Ecology, Biological Sciences, Phylogeny, Mitochondrial DNA, Animals, Upper Mississippi River, Phylogenetic analysis, Species Diversity, Freshwater Fish, North America, Vicariance, Cytochrome B, and Monophyly
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Application of genetic data to species delimitation often builds confidence in delimitations previously hypothesized using morphological, ecological, and geographic data and frequently yields recognition of previously undescribed cryptic... more
Application of genetic data to species delimitation often builds confidence in delimitations previously hypothesized using morphological, ecological, and geographic data and frequently yields recognition of previously undescribed cryptic diversity. However, a recent critique of genomic data-based species delimitation approaches is that they have the potential to conflate population structure with species diversity, resulting in taxonomic oversplitting. The need for an integrative approach to species delimitation, in which molecular, morphological, ecological, and geographic lines of evidence are evaluated together, is becoming increasingly apparent. Here, we integrate phylogenetic, population genetic, and coalescent analyses of genome-wide sequence data with investigation of variation in multiple morphological traits to delimit species within the Antarctic barbeled plunderfishes (Artedidraconidae: Pogonophryne). Pogonophryne currently comprises 29 valid species, most of which are distinguished solely by variation in the ornamentation of the mental barbel that projects from the lower jaw, a structure previously shown to vary widely within a single species. However, our genomic and phenotypic analyses result in a dramatic reduction in the number of distinct species recognized within the clade, providing evidence to support the recognition of no more than six species. We propose to synonymize 24 of the currently recognized species with five species of Pogonophryne. We find genomic and phenotypic evidence for a new species of Pogonophryne from specimens collected in the Ross Sea. Our findings represent a rare example in which the application of molecular data provides evidence of taxonomic oversplitting on the basis of morphology, clearly demonstrating the utility of an integrative species delimitation framework.[ddRADseq; multispecies coalescent; Notothenioidei; SNPs; Southern Ocean.]
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Hypotheses of relationship among genera of Percidae have been conflicting. Based on different phylogenetic premises, the evolution of small benthic forms in Percidae has been interpreted as resulting from either convergence or common... more
Hypotheses of relationship among genera of Percidae have been conflicting. Based on different phylogenetic premises, the evolution of small benthic forms in Percidae has been interpreted as resulting from either convergence or common ancestry. In order to assess various phylogenetic hypotheses of Percidae we collected complete sequences (1140 bp) of mitochondrially encoded cytochrome b for 21 species of percids. Seven species representing four additional families of Perciformes were used as outgroups. Maximum parsimony and minimum evolution analyses both recovered single shortest trees, and the results of these analyses were generally congruent with one another. All analyses consistently recovered three monophyletic groups in Percidae: Etheostomatinae (Ammocrypta, Crystallaria, Etheostoma, and Percina), Percinae (Perca and Gymnocephalus), and Luciopercinae (Stizostedion, Zingel, and Romanichthys). As a result of this analysis we present a revised classification of Percidae and discuss the phylogenetic evidence for the independent evolution of small benthic species within Etheostomatinae and Luciopercinae.
Research Interests: Evolutionary Biology, Genetics, Zoology, Phylogenetics, Molecular Evolution, and 15 moreBiology, Medicine, Phylogeny, Mitochondrial DNA, Sequence alignment, Animals, Fishes, Molecular Phylogenetics and Evolution, Perciformes, Fresh water, Phylogenetic Tree, Genetic variation, Maximum Parsimony, Percidae, and Molecular Sequence Data
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Research Interests: Genetics, Geography, Oceanography, Biology, Biological Sciences, and 13 moreLocality, Population structure, Southern Ocean, Mitochondrial DNA, Population, Demersal Fish, Genetic Differentiation, Polar Biology, Antarctic Peninsula, Relative Abundance, Trawling, Antarctic circumpolar current, and peninsula
Understanding the history that underlies patterns of species richness across the Tree of Life requires an investigation of the mechanisms that not only generate young species-rich clades, but also those that maintain species-poor lineages... more
Understanding the history that underlies patterns of species richness across the Tree of Life requires an investigation of the mechanisms that not only generate young species-rich clades, but also those that maintain species-poor lineages over long stretches of evolutionary time. However, diversification dynamics that underlie ancient species-poor lineages are often hidden due to a lack of fossil evidence. Using information from the fossil record and time calibrated molecular phylogenies, we investigate the history of lineage diversification in Polypteridae, which is the sister lineage of all other ray-finned fishes (Actinopterygii). Despite originating at least 390 million years (Myr) ago, molecular timetrees support a Neogene origin for the living polypterid species. Our analyses demonstrate polypterids are exceptionally species depauperate with a stem lineage duration that exceeds 380 million years (Ma) and is significantly longer than the stem lineage durations observed in other ray-finned fish lineages. Analyses of the fossil record show an early Late Cretaceous (100.5-83.6 Ma) peak in polypterid genus richness, followed by 60 Ma of low richness. The Neogene species radiation and evidence for high-diversity intervals in the geological past suggest a "boom and bust" pattern of diversification that contrasts with common perceptions of relative evolutionary stasis in so-called "living fossils."
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Rotifers are free-living animals usually smaller than 1 mm that possess a characteristic wheel organ. Acanthocephalans (thorny-headed worms) are larger endoparasitic animals that use vertebrates and arthropods to complete their life... more
Rotifers are free-living animals usually smaller than 1 mm that possess a characteristic wheel organ. Acanthocephalans (thorny-headed worms) are larger endoparasitic animals that use vertebrates and arthropods to complete their life cycle. The taxa Acanthocephala and Rotifera are considered separate phyla, often within the taxon Aschelminthes. We have reexamined the relationship between Rotifera and Acanthocephala using 18S rRNA gene sequences. Our results conclusively show that Acanthocephala is the sister group of the rotifer class Bdelloidea. Rotifera was nonmonophyletic in all molecular analyses, which supports the hypothesis that the Acanthocephala represent a taxon within the phylum Rotifera and not a separate phylum. These results agree with a previous cladistic study of morphological characters.
Research Interests: Evolutionary Biology, Genetics, Zoology, Molecular Evolution, Biology, and 15 moreRotifera, Molecular, Cladistics, Phylogeny, Animals, Vertebrates, Life Cycle, Morphological Characters, Arthropods, Acanthocephala, Base Sequence, Biochemistry and cell biology, Molecular Sequence Data, Taxon, and conserved sequence
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Across the Tree of Life, most studies of phenotypic disparity and diversification have been restricted to adult organisms. However, many lineages have distinct ontogenetic phases that do not reflect the same traits as their adult forms.... more
Across the Tree of Life, most studies of phenotypic disparity and diversification have been restricted to adult organisms. However, many lineages have distinct ontogenetic phases that do not reflect the same traits as their adult forms. Non-adult disparity patterns are particularly important to consider for coastal ray-finned fishes, which often have juvenile phases with distinct phenotypes. These juvenile forms are often associated with sheltered nursery environments, with phenotypic shifts between adults and juvenile stages that are readily apparent in locomotor morphology. However, whether this ontogenetic variation in locomotor morphology reflects a decoupling of diversification dynamics between life stages remains unknown. Here we investigate the evolutionary dynamics of locomotor morphology between adult and juvenile triggerfishes. Integrating a time-calibrated phylogenetic framework with geometric morphometric approaches and measurement data of fin aspect ratio and incidence,...
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Antarctic notothenioids represent one of the few strongly supported examples of adaptive radiation in marine fishes. The extent of population connectivity and structure is unknown for many species, thereby limiting our understanding of... more
Antarctic notothenioids represent one of the few strongly supported examples of adaptive radiation in marine fishes. The extent of population connectivity and structure is unknown for many species, thereby limiting our understanding of the factors that underlie speciation dynamics in this radiation. Here, we assess the population structure of the widespread species Cryodraco antarcticus and its sister species Cryodraco atkinsoni, whose taxonomic status is currently debated. Combining both population genetic and phylogenetic approaches to species delimitation, we provide evidence that C. atkinsoni is a distinct species. Our analyses show that C. atkinsoni and C. antarcticus are recently diverged sister lineages, and the two species differ with regard to patterns of population structure. A systematic and accurate account of species diversity is a critical prerequisite for investigations into the complex processes that underlie the history of speciation in the notothenioid adaptive radiation.
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Living reef fishes are one of the most diverse vertebrate assemblages on Earth. Despite its prominence and ecological importance, the origins and assembly of the reef fish fauna is poorly described. A patchy fossil record suggests that... more
Living reef fishes are one of the most diverse vertebrate assemblages on Earth. Despite its prominence and ecological importance, the origins and assembly of the reef fish fauna is poorly described. A patchy fossil record suggests that the major colonization of reef habitats must have occurred in the Late Cretaceous and early Palaeogene, with the earliest known modern fossil coral reef fish assemblage dated to 50 Ma. Using a phylogenetic approach, we analysed the early evolutionary dynamics of modern reef fishes. We find that reef lineages successively colonized reef habitats throughout the Late Cretaceous and early Palaeogene. Two waves of invasion were accompanied by increasing morphological convergence: one in the Late Cretaceous from 90 to 72 Ma and the other immediately following the end-Cretaceous mass extinction. The surge in reef invasions after the Cretaceous–Palaeogene boundary continued for 10 Myr, after which the pace of transitions to reef habitats slowed. Combined, the...
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Notothenioids are a clade of ∼120 species of marine fishes distributed in extreme southern hemisphere temperate near-shore habitats and in the Southern Ocean surrounding Antarctica. Over the past 25 years, molecular and morphological... more
Notothenioids are a clade of ∼120 species of marine fishes distributed in extreme southern hemisphere temperate near-shore habitats and in the Southern Ocean surrounding Antarctica. Over the past 25 years, molecular and morphological approaches have redefined hypotheses of relationships among notothenioid lineages as well as their relationships among major lineages of percomorph teleosts. These phylogenies provide a basis for investigation of mechanisms of evolutionary diversification within the clade and have enhanced our understanding of the notothenioid adaptive radiation. Despite extensive efforts, there remain several questions concerning the phylogeny of notothenioids. In this study, we deploy DNA sequences of ∼100,000 loci obtained using RADseq to investigate the phylogenetic relationships of notothenioids and to assess the utility of RADseq loci for lineages that exhibit divergence times ranging from the Paleogene to the Quaternary. The notothenioid phylogenies inferred from...
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Ostariophysi is a superorder of bony fishes including more than 10,300 species in 1,100 genera and 70 families. This superorder is traditionally divided into five major groups (orders): Gonorynchiformes (milkfishes and sandfishes),... more
Ostariophysi is a superorder of bony fishes including more than 10,300 species in 1,100 genera and 70 families. This superorder is traditionally divided into five major groups (orders): Gonorynchiformes (milkfishes and sandfishes), Cypriniformes (carps and minnows), Characiformes (tetras and their allies), Siluriformes (catfishes), and Gymnotiformes (electric knifefishes). Unambiguous resolution of the relationships among these lineages remains elusive, with previous molecular and morphological analyses failing to produce a consensus phylogeny. In this study, we use over 350 ultraconserved element (UCEs) loci comprising five million base pairs collected across thirty-five representative ostariophysan species to compile one of the most data-rich phylogenies of fishes to date. We use these data to infer higher-level (interordinal) relationships among ostariophysan fishes, focusing on the monophyly of the Characiformes- one the most contentiously debated groups in fish systematics. As ...
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Percomorph fishes represent over 17,100 species, including several model organisms and species of economic importance. Despite continuous advances in the resolution of the percomorph Tree of Life, resolution of the sister lineage to... more
Percomorph fishes represent over 17,100 species, including several model organisms and species of economic importance. Despite continuous advances in the resolution of the percomorph Tree of Life, resolution of the sister lineage to Percomorpha remains inconsistent but restricted to a small number of candidate lineages. Here we use an anchored hybrid enrichment (AHE) dataset of 132 loci with over 99,000 base pairs to identify the sister lineage of percomorph fishes. Initial analyses of this dataset failed to recover a strongly supported sister clade to Percomorpha, however, scrutiny of the AHE dataset revealed a bias towards high GC content at fast-evolving codon partitions (GC bias). By combining several existing approaches aimed at mitigating the impacts of convergence in GC bias, including RY coding and analyses of amino acids, we consistently recovered a strongly supported clade comprised of Holocentridae (squirrelfishes), Berycidae (Alfonsinos), Melamphaidae (bigscale fishes), ...
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A phylogenetic survey is a powerful approach for investigating the evolutionary history of a morphological characteristic that has evolved numerous times without obvious functional implications. Restricted gill openings, an extreme... more
A phylogenetic survey is a powerful approach for investigating the evolutionary history of a morphological characteristic that has evolved numerous times without obvious functional implications. Restricted gill openings, an extreme modification of the branchiostegal membrane, are an example of such a characteristic. We examine the evolution of branchiostegal membrane morphology and highlight convergent evolution of restricted gill openings. We surveyed specimens from 433 families of actinopterygians for branchiostegal membrane morphology and measured head and body dimensions. We inferred a relaxed molecular clock phylogeny with branch length estimates based on nine nuclear genes sampled from 285 species that include all major lineages of Actinopterygii. We calculated marginal state reconstructions of four branchiostegal membrane conditions and found that restricted gill openings have evolved independently in at least 11 major actinopterygian clades, and the total number of independe...
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One of the most striking biodiversity patterns is the uneven distribution of marine species richness, with species diversity in the Indo-Australian Archipelago (IAA) exceeding all other areas. However, the IAA formed fairly recently, and... more
One of the most striking biodiversity patterns is the uneven distribution of marine species richness, with species diversity in the Indo-Australian Archipelago (IAA) exceeding all other areas. However, the IAA formed fairly recently, and marine biodiversity hotspots have shifted across nearly half the globe since the Paleogene. Understanding how lineages have responded to shifting biodiversity hotspots represents a necessary historic perspective on the formation and maintenance of global marine biodiversity. Such evolutionary inferences are often challenged by a lack of fossil evidence that provide insights into historic patterns of abundance and diversity. The greatest diversity of squirrelfishes and soldierfishes (Holocentridae) is in the IAA, yet these fishes also represent some of the most numerous fossil taxa in deposits of the former West Tethyan biodiversity hotspot. We reconstruct the pattern of holocentrid range evolution using time-calibrated phylogenies that include most living species and several fossil lineages, demonstrating the importance of including fossil species as terminal taxa in ancestral area reconstructions. Holocentrids exhibit increased range fragmentation following the West Tethyan hotspot collapse. However, rather than originating within the emerging IAA hotspot, the IAA has acted as a reservoir for holocentrid diversity that originated in adjacent regions over deep evolutionary time scales.
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Cichlid fishes are a key model system in the study of adaptive radiation, speciation and evolutionary developmental biology. More than 1600 cichlid species inhabit freshwater and marginal marine environments across several southern... more
Cichlid fishes are a key model system in the study of adaptive radiation, speciation and evolutionary developmental biology. More than 1600 cichlid species inhabit freshwater and marginal marine environments across several southern landmasses. This distributional pattern, combined with parallels between cichlid phylogeny and sequences of Mesozoic continental rifting, has led to the widely accepted hypothesis that cichlids are an ancient group whose major biogeographic patterns arose from Gondwanan vicariance. Although the Early Cretaceous ( ca 135 Ma) divergence of living cichlids demanded by the vicariance model now represents a key calibration for teleost molecular clocks, this putative split pre-dates the oldest cichlid fossils by nearly 90 Myr. Here, we provide independent palaeontological and relaxed-molecular-clock estimates for the time of cichlid origin that collectively reject the antiquity of the group required by the Gondwanan vicariance scenario. The distribution of cich...
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Spiny-rayed fishes, or acanthomorphs, comprise nearly one-third of all living vertebrates. Despite their dominant role in aquatic ecosystems, the evolutionary history and tempo of acanthomorph diversification is poorly understood. We... more
Spiny-rayed fishes, or acanthomorphs, comprise nearly one-third of all living vertebrates. Despite their dominant role in aquatic ecosystems, the evolutionary history and tempo of acanthomorph diversification is poorly understood. We investigate the pattern of lineage diversification in acanthomorphs by using a well-resolved time-calibrated phylogeny inferred from a nuclear gene supermatrix that includes 520 acanthomorph species and 37 fossil age constraints. This phylogeny provides resolution for what has been classically referred to as the “bush at the top” of the teleost tree, and indicates acanthomorphs originated in the Early Cretaceous. Paleontological evidence suggests acanthomorphs exhibit a pulse of morphological diversification following the end Cretaceous mass extinction; however, the role of this event on the accumulation of living acanthomorph diversity remains unclear. Lineage diversification rates through time exhibit no shifts associated with the end Cretaceous mass ...
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The Southern Ocean around Antarctica is among the most rapidly warming regions on Earth, but has experienced episodic climate change during the past 40 million years. It remains unclear how ancient periods of climate change have shaped... more
The Southern Ocean around Antarctica is among the most rapidly warming regions on Earth, but has experienced episodic climate change during the past 40 million years. It remains unclear how ancient periods of climate change have shaped Antarctic biodiversity. The origin of antifreeze glycoproteins (AFGPs) in Antarctic notothenioid fishes has become a classic example of how the evolution of a key innovation in response to climate change can drive adaptive radiation. By using a time-calibrated molecular phylogeny of notothenioids and reconstructed paleoclimate, we demonstrate that the origin of AFGP occurred between 42 and 22 Ma, which includes a period of global cooling approximately 35 Ma. However, the most species-rich lineages diversified and evolved significant ecological differences at least 10 million years after the origin of AFGPs, during a second cooling event in the Late Miocene (11.6–5.3 Ma). This pattern indicates that AFGP was not the sole trigger of the notothenioid ada...
Research Interests: Climate Change, Biology, Ecology, Biodiversity, Medicine, and 15 moreMultidisciplinary, DNA, Mitochondrial DNA, Molecular clock, Animals, Biological evolution, Antifreeze proteins, Ciencias Biológicas, Buoyancy, Genetic variation, Amino Acid Sequence, Bayes Theorem, Likelihood Functions, Global Cooling, and Oceans and Seas
Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for genomics and developmental biology, and the... more
Ray-finned fishes make up half of all living vertebrate species. Nearly all ray-finned fishes are teleosts, which include most commercially important fish species, several model organisms for genomics and developmental biology, and the dominant component of marine and freshwater vertebrate faunas. Despite the economic and scientific importance of ray-finned fishes, the lack of a single comprehensive phylogeny with corresponding divergence-time estimates has limited our understanding of the evolution and diversification of this radiation. Our analyses, which use multiple nuclear gene sequences in conjunction with 36 fossil age constraints, result in a well-supported phylogeny of all major ray-finned fish lineages and molecular age estimates that are generally consistent with the fossil record. This phylogeny informs three long-standing problems: specifically identifying elopomorphs (eels and tarpons) as the sister lineage of all other teleosts, providing a unique hypothesis on the ra...
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Research Interests: Evolutionary Biology, Genetics, Bayesian, Phylogenetics, Molecular Evolution, and 15 moreBiology, Coral Reefs, Medicine, Mitochondrial DNA, Animals, Fishes, Paraphyly, Coral Reef, Molecular Phylogenetics and Evolution, Nocturnal, Molecular phylogenetics, Cell nucleus, Monophyly, Bayes Theorem, and Likelihood Functions
North America exhibits the most diverse freshwater fish fauna among temperate regions of the world. Species diversity is concentrated in the Central Highlands, drained by the Mississippi, Gulf Slope and Atlantic Slope river systems.... more
North America exhibits the most diverse freshwater fish fauna among temperate regions of the world. Species diversity is concentrated in the Central Highlands, drained by the Mississippi, Gulf Slope and Atlantic Slope river systems. Previous investigations of Central Highlands biogeography have led to conflicting hypotheses involving dispersal and vicariance to explain the diversity and distribution of the freshwater fish fauna. In this investigation predictions of the Central Highlands pre-Pleistocene vicariance hypothesis are tested with a phylogeographic analysis of the percid species Percina evides, which is widely distributed in several disjunct areas of the Central Highlands. Phylogenetic analysis of complete gene sequences of mitochondrially encoded cytochrome b recover three phylogroups, with very low levels of sequence polymorphism within groups. The two western phylogroups are monophyletic with respect to the eastern phylogroup. The recovery of two monophyletic lineages with an eastern and western distribution in the disjunct highland areas is a pattern expected from vicariance, but is not predicted by the Central Highlands pre-Pleistocene vicariance hypothesis. The recovery of very limited mitochondrial DNA polymorphism and lack of phylogeographic structuring across the entire range of the eastern clade, very shallow polymorphism between the disjunct Missouri River and upper Mississippi River populations, and lack of sequence polymorphism in the upper Mississippi River populations, support a hypothesis of dispersal during or following the Pleistocene. The present distribution of P. evides is best explained by both vicariant and dispersal events.
Research Interests: Polymorphism, Phylogeography, Biology, Ecology, Biogeography, and 15 moreMedicine, Historical Biogeography, Molecular Ecology, Biological Sciences, Phylogeny, Mitochondrial DNA, Animals, Upper Mississippi River, Phylogenetic analysis, Species Diversity, Freshwater Fish, North America, Vicariance, Cytochrome B, and Monophyly
Research Interests: Evolutionary Biology, Genetics, Molecular Evolution, Biology, Mitochondria, and 15 moreMedicine, Phylogeny, Mitochondrial DNA, Mutation, Dolphins, Molecular clock, Animals, Molecular biology and evolution, Genome, Biological evolution, Cetacea, Time Factors, Genetic variation, Nucleotides, and Biochemistry and cell biology
Research Interests: Evolutionary Biology, Genetics, Biology, Medicine, Adaptive Radiation, and 15 moreAnimals, New Zealand, Fishes, Antifreeze proteins, Gene Structure, Monophyly, Phylogenetic Tree, Antarctic circumpolar current, Amino Acid Sequence, Base Sequence, FISH FAUNA, Divergence Time, Enzyme Linked Immunosorbent Assay, Biochemistry and cell biology, and Molecular Sequence Data
Understanding the history that underlies patterns of species richness across the Tree of Life requires an investigation of the mechanisms that not only generate young species-rich clades, but also those that maintain species-poor lineages... more
Understanding the history that underlies patterns of species richness across the Tree of Life requires an investigation of the mechanisms that not only generate young species-rich clades, but also those that maintain species-poor lineages over long stretches of evolutionary time. However, diversification dynamics that underlie ancient species-poor lineages are often hidden due to a lack of fossil evidence. Using information from the fossil record and time calibrated molecular phylogenies, we investigate the history of lineage diversification in Polypteridae, which is the sister lineage of all other ray-finned fishes (Actinopterygii). Despite originating at least 390 million years (Myr) ago, molecular timetrees support a Neogene origin for the living polypterid species. Our analyses demonstrate polypterids are exceptionally species depauperate with a stem lineage duration that exceeds 380 million years (Ma) and is significantly longer than the stem lineage durations observed in other ray-finned fish lineages. Analyses of the fossil record show an early Late Cretaceous (100.5-83.6 Ma) peak in polypterid genus richness, followed by 60 Ma of low richness. The Neogene species radiation and evidence for high-diversity intervals in the geological past suggest a "boom and bust" pattern of diversification that contrasts with common perceptions of relative evolutionary stasis in so-called "living fossils."