The trajectory of speciation involves geographic isolation of ancestral populations followed by divergence by natural selection, genetic drift or sexual selection. Once started, the process may experience fits and starts, as sometimes diverging populations intermittently reconnect. In theory populations might cycle between stages of differentiation and never attain species status, a process we refer to as Sisyphean evolution.
View Article and Find Full Text PDFSpecies designations are critically important scientific hypotheses that serve as the foundational units in a wide range of biological subdisciplines. A growing realization that some classes of data fail to delimit species under certain conditions has led to increasingly more integrative taxonomies, whereby species discovery and hypothesis testing are based on multiple kinds of data (e.g.
View Article and Find Full Text PDFThe process of discovering species is a fundamental responsibility of systematics. Recently, there has been a growing interest in coalescent-based methods of species delimitation aimed at objectively identifying species early in the divergence process. However, few empirical studies have compared these new methods with character-based approaches for discovering species.
View Article and Find Full Text PDFThe lowland tailorbirds of Southeast Asia (Orthotomus) offer an excellent opportunity for comparative biogeography because of their diversity in the Greater Sunda and Philippine islands. We reconstructed the phylogeny of all species in the genus using maximum likelihood, Bayesian, and coalescent methods on DNA sequences of three gene segments: an autosomal intron (TGF), a Z-linked intron (MUSK), and a mitochondrial coding gene (ND2). Although resolution is low in parts of the phylogeny, several well defined clades emerge.
View Article and Find Full Text PDFBackground: The subtropical island of Taiwan is an area of high endemism and a complex topographic environment. Phylogeographic studies indicate that vicariance caused by Taiwan's mountains has subdivided many taxa into genetic phylogroups. We used mitochondrial DNA sequences and nuclear microsatellites to test whether the evolutionary history of an endemic montane bird, Steere's Liocichla (Liocichla steerii), fit the general vicariant paradigm for a montane organism.
View Article and Find Full Text PDFPhylogenetic relationships among the 14 manakin genera were inferred from DNA sequence data obtained from both mitochondrial and nuclear DNA loci. Phylogenetic analysis resulted in a well-supported hypothesis that corroborates a sister relationship between tyrant-manakins and the "core" manakins (Antilophia, Chiroxiphia, Corapipo, Dixiphia, Heterocercus, Ilicura, Lepidothrix, Manacus, Masius, Machaeropterus, Pipra, and Xenopipo). Our data strongly support these core manakin genera as a monophyletic group.
View Article and Find Full Text PDFGene tree paraphyly is a potentially serious problem because many phylogenetic and phylogeographic studies assume species are monophyletic. Funk and Omland (Funk, D.J.
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