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Taxonomic Sampling (taxonomic + sampling)

Distribution by Scientific Domains
Life Sciences87%

Kinds of Taxonomic Sampling

  • comprehensive taxonomic sampling
    		•

    Selected Abstracts

    Molecular clocks keep dispersal hypotheses afloat: evidence for trans-Atlantic rafting by rodents

    JOURNAL OF BIOGEOGRAPHY, Issue 2 2010
    Diane L. Rowe
    Abstract Aim, In order to resolve disputed biogeographical histories of biota with Gondwanan continental distributions, and to assess the null hypothesis of vicariance, it is imperative that a robust geological time-frame be established. As an example, the sudden and coincident appearance of hystricognath rodents (Rodentia: Hystricognathi) on both the African and South American continents has been an irreconcilable controversy for evolutionary biologists, presenting enigmas for both Gondwanan vicariance and Late Eocene dispersal hypotheses. In an attempt to resolve this discordance, we aim to provide a more robust phylogenetic hypothesis and improve divergence-date estimates, which are essential to assessing the null hypothesis of vicariance biogeography. Location, The primary centres of distribution are in Africa and South America. Methods, We implemented parsimony, maximum-likelihood and Bayesian methods to generate a phylogeny of 37 hystricognath taxa, the most comprehensive taxonomic sampling of this group to date, on the basis of two nuclear gene regions. To increase phylogenetic resolution at the basal nodes, these data were combined with previously published data for six additional nuclear gene regions. Divergence dates were estimated using two relaxed-molecular-clock methods, Bayesian multidivtime and nonparametric rate smoothing. Results, Our data do not support reciprocal monophyly of African and South American lineages. Indeed, Old World porcupines (i.e. Hystricomorpha) appear to be more closely related to New World lineages (i.e. Caviomorpha) than to other Old World families (i.e. Bathyergidae, Petromuridae and Thryonomyidae). The divergence between the monophyletic assemblage of South American lineages and its Old World ancestor was estimated to have occurred c. 50 Ma. Main conclusions, Our phylogenetic hypothesis and divergence-date estimates are strongly at odds with Gondwanan-vicariance isolating mechanisms. In contrast, our data suggest that transoceanic dispersal has played a significant role in governing the contemporary distribution of hystricognath rodents. Molecular-clock analyses imply a trans-Tethys dispersal event, broadly confined to the Late Cretaceous, and trans-Atlantic dispersal within the Early Eocene. Our analyses also imply that the use of the oldest known South American rodent fossil as a calibration point has biased molecular-clock inferences. [source]

    Continental speciation in the tropics: contrasting biogeographic patterns of divergence in the Uroplatus leaf-tailed gecko radiation of Madagascar

    JOURNAL OF ZOOLOGY, Issue 4 2008
    C. J. Raxworthy
    Abstract A fundamental expectation of vicariance biogeography is for contemporary cladogenesis to produce spatial congruence between speciating sympatric clades. The Uroplatus leaf-tailed geckos represent one of most spectacular reptile radiations endemic to the continental island of Madagascar, and thus serve as an excellent group for examining patterns of continental speciation within this large and comparatively isolated tropical system. Here we present the first phylogeny that includes complete taxonomic sampling for the group, and is based on morphology and molecular (mitochondrial and nuclear DNA) data. This study includes all described species, and we also include data for eight new species. We find novel outgroup relationships for Uroplatus and find strongest support for Paroedura as its sister taxon. Uroplatus is estimated to have initially diverged during the mid-Tertiary in Madagascar, and includes two major speciose radiations exhibiting extensive spatial overlap and estimated contemporary periods of speciation. All sister species are either allopatric or parapatric. However, we found no evidence for biogeographic congruence between these sympatric clades, and dispersal events are prevalent in the dispersal,vicariance biogeographic analyses, which we estimate to date to the Miocene. One sister-species pair exhibits isolated distributions that we interpret as biogeographic relicts, and two sister-species pairs have parapatric distributions separated by elevation. Integrating ecological niche models with our phylogenetic results finds both conserved and divergent niches between sister species. We also found substantial intra-specific genetic variation, and for the three most widespread species, poor intra-specific predictive performance for ecological niche models across the latitudinal span of Madagascar. These latter results indicate the potential for intra-specific niche specialization along environmental gradients, and more generally, this study suggests a complex speciation history for this group in Madagascar, which appears to include multiple speciation processes. [source]

    A butterfly eye's view of birds

    BIOESSAYS, Issue 11-12 2008
    Francesca D. Frentiu
    The striking color patterns of butterflies and birds have long interested biologists. But how these animals see color is less well understood. Opsins are the protein components of the visual pigments of the eye. Color vision has evolved in butterflies through opsin gene duplications, through positive selection at individual opsin loci, and by the use of filtering pigments. By contrast, birds have retained the same opsin complement present in early-jawed vertebrates, and their visual system has diversified primarily through tuning of the short-wavelength-sensitive photoreceptors, rather than by opsin duplication or the use of filtering elements. Butterflies and birds have evolved photoreceptors that might use some of the same amino acid sites for generating similar spectral phenotypes across ,540 million years of evolution, when rhabdomeric and ciliary-type opsins radiated during the early Cambrian period. Considering the similarities between the two taxa, it is surprising that the eyes of birds are not more diverse. Additional taxonomic sampling of birds may help clarify this mystery. BioEssays 30:1151,1162, 2008. © 2008 Wiley Periodicals, Inc. [source]

    A global phylogeny of apple snails: Gondwanan origin, generic relationships, and the influence of outgroup choice (Caenogastropoda: Ampullariidae)

    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009
    KENNETH A. HAYES
    Apple snails (Ampullariidae) are a diverse family of pantropical freshwater snails and an important evolutionary link to the common ancestor of the largest group of living gastropods, the Caenogastropoda. A clear understanding of relationships within the Ampullariidae, and identification of their sister taxon, is therefore important for interpreting gastropod evolution in general. Unfortunately, the overall pattern has been clouded by confused systematics within the family and equivocal results regarding the family's sister group relationships. To clarify the relationships among ampullariid genera and to evaluate the influence of including or excluding possible sister taxa, we used data from five genes, three nuclear and two mitochondrial, from representatives of all nine extant ampullariid genera, and species of Viviparidae, Cyclophoridae, and Campanilidae, to reconstruct the phylogeny of apple snails, and determine their affinities to these possible sister groups. The results obtained indicate that the Old and New World ampullariids are reciprocally monophyletic with probable Gondwanan origins. All four Old World genera, Afropomus, Saulea, Pila, and Lanistes, were recovered as monophyletic, but only Asolene, Felipponea, and Pomella were monophyletic among the five New World genera, with Marisa paraphyletic and Pomacea polyphyletic. Estimates of divergence times among New World taxa suggest that diversification began shortly after the separation of Africa and South America and has probably been influenced by hydrogeological events over the last 90 Myr. The sister group of the Ampullariidae remains unresolved, but analyses omitting certain outgroup taxa suggest the need for dense taxonomic sampling to increase phylogenetic accuracy within the ingroup. The results obtained also indicate that defining the sister group of the Ampullariidae and clarifying relationships among basal caenogastropods will require increased taxon sampling within these four families, and synthesis of both morphological and molecular data. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 61,76. [source]

    Integrating numt pseudogenes into mitochondrial phylogenies: comment on ,Mitochondrial phylogeny of Arvicolinae using comprehensive taxonomic sampling yields new insights'

    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009
    DEBORAH A. TRIANT
    No abstract is available for this article. [source]

    Reply to Triant D and DeWoody J: Integrating numt pseudogenes into mitochondrial phylogenies: comment on Mitochondrial phylogeny of Arvicolinae using comprehensive taxonomic sampling yields new insights

    BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009
    ELENA V. BUZAN
    No abstract is available for this article. [source]

    Reconstructing the origins of praying mantises (Dictyoptera, Mantodea): the roles of Gondwanan vicariance and morphological convergence

    CLADISTICS, Issue 5 2009
    Gavin J. Svenson
    A comprehensive taxonomic sampling of Mantodea (praying mantises), covering virtually all higher-level groups, was assembled to reconstruct the phylogeny of the order. Sequence data were generated from five mitochondrial and four nuclear loci (12S rRNA, 16S rRNA, 18S rRNA, 28S rRNA, Histone III, Cytochrome Oxidase I & II, NADH dehydrogenase subunit 4, and Wingless) for 329 mantis exemplars along with seven cockroach and eight termite species. Only seven of 14 families, 14 of 33 subfamilies, and seven of 14 tribes were recovered as monophyletic, indicating that phylogeny is largely incongruent with classification. Mapping biogeographical regions on the phylogeny demonstrated that our results adhere closer to biogeographical distributions than to classification. Specific patterns in distribution suggest that major morphological convergences have confounded taxonomists' ability to reconstruct natural groups. A major revision of higher-level relationships is in order through a comprehensive investigation of morphology and molecular data. We found that major mantis lineages diverged prior to and during the isolation of geographical regions and subsequent ecomorphic specializations within these regions may have led to convergences in morphology. Divergence time estimation places the origin of Mantodea at the beginning of the Jurassic with most modern mantises originating on Gondwana in the Cretaceous. The first major divergence among modern mantises occurred as a result of the north,south splitting of South America and Africa. Subsequent divergences resulted from the breakup of Gondwana. The position of the Indian subcontinent appears to be central to the diversification of Afrotropical and Indomalayan mantises while Antarctica may have served as the conduit for the mantis invasions into South America and Australasia. When India separated from Antarctica and drifted north it distributed mantis lineages back into the Afrotropics and carried a diverse taxonomic assemblage to Asia. [source]

    Phylogeny of the Trilobite Subgenus Acanthopyge (Lobopyge)

    CLADISTICS, Issue 1 2001
    Malte C. Ebach
    Cladistic analysis of the trilobite subgenus Acanthopyge (Lobopyge) has not been previously attempted, apart from an inferred phylogeny of the Lichida by Thomas and Holloway (1988, Philos. Trans. R. Soc. London B Biol. Sci. 321, 179,262). Results of two separate analyses with variable taxonomic sampling show a possible cosmopolitan affinity for Australian Devonian species of A. (Lobopyge) and corroborate the placement of A. (Lobopyge) rohri in A. (Lobopyge). Benelopyge is a junior subjective synonym of A. (Lobopyge). [source]