Browsing by Subject "Genetic Speciation"
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Item Restricted Delimiting species without nuclear monophyly in Madagascar's mouse lemurs.(PLoS One, 2010-03-31) Weisrock, David W; Rasoloarison, Rodin M; Fiorentino, Isabella; Ralison, José M; Goodman, Steven M; Kappeler, Peter M; Yoder, Anne DBACKGROUND: Speciation begins when populations become genetically separated through a substantial reduction in gene flow, and it is at this point that a genetically cohesive set of populations attain the sole property of species: the independent evolution of a population-level lineage. The comprehensive delimitation of species within biodiversity hotspots, regardless of their level of divergence, is important for understanding the factors that drive the diversification of biota and for identifying them as targets for conservation. However, delimiting recently diverged species is challenging due to insufficient time for the differential evolution of characters--including morphological differences, reproductive isolation, and gene tree monophyly--that are typically used as evidence for separately evolving lineages. METHODOLOGY: In this study, we assembled multiple lines of evidence from the analysis of mtDNA and nDNA sequence data for the delimitation of a high diversity of cryptically diverged population-level mouse lemur lineages across the island of Madagascar. Our study uses a multi-faceted approach that applies phylogenetic, population genetic, and genealogical analysis for recognizing lineage diversity and presents the most thoroughly sampled species delimitation of mouse lemur ever performed. CONCLUSIONS: The resolution of a large number of geographically defined clades in the mtDNA gene tree provides strong initial evidence for recognizing a high diversity of population-level lineages in mouse lemurs. We find additional support for lineage recognition in the striking concordance between mtDNA clades and patterns of nuclear population structure. Lineages identified using these two sources of evidence also exhibit patterns of population divergence according to genealogical exclusivity estimates. Mouse lemur lineage diversity is reflected in both a geographically fine-scaled pattern of population divergence within established and geographically widespread taxa, as well as newly resolved patterns of micro-endemism revealed through expanded field sampling into previously poorly and well-sampled regions.Item Open Access Likelihoods from summary statistics: recent divergence between species.(Genetics, 2005-11) Leman, Scotland C; Chen, Yuguo; Stajich, Jason E; Noor, Mohamed AF; Uyenoyama, Marcy KWe describe an importance-sampling method for approximating likelihoods of population parameters based on multiple summary statistics. In this first application, we address the demographic history of closely related members of the Drosophila pseudoobscura group. We base the maximum-likelihood estimation of the time since speciation and the effective population sizes of the extant and ancestral populations on the pattern of nucleotide variation at DPS2002, a noncoding region tightly linked to a paracentric inversion that strongly contributes to reproductive isolation. Consideration of summary statistics rather than entire nucleotide sequences permits a compact description of the genealogy of the sample. We use importance sampling first to propose a genealogical and mutational history consistent with the observed array of summary statistics and then to correct the likelihood with the exact probability of the history determined from a system of recursions. Analysis of a subset of the data, for which recursive computation of the exact likelihood was feasible, indicated close agreement between the approximate and exact likelihoods. Our results for the complete data set also compare well with those obtained through Metropolis-Hastings sampling of fully resolved genealogies of entire nucleotide sequences.Item Open Access Natural hybridization between genera that diverged from each other approximately 60 million years ago.(Am Nat, 2015-03) Rothfels, CJ; Johnson, AK; Hovenkamp, PH; Swofford, DL; Roskam, HC; Fraser-Jenkins, CR; Windham, MD; Pryer, KMA fern from the French Pyrenees-×Cystocarpium roskamianum-is a recently formed intergeneric hybrid between parental lineages that diverged from each other approximately 60 million years ago (mya; 95% highest posterior density: 40.2-76.2 mya). This is an extraordinarily deep hybridization event, roughly akin to an elephant hybridizing with a manatee or a human with a lemur. In the context of other reported deep hybrids, this finding suggests that populations of ferns, and other plants with abiotically mediated fertilization, may evolve reproductive incompatibilities more slowly, perhaps because they lack many of the premating isolation mechanisms that characterize most other groups of organisms. This conclusion implies that major features of Earth's biodiversity-such as the relatively small number of species of ferns compared to those of angiosperms-may be, in part, an indirect by-product of this slower "speciation clock" rather than a direct consequence of adaptive innovations by the more diverse lineages.Item Open Access Primate diversification inferred from phylogenies and fossils.(Evolution; international journal of organic evolution, 2017-12) Herrera, James PBiodiversity arises from the balance between speciation and extinction. Fossils record the origins and disappearance of organisms, and the branching patterns of molecular phylogenies allow estimation of speciation and extinction rates, but the patterns of diversification are frequently incongruent between these two data sources. I tested two hypotheses about the diversification of primates based on ∼600 fossil species and 90% complete phylogenies of living species: (1) diversification rates increased through time; (2) a significant extinction event occurred in the Oligocene. Consistent with the first hypothesis, analyses of phylogenies supported increasing speciation rates and negligible extinction rates. In contrast, fossils showed that while speciation rates increased, speciation and extinction rates tended to be nearly equal, resulting in zero net diversification. Partially supporting the second hypothesis, the fossil data recorded a clear pattern of diversity decline in the Oligocene, although diversification rates were near zero. The phylogeny supported increased extinction ∼34 Ma, but also elevated extinction ∼10 Ma, coinciding with diversity declines in some fossil clades. The results demonstrated that estimates of speciation and extinction ignoring fossils are insufficient to infer diversification and information on extinct lineages should be incorporated into phylogenetic analyses.Item Open Access Reconciling extreme branch length differences: decoupling time and rate through the evolutionary history of filmy ferns.(Systematic biology, 2006-06) Schuettpelz, E; Pryer, KMThe rate of molecular evolution is not constant across the Tree of Life. Characterizing rate discrepancies and evaluating the relative roles of time and rate along branches through the past are both critical to a full understanding of evolutionary history. In this study, we explore the interactions of time and rate in filmy ferns (Hymenophyllaceae), a lineage with extreme branch length differences between the two major clades. We test for the presence of significant rate discrepancies within and between these clades, and we separate time and rate across the filmy fern phylogeny to simultaneously yield an evolutionary time scale of filmy fern diversification and reconstructions of ancestral rates of molecular evolution. Our results indicate that the branch length disparity observed between the major lineages of filmy ferns is indeed due to a significant difference in molecular evolutionary rate. The estimation of divergence times reveals that the timing of crown group diversification was not concurrent for the two lineages, and the reconstruction of ancestral rates of molecular evolution points to a substantial rate deceleration in one of the clades. Further analysis suggests that this may be due to a genome-wide deceleration in the rate of nucleotide substitution.Item Open Access Whole-genome analyses resolve early branches in the tree of life of modern birds.(Science, 2014-12-12) Jarvis, Erich D; Mirarab, Siavash; Aberer, Andre J; Li, Bo; Houde, Peter; Li, Cai; Ho, Simon YW; Faircloth, Brant C; Nabholz, Benoit; Howard, Jason T; Suh, Alexander; Weber, Claudia C; da Fonseca, Rute R; Li, Jianwen; Zhang, Fang; Li, Hui; Zhou, Long; Narula, Nitish; Liu, Liang; Ganapathy, Ganesh; Boussau, Bastien; Bayzid, Md Shamsuzzoha; Zavidovych, Volodymyr; Subramanian, Sankar; Gabaldón, Toni; Capella-Gutiérrez, Salvador; Huerta-Cepas, Jaime; Rekepalli, Bhanu; Munch, Kasper; Schierup, Mikkel; Lindow, Bent; Warren, Wesley C; Ray, David; Green, Richard E; Bruford, Michael W; Zhan, Xiangjiang; Dixon, Andrew; Li, Shengbin; Li, Ning; Huang, Yinhua; Derryberry, Elizabeth P; Bertelsen, Mads Frost; Sheldon, Frederick H; Brumfield, Robb T; Mello, Claudio V; Lovell, Peter V; Wirthlin, Morgan; Schneider, Maria Paula Cruz; Prosdocimi, Francisco; Samaniego, José Alfredo; Vargas Velazquez, Amhed Missael; Alfaro-Núñez, Alonzo; Campos, Paula F; Petersen, Bent; Sicheritz-Ponten, Thomas; Pas, An; Bailey, Tom; Scofield, Paul; Bunce, Michael; Lambert, David M; Zhou, Qi; Perelman, Polina; Driskell, Amy C; Shapiro, Beth; Xiong, Zijun; Zeng, Yongli; Liu, Shiping; Li, Zhenyu; Liu, Binghang; Wu, Kui; Xiao, Jin; Yinqi, Xiong; Zheng, Qiuemei; Zhang, Yong; Yang, Huanming; Wang, Jian; Wang, Jian; Smeds, Linnea; Rheindt, Frank E; Braun, Michael; Fjeldsa, Jon; Orlando, Ludovic; Barker, F Keith; Jønsson, Knud Andreas; Johnson, Warren; Koepfli, Klaus-Peter; O'Brien, Stephen; Haussler, David; Ryder, Oliver A; Rahbek, Carsten; Willerslev, Eske; Graves, Gary R; Glenn, Travis C; McCormack, John; Burt, Dave; Ellegren, Hans; Alström, Per; Edwards, Scott V; Stamatakis, Alexandros; Mindell, David P; Cracraft, Joel; Braun, Edward L; Warnow, Tandy; Jun, Wang; Gilbert, M Thomas P; Zhang, GuojieTo better determine the history of modern birds, we performed a genome-scale phylogenetic analysis of 48 species representing all orders of Neoaves using phylogenomic methods created to handle genome-scale data. We recovered a highly resolved tree that confirms previously controversial sister or close relationships. We identified the first divergence in Neoaves, two groups we named Passerea and Columbea, representing independent lineages of diverse and convergently evolved land and water bird species. Among Passerea, we infer the common ancestor of core landbirds to have been an apex predator and confirm independent gains of vocal learning. Among Columbea, we identify pigeons and flamingoes as belonging to sister clades. Even with whole genomes, some of the earliest branches in Neoaves proved challenging to resolve, which was best explained by massive protein-coding sequence convergence and high levels of incomplete lineage sorting that occurred during a rapid radiation after the Cretaceous-Paleogene mass extinction event about 66 million years ago.