03109nas a2200205   4500008004100000022001400041245011300055210006900168300001200237490000800249520246300257100001902720700002202739700001902761700002302780700002302803700001902826700002002845856003802865       2011                        eng d  a0024-407400aGenetic variation and phylogenetic relationships of a pantropical species group in Polystachya (Orchidaceae)0 aGenetic variation and phylogenetic relationships of a pantropica  a235-2500 v1653 aAmplified fragment length polymorphism (AFLP) markers were used to investigate the relationships among Polystachya accessions from a group of closely related pantropical tetraploids. Before starting with the fingerprinting analyses, the polyploid accessions were first included in a phylogenetic analysis using low-copy nuclear DNA data to establish their relationships, which confirmed that they belonged to a species group of closely related allotetraploids. Neo- and Palaeotropical polyploid accessions formed two hybrid clades with apparently independent origins. Sampling for the AFLP analyses included single accessions from much of the range of the genus and populations from Costa Rica (CR) and Sri Lanka (SL) to compare population structure and genetic diversity in these two areas in more detail. A splits graph of the complete AFLP data showed three major clusters corresponding to three sources of population sampling (P. concreta, SL; P. foliosa, CR; P. masayensis, CR), with individual accessions from Africa and Indian Ocean islands showing a closer relationship to P. concreta from SL than to the two CR species. Individual accessions from the Neotropics occurred in more isolated positions in the splits network, with little resolution. Some P. foliosa accessions clustered with P. masayensis, suggesting some hybridization between the two species, and this was confirmed by Bayesian structure analysis. However, the splits network, structure and analyses of molecular variance indicated a generally high level of genetic divergence between the two CR species, despite their recent hybrid origin, occurrence in largely the same localities and occasional hybridization. Polystachya foliosa from CR had a higher degree of population-level genetic structure (Phi(ST) = 0.291) than P. masayensis from CR (Phi(ST) = 0.161) and P. concreta from SL (Phi(ST) = 0.138), possibly because of its occurrence within a larger and more environmentally diverse continuous range than the other two species. Genetic divergence between Neo- and Palaeotropical members of the pantropical tetraploid group of Polystachya and the nonmonophyly of P. concreta suggested that P. concreta s.l. should be split and the use of this epithet should be confined to the Neotropics (the type is from Martinique). Other names should be used in Africa and the Asian tropics. (c) 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165, 235-250.1 aRussell, Anton1 aSamuel, Rosabelle1 aBogarin, Diego1 aFernando, Suranjan1 aWijesundera, Siril1 aKlejna, Verena1 aChase, Mark, W.  u<Go to ISI>://WOS:00028719530000202156nas a2200193   4500008004100000022002500041245011300066210006900179300001400248490000700262520151300269100001601782700003501798700001901833700002301852700002001875700002901895856003801924       2012                        eng d  a0014-3820; 1558-564600aTESTING THE LINK BETWEEN POPULATION GENETIC DIFFERENTIATION AND CLADE DIVERSIFICATION IN COSTA RICAN ORCHIDS0 aTESTING THE LINK BETWEEN POPULATION GENETIC DIFFERENTIATION AND   a3035-30520 v663 aSpecies population genetics could be an important factor explaining variation in clade species richness. Here, we use newly generated amplified fragment length polymorphism (AFLP) data to test whether five pairs of sister clades of Costa Rican orchids that differ greatly in species richness also differ in average neutral genetic differentiation within species, expecting that if the strength of processes promoting differentiation within species is phylogenetically heritable, then clades with greater genetic differentiation should diversify more. Contrary to expectation, neutral genetic differentiation does not correlate directly with total diversification in the clades studied. Neutral genetic differentiation varies greatly among species and shows no heritability within clades. Half of the variation in neutral genetic differentiation among populations can be explained by ecological variables, and species-level traits explain the most variation. Unexpectedly, we find no isolation by distance in any species, but genetic differentiation is greater between populations occupying different niches. This pattern corresponds with those observed for microscopic eukaryotes and could reflect effective widespread dispersal of tiny and numerous orchid seeds. Although not providing a definitive answer to whether population genetics processes affect clade diversification, this work highlights the potential for addressing new macroevolutionary questions using a comparative population genetic approach.1 aKisel, Yael1 aMoreno-Letelier, Alejandra, C.1 aBogarin, Diego1 aPowell, Martyn, P.1 aChase, Mark, W.1 aBarraclough, Timothy, G.  u<Go to ISI>://WOS:000309393000004