Phylogeography and genetic differentiation along the distributional range of the orchid Epidendrum fulgens: a Neotropical coastal species not restricted to glacial refugia

Abstract

Aim Phylogeographical studies in the Brazilian Atlantic Forest (BAF) have mostly included species associated with forest habitats, whereas taxa associated with grassland and sand-dune plant communities have so far been largely overlooked. This study examines the phylogeography of the orchid Epidendrum fulgens, which occurs on coastal sand dunes and granitic outcrops, in order to identify major genetic divergences or disjunctions across the range of the species and to investigate the genetic signatures of past range contractions and expansions.Location Southern and south-eastern seashore vegetation along the BAF biome, and granitic and arenitic outcrops that occur in the subtropical grassland plant communities located south of the BAF.Methods Nine nuclear and four plastid microsatellite loci were used to genotype 424 individuals from 16 populations across the distributional range of E. fulgens. For both sets of markers, we estimated genetic diversity and population differentiation, testing for a north-south gradient of genetic diversity. The plastid haplotype network and a Bayesian assignment analysis of nuclear markers were used to infer population structure. Past demographic changes were investigated using a coalescence approach.Results A deep disjunction was found between northern populations within the BAF and southern populations outside the BAF that occur on granitic and arenitic outcrops. Recent demographic reductions were detected in northern populations on coastal sands. Such demographic changes were not expected for those populations, as previous studies with forest species had found evidence of population expansion in the same areas. Higher genetic diversity was found in southern populations on granite, in contrast to patterns observed in previous studies of forest species. Main conclusionsThe results are consistent with the long-term persistence of E. fulgens. Bottlenecks were detected in populations from areas where population expansion events have been detected in other plant (and animal) species, suggesting that forest expansion after the Last Glacial Maximum played a role in the population fragmentation and decrease in genetic diversity in E. fulgens. A substantial genetic division in E. fulgens corresponds to the 'Portal de Torres', a region that demarcates the northern limits of subtropical grassland plant communities and the southern limits of the BAF.

Model-based analysis supports interglacial refugia over long-dispersal events in the diversification of two South American cactus species

“…This is not true for species occurring in xeric and open environments as the rocky savanna habitats in Eastern South America, which show more idiosyncratic patterns (Turchetto-Zolet et al, 2013). For instance, distinct responses have been found in species distribution ranges during the same paleoclimatic phases such as signals of expansion in the Drosophila buzatti cluster, which exclusively uses decaying stems of cactus as breeding sites (Moraes et al, 2009), shrink in a tree species of Cerrado (savanna) biome, Dipteryx alata Vogel (Collevatti et al, 2013) and stability in the Neotropical coastal species of orchid Epidendrum fulgens (Pinheiro et al, 2011), and in the gecko Phyllopezus pollicaris, a specialist species of rocky outcrop habitats (Werneck et al, 2012).…”

Development and characterization of microsatellite loci for Tabebuia cassinoides (Bignoniaceae)

“…Plant population genetic studies have increased substantially in the past years Diniz-Filho et al, 2012;Pinheiro et al, 2010Pinheiro et al, , 2011Pinheiro et al, , 2013). Yet, the development of molecular markers with adequate levels of variation to investigate the genetic structure within and among populations remains one of the greatest limitations of these types of studies.…”

Filogeografia de <i>Cattleya loddigesii</i> Lindl. e <i>Cattleya harrisoniana</i> (ex Lindl.) Bateman (Orchidaceae)

“…(2008) Estudos filogeográficos em espécies neotropicais têm sido importantes para testar zonas de refúgio na fauna e flora brasileira, e além disso, é possível inferir em outros padrões evolutivos que podem estar associados com a distribuição espacial das espécies (NOVAES et al, 2010;COOK et al, 2012;BRANDÃO, 2012;LIMA, 2012;ALVES, 2013;SCOTTI-SAINTAGNE et al, 2013;CORONADO et al, 2014;RUIZ-GARCÍA et al, 2015;MATOS et al, 2016). Entre as regiões mais estudadas se encontra a Mata Atlântica Brasileira, que possui grande parte dessa biodiversidade (CARNAVAL et al, 2009, COLOMBI et al, 2010THOMÉ et al, 2010;PINHEIRO et al, 2011;RIBEIRO et al, 2011;BATALHA-FILHO et al, 2012;AMARO et al, 2012;PINHEIRO et al, 2013;PINHEIRO et al, 2014;CARDOSO et al, 2015;RODRIGUES et al, 2015;RODRIGUES, 2015). Nesse contexto, estudos envolvendo biogeografia e filogeografia de diferentes seres vivos apontam a uma cadeia de eventos evolutivos que podem ter ocorrido no passado e que são responsáveis pela distribuição atual das espécies nos dias de hoje (TURCHETTO-ZOLET, 2013).…”

“…Sua importância em estudos com plantas é explicada pela forma como são adquiridos os dados, pois possuem características apenas materna em muitos organismos, não apresentam recombinação e são muito frequentes nas células (PROVAN; BENNETT, 2008). O modo de herança uniparental é relevante para auxiliar nas relações entre dispersão de pólen e sementes no fluxo gênico em plantas e é eficaz na investigação de processos demográficos históricos (McCAULEY, 1995;COZZOLINO et al, 2003;PINHEIRO et al, 2011). Além disso, pelo fato do genoma do cloroplasto ser haploide, a deriva genética consegue atuar quatro vezes mais rápido comparado ao genoma nuclear e, consequentemente, os haplótipos são fixados mais rapidamente (HEDRICK, 2011).…”