PHYLOGEOGRAPHIC STRUCTURE AND OUTBREEDING DEPRESSION REVEAL EARLY STAGES OF REPRODUCTIVE ISOLATION IN THE NEOTROPICAL ORCHIDEPIDENDRUM DENTICULATUM
Open Access
- 22 February 2013
- Vol. 67 (7), 2024-2039
- https://doi.org/10.1111/evo.12085
Abstract
Phylogeographic studies provide an important framework for investigating the mechanisms operating during the earliest stages of speciation, as reproductive barriers can be examined among divergent lineages in a geographic context. We investigated the evolution of early stages of intrinsic postmating isolation among different populations and lineages of Epidendrum denticulatum, a Neotropical orchid distributed across different biomes in South America. We estimated genetic diversity and structure for both nuclear and plastid markers, using a haplotype network, differentiation tests, Bayesian assignment analysis, and divergence time estimates of the main lineages. Reproductive barriers among divergent lineages were examined by analyzing seed viability following reciprocal crossing experiments. Strong plastid phylogeographic structure was found, indicating that E. denticulatum was restricted to multiple refuges during South American forest expansion events. In contrast, significant phylogeographic structure was not found for nuclear markers, suggesting higher gene flow by pollen than by seeds. Large asymmetries in seed set were observed among different plastid genetic groups, suggesting the presence of polymorphic genic incompatibilities associated with cytonuclear interactions. Our results confirm the importance of phylogeographic studies associated with reproductive isolation experiments and suggest an important role for outbreeding depression during the early stages of lineage diversification.Keywords
This publication has 100 references indexed in Scilit:
- Large-scale phylogeography of the disjunct Neotropical tree species Schizolobium parahyba (Fabaceae-Caesalpinioideae)Molecular Phylogenetics and Evolution, 2012
- STRUCTURE HARVESTER: a website and program for visualizing STRUCTURE output and implementing the Evanno methodConservation Genetics Resources, 2011
- Is floral divergence sufficient to maintain species boundaries upon secondary contact in Mediterranean food-deceptive orchids?Heredity, 2011
- Geographical variation in postzygotic isolation and its genetic basis within and between twoMimulusspeciesPhilosophical Transactions B, 2010
- Speciation genes in plantsAnnals of Botany, 2010
- Phylogeography of endemic toads and post-Pliocene persistence of the Brazilian Atlantic ForestMolecular Phylogenetics and Evolution, 2010
- Recent assembly of the Cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fireProceedings of the National Academy of Sciences of the United States of America, 2009
- Phylogeographic Analyses and Paleodistribution Modeling Indicate Pleistocene In Situ Survival of Hordeum Species (Poaceae) in Southern Patagonia without Genetic or Spatial RestrictionMolecular Biology and Evolution, 2009
- The strength and genetic basis of reproductive isolating barriers in flowering plantsPhilosophical Transactions B, 2008
- The historical bridge between the Amazon and the Atlantic Forest of Brazil: a study of molecular phylogeography with small mammalsJournal of Biogeography, 2003