DOI: 10.5061/dryad.mg5rs
title: Data from: Long-term persisting hybrid swarm and geographic difference in hybridization pattern: genetic consequences of secondary contact between two Vincetoxicum species (Apocynaceae–Asclepiadoideae)

description: Background: During glacial periods, glacial advances caused temperate
 plant extirpation or retreat into localized warmer areas, and subsequent
 postglacial glacial retreats resulted in range expansions, which
 facilitated secondary contact of previously allopatric isolated lineages.
 The evolutionary outcomes of secondary contact, including hybrid zones,
 dynamic hybrid swarm, and resultant hybrid speciation, depends on the
 strengths of reproductive barriers that have arisen through epistatic and
 pleiotropic effects during allopatric isolation. The aim of this study was
 to demonstrate refugia isolation and subsequent secondary contact between
 two perennial Asclepioid species and to assess the genetic consequences of
 the secondary contact. We modeled the range shift of two ecologically
 distinct Vincetoxicum species using the species distribution model (SDM)
 and assessed the genetic consequences of secondary contact by combining
 morphological and genetic approaches. We performed morphometric analysis
 (592 individuals) and examined 10 nuclear microsatellites (671
 individuals) in V. atratum, V. japonicum, and putative hybrid populations.
 Results: Multivariate analysis, model-based Bayesian analysis, and
 non-model-based discriminant analysis of principal components confirmed
 the hybridization between V. atratum and V. japonicum. High pollen
 fertility and a lack of linkage disequilibrium suggested that the hybrid
 populations may be self-sustaining and have persisted since V. atratum and
 V. japonicum came into contact during the post-glacial period. Moreover,
 our findings show that the pattern of hybridization between V. atratum and
 V. japonicum is unidirectional and differs among populations.
 Geographically-isolated hybrid populations exist as genetically distinct
 hybrid swarms that consist of V. atratum-like genotypes, V. japonicum-like
 genotypes, or admixed genotypes. In addition, Bayesian-based clustering
 analysis and coalescent-based estimates of long-term gene flow showed
 patterns of introgressive hybridization in three morphologically ‘pure’ V.
 japonicum populations. Conclusion: In this study, we demonstrated that
 climatic oscillations during the Quaternary period likely led to species
 range shift and subsequently secondary contact. Hybrid populations may be
 self-sustaining and have persisted since V. atratum and V. japonicum came
 into contact during the post-glacial period. Pattern of hybridization
 between V. atratum and V. japonicum is unidirectional and differs among
 populations. We concluded that these differences in the genetic
 consequences of secondary contact are caused by historical colonization
 processes and/or natural selection.
description: Morphological
 measurements on VincetoxicumTable (.csv format) with
 data on 17 morphological characters studied on hybridization between
 Vincetoxicum atratum, V. japonicum and hybrid populations in
 Japan.morphology--vincetoxicum.csvMicrosatellite--VincetoxicumMicrosatellite dataset (10 markers) given here as a Genepop input file.ssr--vincetoxicum.txt