Dataset Information

The long-term consequences of hybridization between the two Daphnia species, D. galeata and D. dentifera, in mature habitats.

ABSTRACT:

Background

Ecological specializations such as antipredator defense can reinforce morphological and distributional divergence within hybridizing species. Two hybridizing species of Daphnia (D. galeata and D. dentifera) are distributed in both Japan and North America; however, these populations have a longer history in Japan than in North America due to the differing impact of the last glaciation on these two regions. We tested the hypothesis that this longer coexistence in Japan would lead to extensive genetic admixture in nuclear and mitochondrial DNA whilst the distinct morphological traits and distributional patterns would be maintained.

Results

The high level of correspondence among morphological traits, distribution, and mitochondrial and nuclear DNA types for the specimens with D. dentifera mtDNA indicated that the species distinction has been maintained. However, a discordance between mtDNA and nuclear ITS-1 types was observed for most specimens that had D. galeata mtDNA, consistent with the pattern seen between the two species in North America. This observation suggests nuclear introgression from D. dentifera into D. galeata without mitochondrial introgression.

Conclusions

The separation of morphological traits and distribution ranges of the two hybridizing species in Japan, as well as in North America, has been maintained, despite large differences in climatic and geographical histories of these two regions. Variations in environmental factors, such as predation pressure, might affect maintenance of the distribution, although the further studies are needed to confirm this.

SUBMITTER: Ishida S

PROVIDER: S-EPMC3156774 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Publications

The long-term consequences of hybridization between the two Daphnia species, D. galeata and D. dentifera, in mature habitats.

Ishida Seiji S Takahashi Akiko A Matsushima Noe N Yokoyama Jun J Makino Wataru W Urabe Jotaro J Kawata Masakado M

BMC evolutionary biology 20110715

<h4>Background</h4>Ecological specializations such as antipredator defense can reinforce morphological and distributional divergence within hybridizing species. Two hybridizing species of Daphnia (D. galeata and D. dentifera) are distributed in both Japan and North America; however, these populations have a longer history in Japan than in North America due to the differing impact of the last glaciation on these two regions. We tested the hypothesis that this longer coexistence in Japan would lea ...[more]

PMID: 21756366

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Project 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.

Dataset Information

The long-term consequences of hybridization between the two Daphnia species, D. galeata and D. dentifera, in mature habitats.

Background

Results

Conclusions

Publications

The long-term consequences of hybridization between the two Daphnia species, D. galeata and D. dentifera, in mature habitats.

Similar Datasets

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