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Species divergence and repeated ancient hybridization in a Sulawesian lake system

Citation

Yamahira, Kazunori et al. (2021), Species divergence and repeated ancient hybridization in a Sulawesian lake system, Dryad, Dataset, https://doi.org/10.5061/dryad.8cz8w9gr2

Abstract

An increasing volume of empirical studies demonstrated that hybridization between distant lineages may have promoted speciation in various taxa. However, the timing, extent, and direction of introgressive hybridization remain unknown in many cases. Here, we report a possible case in which repeated hybridization promoted divergence of Oryzias ricefishes (Adrianichthyidae) on Sulawesi, an island of Wallacea. Four Oryzias species are endemic to the Malili Lake system in central Sulawesi, which is composed of five tectonic lakes; of these, one lake is inhabited by two species. Morphological and population genomic analyses of genome-wide single-nucleotide polymorphisms revealed that these two sympatric species are phylogenetically sister to but substantially reproductively isolated from each other. Analyses of admixture and comparison of demographic models revealed that the two sympatric species experienced several substantial introgressions from outgroup populations that probably occurred soon after they had secondary contact with each other in the lake. However, the ratio of migrants from the outgroups was estimated to be different between the two species, which is consistent with the hypothesis that these introgressions aided their divergence or prevented them from forming a hybrid swarm. Repeated lake fragmentations and fusions may have promoted diversification of this freshwater fish species complex that is endemic to this ancient lake system.

Funding

Japan Society for the Promotion of Science, Award: KAKENHI 16H06279 (PAGS)

Japan Society for the Promotion of Science, Award: KAKENHI 26291093

Japan Society for the Promotion of Science, Award: KAKENHI 17H01675

Japan Science and Technology Agency, Award: CREST JPMJCR20S2