Genomic Evidence for Speciation with Gene Flow in Broadcast Spawning Marine Invertebrates

Shotaro Hirase, Yo Y. Yamasaki, Masashi Sekino, Masato Nishisako, Minoru Ikeda, Motoyuki Hara, Juha Merilä, Kiyoshi Kikuchi

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


How early stages of speciation in free-spawning marine invertebrates proceed is poorly understood. The Western Pacific abalones, Haliotis discus, H. madaka, and H. gigantea, occur in sympatry with shared breeding season and are capable of producing viable F1 hybrids in spite of being ecologically differentiated. Population genomic analyses revealed that although the three species are genetically distinct, there is evidence for historical and ongoing gene flow among these species. Evidence from demographic modeling suggests that reproductive isolation among the three species started to build in allopatry and has proceeded with gene flow, possibly driven by ecological selection. We identified 27 differentiation islands between the closely related H. discus and H. madaka characterized by high FST and dA, but not high dXY values, as well as high genetic diversity in one H. madaka population. These genomic signatures suggest differentiation driven by recent ecological divergent selection in presence of gene flow outside of the genomic islands of differentiation. The differentiation islands showed low polymorphism in H. gigantea, and both high FST, dXY, and dA values between H. discus and H. gigantea, as well as between H. madaka and H. gigantea. Collectively, the Western Pacific abalones appear to occupy the early stages speciation continuum, and the differentiation islands associated with ecological divergence among the abalones do not appear to have acted as barrier loci to gene flow in the younger divergences but appear to do so in older divergences.

Original languageEnglish
Pages (from-to)4683-4699
Number of pages17
JournalMolecular biology and evolution
Issue number11
Publication statusPublished - 2021 Nov 1


  • Ecological speciation
  • Fertilization protein
  • GRAS-Di
  • Introgression
  • Marine speciation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics


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