Detecting no natural hybridization and predicting range overlap inSaccharina angustataandSaccharina japonica

Natural hybridization can play a significant role in evolutionary processes and influence the adaptive diversification and speciation of brown seaweeds. However, this phenomenon is as yet unknown inSaccharinakelps.Saccharina angustataand two varieties ofSaccharina japonica(S. japonicavar.japonicaandS. japonicavar.diabolica) partly overlap in distribution along the Pacific coast of Hokkaido, which makes them a good model system to study hybridization and introgression among species of the genusSaccharina. Based on 13 highly variable nuclear microsatellites and a mitochondrial marker, we assessed the genetic diversity levels ofS. angustatafor the first time and populations from Muroran to Shiranuka (western part of the Pacific coast in Hokkaido) exhibited highest genetic diversity. Genetic diversity ofS. japonicawas higher inS. japonicavar.japonicaas compared withS. japonicavar.diabolica. There was significant genetic differentiation (F-ST > 0.25,p < 0.05) betweenS. japonicaandS. angustatabased on both markers. Moreover, there was poor genetic connectivity and limited interspecific hybridization among these closely relatedSaccharinaspecies. Ecological niche models projected a northward expansion of bothS. japonicaandS. angustataunder future climate scenarios and a range overlap between two species along the coast of Okhotsk Sea in Kamchatka Peninsula. The interspecific hybridization and genetic diversity among these kelps provide insights for kelp selection and cultivation as well as future conservation strategies of wild stocks. National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [31900279] Shandong Provincial Natural Science FoundationNatural Science Foundation of Shandong Province [ZR2019BC024] Bilateral Joint Research Project between China and Japan [2017YFE0130900] Foundation for Science and Technology (FCT) of PortugalPortuguese Foundation for Science and Technology [UID/Multi/04326/2020, DL57/2016/CP1361/CT0035] info:eu-repo/semantics/publishedVersion