Patterns of genotype variation and demographic history in Lindera glauca (Lauraceae), an apomict‐containing dioecious forest tree

Abstract

AbstractAimThe historical circumstances promoting the transition from sexual to apomictic reproduction in dioecious plant species remain poorly understood. Here, we investigated the divergence and demographic history of Lindera glauca, a dioecious tree generally considered to be obligate sexual in China while comprising only females (apomicts) in Japan.LocationEast Asia (China and Japan).TaxonLindera glauca (Lauraceae)MethodsSamples from 42 populations were genotyped using chloroplast DNA and nuclear microsatellite (nSSR) loci to assess genetic diversity and structure. The nSSR genotypes were also used to detect the mode of reproduction in Chinese and Japanese populations, respectively. Approximate Bayesian Computation on nSSRs and palaeoclimatic niche models provided further insights into the evolutionary and population demographic history.ResultsChinese L. glauca was found to harbour both sexual and asexual genotypes. Chinese and Japanese L. glauca underwent likely severe bottlenecks during a mid‐Pleistocene glacial period, possibly marking the split time of the island lineage from its mainland ancestor. In contrast to Chinese L. glauca, the Japanese lineage experienced a massive range contraction during the Last Glacial Maximum and postglacial expansions.Main ConclusionsWhile reproductive assurance plays an important role in the selection of apomixis in Chinese L. glauca, the lack of male plants in Japan likely reflects population demographic history driven by (Late) Quaternary climate change. Hence, the present study demonstrates a possible link between palaeoclimate change and the transition to exclusively apomictic reproduction in a dioecious tree.