Recent colonization by a coastal plant of inland habitats at an ancient freshwater lake, Lake Biwa: multilocus sequencing and a demographic history of Lathyrus japonicus (Fabaceae)
Article first published online: 1 JUL 2013
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Ecology and Evolution
Volume 3, Issue 8, pages 2600–2611, August 2013
How to Cite
Ecology and Evolution 2013; 3(8): 2600–2611
- Issue published online: 12 AUG 2013
- Article first published online: 1 JUL 2013
- Manuscript Accepted: 14 MAY 2013
- Manuscript Revised: 13 MAY 2013
- Manuscript Received: 21 APR 2013
- Japan Society for the Promotion of Science
- Ancient lake;
- coastal plants;
- isolation with migration model;
- Lake Biwa;
- Lathyrus japonicus ;
- postglacial period
Ancient lakes have been recognized as “long-term isolated islands” in terrestrial ecosystems. Lake Biwa, one of the few ancient lakes that formed around 4 million years ago, harbors many coastal species that commonly inhabit seashores. The beach pea, Lathyrus japonicus, is a typical coastal species of this freshwater lake, where morphological, physiological, and genetic differentiations have been reported between Biwa and coastal populations. Whether Biwa populations were isolated for long periods throughout Pleistocene climatic oscillations and subsequent range shifts is unclear. We assessed population genetic structure and demography of beach pea in this ancient freshwater lake using the sequences of eight nuclear loci. The results of STRUCTURE analyses showed evidence of admixture between Biwa and coastal populations, reflecting recent gene flow. The estimated demographic parameters implemented by the isolation with migration model (IM model) revealed a recent divergence (postglacial period) of Biwa populations, with some gene flow from Biwa to coastal populations. In addition, Biwa populations were significantly smaller in size than the ancestral or coastal populations. Our study suggests that a Holocene thermal maximum, when transgression could allow seeds from coastal plants to access Lake Biwa, was involved in the origin of the Biwa populations and their genetic divergence. Thus, coastal populations might have migrated to Lake Biwa relatively recently. Our study concluded that ancestral migrants in Lake Biwa were derived from small founding populations and accelerated genetic isolation of Biwa populations during short-term isolation.