Genetic differentiation in Elaeocarpus photiniifolia (Elaeocarpaceae) associated with geographic distribution and habitat variation in the Bonin (Ogasawara) Islands

Abstract

Gene flow between populations in different environmental conditions can be limited due to divergent natural selection, thus promoting genetic differentiation. Elaeocarpus photiniifolia, an endemic tree species in the Bonin Islands, is distributed in two types of habitats, dry scrubs and mesic forests. We aim to elucidate the genetic differentiation in E. photiniifolia within and between islands and between the habitat types. We investigated genotypes of 639 individuals from 19 populations of E. photiniifolia and its closely-related E. sylvestris at 24 microsatellite loci derived from expressed sequence tags. The data revealed genetic differentiation (1) between E. photiniifolia and E. sylvestris (0.307 ≤ F ST ≤ 0.470), (2) between the E. photiniifolia populations of the Chichijima and Hahajima Island Groups in the Bonin Islands (0.033 ≤ F ST ≤ 0.121) and (3) between E. photiniifolia populations associated with dry scrubs and mesic forests in the Chichijima Island Group (0.005 ≤ F ST ≤ 0.071). Principal coordinate analysis and Bayesian clustering analysis also showed that genetically distinct groups were associated with the habitat types, and isolation by distance was not responsible for the genetic differentiation. These findings suggest that E. photiniifolia is divided into genetically differentiated groups associated with different environmental conditions in the Bonin Islands.

Genetic diversity, structure, and demography of Pandanus boninensis (Pandanaceae) with sea drifted seeds, endemic to the Ogasawara Islands of Japan: Comparison between young and old islands

“…Due to clear geological and ecological differences between these island groups, the genetic divergence and diversity of plants is expected to differ between them. However, population genetic studies in the Volcano Islands are limited (Ando et al, 2014; Sugai et al, 2013), largely due to the inaccessibility of the region.…”

“…pachycarpus , endemic to the Volcano Islands, is likely to have speciated from E. sylvetris var. sylvetris , which is distributed in mainland Japan (Sugai et al, 2013). Therefore, the origin of plants in the Volcano Islands is not straightforward and requires careful investigation.…”

Genetic variation of pantropical Terminalia catappa plants with sea‐drifted seeds in the Bonin Islands: suggestions for transplantation guidelines

“…In the Bonin Islands, several tree species include genetically distinct groups that are associated with different habitats, such as dry scrubs and mesic forests, within islands (Sugai et al . ; Tsuneki et al . ).…”

Spatial and ecological population genetic structures within two island‐endemic Aeonium species of different niche width

“…Such interactions of different habitat conditions and topographical gene flow barriers on plant population divergence on the island scale have recently been shown, for example, in Elaeocarpus photiniifolia on the Bonin Islands, Japan (Sugai et al. ) or in Jumellea rossii on Réunion, Mascarene Islands (Mallet et al. ).…”

“…Although the evolutionary potential of the found variation in UBC809_292 remains an open question, it indicates that ecological heterogeneity in combination with topography (in this case, the old Taburiente edifice and ridge systems separating eastern and western parts of the island) can foster initial population divergence on the small scale of an island. Such interactions of different habitat conditions and topographical gene flow barriers on plant population divergence on the island scale have recently been shown, for example, in Elaeocarpus photiniifolia on the Bonin Islands, Japan (Sugai et al 2013) or in Jumellea rossii on R eunion, Mascarene Islands (Mallet et al 2014).…”