Anagenetic speciation in Ullung Island, Korea: genetic diversity and structure in the island endemic species, Acer takesimense (Sapindaceae)

Abstract

Anagenetic speciation is an important mode of speciation in oceanic islands; one-fourth of the endemic plants are estimated to have been derived via this process. Few studies, however, have critically examined the genetic consequences of anagenesis in comparison with cladogenesis (involved with adaptive radiation). We hypothesize that endemic species originating via anagenetic speciation in a relatively uniform environment should accumulate genetic variation with limited populational differentiation. We undertook a population genetic analysis using nine nuclear microsatellite loci of Acer takesimense, an anagenetically derived species endemic to Ullung Island, Korea, and its continental progenitor A. pseudosieboldianum on the Korean Peninsula. Microsatellite data reveal a clear genetic distinction between the two species. A high F value in the cluster of A. takesimense was found by Bayesian clustering analysis, suggesting a strong episode of genetic drift during colonization and speciation. In comparison with A. pseudosieboldianum, A. takesimense has slightly lower genetic diversity and possesses less than half the number of private and rare alleles. Consistent with predictions, weak geographical genetic structure within the island was found in A. takesimense. These results imply that anagenetic speciation leads to a different pattern of specific and genetic diversity than often seen with cladogenesis.

Influence of northern limit range on genetic diversity and structure in a widespread North American tree, sugar maple (Acer saccharum Marshall)

“…Large variation was observed in the inbreeding coefficient estimates for sugar maple populations in Québec ( F IS = 0.138, range: −0.051–0.302). Similar results were reported with microsatellites for Acer takesimense ( F IS = 0.28, range: 0.08–0.47; Takayama, Sun, & Stuessy, ) and for A. campestre ( F IS = 0.107, range: 0.015–0.300; Chybicki et al., ; Table ).…”

Do island plant populations really have lower genetic variation than mainland populations? Effects of selection and distribution range on genetic diversity estimates

“…; Takayama et al . ). In addition, allozymes and PCR‐based techniques allowing the detection of allele size variants have been the most recurrent tool for generating GD estimates of wild populations.…”

“…Thus far, comparisons of GD estimates between island and mainland populations have represented the most straightforward approach to evaluate levels of GD in island populations, either considering populations of species with an island-mainland distribution or island endemics and closely related mainland taxa (Frankham 1997;Chiang et al 2006;Takayama et al 2012). In addition, allozymes and PCR-based techniques allowing the detection of allele size variants have been the most recurrent tool for generating GD estimates of wild populations.…”

Genetic consequences of selection cutting on sugar maple (Acer saccharum Marshall)

“…; Takayama et al. ). Thus, our F IS values likely reflected the level of genetic diversity that we observed for sugar maple in our study area.…”

“…In the present study, sugar maple stands were localized within a small area relative to the species range and F IS values can vary widely among populations (Table 5 and Graignic 2014). Significant variation in F IS (heterozygote excess to deficiency) has been reported for trembling aspen and Korean maple (A. takesimense Nakai), across their natural geographic ranges (Table 5; Namroud et al 2005;Callahan et al 2013;Takayama et al 2013). Thus, our F IS values likely reflected the level of genetic diversity that we observed for sugar maple in our study area.…”