Open AccessExploring Species Limits in Two Closely Related Chinese Oaks
Author(s) -
YanFei Zeng,
WanJin Liao,
Rémy J. Petit,
Dayong Zhang
Publication year - 2010
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0015529
Subject(s) - introgression , biology , amplified fragment length polymorphism , evolutionary biology , gene flow , population , sympatry , taxon , interspecific competition , microsatellite , genetics , ecology , genetic variation , sympatric speciation , genetic diversity , gene , allele , demography , sociology
Background The species status of two closely related Chinese oaks, Quercus liaotungensi s and Q. mongolica , has been called into question. The objective of this study was to investigate the species status and to estimate the degree of introgression between the two taxa using different approaches. Methodology/Principal Findings Using SSR (simple sequence repeat) and AFLP (amplified fragment length polymorphism) markers, we found that interspecific genetic differentiation is significant and higher than the differentiation among populations within taxa. Bayesian clusters, principal coordinate analysis and population genetic distance trees all classified the oaks into two main groups consistent with the morphological differentiation of the two taxa rather than with geographic locations using both types of markers. Nevertheless, a few individuals in Northeast China and many individuals in North China have hybrid ancestry according to Bayesian assignment. One SSR locus and five AFLPs are significant outliers against neutral expectations in the interspecific F ST simulation analysis, suggesting a role for divergent selection in differentiating species. Main Conclusions/Significance All results based on SSRs and AFLPs reached the same conclusion: Q. liaotungensi s and Q. mongolica maintain distinct gene pools in most areas of sympatry. They should therefore be considered as discrete taxonomic units. Yet, the degree of introgression varies between the two species in different contact zones, which might be caused by different population history or by local environmental factors.