科研之友
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摘要
Despite the biological, ecological and conservational interest of halo-gypsophytes, which are frequently found in endangered ecosystems, such plant species have received little attention from a phylogeographical point of view. Jacobaea auricula is an endangered perennial member of Asteraceae, which has a fragmented distribution restricted to gypsum and/or saline outcrops in the Iberian Peninsula. It includes populations with few individuals. Amplified fragment length polymorphism markers and nuclear and plastid sequences were used to explore the phylogeographical and evolutionary history of the species and to determine whether the classical taxonomic differentiation in subspecies is genetically supported. Estimation of divergence times indicated that intraspecific divergence took place during the Pleistocene glaciations. Unlike other species from the area that grow under unusual soil conditions, northern and central Spain appeared to be ancestral with respect to the southern areas. Overall population differentiation was low, which does not completely match with the expected pattern in plant species from discontinuous habitats. Considering the bi-edaphic character of J. auricula, low levels of among-population differentiation may be explained by the fact that more continuous habitat availability could have favoured connectivity among fragments in the past. Haplotype differentiation reflects survival of ancestral polymorphism, instead of phylogeographical structure. Finally, a poor correlation among genetic groups and subspecies was found. This study illustrates the importance of exploring the evolutionary history of each particular species more deeply when determining conservation strategies for edaphoendemics.
- 出版日期2017-11
