INRA, UMR 1202 BIOGECO, INRA, F-33610, Cestas, France.
Mol Ecol. 2013 Sep;22(17):4397-412. doi: 10.1111/mec.12403.
Extant rear-edge populations located in former glacial refugia remain understudied despite their high conservation value. These populations should have experienced strong genetic drift due to their small size and long isolation. Moreover, the prolonged action of isolation by distance in refugial areas should result in stronger regional spatial genetic structure (SGS) than in recolonized areas, but empirical tests of this prediction are scarce. To fill this gap, we first used a set of 16 microsatellite markers to investigate the genetic structure of European beech in France in 65 populations from three refugial areas and one control recolonized (nonrefugial) area. Then, using the same approach, we reanalysed published isozyme data from 375 populations distributed across the entire species range. We found stronger genetic differentiation among populations in refugia than in recolonized areas. However, contrary to expectations, regional SGS was lower within refugia than within recolonized areas. Published studies presenting similar analyses suggest that our results could have generality across different biogeographical settings and types of organisms. Strong and prolonged genetic drift in refugial areas could have erased the signature of range expansions that is still visible in recolonized areas. Our results therefore suggest that Pleistocene population isolation has played a key role in increasing the genetic complexity of extant rear-edge populations.
尽管具有很高的保护价值，但现存的位于先前冰川避难所的后缘种群仍未得到充分研究。这些种群由于规模小且长期隔离，应该经历了强烈的遗传漂变。此外，在避难区，隔离距离的长期作用应该导致比再殖区更强的区域空间遗传结构（SGS），但对这一预测的实证检验很少。为了填补这一空白，我们首先使用了一组 16 个微卫星标记，在法国三个避难区和一个控制再殖区（非避难区）的 65 个种群中研究了欧洲山毛榉的遗传结构。然后，我们使用相同的方法，重新分析了发表的来自整个物种分布范围内的 375 个种群的同工酶数据。我们发现避难区种群之间的遗传分化比再殖区强。然而，与预期相反，避难区内的区域 SGS 低于再殖区。发表的类似分析的研究表明，我们的结果可能在不同的生物地理背景和生物类型中具有普遍性。避难区强烈和长期的遗传漂变可能已经抹去了在再殖区仍然可见的范围扩张的特征。因此，我们的研究结果表明，更新世种群隔离在增加现存后缘种群的遗传复杂性方面发挥了关键作用。
