Department of Physics, University of Gothenburg, Gothenburg, Sweden.
PLoS One. 2013 Oct 28;8(10):e75587. doi: 10.1371/journal.pone.0075587. eCollection 2013.
Genetic variation within and among populations is influenced by the genetic content of the founders and the migrants following establishment. This is particularly true if populations are small, migration rate low and habitats arranged in a stepping-stone fashion. Under these circumstances the level of multiple paternity is critical since multiply mated females bring more genetic variation into founder groups than single mated females. One such example is the marine snail Littorina saxatilis that during postglacial times has invaded mainland refuge areas and thereafter small islands emerging due to isostatic uplift by occasional rafting of multiply mated females. We modelled effects of varying degrees of multiple paternity on the genetic variation of island populations colonised by the founders spreading from the mainland, by quantifying the population heterozygosity during both the transient colonisation process, and after a steady state (with migration) has been reached. During colonisation, multiple mating by [Formula: see text] males increased the heterozygosity by [Formula: see text] in comparison with single paternity, while in the steady state the increase was [Formula: see text] compared with single paternity. In the steady state the increase of heterozygosity due to multiple paternity is determined by a corresponding increase in effective population size. During colonisation, by contrast, the increase in heterozygosity is larger and it cannot be explained in terms of the effective population size alone. During the steady-state phase bursts of high genetic variation spread through the system, and far from the mainland this led to short periods of high diversity separated by long periods of low diversity. The size of these fluctuations was boosted by multiple paternity. We conclude that following glacial periods of extirpation, recolonization of isolated habitats by this species has been supported by its high level of multiple paternity.
种群内和种群间的遗传变异受奠基者的遗传组成和建立后移民的影响。如果种群较小、迁移率低且栖息地呈阶梯式排列，情况尤其如此。在这些情况下，多父本的水平至关重要，因为多次交配的雌性比单次交配的雌性将更多的遗传变异带入奠基者群体中。海洋蜗牛 Littorina saxatilis 就是一个这样的例子，在冰川时代之后，它入侵了大陆避难所地区，此后，由于偶尔的浮筏使多次交配的雌性得以迁徙，从而导致海平面上升，出现了小岛。我们通过量化由从大陆扩散的奠基者建立的岛屿种群的种群杂合性，来模拟不同程度的多父本对岛屿种群遗传变异的影响，该杂合性在短暂的殖民过程中和达到稳定状态（具有迁移）期间都进行了量化。在殖民过程中，与单父本相比，[Formula: see text] 个雄性的多次交配使杂合度增加了 [Formula: see text]，而在稳定状态下，与单父本相比，杂合度增加了 [Formula: see text]。在稳定状态下，多父本导致的杂合度增加是由有效种群大小的相应增加决定的。相比之下，在殖民过程中，杂合度的增加更大，并且不能仅用有效种群大小来解释。在稳定状态阶段，高遗传变异的爆发会在整个系统中传播，并且远离大陆，这导致了高多样性的短暂时期与低多样性的长期时期交替出现。多父本增加了这些波动的幅度。我们得出的结论是，在冰川灭绝时期之后，该物种通过高水平的多父本支持其对孤立栖息地的重新殖民。
