Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada; Department of Zoology, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.
Department of Zoology, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.
PLoS One. 2014 May 23;9(5):e96679. doi: 10.1371/journal.pone.0096679. eCollection 2014.
Cyclic or fluctuating populations experience regular periods of low population density. Genetic bottlenecks during these periods could give rise to temporal or spatial genetic differentiation of populations. High levels of movement among increasing populations, however, could ameliorate any differences and could also synchronize the dynamics of geographically separated populations. We use microsatellite markers to investigate the genetic differentiation of four island and one mainland population of western tent caterpillars, Malacosoma californicum pluviale, in two periods of peak or pre-peak density separated by 8 years. Populations showed high levels of genetic variation and little genetic differentiation either temporally between peaks or spatially among sites. Mitochondrial haplotypes were also shared between one island population and one mainland population in the two years studied. An isolation-by-distance analysis showed the FST values of the two geographically closest populations to have the highest level of differentiation in both years. We conclude that high levels of dispersal among populations maintain both synchrony of population dynamics and override potential genetic differentiation that might occur during population troughs. As far we are aware, this is the first time that genetic similarity between temporally separated population outbreaks in insects has been investigated. A review of genetic data for both vertebrate and invertebrate species of cyclic animals shows that a lack of spatial genetic differentiation is typical, and may result from high levels of dispersal associated with fluctuating dynamics.
周期性或波动性种群经历着种群密度的周期性低谷。在这些时期，遗传瓶颈可能导致种群的暂时或空间遗传分化。然而，随着种群数量的增加，高水平的迁移可以缓解任何差异，并使地理上分离的种群的动态同步化。我们使用微卫星标记来研究两年高峰期或高峰期前密度的四个岛屿和一个大陆种群的遗传分化，期间相隔 8 年。种群表现出高水平的遗传变异和很小的遗传分化，无论是在高峰期之间的时间上还是在地点之间的空间上。在研究的两年中，一个岛屿种群和一个大陆种群也共享线粒体单倍型。隔离距离分析表明，在两年中，两个地理位置最接近的种群的 FST 值分化程度最高。我们得出结论，种群之间高水平的扩散既维持了种群动态的同步性，又克服了种群低谷期间可能发生的潜在遗传分化。据我们所知，这是首次调查昆虫中暂时分离的种群爆发之间的遗传相似性。对周期性动物的脊椎动物和无脊椎动物的遗传数据的综述表明，缺乏空间遗传分化是典型的，这可能是由于与波动动态相关的高水平扩散所致。
