Muñoz-Pajares A Jesús, Abdelaziz Mohamed, Picó F Xavier
Departamento de Genética, Universidad de Granada, Granada, Spain.
Research Center in Biodiversity and Genetic Resources (CIBIO), Campus Agrário de Vairão, Vairão, Portugal.
AoB Plants. 2020 Jul 25;12(4):plaa037. doi: 10.1093/aobpla/plaa037. eCollection 2020 Aug.
Migration is a process with important implications for the genetic structure of populations. However, there is an aspect of migration seldom investigated in plants: migration between temporally isolated groups of individuals within the same geographic population. The genetic implications of temporal migration can be particularly relevant for semelparous organisms, which are those that reproduce only once in a lifetime after a certain period of growth. In this case, reproductive asynchrony in individuals of the same population generates demes of individuals differing in their developmental stage (non-reproductive and reproductive). These demes are connected by temporal migrants, that is, individuals that become annually asynchronous with respect to the rest of individuals of their same deme. Here, we investigated the extent of temporal migration and its effects on temporal genetic structure in the biennial plant . To this end, we conducted two independent complementary approaches. First, we empirically estimated temporal migration rates and temporal genetic structure in four populations of during three consecutive years using nuclear microsatellites markers. Second, we developed a demographic genetic simulation model to assess genetic structure for different migration scenarios differing in temporal migration rates and their occurrence probabilities. We hypothesized that genetic structure decreased with increasing temporal migration rates due to the homogenizing effect of migration. Empirical and modelling results were consistent and indicated a U-shape relationship between genetic structure and temporal migration rates. Overall, they indicated the existence of temporal genetic structure and that such genetic structure indeed decreased with increasing temporal migration rates. However, genetic structure increased again at high temporal migration rates. The results shed light into the effects of reproductive asynchrony on important population genetic parameters. Our study contributes to unravel the complexity of some processes that may account for genetic diversity and genetic structure of natural populations.
迁移是一个对种群遗传结构具有重要影响的过程。然而，植物迁移中很少被研究的一个方面是：同一地理种群内时间上隔离的个体群体之间的迁移。时间迁移的遗传影响对于一年生植物可能尤为相关，一年生植物是指在一定生长时期后一生中只繁殖一次的植物。在这种情况下，同一种群个体的生殖异步会产生发育阶段不同（非生殖和生殖）的个体群。这些个体群通过时间迁移者相连，即那些与同一群体中其他个体每年出现异步的个体。在此，我们研究了二年生植物中时间迁移的程度及其对时间遗传结构的影响。为此，我们采用了两种独立的互补方法。首先，我们使用核微卫星标记连续三年对四个种群的时间迁移率和时间遗传结构进行了实证估计。其次，我们开发了一个种群遗传模拟模型，以评估不同时间迁移率及其发生概率的迁移情景下的遗传结构。我们假设由于迁移的同质化效应，遗传结构会随着时间迁移率的增加而降低。实证和建模结果一致，表明遗传结构与时间迁移率之间呈U形关系。总体而言，它们表明存在时间遗传结构，并且这种遗传结构确实随着时间迁移率的增加而降低。然而，在高时间迁移率下，遗传结构又会增加。这些结果揭示了生殖异步对重要种群遗传参数的影响。我们的研究有助于揭示一些可能解释自然种群遗传多样性和遗传结构的过程的复杂性。
