González-Varo Juan P, Aparicio Abelardo, Lavergne Sébastien, Arroyo Juan, Albaladejo Rafael G
Estación Biológica de Doñana-EBD-CSIC, Avda. Américo Vespucio s/n, Isla de La Cartuja, 41092 Sevilla, Spain.
Genetica. 2012 Mar;140(1-3):31-8. doi: 10.1007/s10709-012-9655-8. Epub 2012 May 3.
The mechanisms underlying heterozygosity-fitness correlations (HFCs) are subject of intense debates, especially about how important population features such as size or degree of isolation influence HFCs. Here, we report variation in HFCs between Large and Small populations of a self-compatible shrub (Myrtus communis) occurring within an extremely fragmented landscape. In each of the five study populations, we obtained data on both heterozygosity and fitness for 9-12 maternal families (i.e. offspring from the same mother plant). Whereas heterozygosity explained most of the variance (60-86 %) in growth rate of seedling families within Large populations, this relationship was absent within Small populations. Our results suggest that inbreeding may explain the observed HFCs within Large populations, and that different genetic processes (such as genetic drift and/or selection) could have overridden HFCs within Small populations. While it is difficult to draw general conclusions from five populations, we think our results open new research perspectives on how different genetic processes underlie variation in HFCs under different population contexts. Our study also points to a need for further attention on the complex relationships between heterozygosity in self-compatible plants and their progeny in relation to mating system variation. Finally, our results provide interesting new insights into how population genetic diversity is maintained or lost in a highly fragmented landscape.
杂合度-适合度相关性（HFCs）背后的机制是激烈辩论的主题，尤其是关于种群特征（如大小或隔离程度）对HFCs的影响有多重要。在此，我们报告了在一个极度破碎化景观中出现的自交亲和灌木（香桃木）的大种群和小种群之间HFCs的差异。在五个研究种群中的每一个种群中，我们获取了9 - 12个母系家族（即同一母本植物的后代）的杂合度和适合度数据。在大种群中，杂合度解释了幼苗家族生长率的大部分方差（60 - 86%），而在小种群中这种关系不存在。我们的结果表明，近亲繁殖可能解释了大种群中观察到的HFCs，并且不同的遗传过程（如遗传漂变和/或选择）可能在小种群中掩盖了HFCs。虽然很难从五个种群中得出一般性结论，但我们认为我们的结果为不同遗传过程如何在不同种群背景下构成HFCs变异的基础开辟了新的研究视角。我们的研究还指出，需要进一步关注自交亲和植物的杂合度与其后代在交配系统变异方面的复杂关系。最后，我们的结果为在高度破碎化景观中种群遗传多样性如何得以维持或丧失提供了有趣的新见解。
