ETH Zürich, Institute of Integrative Biology, Experimental Ecology, Zürich, Switzerland.
BMC Evol Biol. 2013 Feb 4;13:29. doi: 10.1186/1471-2148-13-29.
Coevolution with parasites and population size are both expected to influence the evolution of mating rates. To gain insights into the interaction between these dual selective factors, we used populations from a coevolution experiment with the red flour beetle, Tribolium castaneum, and its microsporidian parasite, Nosema whitei. We maintained each experimental population at two different population sizes. We assayed the mating behaviour of both males and females from coevolved and paired non-coevolved control populations after 24 generations of coevolution with parasites.
Males from large, coevolved populations (i.e. ancestors were exposed to parasites) showed a reduced eagerness to mate compared to males from large, non-coevolved populations. But in small populations, coevolution did not lead to decreased male mating rates. Coevolved females from both large and small populations appeared to be more willing to accept mating than non-coevolved females.
This study provides unique, experimental insights into the combined roles of coevolving parasites and population size on the evolution of mating rate. Furthermore, we find that males and females respond differently to the same environmental conditions. Our results show that parasites can be key determinants of the sexual behaviour of their hosts.
寄生虫的协同进化和种群大小都有望影响交配率的进化。为了深入了解这两个双重选择因素之间的相互作用，我们使用了与红粉甲虫及其微孢子虫寄生虫白僵菌协同进化的实验种群。我们在两个不同的种群大小下维持每个实验种群。在与寄生虫协同进化 24 代后，我们对来自协同进化和配对非协同进化对照种群的雄性和雌性进行了交配行为的检测。
来自大种群（即祖先曾暴露于寄生虫）的雄性与来自大非协同进化种群的雄性相比，交配的渴望降低了。但是在小种群中，协同进化并没有导致雄性交配率降低。来自大、小种群的协同进化雌性似乎比非协同进化雌性更愿意接受交配。
本研究为协同进化寄生虫和种群大小对交配率进化的综合作用提供了独特的、实验性的见解。此外，我们发现雄性和雌性对相同的环境条件有不同的反应。我们的研究结果表明，寄生虫可以成为其宿主性行为的关键决定因素。
