球虫感染与捕食对根田鼠繁殖性能的影响

The effects of coccidian infection and predators on reproductive performance of root vole(Alexandromys oeconomus)

在自然界,捕食者和寄生物是两种主要的种群外部调节因子,二者的交互作用会对猎物和宿主种群波动产生深远影响。较低的球虫感染强度与捕食对根田鼠(Alexandromys oeconomus)繁殖无显著的交互作用。自然界球虫感染存在季节性变化,秋季感染强度最高。为了探究较高感染强度下,球虫与捕食对根田鼠繁殖的主效应及交互作用,本研究采用2×2析因实验设计,在野外围栏中测定了根田鼠种群肠道内寄生物的感染率和感染强度、雄性睾丸指数、睾酮水平、精子密度、精子活力以及雌性卵巢指数。结果表明,较高的感染强度下,球虫能显著抑制根田鼠的繁殖性能,但球虫感染与捕食对根田鼠的繁殖无显著的交互作用,这可能与球虫感染和捕食效应在时间上的错配有关。本研究认为,球虫感染对繁殖期小哺乳动物种群的调节作用虽有限,但其可通过与捕食者的耦合来降低宿主越冬时的存活率,进而影响宿主种群波动。

In nature,predators and parasites are two major extrinsic population regulators,their interaction can play important roles on the prey/host population dynamics.However,some studies found that coccidia with lower infection intensity and predators have no significant interactive effects on the reproduction of root voles(Alexandromys oeconomus).In the wild,coccidian infection in root voles has seasonal variation,and their infection peak of prevalence and intensity occur in autumn.Whether the primary effect of coccidian infection or the interactive effects of coccidian infection and predators can affect the reproduction of root voles are obscure.To test the main and interactive effects of coccidian infection with higher intensity and predators on reproduction of root voles,the two-level factorial design was conducted.Then,the prevalence and intensity of intestinal parasites,testicular index,testosterone levels,sperm density,sperm motility and ovary index were evaluated.Our results showed that coccidian infection with higher intensity significantly suppressed the reproductive performance of voles,but had no significant difference in the interaction between coccidian infection and predators,which may correlate with the time mismatch.We suggested that coccidian infection had a slightly limited effect on the reproduction of small mammal populations,but they could affect the fluctuation of host populations via reducing the overwinter survival of the host when interacted with predators.