Møller Anders Pape, Nielsen Jan Tøttrup
Laboratoire de Parasitologie Evolutive, CNRS UMR 7103, Université Pierre et Marie Curie, Bât. A, 7ème etage, 7 quai St. Bernard, Case 237, F-75252 Paris 05, France.
Ecology. 2007 Apr;88(4):871-81. doi: 10.1890/06-0747.
Predators have been hypothesized to prey on individuals in a poor state of health, although this hypothesis has only rarely been examined. We used extensive data on prey abundance and availability from two long-term studies of the European Sparrowhawk (Accipiter nisus) and the Eurasian Goshawk (Accipiter gentilis) to quantify the relationship between predation risk of different prey species and infection with malaria and other protozoan blood parasites. Using a total of 31 745 prey individuals of 65 species of birds from 1709 nests during 1977-1997 for the Sparrowhawk and a total of 21 818 prey individuals of 76 species of birds from 1480 nests for the Goshawk during 1977-2004, we show that prey species with a high prevalence of blood parasites had higher risks of predation than species with a low prevalence. That was also the case when a number of confounding variables of prey species, such as body mass, breeding sociality, sexual dichromatism, and similarity among species in risk of predation due to common descent, were controlled in comparative analyses of standardized linear contrasts. Prevalence of the genera Haemoproteus, Leucocytozoon, Plasmodium, and Trypanosoma were correlated with each other, and we partitioned out the independent effects of different protozoan genera on predation risk in comparative analyses. Prevalence of Haemoproteus, Leucocytozoon, and Plasmodium accounted for interspecific variation in predation risk for the two raptors. These findings suggest that predation is an important factor affecting parasite-host dynamics because predators tend to prey on hosts that are more likely to be infected, thereby reducing the transmission success of parasites. Furthermore, this study demonstrates that protozoan infections are a common cause of death for hosts mediated by increased risk of predation.
尽管捕食者会捕食健康状况不佳个体的假说很少得到验证，但已有研究提出这一假说。我们利用欧洲雀鹰（Accipiter nisus）和欧亚苍鹰（Accipiter gentilis）两项长期研究中关于猎物丰度和可获得性的大量数据，来量化不同猎物物种的捕食风险与疟疾及其他原生动物血液寄生虫感染之间的关系。在1977 - 1997年期间，我们共使用了来自雀鹰1709个巢穴中65种鸟类的31745个猎物个体；在1977 - 2004年期间，对于苍鹰，我们共使用了来自1480个巢穴中76种鸟类的21818个猎物个体。我们发现，血液寄生虫患病率高的猎物物种比患病率低的物种面临更高的捕食风险。在对标准化线性对比进行比较分析时，控制了猎物物种的一些混杂变量，如体重、繁殖社会性、性二态性以及由于共同祖先导致的物种间捕食风险相似性等，结果依然如此。血变原虫属（Haemoproteus）、白细胞原虫属（Leucocytozoon）、疟原虫属（Plasmodium）和锥虫属（Trypanosoma）的患病率相互关联，我们在比较分析中划分出不同原生动物属对捕食风险的独立影响。血变原虫属、白细胞原虫属和疟原虫属的患病率解释了这两种猛禽捕食风险的种间差异。这些发现表明，捕食是影响寄生虫 - 宿主动态的一个重要因素，因为捕食者倾向于捕食更易感染的宿主，从而降低了寄生虫的传播成功率。此外，本研究表明原生动物感染是由捕食风险增加介导的宿主常见死亡原因。
