Modanu Maria, Li Lucy Dong Xuan, Said Hosay, Rathitharan Nizanthan, Andrade Maydianne C B
Integrative Behaviour and Neuroscience Group, Department of Biological Sciences, University of Toronto, Scarborough, 1265 Military Trail, Toronto, ON, Canada M1C1A4(2); Department of Neurobiology and Behavior, Cornell University, 215 Tower Road, Ithaca, NY 14853, USA(3).
Integrative Behaviour and Neuroscience Group, Department of Biological Sciences, University of Toronto, Scarborough, 1265 Military Trail, Toronto, ON, Canada M1C1A4(2).
Behav Processes. 2014 Jul;106:12-6. doi: 10.1016/j.beproc.2014.03.011. Epub 2014 Apr 12.
Sibling cannibalism occurs across diverse taxa and can affect population size and structure, as well as the fitness of parents and the cannibal, via density effects and variation in individual propensity to cannibalize. We examined these effects on sibling cannibalism in juveniles of a web-building spider (Latrodectus hasselti, Australian redbacks). Adult redbacks are solitary, but juveniles live in clusters of variable density for a week after hatching. We confined newly hatched siblings from a singly-mated female to a low or high density treatment in a split-clutch design, then left spiderlings unfed for a week. Our results showed no effect of density on overall cannibalism levels, but a strong correlation between cannibalism counts from the same maternal lines across densities. Unlike web-bound sit-and-wait predators, wandering spiders that are active hunters have been shown to experience density-dependent cannibalism. In contrast, we suggest sibling cannibalism in web-building spiders may be density independent because early cohabitation on the web selects for elevated tolerance of conspecifics. We conclude that, rather than being linked to density, cannibalism of siblings in these species may be controlled more strongly by variation in individual propensity to cannibalize.
同胞相食现象在多种生物分类群中都有发生，并且会通过密度效应以及个体同类相食倾向的差异，影响种群规模和结构，以及亲代和同类相食者的适合度。我们研究了这些因素对一种结网蜘蛛（澳洲红背蜘蛛，Latrodectus hasselti）幼蛛同胞相食行为的影响。成年红背蜘蛛独自生活，但幼蛛在孵化后会以不同密度聚集生活一周。我们采用分组设计，将来自单只交配雌蛛的新孵化同胞幼蛛分为低密度或高密度处理组，然后让幼蛛一周不进食。我们的结果表明，密度对总体同类相食水平没有影响，但在不同密度下，来自同一母系的同类相食数量之间存在很强的相关性。与结网坐等捕食者不同，活跃的游走型蜘蛛已被证明会经历密度依赖型同类相食。相比之下，我们认为结网蜘蛛的同胞相食可能与密度无关，因为在网上的早期共同生活选择了对同种个体更高的耐受性。我们得出结论，这些物种中同胞相食现象与其说是与密度相关，不如说是更强烈地受个体同类相食倾向差异的控制。
