Ziemba Robert E, Collins James P
Department of Biology, Arizona State University, Tempe, AZ 85287, USA, , , , , , US.
Oecologia. 1999 Sep;120(4):524-529. doi: 10.1007/s004420050886.
Cannibalism affects patterns of density-dependent mortality and may regulate population size. In many cases, rates of cannibalism depend on size structure, the frequency distribution of body sizes in the population, because cannibals can often only capture and consume smaller individuals. Size differences within single-age groups can be caused by a variety of factors. In this research we tested the hypothesis that size variation among larval tiger salamanders is due, in part, to interference interactions among individuals of different sizes. We found that size variation was greater when we raised larvae in groups rather than in isolation. This increase in size variation was due more to a relative deceleration of growth among smaller individuals rather than acceleration among larger individuals. We also found that smaller larvae had lower feeding rates than larger larvae when in groups, but not when isolated. Including spatial structure to limit physical interactions did not affect the size specificity of feeding rate, although it reduced feeding rates overall. We argue that these results are consistent with the hypothesis that larger larvae interfere, probably indirectly, with the feeding behavior of small individuals and this contributes to increases in size variation over time. We hypothesize that this indirect interference is caused by a behavioral response of smaller larvae to the risk of predation (cannibalism) by larger individuals.
同类相食会影响密度依赖型死亡率模式，并可能调节种群规模。在许多情况下，同类相食的发生率取决于体型结构，即种群中个体体型的频率分布，因为同类相食者通常只能捕获并吃掉较小的个体。单一年龄组内的体型差异可能由多种因素造成。在本研究中，我们检验了这样一个假设：虎螈幼体之间的体型差异部分是由于不同体型个体之间的干扰性相互作用所致。我们发现，将幼体分组饲养而非单独饲养时，体型差异更大。这种体型差异的增加更多是由于较小个体的生长相对减速，而非较大个体的生长加速。我们还发现，幼体在群体中时，较小的幼体摄食率低于较大的幼体，但单独饲养时并非如此。尽管限制身体相互作用的空间结构总体上降低了摄食率，但并未影响摄食率的体型特异性。我们认为，这些结果与以下假设一致：较大的幼体可能间接干扰较小个体的摄食行为，这导致随着时间推移体型差异增大。我们推测，这种间接干扰是由较小幼体对较大个体捕食（同类相食）风险的行为反应引起的。
