Kin selection theory states that when resources are limited and all else is equal, individuals will direct competition away from kin. However, when competition between relatives is completely local, as is the case in granivorous insects whose larval stages spend their lives within a single seed, this can reduce or even negate the kin-selected benefits. Instead, an increase in competition may have the same detrimental effects on individuals that forage with kin as those that forage with non-kin. In a factorial experiment we assessed the effects of relatedness and competition over food on the survival and on fitness-related traits of the bruchid beetle Callosobruchus maculatus. Relatedness of competitors did not affect the survival of larvae. Larval survival substantially decreased with increasing larval density, and we found evidence that beetles maturing at a larger size were more adversely affected by competition, resulting in lower survival rates. Furthermore, females showed a reduction in their growth rate with increasing larval density, emerging smaller after the same development time. Males increased their growth rate, emerging earlier but at a similar size when food was more limited. Our results add to the growing number of studies that fail to show a relationship between relatedness and a reduction in competition between relatives in closed systems, and emphasize the importance of the scale at which competition between relatives occurs.

中文翻译：

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觅食亲属之间的本地竞争：布鲁奇德甲虫幼虫的生长和生存

亲属选择理论指出，当资源有限而其他一切都相同时，个人将直接与亲属竞争。然而，当亲属之间的竞争完全是局部的时，就像食谷昆虫的幼虫阶段在一个种子中度过他们的生活一样，这会减少甚至否定亲属选择的好处。相反，竞争的增加可能对与亲属一起觅食的人与与非亲属一起觅食的人产生相同的不利影响。在析因实验中，我们评估了食物的相关性和竞争对 bruchid 甲虫 Callosobruchus maculatus 的生存和健康相关特征的影响。竞争者的亲缘关系不影响幼虫的存活。随着幼虫密度的增加，幼虫存活率显着下降，我们发现有证据表明，以较大尺寸成熟的甲虫受到竞争的不利影响更大，从而导致存活率较低。此外，随着幼虫密度的增加，雌性的生长速度降低，在相同的发育时间后变得更小。当食物更有限时，雄性增加了它们的增长率，出现得更早，但大小相似。我们的结果增加了越来越多的研究未能显示亲缘关系与封闭系统中亲属之间竞争减少之间的关系，并强调亲属之间竞争发生的规模的重要性。在相同的开发时间后变得更小。当食物更有限时，雄性增加了它们的增长率，出现得更早，但大小相似。我们的结果增加了越来越多的研究未能显示亲缘关系与封闭系统中亲属之间竞争减少之间的关系，并强调亲属之间竞争发生的规模的重要性。在相同的开发时间后变得更小。当食物更有限时，雄性增加了它们的增长率，出现得更早但大小相似。我们的结果增加了越来越多的研究，这些研究未能显示相关性与封闭系统中亲属之间竞争减少之间的关系，并强调亲属之间竞争发生的规模的重要性。