RSPB：屎壳郎—力量最大的昆虫

新手必读秘籍大全！（对权限及积分的说明，更新中）屎壳郎因推粪球而闻名，但直至最近，科学家才以数据证明它们是地球上已知的最强壮昆虫：一种名为食粪金龟的屎壳郎可以推动相当于自身体重1000多倍的粪球。

英国《皇家学会生物学分会学报》24日刊登伦敦大学和西澳大利亚大学研究者联合发表的一项研究报告。报告说，可监测到的数据显示，蜣螂目中的雄性食粪金龟最多可推动相当于自身体重1141倍的粪球。

报告形象地比喻，雄性食粪金龟之强壮好比一名体重70千克的人推动80吨重物。目前，世界上已知相对力气最大的动物是一种螨，这种螨的力气比雄性食粪金龟略大。但在昆虫界，没有任何昆虫可与食粪金龟比强壮。

科学家在研究雄性食粪金龟的生活习性后发现，争夺交配权是这一物种在进化过程中气力不断增加的主要动因。在交配时，雌性食粪金龟一般藏在隧道内，争夺雌性配偶的雄性食粪金龟须在隧道内两两对决，以各自的角顶牛，被推出隧道者出局。

正是在长期争夺“女友”过程中，食粪金龟得以进化体格，成为昆虫界的大力士。（生物谷Bioon.com）
生物谷推荐原文出处：

the journal Proceedings of the Royal Society B doi: 10.1098/rspb.2010.0257 、

Mating tactics determine patterns of condition dependence in a dimorphic horned beetle
Robert J. Knell1,* and Leigh W. Simmons2

The persistence of genetic variability in performance traits such as strength is surprising given the directional selection that such traits experience, which should cause the fixation of the best genetic variants. One possible explanation is ‘genic capture’ which is usually considered as a candidate mechanism for the maintenance of high genetic variability in sexual signalling traits. This states that if a trait is ‘condition dependent’, with expression being strongly influenced by the bearer's overall viability, then genetic variability can be maintained via mutation-selection balance. Using a species of dimorphic beetle with males that gain matings either by fighting or by ‘sneaking’, we tested the prediction of strong condition dependence for strength, walking speed and testes mass. Strength was strongly condition dependent only in those beetles that fight for access to females. Walking speed, with less of an obvious selective advantage, showed no condition dependence, and testes mass was more condition dependent in sneaks, which engage in higher levels of sperm competition. Within a species, therefore, condition dependent expression varies between morphs, and corresponds to the specific selection pressures experienced by that morph. These results support genic capture as a general explanation for the maintenance of genetic variability in traits under directional selection.

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