Nutritional implications for sexual cannibalism in a sexually dimorphic orb web spider
Nutritional implications for sexual cannibalism in a sexually dimorphic orb web spider
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DOI：
10.1111/j.1442-9993.2010.02161.x
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发表时间：
2011-06-01
期刊：
影响因子：
1.5
通讯作者：
Blamires, Sean J.
中科院分区：
文献类型：
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作者：
Blamires, Sean J.
模型预测机制驱动性食同类的蜘蛛与性大小二态性（SSD）通常假设，蜘蛛使用交配后的食物通道营养进入鸡蛋和繁殖力是通过改变离合器大小或蛋质量。我使用带有极端SSD的orb web spider测试了这些假设，Argiope keyserlingi。我给交配的雌性蜘蛛喂食高蛋白低能量或低蛋白高能量的猎物。我测量了鸡蛋的能量密度，即蛋黄和蛋白的相对体积。我预测如果A. Keyserlingi增加了他们的蛋能量密度后，在特定的营养成分的猎物喂养，他们可以提高其繁殖力，投资更多的能量密度的蛋。然而，如果卵子的能量密度与交配后的猎物不同，它们必须从体细胞储备中获取能量来投资于卵子。在进一步的实验中，我让雌性蜘蛛与雄性蜘蛛交配并吃同类，以确定同类相食是否会对卵的能量密度产生类似的影响。雄性蜘蛛蛋白质能量比的测量和发现类似于高蛋白质低能量的猎物。我发现在两个实验中交配后食物和鸡蛋的成分之间存在分歧。此外，喂食高蛋白低能量猎物的蜘蛛体重减轻，表明它们利用能量储备来投资于蛋。因此，我得出结论，以高蛋白低能量猎物或雄性为食的蜘蛛会增加卵的能量密度，并可能增加繁殖力。然而，猎物或雄性的营养成分不能提供对卵的投资。卵细胞所消耗的能量来自躯体的储备，可能是由一种尚未描述的生理触发因素引起的。
Models predicting mechanisms driving sexual cannibalism in spiders with sexual size dimorphism (SSD) often assume that spiders use post-copulatory food to channel nutrients into eggs and fecundity is altered through changes in clutch size or egg mass. I tested these assumptions using an orb web spider with extreme SSD, Argiope keyserlingi. I fed mated female spiders prey of either high protein-low energy or low protein-high energy composition. I measured egg energy density; a measure of the relative volumes of yolk and albumen. I predicted that if A. keyserlingi increase their egg energy density upon feeding on prey of a specific nutrient composition, they could enhance their fecundity by investing in more energy dense eggs. However, if the egg energy densities are dissimilar to their post-copulatory prey they must be drawing energy from their somatic reserves to invest in eggs. In a further experiment I allowed female spiders to mate with and cannibalize males to determine if cannibalism induces similar effects on egg energy density. Male spider protein energy ratio was measured and found to resemble the high protein-low energy prey. I found disagreement between the composition of post-copulatory food and eggs in both experiments. Additionally, spiders fed high protein-low energy prey lost weight indicating that they draw on their energy reserves to invest in eggs. I thus concluded that spiders that feed on high protein-low energy prey or on males increase their egg energy density and, possibly, fecundity. However, the nutrient content of the prey or males cannot provide for investment in eggs. The energy invested in eggs is drawn from somatic reserves, probably induced by an as yet undescribed physiological trigger.