Females not only produce costly gametes, but also store the eggs until laying them, a period called gravidity. The volume that eggs occupy in the female abdomen may decrease female foraging ability by making them slower. Although females of all species are subjected to these potential costs, it remains an unexplored matter in invertebrates. Females of the spider Paratrechalea ornata carry their egg sac after oviposition and thus represent a unique opportunity to evaluate gravidity costs because females carry an extra volume before and after laying eggs. We conducted foraging ability experiments using P. ornata females on different treatments regarding gravidity and maternal care. We first hypothesized that internal egg load and egg sac carrying decrease female foraging ability. We also hypothesized that greater egg sac size decreases female foraging ability. We found that both internal egg load and egg sac carrying decreased female foraging ability, and females about to oviposit had a similar foraging ability to females carrying an egg sac. Egg sac size did not influence female foraging ability. Our results show that females’ foraging ability changes before the maternal care period and therefore may influence their life-history evolution. The little support for our second hypothesis may also suggest that the decrease in foraging ability is not due to the volume being carried per se, but possibly an associated physiological state.

中文翻译：

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与新热带蜘蛛繁殖相关的雌性觅食障碍

雌性不仅会产生昂贵的配子，还会在产卵前储存卵子，这一时期称为受孕。卵在雌性腹部占据的体积可能会使它们变慢，从而降低雌性的觅食能力。尽管所有物种的雌性都会承受这些潜在的成本，但在无脊椎动物中这仍然是一个未开发的问题。Paratrechalea ornata 蜘蛛的雌性在产卵后携带卵囊，因此代表了评估妊娠成本的独特机会，因为雌性在产卵前后携带额外的体积。我们使用 P. ornata 雌性对怀孕和母体护理的不同处理进行了觅食能力实验。我们首先假设内部卵子负荷和卵囊携带会降低雌性觅食能力。我们还假设更大的卵囊会降低雌性的觅食能力。我们发现内部卵子负荷和携带卵囊的雌性觅食能力均降低，即将排卵的雌性与携带卵囊的雌性具有相似的觅食能力。卵囊大小不影响雌性觅食能力。我们的研究结果表明，雌性的觅食能力在母亲照顾期之前发生了变化，因此可能会影响它们的生活史演变。对我们的第二个假设的支持也可能表明，觅食能力的下降不是由于携带的体积本身，而是可能与相关的生理状态有关。即将排卵的雌性与携带卵囊的雌性具有相似的觅食能力。卵囊大小不影响雌性觅食能力。我们的研究结果表明，雌性的觅食能力在母亲照顾期之前发生了变化，因此可能会影响它们的生活史演变。对我们的第二个假设的支持也可能表明，觅食能力的下降不是由于携带的体积本身，而是可能与相关的生理状态有关。即将排卵的雌性与携带卵囊的雌性具有相似的觅食能力。卵囊大小不影响雌性觅食能力。我们的研究结果表明，雌性的觅食能力在母亲照顾期之前发生了变化，因此可能会影响它们的生活史演变。对我们的第二个假设的支持也可能表明，觅食能力的下降不是由于携带的体积本身，而是可能与相关的生理状态有关。