Department of Biology, California State University, Northridge, California, USA.
J Fish Biol. 2019 Aug;95(2):472-479. doi: 10.1111/jfb.13981. Epub 2019 Apr 26.
To test life-history theory that body size and sex should influence how animals allocate time to foraging versus reproductive activities, we measured the effects of size and sex on courting success and foraging behaviour of black surfperch Embiotoca jacksoni off Santa Catalina Island, southern California. Observations of focal fish were made while snorkelling, during which the length of each fish (estimated to the nearest cm), total duration of courting encounters and foraging rates were recorded. We made observations during and outside the mating season. Courtship occurred only between pairs and its duration increased with the size of both the male and female. Although males would court females that were smaller or larger than themselves, pairs that were closely matched in size had long courting sessions, whereas those that differed considerably in size courted only briefly. Small fish foraged more than larger fish, both during and outside the mating season. Males and females foraged at similar rates outside of the mating season, but during the mating season males reduced their foraging rates to less than half that seen outside of the mating season, whereas females continued to forage at the same rate. This decrease in foraging rate of males during the mating season was seen in all sizes of males but was proportionally greatest in the largest males. These observations indicate that males trade off time spent on foraging for time spent courting during the mating season, whereas females do not.
为了检验体型和性别应该会影响动物在觅食和繁殖活动之间分配时间的生活史理论，我们测量了体型和性别对加利福尼亚州南部圣卡塔利娜岛外黑鲈 Embiotoca jacksoni 的求偶成功率和觅食行为的影响。在浮潜时对焦点鱼进行观察，记录每条鱼的长度（估计到最接近的厘米）、求偶遭遇的总持续时间和觅食率。我们在交配季节内外进行观察。求偶仅发生在配对之间，其持续时间随雄性和雌性的体型增加而增加。尽管雄性会向比自己小或大的雌性求偶，但体型匹配的配对求偶时间较长，而体型差异较大的配对仅求偶很短时间。小鱼在交配季节内外觅食的频率都高于大鱼。在交配季节之外，雄性和雌性的觅食率相似，但在交配季节，雄性将觅食率降低到交配季节之外的一半以下，而雌性则继续以相同的速度觅食。在交配季节，所有体型的雄性都表现出这种觅食率下降的情况，但最大的雄性下降幅度最大。这些观察结果表明，雄性在交配季节会牺牲觅食时间来换取求偶时间，而雌性则不会。
