Mate choice, fecundity and sexual dimorphism in two pipefish species (Syngnathidae)
Mate choice, fecundity and sexual dimorphism in two pipefish species (Syngnathidae)
复制标题
两种尖嘴鱼（Syngnathidae）的配偶选择、繁殖力和性二态性
DOI：
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发表时间：
1986
影响因子：
2.3
通讯作者：
I. Svensson
中科院分区：
文献类型：
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作者：
A. Berglund;G. Rosenqvist;I. Svensson
摘要为了了解海豚两性异型的原因，研究了两种海豚的交配选择和与大小相关的繁殖力。北极熊的性二型性更明显；雌性体型较大，有性色彩，在求爱时也更活跃。在S.typhle中，两性在所有这些方面都是相似的。在这两个物种中，雄性都会孵化后代。雌鸟的繁殖力与个体大小和性染色量呈正相关。在雄性中，身体大小和繁殖力之间或身体大小和胚胎大小之间不存在相关性。不出所料，在与同等体型的女性进行的择偶实验中，男性会选择性色更丰富的女性。我们解释说，这种物种的性二型性是自然选择(雌性生殖力随着体型增加而增加，但雄性不是)和性选择(雄性更喜欢体型较大的雌性)的结果。我们认为，性别大小的二形性并不是通过选择最小化两性之间食物生态位的重叠而进化的，因为在鱼类生活的Zostera床上的食物产量很高，而在共生的伤寒沙门氏菌中没有发现大小二型性。此外，在北极熊中，特定嘴部特征的二型性并不比整个身体大小更大。斑疹伤寒沙门氏菌的卵子大小和每次产卵的平均转移数与雌体大小呈正相关。显然，每个后代由体型较大的雄性比体型较小的雄性提供更多的能量，并且体型较大的雄性也会产生更多的后代。正如预测的那样，在择偶实验中，两种性别都更喜欢体型较大的配偶。这在自然选择(两性的繁殖力随着体型的增加)和性选择(两性都喜欢较大的配偶)两个方面都是可以解释的。由于两性选择的方向一致，伤寒沙门氏菌中不存在性别二型性。
SummaryIn order to understand the causes of sexual dimorphism, mate choice and size-related fecundity were studied in two pipefish species, Syngnathus typhle and Nerophis ophidion. Sexual dimorphism is more pronounced in N. ophidion; females are larger, have sexual colourings, and are more active during courtship. In S. typhle the sexes are alike in all these respects. Males brood their offspring in both species. In N. ophidion fecundity was positively correlated with both body size and the amount of sexual colouring in females. In males no correlation between body size and fecundity, or between body size and embryo size existed. Predictably, in mate choice experiments with equal-sized females, males chose females with more extensive sexual colourings. We explain sexual dimorphism in this species as a consequence of both natural selection (fecundity increases with size in females but not in males) and sexual selection (males prefer larger females). We argue that sexual size dimorphism did not evolve by selection minimizing overlap in food niches between the sexes, because food production is high in the Zostera beds where the fishes live, and no size dimorphism was found in the sympatrically occurring S. typhle. Furthermore, in N. ophidion dimorphism is not greater in a particular mouth character than in overall body size. In S. typhle egg size and the average number of eggs transferred per spawning were positively correlated with female body size. Apparently more energy per offspring was provided by larger males than by smaller males, and larger males also carried more offspring. As predicted, large mates were preferred by both sexes in mate choice experiments. This is explicable in terms of both natural selection (fecundity increases with size in both sexes) and sexual selection (both sexes prefer large mates). As a consequence of selection acting in the same direction in both sexes, sexual dimorphism is absent in S. typhle.