Altitude underlies variation in the mating system, somatic condition, and investment in reproductive traits in male Asian grass frogs (Fejervarya limnocharis)
Altitude underlies variation in the mating system, somatic condition, and investment in reproductive traits in male Asian grass frogs (Fejervarya limnocharis)
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DOI：
10.1007/s00265-016-2128-9
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发表时间：
2016-08-01
影响因子：
2.3
通讯作者：
Lupold, Stefan
中科院分区：
文献类型：
--
作者：
Jin, Long;Yang, Sheng Nan;Lupold, Stefan
有大量的比较和越来越多的实验证据表明，来自不同男性的精子之间的受精竞争可以驱动男性生殖投资的变化。然而，鲜为人知的是，在这些投资相对于环境变量的自然变化的程度影响资源的可用性和交配系统的动态，这将使深入了解生殖分配的机制。在这里，我们研究了在中国沿着1550公里的纬度和1403米的海拔样带在25个种群的亚洲草蛙Fejervarya limnocharis的睾丸大小和精子长度的男性投资的种群间变异。我们发现相对睾丸质量和精子长度，男性躯体状况，和男性/女性的性别比增加海拔，但不是纬度或经度。我们的研究结果表明，环境变化可能是自然种群对生殖投资的局部适应的基础，其介导因素是资源和性伴侣的可用性差异（包括由此产生的雄性与雄性竞争）。这些研究结果与以前的预测，增加纬度和/或海拔应导致雄性无尾两栖类生殖投资下降，由于繁殖季节缩短，资源供应下降，降低（而不是增加）男性/女性的性别比例。我们讨论了这些物种的差异的背景下，不同的资源分配策略，繁殖生态，和模式的男性-男性竞争。这些差异表明，未来的工作需要在无尾两栖动物的生殖投资超出了几个模型系统和潜在的扩展的理论框架，以不同的交配系统和strategy.Despite广泛的理论框架，环境参数如何可以塑造交配系统，这些，反过来，推动生殖性状的进化，有有限的经验证据，从自然种群。我们研究了睾丸和精子的大小之间的差异，男性之间的自然种群沿着纬度和海拔横断面。我们发现，在高海拔地区，男性相对较重，精子较长，睾丸不成比例地大，性别比例更偏向男性。这些种群间的差异可能反映了当地的适应性变化的资源可用性和时间模式的女性可用性，这影响了育种同步，精子需求，男性和男性的配偶和父权竞争。然而，我们的研究结果不同于以往的研究青蛙，可能是由于不同的繁殖生态，这突出了需要进一步的工作和潜在的扩展的理论预测非模型无尾类。
There is substantial comparative and growing experimental evidence that the competition for fertilization among sperm from different males can drive variation in male reproductive investments. However, less is known about the extent of natural variation in these investments relative to environmental variables affecting resource availability and mating system dynamics, which would allow insights into the mechanisms shaping reproductive allocation. Here, we studied interpopulation variation in male investments in testis size and sperm length across 25 populations of the Asian grass frog Fejervarya limnocharis along a 1550-km latitudinal and 1403-m altitudinal transect in China. We found relative testis mass and sperm length, male somatic condition, and the male/female sex ratio to increase with elevation but not latitude or longitude. Our results suggest that environmental variation may underlie local adaptations to reproductive investments among natural populations, mediated by differences in the availability of both resources and sexual partners (including the resulting male-male competition). These findings contrast with previous predictions that increasing latitude and/or elevation should lead to declining reproductive investments in male anurans due to shortening breeding seasons, declining resource availability, and lowering (rather than increasing) male/female sex ratios. We discuss these species differences in the context of differential resource allocation strategies, breeding ecology, and patterns of male-male competition. These differences show the need for future work on reproductive investments in anurans beyond the few model systems and for potential extension of the theoretical framework to species with different mating systems and strategies.Despite a broad theoretical framework of how environmental parameters can shape mating systems and these, in turn, drive the evolution of reproductive traits, there is limited empirical evidence from natural populations. We examined differences in the size of testes and sperm between males between natural populations along latitudinal and altitudinal transects. We found that at high elevation, males were relatively heavier and had longer sperm and disproportionately large testes, and the sex ratio was more male-biased. These interpopulation differences may reflect local adaptations to variation in the resource availability and temporal patterns of female availability, which affects the breeding synchrony, sperm demand, and male-male competition for mates and paternity. However, our results differ from previous studies of frogs, possibly due to different breeding ecology, which highlights the need for further work and potential extension of theoretical predictions to non-model anurans.