Sherman Craig D H, Careau Vincent, Gasparini Clelia, Weston Kim J, Evans Jonathan P
School of Life and Environmental Sciences Deakin University Geelong Victoria Australia.
Department of Biology University of Ottawa Ottawa Ontario Canada.
Ecol Evol. 2024 May 2;14(5):e11338. doi: 10.1002/ece3.11338. eCollection 2024 May.
Gamete traits can vary widely among species, populations and individuals, influencing fertilisation dynamics and overall reproductive fitness. Sexual selection can play an important role in determining the evolution of gamete traits with local environmental conditions determining the strength and direction of sexual selection. Here, we test for signatures of post-mating selection on gamete traits in relation to population density, and possible interactive effects of population density and sperm concentration on sperm motility and fertilisation rates among natural populations of mussels. Our study shows that males from high-density populations produce smaller sperm compared with males from low-density populations, but we detected no effect of population density on egg size. Our results also reveal that females from low-density populations tended to exhibit lower fertilisation rates across a range of sperm concentrations, although this became less important as sperm concentration increased. Variances in fertilisation success were higher for females than males and the effect of gamete compatibility between males and females increases as sperm concentrations increase. These results suggest that local population density can influence gamete traits and fertilisation dynamics but also highlight the importance of phenotypic plasticity in governing sperm-egg interactions in a highly dynamic selective environment.
配子特征在物种、种群和个体之间可能存在很大差异，影响受精动态和整体繁殖适应性。性选择在决定配子特征的进化方面可以发挥重要作用，而当地环境条件则决定了性选择的强度和方向。在这里，我们测试了与种群密度相关的配子特征的交配后选择特征，以及种群密度和精子浓度对贻贝自然种群中精子活力和受精率的可能交互作用。我们的研究表明，与低密度种群的雄性相比，高密度种群的雄性产生的精子更小，但我们未检测到种群密度对卵大小的影响。我们的结果还表明，低密度种群的雌性在一系列精子浓度下往往表现出较低的受精率，不过随着精子浓度的增加，这种影响变得不那么重要。雌性受精成功率的方差高于雄性，并且随着精子浓度的增加，雌雄配子兼容性的影响也会增加。这些结果表明，当地种群密度可以影响配子特征和受精动态，但也凸显了表型可塑性在高度动态的选择环境中控制精卵相互作用的重要性。
