Rezaei Abolhasan, Krishna Mysore Siddaiah, Santhosh Hassan T
Drosophila Stock Center, Department of Studies in Zoology, University of Mysore, Manasagangotri, Mysore 560 006, Karnataka, India.
Zoolog Sci. 2015 Jan;32(1):16-24. doi: 10.2108/zs140121.
For species in which mating is resource-independent and offspring do not receive parental care, theoretical models of age-based female mate preference predict that females should prefer to mate with older males as they have demonstrated ability to survive. Thus, females should obtain a fitness benefit from mating with older males. However, male aging is often associated with reductions in quantity of sperm. The adaptive significance of age-based mate choice is therefore unclear. Various hypotheses have made conflicting predictions concerning this issue, because published studies have not investigated the effect of age on accessory gland proteins and sperm traits. D. melanogaster exhibits resource-independent mating, and offspring do not receive parental care, making this an appropriate model for studying age-based mate choice. In the present study, we found that D. melanogaster females of all ages preferred to mate with the younger of two competing males. Young males performed significantly greater courtship attempts and females showed least rejection for the same than middle-aged and old males. Young males had small accessory glands that contained very few main cells that were larger than average. Nevertheless, compared with middle-aged or old males, the young males transferred greater quantities of accessory gland proteins and sperm to mated females. As a result, females that mated with young male produced more eggs and progeny than those that mated with older males. Furthermore, mating with young male reduced female's lifespan. These studies indicate that quantity of accessory gland proteins and sperm traits decreased with male age and females obtain direct fitness benefit from mating with preferred young males.
对于交配与资源无关且后代得不到亲代照料的物种，基于年龄的雌性配偶偏好理论模型预测，雌性应更倾向于与年长雄性交配，因为它们已展现出生存能力。因此，雌性与年长雄性交配应能获得适应性益处。然而，雄性衰老往往与精子数量减少有关。因此，基于年龄的配偶选择的适应性意义尚不清楚。关于这个问题，各种假说做出了相互矛盾的预测，因为已发表的研究尚未调查年龄对附腺蛋白和精子特征的影响。黑腹果蝇表现出与资源无关的交配行为，且后代得不到亲代照料，这使其成为研究基于年龄的配偶选择的合适模型。在本研究中，我们发现所有年龄段的黑腹果蝇雌性都更倾向于与两只竞争雄性中较年轻的一只交配。年轻雄性进行求偶尝试的次数显著更多，与中年和老年雄性相比，雌性对年轻雄性的拒绝最少。年轻雄性的附腺较小，其中包含的主细胞很少，且这些主细胞比平均水平大。然而，与中年或老年雄性相比，年轻雄性向已交配雌性转移的附腺蛋白和精子数量更多。结果，与年轻雄性交配的雌性比与年长雄性交配的雌性产生更多的卵和后代。此外，与年轻雄性交配会缩短雌性的寿命。这些研究表明，附腺蛋白的数量和精子特征会随着雄性年龄的增长而下降，雌性通过与偏好的年轻雄性交配获得直接的适应性益处。
