Data from: No evidence for postcopulatory inbreeding avoidance in Drosophila melanogaster

Selection to avoid inbreeding is predicted to vary across species due to differences in population structure and reproductive biology. Over the past decade, there have been numerous investigations of postcopulatory inbreeding avoidance, a phenomenon that first requires discrimination of mate (or sperm) relatedness and then requires mechanisms of male ejaculate tailoring and/or cryptic female choice to avoid kin. The number of studies that have found a negative association between male-female genetic relatedness and competitive fertilization success is roughly equal to the number of studies that have not found such a relationship. In the former case, the underlying mechanisms are largely unknown. The present study was undertaken to verify and expand upon a previous report of postcopulatory inbreeding avoidance in D. melanogaster, as well as to resolve underlying mechanisms of inbreeding avoidance using transgenic flies that express a sperm head-specific fluorescent tag. However, siblings did not have a lower fertilization success as compared to unrelated males in either the first (P1) or second (P2) mate role in sperm competition with a standard unrelated competitor male in our study population of D. melanogaster. Analyses of mating latency, copulation duration, egg production rate and remating interval further revealed no evidence for inbreeding avoidance.

由于种群结构与生殖生物学特征的差异，避免近交的选择作用在不同物种间存在差异。近十年来，学界针对交配后近交回避（postcopulatory inbreeding avoidance）开展了大量研究：该现象首先需要对配偶（或精子）的亲缘关系进行识别，随后需要通过雄性射精调控和/或隐蔽雌性选择等机制来规避近交。发现雌雄个体遗传亲缘关系与竞争受精成功率呈负相关的研究数量，与未发现该关联的研究数量大致相当。在前一类研究中，其潜在作用机制目前尚不完全明确。本研究旨在验证并拓展此前关于黑腹果蝇（D. melanogaster）交配后近交回避的研究报道，并通过表达精子头部特异性荧光标记的转基因果蝇解析近交回避的潜在作用机制。然而，在本研究使用的黑腹果蝇种群中，无论是在与标准无关竞争者雄性进行精子竞争时的第一配偶（P1）还是第二配偶（P2）角色中，同胞雄性的受精成功率均未低于无关雄性。对交配潜伏期、交配时长、产卵率以及再次交配间隔的分析同样未发现存在近交回避的证据。