Müller Thorben, Lamprecht Tabea Dagmar, Schrieber Karin
Department of Chemical Ecology Bielefeld University Bielefeld Germany.
Martin-Luther-University Halle-Wittenberg Institute of Biology, Geobotany and Botanical Garden Halle (Saale) Germany.
Ecol Evol. 2018 Jun 22;8(14):6889-6898. doi: 10.1002/ece3.4205. eCollection 2018 Jul.
Ongoing habitat loss and fragmentation result in rapid population size reductions, which can increase the levels of inbreeding. Consequently, many species are threatened by inbreeding depression, a loss of individual fitness following the mating of close relatives. Here, we investigated inbreeding effects on fitness-related traits throughout the lifetime of the mustard leaf beetle () and mechanisms for the avoidance of inbreeding. Previously, we found that these beetles have family-specific cuticular hydrocarbon profiles, which are likely not used as recognition cue for precopulatory inbreeding avoidance. Thus, we examined whether adult beetles show postcopulatory inbreeding avoidance instead. For this purpose, we determined the larval hatching rate of eggs laid by females mated sequentially with two nonsiblings, two siblings, a nonsibling, and a sibling or . The beetles suffered from inbreeding depression throughout their entire ontogeny, as evinced by a prolonged larval development, a decreased larval and adult survival and a decreased reproductive output of inbred compared to outbred individuals. The highest larval hatching rates were detected when females were mated with two nonsiblings or first with a sibling and second with a nonsibling. Significantly lower hatching rates were measured in the treatments with a sibling as second male. Thus, the results do not support the existence of postcopulatory inbreeding avoidance in , but revealed evidence for second male sperm precedence. Consequently, an alternative strategy to avoid inbreeding costs might exist in this beetle, such as a polyandrous mating system, potentially coupled with a specific dispersal behavior.
持续的栖息地丧失和破碎化导致种群数量迅速减少，这可能会增加近亲繁殖的程度。因此，许多物种受到近亲繁殖衰退的威胁，即近亲交配后个体适应性的丧失。在这里，我们研究了近亲繁殖对芥菜叶甲一生中性状适应性的影响以及避免近亲繁殖的机制。此前，我们发现这些甲虫具有家族特异性的表皮烃类特征，这可能不是用于交配前避免近亲繁殖的识别线索。因此，我们转而研究成年甲虫是否表现出交配后避免近亲繁殖的行为。为此，我们测定了雌性甲虫依次与两只非同胞、两只同胞、一只非同胞和一只同胞或[此处原文缺失具体内容]交配后所产卵的幼虫孵化率。与非近亲个体相比，近亲繁殖的甲虫在整个个体发育过程中都受到近亲繁殖衰退的影响，表现为幼虫发育时间延长、幼虫和成虫存活率降低以及繁殖产出减少。当雌性与两只非同胞交配或先与一只同胞交配然后再与一只非同胞交配时，幼虫孵化率最高。当同胞作为第二只雄性进行交配时，测得的孵化率显著较低。因此，结果不支持芥菜叶甲存在交配后避免近亲繁殖的现象，但揭示了第二只雄性精子优先的证据。因此，这种甲虫可能存在一种避免近亲繁殖成本的替代策略，比如多配偶交配系统，可能与特定的扩散行为相结合。
