College of Life and Environmental Sciences, Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, Cornwall, UK.
Mol Ecol. 2013 Mar;22(6):1640-9. doi: 10.1111/mec.12187. Epub 2013 Jan 7.
Mechanisms that prevent different species from interbreeding are fundamental to the maintenance of biodiversity. Barriers to interspecific matings, such as failure to recognize a potential mate, are often relatively easy to identify. Those occurring after mating, such as differences in the how successful sperm are in competition for fertilisations, are cryptic and have the potential to create selection on females to mate multiply as a defence against maladaptive hybridization. Cryptic advantages to conspecific sperm may be very widespread and have been identified based on the observations of higher paternity of conspecifics in several species. However, a relationship between the fate of sperm from two species within the female and paternity has never been demonstrated. We use competitive microsatellite PCR to show that in two hybridising cricket species, Gryllus bimaculatus and G. campestris, sequential cryptic reproductive barriers are present. In competition with heterospecifics, more sperm from conspecific males is stored by females. Additionally, sperm from conspecific males has a higher fertilisation probability. This reveals that conspecific sperm precedence can occur through processes fundamentally under the control of females, providing avenues for females to evolve multiple mating as a defence against hybridization, with the counterintuitive outcome that promiscuity reinforces isolation and may promote speciation.
防止不同物种杂交的机制是生物多样性维持的基础。种间交配的障碍，如无法识别潜在的配偶，通常相对容易识别。而那些发生在交配之后的障碍，如精子在竞争受精时的成功率差异，则是隐蔽的，有可能对雌性进行选择，使其多次交配，以防止适应性杂交。同种精子的隐蔽优势可能非常广泛，并且已经根据在几个物种中观察到的同种精子具有更高的父权地位的现象而得到证实。然而，在雌性体内两种物种的精子的命运与父权地位之间的关系从未得到证明。我们使用竞争性微卫星 PCR 表明，在两种杂交蟋蟀物种，Gryllus bimaculatus 和 G. campestris 中，存在连续的隐蔽生殖障碍。在与异配种的竞争中，雌性会储存更多来自同种雄性的精子。此外，来自同种雄性的精子具有更高的受精概率。这表明同种精子优先可能通过受雌性基本控制的过程发生，为雌性进化多次交配提供了途径，以防止杂交，其结果与直觉相反，滥交加强了隔离，并可能促进物种形成。
