تداخل باروری در حشرات Reproductive interference in insects

Introduction Mating systems are sexual networks of individuals, describing how, where, when and how often animals come together to mate and raise offspring (Emlen & Oring, 1977; Thornhill & Alcock, 1983; Davies, 1991). Alongside recent reappraisals of how best to quantify and model key mating system parameters (Kokko et al., 2014), there has been growing interest in recent years in – to borrow a popular expression – ‘when good mating systems go bad’, i.e. when unexpected and seemingly non-adaptive behavioural phenotypes arise during reproductive encounters. For instance, there is an increasing realisation that same-sex sexual behaviour is more widespread than previously thought, challenging our understanding of mate recognition and sexual function (including in insects: Bailey & Zuk, 2009). Similarly, it is now clear that mating failure – the failure of individuals, particularly females, to produce offspring – is a more common phenomenon than predicted by our assumptions of strong natural and sexual selection on primary sexual function (Rhainds, 2010). Mating failure can arise in a number of ways (Greenway et al., 2015), with failure to achieve successful insemination despite successful intromission perhaps being one of the more perplexing examples, but this too can be surprisingly common (e.g. 40–60% in Lygaeus seed bugs; Tadler et al., 1999; Dougherty & Shuker, 2014; Greenway & Shuker, 2015). Here we will consider another unexpected aspect of mating systems, again apparent in insects, reproductive interference. Reproductive interference (RI) arises when individuals of different species sexually interact during reproduction, with one or both actors suffering a fitness cost. A groundbreaking review by Gröning and Hochkirch in 2008 revealed that costly heterospecific interactions were widespread in nature (167 bi-species systems, excluding the very many studies on hybridisation). However, the study of RI was perhaps hampered by the various synonyms used (at least 22 different names for the same phenomenon: Gröning & Hochkirch, 2008). Their review also showed that heterospecific interactions were often studied by different groups of biologists, asking different kinds of questions. On the one hand, evolutionary biologists interested in speciation have very often studied heterospecific mating interactions and outcomes, given their obvious interest in reproductive isolation and population divergence (Coyne & Orr, 2004). On the other, ecologists have been interested in RI in the context of its role in ecological character displacement (Dayan & Simberloff, 2005). What perhaps was missing was the middle ground, between ecology and evolution. Here we hope to begin to fill that gap, considering the causes and consequences of reproductive interference in terms of mating system evolution in insects.