Meeting Abstract
Reproductive interference, or reproductive interactions between heterospecific individuals, is commonly reported across taxa, but its drivers are still far from clear. One potentially powerful approach to uncover its causes is to examine an individual’s heterospecific interactions in relation to it’s conspecific mating behavior, within the broader context of the species’ mating system. Here we use a social network approach to compare inter- and intraspecific mating dynamics in the squash bug Anasa tristis and its close relative A. andresii. Using replicated semi-natural enclosures, we surveyed the mating behavior of individually marked A. tristis bugs (10 males and 10 females per trial) at hourly intervals over a 10 day period using a robotic camera system. We then repeated this, replacing 5 A. tristis males and females per enclosure with A. andresii counterparts. Mating networks in intraspecific trials were highly saturated. Bugs mated with almost all available partners, inducing potentially high levels of post-copulatory sperm competition with little evidence of pre-copulatory selection. Despite high promiscuity, male mating effort was unevenly distributed across females; males typically had strong mating associations with just one or two females and weaker associations with all other partners. Similar patterns were observed in interspecific trials: around 20% of individuals engaged in heterospecific matings, but the majority of mating activity took place between conspecifics. Females from interspecific trials had comparable hatching success with those from conspecific trials. Consequently, relatively high levels of reproductive interference may emerge under semi-natural conditions as a byproduct of limited intraspecific pre-copulatory choice paired with limited fitness penalties.
