New papers (9 – 16 Jan): crickets, tree frogs, and great tits

Comparing pre- and post-copulatory mate competition using social network analysis in wild crickets (open access article!)

The two types of mating competition – pre- and post-copulatory are usually seen as alternative tactics that male animals can adopt as they try to ensure they sire as many offspring as possible. This study, however, shows this not to be the case, at least in crickets. Using social network analysis, the authors found no trade-off between pre- and post-copulatory competition: males who fought each other more during pre-copulatory competition also interacted indirectly with one another later on, during the post-copulatory phase. The really interesting bit is how post-copulatory social networks were constructed. Males were linked to one another if they successfully mated (by transferring a batch of sperm in a spermatophore, a structure typical of insects) with the same female and were thus considered to be in sperm competition. Fighting off competitors was not an effective means from preventing them from copulating with particular females. The authors conclude their data support the idea that in species where males cannot monopolize mating, the evolution of alternative male phenotypes is unlikely. They also suggest that mating success can be a poor proxy for reproductive success, given that males who mate more often may lose out more paternity via sperm competition. A useful reminder for those of us, studying primate mating behaviour and mating success.

Male treefrogs in low condition resume signaling faster following simulated predator attack

Individuals that have less to loose are expected to take greater risks (especially when the reproductive payoffs of doing so may be significant). This study shows this to be true in male treefrogs as they called to attract mates. The time they took to resume calling (advertising themselves as potential mating partners to nearby females) after a simulated predator attack (grabbing the frog) was shorter in males who were in poor condition – i.e. low-quality males were willing to take greater risks in the face of potential predation. Some caveats apply (condition predicted response in only one of two years; old age did not predict shorter call resumption times, contrary to predictions) but the results provide a nice example of the how individual physical condition may affect risk-taking behavior and thus potentially affect male mating success.

To sing or not to sing: seasonal changes in singing vary with personality in wild great tits

Staying with the topic of signalling, this study adds another dimension to our understanding of what determines how much effort males put into advertising their presence to mates and competitors. Personality matters, too. Male great tits that were determined to be ‘faster explorers’ (i.e. less shy), increased their singing more during the periods their mate was most fertile and during periods of maximum maternal investment (egg laying and incubation). This contrasts with earlier ideas that faster explorers pay less attention to changes in their social environment than slow explorers. The increased singing of fast explorers during key stages of the reproductive cycle was also correlated with more fledged chicks. This finding supports the idea that greater singing activity may reflect the quality of the males or the territory they occupy but the exact mechanism that links male personality and their singing patterns to increased reproductive success remains an open question.

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