Male-lure type, lure dosage, and fly age at feeding all influence male mating success in Jarvis’ fruit fly

Males of certain Dacini fruit flies are strongly attracted to, and feed upon, plant secondary compounds such as methyl eugenol, raspberry ketone and zingerone. The consumed lure is generally found to induce physiological and behavioural changes that enhance the mating performance of lure-fed males. Male Bactrocera jarvisi respond strongly to zingerone from a young age, but only weakly respond to raspberry ketone. We hypothesized that this selective lure-response would be reflected in the physiological importance of the lure to the fly. We found that zingerone feeding by young males resulted in significantly greater mating success in competitive mating trials with lure-deprived flies, but the mating advantage was lost in older males. Lure dosage had a significant effect on the duration of the mating advantage, for example when fed 20 µg of zingerone, the advantage lasted only 1 day post-feeding, but when fed of 50 µg zingerone the advantage lasted 7 days. Raspberry ketone feeding did not confer any mating advantage to males except at one dosage (50 µg) for 1 day after feeding. When given a choice, B. jarvisi females preferred to mate with zingerone-fed versus to raspberry ketone-fed males. This study revealed lure, dosage and age of fly at time of lure administration are all important factors for maximising lure-enhanced fruit fly mating performance. These findings contribute to a better theoretical understanding of the evolution of fruit fly-lure interactions and may help improve fruit fly pest management via the Sterile Insect Technique through semiochemical-mediated enhancement of sterile male mating performance.

Women’s Talk?

According to some feminist critiques, gossip is merely a form of women’s talk and thus an activity that men do not participate in. Yet gossip may be an ideal strategy for both men and women to engage in when involved in mate competition, allowing the individual to covertly damage a competitor’s reputation while simultaneously preserving his or her own. This chapter investigates the role of gossip in mate competition, considering the influence of variables including sex and attraction context on both the usage and success of a gossip-based competition strategy. Evidence shows that, although sex differences do exist in reputation-based gossip, both men and women are willing to use gossip strategically in order to gain a mating advantage. Overall, it appears that gossip is an effective, low-risk, and non-sex-specific intrasexual competition strategy for individuals to employ in both traditional and poaching attraction contexts.

Experimental evidence that extra-pair mating drives asymmetrical introgression of a sexual trait

Theory suggests that traits under positive selection may introgress asymmetrically across a hybrid zone, potentially driven by sexual selection. Two subspecies of the red-backed fairy-wren ( Malurus melanocephalus ) differ primarily in a sexual signal used in mate choice—red versus orange male back plumage colour—but phylogeographic analyses suggest asymmetrical introgression of red plumage into the genetic background of the orange subspecies. We hypothesized that this asymmetrical introgression may be facilitated by sexual selection if red males have a mating advantage over orange males. We tested this hypothesis with correlational data and a plumage manipulation experiment where we reddened the back plumage of a subset of orange males to mimic males of the red subspecies. There was no correlational evidence of a mating advantage to naturally redder males in this population. Experimentally reddened males sired a similar amount of within-pair young and lost paternity at the same rate as orange males, but they sired significantly more extra-pair young, leading to substantially higher total reproductive success. Thus, we conclude that sexual selection via extra-pair mating is a likely mechanism responsible for the asymmetrical introgression of plumage colour in this system, and is potentially driven by a sensory bias for the red plumage signal.

Mating patterns of Rana kukunoris from three populations along an altitudinal gradient on the Tibetan Plateau

Large-male mating advantage and size-assortative mating are two different size-dependent mating patterns which deviate from random mating in frogs. These two pairing patterns may arise due to female choice, male-male competition, male choice, or a combination of these. Our study investigated the mating system of Rana kukunoris at three elevations on the Tibetan Plateau, southwestern China, throughout a breeding season. We compared body size between amplectant and non-amplectant males, and among amplectant pairs. For R. kukunoris, the results showed a large-male mating advantage at the two higher elevations and a size-assortative mating at the highest elevation. In addition to sexual selection, we found that the length of the breeding season, population density and operational sex ratio may influence mating patterns.