Monandrous Females Regain Sexual Receptivity and Produce Fewer Offspring After Short Copulations
Mentor 1
Rafael Rodriguez Sevilla
Start Date
28-4-2023 12:00 AM
Description
Male fitness is a function of the number of mates they can inseminate, yet males often engage in prolonged copulations rather than seek out new mates. Potential explanations for this behavior include the ejaculate transfer hypothesis, which states that longer copulations function to achieve higher levels of insemination, and the mate-guarding hypothesis which states longer copulations function to prevent the female from mating again. Interestingly, prolonged copulations can occur in monandrous species where these functions would not seem to apply. We investigated prolonged mating in a monandrous-polygynous species, a member of the Enchenopa treehoppers (Hemiptera: Membracidae). These insects form pairs by using plant-borne vibrational signals. Copulation can last up to three hours. We tested a version of the mate-guarding hypothesis by which prolonged copulation functions to reduce female receptivity and promote offspring production. In other words, monandry in this species may be due to male ejaculate substances. If so, females would be more likely to duet with male signals and less likely to produce offspring as mating duration declines. We randomly assigned receptive females to copulation duration treatments of either 10, 30, 45, or 60 minutes before we separated the pairs. We also included a control group where the pairs were not interrupted during copulations. We found that females that experienced copulations lasting ≤30 minutes were more likely to duet with playbacks after mating compared to females that had uninterrupted matings. These control females (copulations lasting 104 minutes, on average) rarely duetted with subsequent playbacks. Further, we found that females that mated for ≤45 minutes were less likely to produce offspring than females in other treatments. Our results suggest that extreme copulation length may function to lower female receptivity and promote offspring production by the transfer of ejaculate substances, effectively causing monandry in some species.
Monandrous Females Regain Sexual Receptivity and Produce Fewer Offspring After Short Copulations
Male fitness is a function of the number of mates they can inseminate, yet males often engage in prolonged copulations rather than seek out new mates. Potential explanations for this behavior include the ejaculate transfer hypothesis, which states that longer copulations function to achieve higher levels of insemination, and the mate-guarding hypothesis which states longer copulations function to prevent the female from mating again. Interestingly, prolonged copulations can occur in monandrous species where these functions would not seem to apply. We investigated prolonged mating in a monandrous-polygynous species, a member of the Enchenopa treehoppers (Hemiptera: Membracidae). These insects form pairs by using plant-borne vibrational signals. Copulation can last up to three hours. We tested a version of the mate-guarding hypothesis by which prolonged copulation functions to reduce female receptivity and promote offspring production. In other words, monandry in this species may be due to male ejaculate substances. If so, females would be more likely to duet with male signals and less likely to produce offspring as mating duration declines. We randomly assigned receptive females to copulation duration treatments of either 10, 30, 45, or 60 minutes before we separated the pairs. We also included a control group where the pairs were not interrupted during copulations. We found that females that experienced copulations lasting ≤30 minutes were more likely to duet with playbacks after mating compared to females that had uninterrupted matings. These control females (copulations lasting 104 minutes, on average) rarely duetted with subsequent playbacks. Further, we found that females that mated for ≤45 minutes were less likely to produce offspring than females in other treatments. Our results suggest that extreme copulation length may function to lower female receptivity and promote offspring production by the transfer of ejaculate substances, effectively causing monandry in some species.
