An examination of the reproduction-flight syndrome in the Texas field cricket, Gryllus texensis

In flying insects, migration by flight and reproduction commonly trade-off as each are energetically costly activities. This trade-off is found among wing dimorphic species, where a long-winged (LW) morph can fly and invests in flight-capability at the cost of reproduction, while a short-winged (SW) morph cannot fly but has greater reproductive output. In a meta-analysis of the literature on wing dimorphic insects, I found that the trade-off was evident in females, where LW females typically have delayed ovarian development and reduced fecundity, relative to SW females. In contrast, less work has been done with males, and it was unclear if the trade-off occurs in males.;In previous studies, animals were not flown, hence the role of flight-capability on the trade-off, and not flight itself, was investigated. I found that flight had a profound effect on the trade-off in both sexes in G. texensis. After flight, the ovary development of LW females was similar to that of SW females and greater than LW females who did not fly. Flown LW males had a greater probability of courting females, and were more aggressive than LW males who did not fly under certain contexts.;My results suggest that the trade-off may have been previously overestimated in wing dimorphic insects, as animals were not flown in previous studies. Moreover, wing dimorphism might reflect a reproduction-flight syndrome, where members of the different flight-morphs possess alternative strategies with respect to reproduction and aggression. Here, flight initiates reproductive investment in LW males and females. Less mobile SW males appear to have behavioural and morphological adaptations to better compete in variable habitats where resources can be limited.;To determine whether or not a trade-off occurs in males, I compared the male flight-morphs in the wing dimorphic cricket, Gryllus texensis, in two behaviours that can greatly influence male reproductive success: courtship and aggression. I found that LW males had a lower probability of courting a female and of fighting a rival relative to SW males. Once LW males could no longer fly through the histolysis of their flight-muscles, I found that they had a similar probability of courting females as SW males, and that they were more aggressive than LW males who could still fly. I also compared the sizes of the mandibles of the male flight-morphs. Mandibles can be used in aggressive displays and as weapons, and previous work has shown that males with larger mandibles are more likely to win fights. I found that in addition to being more aggressive than LW males in encounters with rivals, SW males had significantly larger mandibles for their body size than LW males.