Sherratt Lab

I am studying signal detection theory as part of the reproductive behavior of two damselfly species, Nehalennia irene and Nehalenni gracilis. N. irene is a polymorphic species with a female morph (andromorph) resembling the colour of the conspecific male and a female (gynomorph) that has strikingly different colouring than the other two. N. gracilis is currently known to be monomorphic with a female generally resembling the male. What makes this system interesting is that the monomorphic female of N. gracilis is identical in colour pattern to the male and andromorph of N. irene. Furthermore, both species may be found in the same habitat. It is believed that polymorphism arises as a consequence of intensive male harassment, and that males choose mates due to a combination of learned mate recognition and male mimicry hypotheses. In sympatric populations, N. irene andromorphs would be a mimic of N. gracilis females; increasing the overall number of “mimics” and we should see increased attempts to mate with andromorphs, without less mating attempts with gynomorphs compared to allopatric populations. I will also investigate the possibility that N. irene andromorphs, in sympatric populations, may evolve a morphology more similar to N. gracilis females in order to more efficiently repel male harassment compared to allopatric sites.

Since N. irene is unable to successfully mate with N. gracilis females and vice versa, N. irene and N. gracilis males in sympatric populations should be able to discriminate between morphs and species, while males from allopatric sites should attempt more incorrect matings, relative to the abundances of each of the morphs. In response, sympatric sites where N. irene is predominant, male N. gracilis mate selection behaviour, and female morphology may be different in order to find and mate with the correct “rare” species. I will be examining the rate of mate recognition errors between both species and their associated morphs at sympatric and allopatric sites. I will explore the role of learning in mate recognition for both these species. I will also investigate colour and morphology between species and colour morphs and between sympatric and allopatric sites with different abundance ratios to see if each morph and species is changing in response to pressure from co-existence with the other species.