Tuesday, November 22, 2016

Visit and talk by Lars Lønsmann Iversen on antagonistic coevolution and polymorphisms in beetles


 Posted by Erik Svensson

For next week's EXEB-meeting, we will have a visitor by a collaborator of mine from Copenhagen University (Lars Lønsmann Iversen), who will present the results of some ongoing research on diving beetle polymorphisms and antagonistic co-evolution. Time and place of meeting as usual:
When: Tuesday, October 29 at 10.00
Where: "Darwin" seminar room, 2nd floor Ecology Building.
Fika will be served!
About  Lars Lønsmann Iversen
I am a postdoctoral research fellow at the Freshwater biology laboratory at The University of Copenhagen. I have a background as a spatial ecologist and entomologist working with different aspects of community assembly in freshwater habitats. Currently, most of my work addresses community and functional trait compositions along lake to pond gradients in plant communities and freshwater invertebrates.

Can pairs of antagonistic traits create stable polymorphic populations?
The suction cups of male diving beetles (Dytiscidae) and the rough modifications on female beetles' elytra, is one of the few well known pair of antagonistic traits in the animal kingdom. It has been suggested that the interplay between these two traits might in some cases hold species at an evolutionary standstill, creating stable polymorphic populations. In this talk I will present some of our resent work on Swedish populations of the species Graphoderus zonatus, extending the current knowledge on the interaction between male and female antagonistic traits. By studying the male suction cup morphology along a female elytra morph frequency gradient, we are able to show that the dimorphic antagonistic trait of the female is met by a dimorphic trait of the male suction cups. Male and female morphs follow a near 1:1 relationship along the studied morph frequency gradient. But, form did not follow function of the male suction cups and there was no difference in mating abilities between the two morph types on females with rough elytra. This suggests an adaptive lag in the males counter adaptive trait to rough female elytra structure. Our results confirm that within Graphoderus zonatus populations, the occurrence of antagonistic traits is closely balanced between sexes. However, we find very little evidence of stable polymorphic populations due to sexual conflicts and in our case study, polymorphic populations might very well be a transitional stage moving toward stable monomorphic populations.

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