Remembering the summer: field work with damselflies in Skåne

 

Winter is approaching fast, and what could be better then than to try to remember the past beatiful summer for as long as possible?Varm summers means field work with insects, at least for some of us. This was also the case for myself, CAnMove postdoc Sophia Engel and a number of other students and postdocs working with field studies of calopterygid damselflies. Here is a nice movie about CAnMove-related field work from Lund University's Youtube-channel. This movie contains an interview with Sophia and myself, where we explain what kind of experiments we did, and why. Unfortunately, this movie is in Swedish, not English, but at least you can enjoy the pictures!

Basically, we have quantified flight speeds of individually marked damselflies of two species (Calopteryx virgo and C. splendens), and we relate this performance-trait to wing morphology (shape), longevity in the field and mating success (sexual selection). A key player in this system is an enigmatic avian predator which kills these insects: The white wagtail (Motacilla alba), which also appears in the movie. The ornithologists among you readers will hopefully also realise how fascinating this insect system actually is, since it obviously also involves a bird! A key goal of ours is to link morphology to performance and fitness, and combine flight speed estimates with data on morphology and fitness. Such studies are rarely possible to perform, particularly not in natural populations of insects, so we are quite excited about the results that will hopefully come out from this work.

If the movie above does not work, you could follow this link instead. Enjoy! And go back and watch this movie whenever you miss the summer...

Former lab-member publishes paper on intralocus sexual conflict on wing shape and wing size

As a follow-up to my previous blogpost about intralocus sexual conflict, it is worth pointing to a new and interesting study by a former lab-member and PhD-student: Jessica Abbott (now postdoc in Ted Morrow's lab in Uppsala). Jessica has studied intralocus sexual conflict over wing size and wing shape in Drosophila melanogaster, during her first postdoc in Adam Chippindale's laboratory at Queens University (Canada). The paper will appear in Journal of Evolutionary Biology, and it can be downloaded here (scroll down the list of publications to the bottom), for those who are interested in details. An abstract is posted below.

The fascinating topic of the evolution of wing shape and the selection pressure operating on wings have also been subject of several other studies in our laboratory, mainly related to natural selection and predation on Calopteryx-wings. Like Jessica, we (Shawn Kuchta, I and Sophia Engel) have been using landmark-based geometric morphometric techniques to quantify wing shape and have been used these measures to estimate the strength of natural selection on wings. More will follow, and in addition to sexual selection and intralocus sexual conflict, natural selection is also likely to play a major role in shaping wing size and wing shape in both fruitflies, damselflies and other insects.

Abbott, J. K., Bedhomme, S., & Chippindale, A. K. (2010) Sexual conflict in wing size and shape in Drosophila melanogaster. Journal of Evolutionary Biology, in press.

Intralocus sexual conflict occurs when opposing selection pressures operate on loci expressed in both sexes, constraining the evolution of sexual dimorphism and displacing one or both sexes from their optimum. We eliminated intralocus conflict in Drosophila melanogaster by limiting transmission of all major chromosomes to males, thereby allowing them to win the intersexual tug-of-war. Here we show that this male-limited (ML) evolution treatment led to the evolution (in both sexes) of masculinized wing morphology, body size, growth rate, wing loading, and allometry. In addition to more male-like size and shape, ML evolution resulted in an increase in developmental stability for males. However females expressing ML chromosomes were less developmentally stable, suggesting that being ontogenetically more male-like was disruptive to development. We suggest that sexual selection over size and shape of the imago may therefore explain the persistence of substantial genetic variation in these characters and the ontogenetic processes underlying them.