Thursday, April 29, 2010
This week, I was thinking that we should discuss sexual dimorphism from two different perspectives: a "G-matrix" perspective and a gene expression perspective. The two different papers I have chosen hopefully shed different light on sexual selection and the process of sexual selection. The two papers show how sexual selection might leave a signature, either on the molecular level (the first paper) or on the trait-level (the second paper).
The first paper I would like to discuss is from Locke Rowe's group at University of Ontario (Canada), and you can download it here. I heard Locke give a talk about this at the European Evolutionary Biology Meeting ("ESEB") in Italy in August last year, and I already then thought that this was a very interesting subject.
In particular since most of us (at least me!) are not particularly interested in these novel molecular tools per se, but rather wish to understand how they can be used to illuminate problems and processes in phenotypic evolution, at the whole-organism level, I was thinking that we could get some idéa of how transcriptomics might be used to achieve this goal. Hopefully, we will have a good discussion about this on this coming lab-meeting.
The second paper is a more tradition quantitative-genetic study of intersexual genetic correlations by Steve Arnold's group, and this other paper can be downloaded here.
We meet at the usual time and place, i. e.:
Where: "Darwin" room, 2nd floor (Ecology Building)
When: Wednesday, May 5, at 10.15.
Sunday, April 18, 2010
Good morning everybody,
We will have a lab meeting this week. Two things are on the agenda:
1) Fabrice has been invited to give a seminar in Linköping and would like to get your feedback on his presentation. He will speak about
Joint effects of migration modification and assortative mating in the early stages of ecological speciation
Fabrice Eroukhmanoff, Anders Hargeby & Erik I. Svensson
ABSTRACT: The question of how diverging populations might become separate species by restraining gene flow is a central issue in evolutionary biology. Assortative mating might emerge early during divergence, but migration modification can also play an important role in speciation. We demonstrate that two recently diverged ecotypes of a freshwater isopod have rapidly developed pre-mating isolation. This is consistent with ecological speciation theory, which predicts that sexual isolation arises as a byproduct of ecological divergence. However, migration modification acts as the main barrier to gene flow, although the joint emergence of these two isolating mechanisms has facilitated adaptive divergence. These results underscore that migration modification might be as important as assortative mating in the early stages of ecological speciation.
Any fika volunteers for this week? See you all on Wednesday, Maren
Wednesday, April 7, 2010
this is being posted late-as I had problems to upload something to the blog yesterday.
This is what I sent around yesterday (by email):
Erik is in South Africa now, but we will continue with the weekly meetings as much as we can.
The paper this week is by Anne Runemark et al. and investigates mate choice in Podarcis gaigae, the Skyros Wall Lizard.
Anna and her co-workers were interested to compare the strength of premating isolation between mainland and island populations of this species, and tested male and female preferences for chemical scents in several populations. Comparisons showed that the island populations preferred the smell of individuals from their own population, whereas no such preference was found in mainland populations. These results are discussed in light of the pheromone compositions and population genetic models. Anna's abstract is posted below.
Reproductive isolation can arise when populations reside in different natural environments and experience either divergent natural or sexual selection, or both. When traits that are involved in mate choice diverge due to differences in local selective environments, parallel divergence in allopatric populations inhabiting similar environments strongly indicates that divergence is adaptive. The evolution of mate choice and degree of choosiness in isolated island populations has been topic to some debate. Here we show mate odour-based mate preferences for chemical cues and scent composition has diverged in island-mainland populations of Skyros wall lizard Podarcis gaigeae. We address the issue whether mate choice traits and mate preferences have diverged in parallel on geographically isolated islet populations, and if lizards on these islet populations are more or less choosy than neighbouring mainland populations. We found a heightened preference in islet lizards to prefer the scent from islet lizards, whereas the mainland populations were less discriminant and did not show a heightened preference for the scent of mainland lizards. However, the pheromone compositions of the islets were clearly more divergent from each other than between mainland populations and between mainland and islets. We found a parallel increase in one chemical substance (dl-a-tocopherol) in the islet populations, and a preference for that compound could potentially partly explain the islet populations’ preference for islet scent. Our result supports the recent population genetic models that suggest that islet populations are expected to be more choosy in their mate preferences than their founding populations. Local microenvironmental factors such as diets are likely to play a role in the more accelerated population divergence in chemical signals on the islets, possibly with some role for phenotypic plasticity in the development of these sexual signals.
Please send any suggestions for upcoming lab meetings to my email address