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.
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