Today, it is my turn to recommend two of the most brilliant papers ever written!!!
The first one deals with parallel evolution and historical contingency, and more precisely on the interaction between selection and history in the early stages of divergence. We have quantified the percentages of variance explained by the habitat componenet, the lake component and their interaction during the parallel diversification of several morphological and behavioral traits in Asellus aquaticus during the last twenty years. Theory predicts that historical and genetic constraints should be stronger in the early stages of divergence (Schluter 1996 Evolution) but in our case it seems that selection has rapidly overridden historical contingencies in many of these traits. This paper also reports that in the two lakes studied, molecular data suggests that diversification occurred independently, that is, we have a case of parallel evolution. This paper is very special to me because it is my first published works on these isopods but also because we really had to fight for a long time (18 months and three journals in total) with editors and referees before we could publish it, and this taught me how hard research is and how you should never give-up…
The second one is about covariance structure and of course in a way, constraints. We used several species of the genus Calopteryx to compare their P-matrices between populations, environments and species. We found with no great surprise that divergence in covariance structure increases with the taxonomical level used in the comparison, but this is not a linear relationship and the environment might also affect P. Another cool finding in this study is that the wing patch, that we know is under various and divergent selective pressures between species and populations, is of importance as well in terms of constraints because divergence of the wing-patch between populations is positively correlated with divergence in P. It actually suggests that divergent selection on a single trait can affect the stability of the P-matrix.
The first paper can be find here:
Eroukhmanoff, F., Hargeby, A., Nowshiravani Arnberg N., Hellgren, O., Bensch, S. & E. I. Svensson. 2009. Parallelism and historical contingency during rapid ecotype divergence in an isopod. J. Evol. Biol. 22: 1098-1110.
on the website of Journal of Evolutionary Biology,
and the second here:
Eroukhmanoff, F., Outomuro, D., Ocharan, F. J. & E. I.Svensson. 2009. Patterns of phenotypic divergence in the wing covariance structure of calopterygid damselflies. Evol. Biol. 36:214-224.
on the website of Evolutionary Biology, a new exciting journal which I recommend both for its content and its rapidity in processing reviews or publishing work. I hope you enjoy the reading.