Tuesday, November 23, 2010
Seminar by Nina Wedell on selfish genetic elements and sexual selection and PhD-thesis defency by Kristina Karlsson
This week our department will be visited by Professor Nina Wedell (Exeter University, UK), who will act as an external faculty opponent on the thesis of Kristina Karlsson Green, on Friday November 26 (09.30, "Blue Hall", Ecology Building).
Nina Wedell is well-known for her research on sperm competition, sexual selection and mating system evolution in insects. You can read more about her research here, and here you can find some of her publications. Here is an article about Ninas recent research on the evolutionary consequences and benefits of female promiscuity.
Nina Wedell will arrive to our department already on Thursday (November 25), and will present a research seminar at 14.00 entitled:
"Selfish genetic elements and sexual selection"
This talk is co-arranged with The Research School in Genomic Ecology (GENECO), and there will also be another talk by Sören Molin the same afternoon and the same place (Lecture Hall, Biology Building, Sölvegatan 35 A), but at 15.15. Note that both these talks do not take place in the "Blue Hall", but in a separate building ("The Biology Building").
Sunday, November 21, 2010
I hope you enjoy these papers and that we will have a good discussion. Time and place as usual: "Darwin" at 10.15 (Wednesday November 24). Fika volunteers are encouraged to step forward.
Population resequencing reveals local adaptation of Arabidopsis lyrata to serpentine soils
- A powerful way to map functional genomic variation and reveal the genetic basis of local adaptation is to associate allele frequency across the genome with environmental conditions. Serpentine soils, characterized by high heavy-metal content and low calcium-to-magnesium ratios, are a classic context for studying adaptation of plants to local soil conditions. To investigate whether Arabidopsis lyrata is locally adapted to serpentine soil, and to map the polymorphisms responsible for such adaptation, we pooled DNA from individuals from serpentine and nonserpentine soils and sequenced each 'gene pool' with the Illumina Genome Analyzer. The polymorphisms that are most strongly associated with soil type are enriched at heavy-metal detoxification and calcium and magnesium transport loci, providing numerous candidate mutations for serpentine adaptation. Sequencing of three candidate loci in the European subspecies of A. lyrata indicates parallel differentiation of the same polymorphism at one locus, confirming ecological adaptation, and different polymorphisms at two other loci, which may indicate convergent evolution.
Hello from the wilds of Athens, Ohio! As Sophia said, we're geeking out on the study of shape. Such analyses receive less attention than they should, but think about it: everything has shape! Its a serious matter. As Houle (2010 PNAS) noted, we would benefit greatly from a revolution in "phenomics" to compliment recent advances in genomics.
Saturday, November 20, 2010
Hi from Athens.
I’m having a good time here, filled with damselfly wings and the theory of Geometric Morphometrics during the daytime, and socializing and beers in the evenings. Shawn is part of a very lively and nice department!
The first week spoiled me with balmy summer temperatures (well, almost) and a spontaneous multiplication of my salamander species counts! There are gorgeous species to be found here, my favorite is the Red Salamander (Pseudotriton ruber) because of its beautiful coloration, and it is well worth strolling through the beautiful forest and looking under logs and stones for a (rare, I’ve been told) glimpse of it.
Our literature seminars are usually attended just by Shawn and me, but we gladly share our reading list in the hope to spark your interest in morphology and the statistical methods for its analysis:
The study of Dean C. Adams (Evolutionary Biology 2010, 10:72) is a nice real-world example of character displacement in salamanders driven by competitive selection in sympatric populations.
The underlying theoretical framework for such studies is described in an earlier paper by the same author (Dean C. Adams and Michael L. Collyer (2009) Evolution 63-5: 1143-1154), and historical overview and review of available methods for shape analysis can be found in Adams et al. 2004 (Ital. J. Zool. 71: 5-16. Another review paper by Christian P. Klingenberg (Nature 2010, Vol 11, 623-635) approaches the topic from an evo-devo perspective.
Dreaming of partial warps in Procrustes space…
Friday, November 19, 2010
Recently we have published two studies based on the isopod system of Asellus aquatics. This species occurs in two ecotypes, which resides in different habitats. As the ecotypes are present in several Swedish lakes, this system has been studied in depth with regard to parallel evolution. Our new articles address differences in mating behavior between the ecotypes. As other crustaceans, A. aquaticus exhibits precopulatory mate guarding where the male captures a female before she is receptive and carries her beneath him until she is ready to mate. This behavior is target for sexual conflict in several isopods as the optimal initiation of pairbonding may differ between the sexes.
One of our articles, published in the latest number of Journal of Evolutionary Biology, deals with differences between the ecotypes in mate guarding duration, but also in differences in female survival and offspring production. Among other things, we found a pattern of parallel evolution in these traits. The other article, published in open access journal PLoS ONE, deals with differences in mating propensity between the ecotypes and how this is affected by demographic factors. Here, we found that the novel ecotype seem to have evolved a plastic behavior as response to sex ratio, in contrast to the ancestral ecotype.
You could find both abstracts below, and both articles are included in Kristina Karlsson Green’s thesis that will be defended on next Friday.
Phenotypic Plasticity in Response to the Social Environment: Effects of Density and Sex Ratio on Mating Behaviour Following Ecotype Divergence
The ability to express phenotypically plastic responses to environmental cues might be adaptive in changing environments. We studied phenotypic plasticity in mating behaviour as a response to population density and adult sex ratio in a freshwater isopod (Asellus aquaticus). A. aquaticus has recently diverged into two distinct ecotypes, inhabiting different lake habitats (reed Phragmites australis and stonewort Chara tomentosa, respectively). In field surveys, we found that these habitats differ markedly in isopod population densities and adult sex ratios. These spatially and temporally demographic differences are likely to affect mating behaviour. We performed behavioural experiments using animals from both the ancestral ecotype (‘‘reed’’ isopods) and from the novel ecotype (‘‘stonewort’’ isopods) population. We found that neither ecotype adjusted their behaviour in response to population density. However, the reed ecotype had a higher intrinsic mating propensity across densities. In contrast to the effects of density, we found ecotype differences in plasticity in response to sex ratio. The stonewort ecotype show pronounced phenotypic plasticity in mating propensity to adult sex ratio, whereas the reed ecotype showed a more canalised behaviour with respect to this demographic factor. We suggest that the lower overall mating propensity and the phenotypic plasticity in response to sex ratio have evolved in the novel stonewort ecotype following invasion of the novel habitat. Plasticity in mating behaviour may in turn have effects on the direction and intensity of sexual selection in the stonewort habitat, which may fuel further ecotype divergence.
Most of you have already seen this - but I post it again in case somebody missed it. We've got the journal cover in the November 2010 issue of Evolution, featuring our article about learned mate preferences in the banded demoiselle (Calopteryx splendens). This paper has also been highlighted by the popular science site Science Daily, and it will also be covered in a popular science radio programme in Germany, since I was recently interviewed about the study by a journalist from our southern neighboring country.
Apart from our own article, the same issue contains a number of interesting other articles about sexual selection, most notably Richard Prums paper about null models in sexual selection in which he argues that the Lande-Kirkpatrick (NK)-model as the most appropriate such null model, a paper we discussed at the lab-meeting last week. Here is the title and abstract of our own paper:
A ROLE FOR LEARNING IN POPULATION DIVERGENCE OF MATE PREFERENCES
Erik I. Svensson, Fabrice Eroukhmanoff, Kristina Karlsson, Anna Runemark & Anders Brodin
Learning and other forms of phenotypic plasticity have been suggested to enhance population divergence. Mate preferences can develop by learning, and species recognition might not be entirely genetic. We present data on female mate preferences of the banded demoiselle (Calopteryx splendens) that suggest a role for learning in population divergence and species recognition. Populations of this species are either allopatric or sympatric with a phenotypically similar congener (C. virgo). These two species differ mainly in the amount of wing melanization in males, and wing patches thus mediate sexual isolation. In sympatry, sexually experienced females discriminate against large melanin wing patches in heterospecific males. In contrast, in allopatric populations within the same geographic region, females show positive (“open-ended”) preferences for such large wing patches. Virgin C. splendens females do not discriminate against heterospecific males. Moreover, physical exposure experiments of such virgin females to con- or hetero-specific males significantly influences their subsequent mate preferences. Species recognition is thus not entirely genetic and it is partly influenced by interactions with mates. Learning causes pronounced population divergence in mate preferences between these weakly genetically differentiated populations, and results in a highly divergent pattern of species recognition at a small geographic scale.
Thursday, November 11, 2010
Wednesday, November 3, 2010
Probably, the proudest moment in the life of PhD-student advisors is when their students has finished his/her thesis. This has now happened once again in our lab, and I am of course extremely happy that my fourth PhD-student Kristina Karlsson has now gotten her PhD-thesis back from the printer. Before Tina, Jessica Abbott (2006), Tom Gosden (2008) and Fabrice Eroukhmanoff (2009) has previously succesfully finished their theses, and I am of course happy to soon be able to kall Tina Dr. Karlsson.
The second proudest moment in the life of the PhD-student advisors is usually the thesis defence. This will take place on Friday November 26 2010 in the "Blue Hall" (Ecology Building). The external opponent on Tinas thesis will be Professor Nina Wedell (Exeter University, UK), and the thesis defence will start at 09.30.
Prof. Wedell will also give an invited research seminar the day before Tinas thesis dissertation (November 25) with the title: "Sexual selection and selfish genetic elements". This talk will take place in the "Red Room" (Ecology Building) at 14.00 on November 25 2010. Needless to say, both Prof. Wedell's talk on November 25 as well as the dissertation ceremony on November 26 are open to the general public and everybody who is interested.
Tina will "nail" her thesis on the "Oak" outside the Biology Library next Wednesday (November 10, 2010) at 15.00. Drinks will be served after this ceremony, and again, it is open to anyone who wish to attend. The same day, our regular lab-meeting will take place as usual (10.15-12.00 in "Darwin"). Anna Runemark will send out a manuscript of ours about sexual selection in mainland and island populations, with the hope to get some input and criticisms. If you do not receive this manuscript, please send Anna an e-mail and she can send you a copy (firstname.lastname@example.org). Fika volunteers are particularly welcome to this meeting.