Tuesday, December 22, 2015

Merry Christmas and Happy New EXEB-year!

Posted by Erik Svensson

The year 2015 is approaching the end, and I wish all EXEB-members a Merry Christmas and a Happy New Year. I think we have had a great year and many exciting and intellectually stimulating lab-meetings where (at least I) have learned a lot and got many new insights. EXEB has grown rapidly in short time - particularly since Tobias Uller have recruited several new co-workers - and we do now also have several hardworking interns, field assistants, laboratory assistants, PhD-students, Master's students and postdocs. All our permanent and temporary co-workers - nobody mentioned, nobody forgotten - do a tremendous job, both in terms of actual work performed, but also in contributing to a friendly and intellectually stimulating research environment.

Some statistics: If we count only the "core" EXEB members (who are in Lund and have formal positions), we are 11 in total (3 PI:s, 3 PhD-students, 4 postdocs and one research engineer). Counting a bit more generously, we are 13, since we have two affiliated PhD-students from Sussex University (Katrine Lund-Hansen)  and Manchester University (Miguel Gomez), who Jessica Abbott and I are co-advisors of, respectively.

Looking back upon 2015 in terms of research achievements, it has been a very succesful year, I think we can say without any hesitation. I have not made an official tally of joint publications, but I note that Tobias team had an interesting article about asymmetric species interactions in hybrid zones of lizards in Ecology Letters, and Jessica published a model paper about how self-fertilization and inbreeding might limit sexual antagonism in Journal of Evolutionary Biology. As for myself, I was happy to get our long-term time-series analysis of the signature of negative frequency-dependent selection in damselfly morphs published in American Naturalist. John Waller got his first thesis-chapter about imperfect detection and mark-recapture analysis of selection published in Methods in Ecology & Evolution. Lastly, and importantly, Jessica Abbott was awarded an ERC Starting Grant in October, the first of two at the Biology Department in Lund. All in all, a very succesful year for EXEB and its members, I think.

The future looks bright, I think, if the trend in 2015 will continue, but now for something lighter: the evolutionary origin of Santa Claus. It was Beatriz Willink pointed me to this very interesting blog post, which aims to do a phylogenetic analysis of the evolutionary origin and allopatric divergence of different Santa Claus phenotypes. It is from the blog "EEB and Flow", and R-code is provided, should you be interested in exploring this fascinating topic in depth. Enjoy!

Friday, December 4, 2015

Lab meeting on 8th of December: Genomic targets of natural selection on bill morphology

Posted by Hanna Laakkonen

Martin Stervander's cool PhD is out and since there is a lot of interesting reading in the book I suggest we pick a paper from there for next Tuesday. This topic is a manuscript, but Martin was kind to provide us the pdf for reading. I'll print out a few copies and put them into my pigeon hole, pick one from there if your missing the actual thesis!

Title: Identifying the genomic targets of natural selection on bill morphology in the Inaccessible Island finch Nesospiza acunhae

Abstract: Adaptation to food sources is a key element in divergence processes, and may promote ecological speciation in the face of gene flow. In birds, the size and shape of the bill is the target for natural selection on feeding efficiency, and it can also affect male song, a sexually selected trait. Here, we investigate the Inaccessible Island finch Nesospiza acunhae, part of a small radiation endemic to the South Atlantic islands of Tristan da Cunha. Inaccessible Island hosts two subspecies: a smallbilled generalist feeding mainly on grass seeds, and a large-billed specialist foraging on the seeds of Phylica trees. Notably, despite the extremely small geographic scale – Inaccessible Island is only 16 km2 – there is simultaneous occurrence of strong bill size-associated assortative mating, and parallel hybridization between the two subspecies in confined parts of the highland plateau. Here we report on the genomic landscape of bill morphology and detect two genomic regions with significantly elevated differentiation between small- and large-billed birds. The first region, on chromosome 1, contains 4–6 genes, of which one (KPNA3) is part of a large pathway where several bill morphology candidate genes are included. The second region, residing on the sex chromosome Z, contains 8 genes, all of which are associated with previously known bill morphology candidate genes. One of them is ISL1, a homeobox transcription factor included in the neural crest differentiation pathway, which affects bill morphology in Darwin’s finches through the expression of bone morphogenetic proteins. The effect of the combined chromosome 1/Z genotypes on bill phenotype indicates an epistatic interaction between the regions. Our results show that minute proportions of the genome contribute to extreme bill variation in the Inaccessible Island finch, which in turn is associated with strong differential food preference, habitat selection and assortative mating.