A subset of the Molecular Ecologist team is attending this year’s Evolution meeting in Portland, Oregon. As part of our coverage of the meeting, we will recapping the highlights of each day here on the blog, and occasionally previewing upcoming presentations. You can find all of the TME contributors on Twitter using the sidebar on the right or compiled in a handy Twitter list here; follow along with all meeting news using the hashtag #Evol2017.
Joachim Hermisson — Footprints of Adaptive Introgression
Identifies a “volcano” profile of nucleotide diversity flanking an adaptive locus that introgressed from another species (or population, I think), and some variation in the shape of the volcano depending on the fitness effects of linked variants. A formal method to test for these effects is provided in
VolcanoFinder, which does not appear to be released yet (or is not visible to Google, anyway), so that’s a publication to watch out for.
Miranda Sinnott-Armstrong — Evolutionary transitions in fruit colors with respect to climate
Cool first results from a big dataset of data on fruit morphologies and color in plant communities from about a hundred different sites worldwide. It looks like the diversity of fruit color is greater in the tropics than at higher latitudes (though the southern hemisphere looks more “tropical” than the north, which is odd), and frequency of transitions to particular fruit colors may be correlated with transitions to particular climate regimes.
Ailene MacPheson — Finding disease genes in the face of the Red Queen
Genome-wide association is pretty dependent on variation in the population studied; if a locus isn’t variable, by definition GWAS can’t identify it as associated with a given trait. In the case of disease resistance, we know that negative frequency-dependent selection can create sequential sweeps that remove variation from host and pathogen populations at resistance and virulence loci. MacPherson develops a method of GWAS based on both host and pathogen allele frequencies that can maybe overcome this limitation. (Disclaimer: She’s at UBC, my current institution, and is working with a member of my PhD committee)
Sally Chang – Genomic signatures of asexual and sexual reproduction within the colonial hydrozoan Ectopleura larynx
Anything with clonality is pretty much guaranteed to be a major draw for me! Sally is one of the first talks I’ve seen that has used RClone to look at clonality among colonies of the cnidarian Ectopleura. RClone is the fantastic R update to GenClone (the old Excel-like macro that required individual analyses per population!!) led by the work of Sophie Arnaud-Haond’s lab. It’s something that we’ve struggled with … with so many SNPs, you’re not going to get matching genotypes in the way you would with microsatellites. So, where do you draw that line? What’s a clonal lineage? Interesting to see Sally’s work on using called genotypes (20x per our subsequent meeting over coffee trading war stories of working with clonal species) and looking at super close genotypes (likely MLLs), different ones that are clearly the product of sex, and those that so different … totally unrelated polyps? Excited for her work to come out and more studies using RClone and SNPs!
Maurine Neiman – Genomic consequences of asexuality
Maurine described a ton of work out of their group on the snail Potamopyrgus antipodarum. It’s native to New Zealand lakes and populations vary in frequency of sexual and asexual. This snail could be a lovely, modern model for understanding when to have sex and when to maybe be asexual. The coolest thing I found was the fact that radical changes persist for a whole lot longer in asexuals!
Sally Otto – Evolution of sex, evolution of ploidies (SSE Presidential address)
… need I say anymore?
Finally, I neglected to add an awesome poster from Sunday night in my wrap up yesterday!
Kazuhiro Bessho presented work on the evolution of energy from haploid gametophytes to diploid sporophtyes. He used my favorite red algae as a model. Red algae are thought to have poor fertilization success since the female gamete doesn’t disperse at all and male gametes have no flagella. They found if the female totally controls the development of the sporophyte, then an ESS exists and females can maximize their fitness. In contrast, if there is increasing paternal control and fewer sporophytes, then parental care may be favored … this is an excellent model and I look forward to talking more to Bessho-San about this in terms of red algal fertilization success that is actually quite high!
Leonardo Campagna – Repeated divergent selection on pigmentation genes in a rapid finch radiation
A number of bird speciation studies from the last few years have shown that recently diverged lineages differ in little beyond genes associated with plumage. Campagna’s talk contributed to this growing consensus, showing that in a species complex of South American birds known as the capuchino seedeaters, divergence peaks in genome scans from different pairwise comparisons are primarily associated with coloration.
Marc Tollis – The tuatara genome sheds light on phylogenetics and rates of evolution during the amniote radiation
It turns out the tuatara genome is about as cool as you’d expect it to be.