Friday, July 29, 2011

Selection, mutation, gene flow, and drift: the Canadian Institute of Ecology and Evolution

I spent the last two days at the meeting of the Management Board of the Canadian Institute of Ecology and Evolution (CIEE). The meeting was hosted by CIEE Director Art Weis at the University of Toronto’s Koffler Scientific Reserve. Additional conspirators in attendance were Mark Forbes (Carleton University), Steve Heard (University of New Brunswick), and Locke Rowe (University of Toronto). Sally Otto (University of British Columbia) joined us by Skype. Our task was to plan and implement the continuing development of the CIEE and its programs.

The setting was unique – the former country ranch (800+ acres) of Murray Koffler, founder of Shopper’s Drug Mart and the Four Seasons Hotels. The house was once decadent and, although now in some disrepair, was still memorable - and not just because we could visit the bedroom where Pierre and Margaret Trudeau reportedly conceived Justin. My favorite part of the house was (no surprise here) the bar – an oval room paneled with wood from an old barn and stocked by Art, and his wife Donna, with an extensive collection of spirits – including a 21 year old Balvenie, now sadly much diminished. The evenings passed pleasantly in such surroundings and, with the ample liquid encouragement, Art’s sister gave us all tattoos befitting our inspirations and aspirations. No word yet on whether Locke and Sally will follow suit.

The grounds themselves were an interesting mix of forest and old fields, with the fields swimming in flowers and swarming in their pollinators. Several large ponds had been built along the course of a creek and these were home to squadrons of fighting and mating dragonflies – the photographing of which made me late on several occasions. I was also distracted by a group of sparrows foraging for caterpillars on the driveway under the large trees that lined it. It seems that green caterpillars were literally raining down on the pavement and were much more conspicuous there than they would have been on the ground. As far as I could tell, the sparrows would unendingly walk up and down the driveway getting a caterpillar every meter or so – all day long. One wonders if the result will be selection on the adult insects to not lay eggs on trees with pavement below them – but perhaps no genetic variation (and therefore evolutionary potential) exists in such behavior.

And, yes, we did actually do work. We crafted a statement of the vision and mission of the CIEE (a DRAFT is reproduced below); we finalized a plan for funding, membership and governance; we worked on a prospectus and progress report; and we brainstormed candidates for the next Director and the Scientific Advisory Group. On departure, we all promised to get together for another round of drinks and tattoos in the future.

Vision and Mission (DRAFT)

The CIEE provides a national platform for breakthroughs that integrate ecological and evolutionary sciences to address fundamental challenges and practical concerns of importance to Canadians. This integration will be critical to the generation, translation, and mobilization of important knowledge about the world around us. This knowledge then enlightens society as to how best to identify and protect critical components and services of the biosphere now and in the future.

The CIEE will accomplish its vision by

· Identifying existing and emerging challenges that require expertise in ecological and evolutionary analyses;

· Assembling the best teams of scientists to tackle those problems with synthetic and integrative approaches;

· Mobilizing those teams by providing support for them to focus on solutions to those challenges; and,

· Involving students and young researchers, thereby shaping and empowering the next generation of experts who will use synthetic and integrative approaches to solve future challenges.

Saturday, July 23, 2011

Quantitative genetics in stickleback: implications for reproductive isolation

We now have a study online in JEB that examines how differences between lake and stream stickleback ecotypes in foraging-related traits (gill raker number and aspects of body shape) are inherited quantitative genetically. The study is a line cross analysis of different lab-reared pure and hybrid lines derived from the well-known ecotype pair residing in Misty Lake and its inlet stream on Vancouver Island. We find that gill raker number is inherited additively (e.g., F1 hybrids are intermediate between the pure ecotypes), whereas there is strong dominance in body depth. That is, F1s and other hybrids between the lake and stream types display the body depth typical of the lake ecotype. We argue that this difference in inheritance has implications for the speciation process between the ecotypes: given divergent selection on gill raker number, hybrids should be at a disadvantage relative to pure types in both the lake and the stream. By contrast, asymmetric introgression from the stream to the lake (but not vice versa) should be easier for body depth because hybrids resemble the lake resident and should therefore not be selected against. It would now be great to have direct information on the strength of selection acting on these phenotypes, and to look into the molecular basis of their divergence.

In addition to these biological findings, the paper has some methodological relevance because we found that a geometric morphometric (relative warp) approach to shape analysis yielded results qualitatively different from an approach based on traditional distance traits. Given that relative warps are principal components extracted from shape variables and that principal component analysis creates artifacts (see Berner 2011, Oecologia), we hypothesize in the paper that the patterns identified through relative warp analysis are artificial to some extent. We have now confirmed this with simulated data; a formal analysis should come soon.

...And who does not agree relative warps indeed look artiFISHal:
If interested, check out "Quantitative genetic inheritance of morphological divergence in a lake-stream stickleback ecotype pair: implications for reproductive isolation".

Daniel and Joost

Wednesday, July 20, 2011

We threw the S bomb

We resist it for the first three chapters of my thesis, but for the last one we threw the S bomb. That is right, a plain and simple sympatric speciation model. The paper recently went online at the Journal of Evolutionary Biology. In that paper we have separated three different factors that potentially contribute to sympatric speciation. The first one is assortative mating, the second one is intraspecific competition and the last one is resource distribution, not in the spatial sense, but unimodal resource distribution versus bimodal resource distribution.

We found that the most important factor was assortative mating, but other factors must also be present. Bimodal resource distribution was found to be the next most important factor. And, at last but not least, intermediate competition among phenotypes promotes sympatric speciation. To spice up the conclusions, there was no recipe to always end up in sympatric speciation, stochastic factors play also an important role.

The paper already received a lot of press Science Daily, Science 360, etc. What grabbed my attention is coverage from Uncommon Descent, where they highlight in bright red change they made in a quotation, to reverse the conclusion of the paper in the favor of a weird argument.

Do not let the 17Mo file size deter you from downloading are reading this paper. Next time when they ask me for a high resolution figure, I will be more careful, I promise.