Author Archives: lucbussiere

Tom’s thesis submission

This announcement is quite late, in part because in the post-submission haze and good cheer I forgot to let the rest of the world know via blog: Tom Houslay submitted his PhD thesis with dozens of minutes to spare at the end of last month. Congratulations Tom! This was a rather heroic effort. More news to follow once the viva preparations are in place.

Some photos:

Tom Submitting

Tom handing in (blurry camera photo, but probably appropriately mirrors Tom’s hazy view of the world as he submitted)

 

PartyPopper

Lilly celebrating shortly thereafter by firing a party popper in Tom’s face

Trivers 1972: Parental investment and sexual selection

Continuing the series of classic papers on mating systems, Hazel and I lead some discussion on Bob Trivers’ book chapter on how parental investment relates to the sex roles. Bateman (1948) had already suggested that the difference between the sexes in the returns on investment might be related to anisogamy (the difference in gamete size across the sexes), but Trivers examined (using formal theory rather than empirical experiments) the possible effects of investment in all stages of offspring (not just the gametes themselves). He reasoned that since all kids have two parents, the sex that invests more becomes limiting to the other one. The relative investment of the sexes in their young is therefore the key variable controlling sexual selection.

Trivers was careful to point out that although “investment” can be energetic or metabolic, it doesn’t need to be for his theory to work. For example, risky behaviour like hunting or singing (which could lead to predation or parasitism) is also a form of investment and needs to be part of any calculations comparing the sexes.

Trivers also was careful to notes the circular nature of the relationship between investment and mating system, a theme that will undoubtedly resurface as we continue our tour through classic papers on mating systems: parental investment affects sexual selection (e.g., by controlling which sex is in short supply), but sexual selection also affects parental investment (e.g., by determining how much energy is left for care, for example).

The paper also pointed out a few features of the natural history of mating in animals that were likely to be important (observations whose importance we might be able to confirm with the benefit of hindsight). Here are a few haphazardly selected points that will probably feature in future discussions:

  1. The timing of investment (females usually invest substantially in gametes before mating) creates asymmetry between mating partners in the risk of desertion: males may have invested comparatively little in a clutch after mating and so they risk little by deserting, whereas a female may be trapped into caring for the young or losing all of her investment. Conversely, the risk of cuckoldry is asymmetrical in the opposite direction, because males can rarely be completely certain about paternity in the same way that females can trust their relationship to eggs.
  2. The differential risks and returns on parental investment have important implications for sexual differences in mortality. Trivers spent some time arguing that differences in mortality are not simply a consequence of chromosomal differences (i.e., the fact that in most mammals males are heterogametic), but rather imply adaptive differences in investment in longevity. Whether sexual differences in lifespan are generally adaptive is a continuing focus of quite a lot of research, including by our own Tom H.
  3. Female choice is probably related to some important aspects of paternal investment. Research over the past twenty years on the relative importance of direct and indirect benefits owes much to this initial analysis.
  4. In his closing sentence, Trivers reaffirms one of the fundamental insights that has shaped sexual selection research since this paper:

“Throughout, I emphasize that sexual selection favors different male and female reproductive strategies and that even when ostensibly cooperating in a joint task male and female interests are rarely identical.”

This recognition of sexual conflict would have to wait some time to be fully appreciated, in part because the empirical literature had plenty of work to do in testing Trivers’ theory on how parental investment affects sexual selection. In future posts, perhaps we can assess how much of that work remains to be done.

Science Drinks Nov. 19, 2013

Attendees: Claudia Santori, Tim Paine, Moha Abdelaziz Mohamed, Gregor Hogg, Lilly Herridge, Toby Hector, Luc Bussière, Nils Bunnefeld

After an unplanned relocation of the Nov 5 Science Drinks, we found ourselves back at the Wallace, where the smell of new varnish only somewhat made up for the lack of other renovation surprises. Spoiler: the newly renovated pub does not provide free house port on every table after all, at least not yet.

Before the whole crowd had assembled, the keen early arrivals started chatting about spatial autocorrelation, because why not? Both Gregor and Toby face this problem in different respects in their honours work: Gregor finds spatial autocorrelation in his geographic information about species distributions, while Toby faces similar problems when assessing morphological information from different positions on a single animal. As soon as they sat down, we asked Tim and Nils if and how they might have addressed similar issues involving transects (not trans sex) in their ecological work. They respectively pointed to couple of potentially helpful sources. Tim suggested consulting Mark McPeek‘s work on the evolution of dragonfly morphology, while Nils referred us to his better half Lynsey McInnes‘ work on geographic ranges. Very helpful pointers — we’ll expect a status update from Toby and Gregor in a few weeks once they have digested some of these papers.

Lilly’s contribution was recent paper by Dowling and colleagues, recently published in JEB, demonstrating trans-generational effects (not trans sex) of exposure to mates on offspring fitness in Drosophila melanogaster flies. They manipulated female exposure to sexual conflict by both manipulating access to males and by cauterizing the genitals of males in some treatments, so that while there were many males they could not mate and transfer ejaculate accessory gland proteins that are known to impose conflict. Intriguingly, the offspring of the cauterized multiple male treatment did worst of all. It seems like the mechanisms that might cause this are numerous, and worth further study.

Nils then provided a fascinating and long discussion involving both the humanities and sciences, both pure and applied, and which provoked some fairly nuanced philosophy as well as no small amount of depression in the author of this blog. However, because the exact topic is the subject of ongoing work that might just be subject to embargo, I have to write very little here (I know, the readership of this blog is hardly wide enough to pose a risk, but better safe than sorry!) This is a lesson in the benefits of experiencing science drinks in person! Some topics are too hot to summarize later on. Maybe we can link to the paper in due course….

Before anyone could escape for the evening, I asked the crowd for advice on a project proposal concerning cotton plants and Spodoptera caterpillars that a colleague from Bangladesh and I are writing for an upcoming travel grant. Tim and Moha both had some very good insight on the plant biology and herbivory that will be useful in refining our ideas, and suggested some references by Anurag Agrawal and Sharon Strauss that I need to follow up on.

So as you can see (at least for the unexpurgated components of this summary), Science Drinks is usually fun AND productive! Join us for the next session if you can…

Research Group Meeting Nov. 12, 2013

For the second consecutive week, we were forced to relocate from the Wallace Pub on account of renovations. Instead we met at the Meadowpark. After dealing with minor matters related to our own research projects, we discussed the organization of a new initiative for the research group: Journal Pub (aka Beer Review).

As part of an effort to catch up to some of the information age, we’re devoting ourselves to collectively reading some new and classic papers in several corners of evolutionary biology. We’ll organize our efforts using the newest page on our website: Journal Pub. Navigate there to learn about the topics and papers under discussion prior to a particular Journal Pub session, or go there after a session to see the brief written summaries of the papers as well as some annotations of our discussions on each of them. So there’s a bit of wrangling ahead to wrap our heads around a lot of difficult concepts, but it’s exciting to think that we might collectively learn about some very big and important ideas rather productively and quickly.

The first Journal Pub (location TBC) will occur on Nov 26. I have taken the liberty to assign responsibility for chief and adjunct reviewers of each paper, though naturally anyone can read more than the focal assigned papers. Looking forward to the discussions!

Movember

Not science, but maybe still worth noting:

It’s Movember 1st today — the start of a new field season for a rare annual species one finds only at this time of year on the upper lips of folks like me who forego shaving for a good cause. Feel free to donate to the cause of men’s health if you can: find our Institute’s Movember page here, where you’ll see links to the Movember pages for the whole clan. We’ll post updates to the facial hair phenology as it develops….

With

Jan Lindström’s Seminar: Sexual signals and senescence in Sticklebacks

Today Jan Lindström from the University of Glasgow gave a fantastic talk in the BES seminar series. It’s always a special pleasure when you host an amazing speaker, because you can briefly pretend that inviting someone who gives a good talk is a matter of good taste and skill.

Ignoring this needless vanity on my part, Jan’s talk was particularly notable for several qualities: its skillful staging of the motivation for this work, its careful explanation of the theoretical framework (including slides containing — gasp — equations!), and the marriage of this theory with relatively simple (to understand, although undoubtedly not so simple to execute) experimental work validating some of the not-so-intuitive findings from theory. Motivation enough (though I shouldn’t need it) to revisit the papers describing this work by Lindstrom and his team, including former postdoc Tom Pike:

Jan Lindström, Thomas W. Pike, Jonathan D. Blount, and Neil Metcalfe. 2009. Optimization of resource allocation can explain the temporal dynamics and honesty of sexual signals. Am. Nat. 174: 515-525.

Thomas W. Pike, Jonathan D. Blount, Bjørn Bjerkeng, Jan Lindström, and Neil Metcalfe. 2007. Carotenoids, oxidative stress, and female preference for longer-lived males. Proc. R. Soc. Lond. B 274:1591-1596.

After the talk, a few of the regulars took in some beer and engaged in post-seminar science chat. In addition to plenty of questions about sticklebacks, we discussed the community dynamics of human pharyngeal microbes, and of lichens in haunted graveyards, and the proper attitude that a psychic should adopt if he or she happens to be in a casino on the Titanic (never mind the obvious bad planning or shortsightedness that this implies for the psychic). It made sense at the time.

Anywaaayyys, lotsa food for thought. Should be enough to keep us chewing until Hazel’s rundown of her summer work tomorrow night….

Research group meeting Oct 1, 2013

Tonight was just the second official research group meeting of the semester (we alternate meetings within the group with “Science Drinks”, a biweekly session we’ll start reporting on next week). I can summarize our meeting as composed of four main topics:

  1. Naturally, we discussed the brand new website, and one of our conclusions (along with many suggestions for cosmetic improvements, which will be implemented asap) was that we should provide brief summaries of our lab meetings for the purpose of archiving our activities, providing convenient links to papers we discussed, dealing with follow-up issues, and allowing some of our far-afield members (busy being in Hawaii or being Mom) to keep up with happenings. Since I’m the editor-in-chief, it falls to me to provide the first summary. Trust the quality of these to pick up once I hand over the reins starting next week.
  2. In addition to discussing web issues, Tom advertised Susan Johnston‘s seminar in the Stirling BES seminar series next Monday. Susan has promised to discuss her recent work, including the Nature paper showing exciting fluctuating selection on horn size in Soay sheep. I anticipate we’ll have more to say on this next week after her visit, so I’ll avoid saying more just now.
  3. I briefly presented some analyses of data collected by Eilidh Macleod, a recent hons student whose excellent thesis we have yet to publish. Eilidh studied the relationships between mating status, fecundity, and ornamentation of females in a Scottish dance fly, Rhamphomyia longipes. Because she was making her observations on specimens collected from Malaise traps, the alternative causal mechanisms for covariation between these measures is unclear, and we’re struggling with a number of approaches to disentangling them. One of the techniques I’ve been toying with for a couple of years now is Structural Equation Modelling (SEM), but my progress has been slowed in part by the peculiarities of our data. Tom mentioned that Michael Morrissey (from the University of St. Andrews) gave an excellent talk on measuring selection using SEM at the recent ESEB meeting in Lisbon, and that there may soon be Youtube videos of these talks available? I’ll edit this with a link if Tom or I can find one….
  4. Finally, we had an extra round of beer and a few laughs. Tom and Lilly agreed to give talks for the Biology Society, I think. And maybe there’s a game of PowerPoint roulette on the horizon?

Hot off the press!

After a long slog, my colleague Claudia Buser (now in New Zealand) and I (along with our late supervisor from Zurich, Paul Ward) have gone to press at Functional Ecology with her (I think I am allowed to say so) excellent work on maternal plasticity in yellow dung flies.

As yet non-copy-edited pdf here.

Lay summary here.

RolandScathophaga

This photo (by an old mate from Zurich, Roland Gautier) shows yellow males perched above ovipositing olive-coloured females on a dung pat. We experimentally studied whether female perceptions of the conditions their larvae would encounter affected larval fitness. I won’t spoil the punchline, but females are very clever, obviously. Nevertheless, we found no evidence that they are doing anything funny via sperm choice….