On behalf of myself and my research laboratory, I wish you all (PhD-students, undergraduates, postdocs and senior collaborators) a Merry Christmas and a Happy New Year! Although the official celebration of the "Darwin Year" is now over, for us evolutionary biologists every year will indeed be another "Darwin Year", including 2010. I am looking forward to some exciting new research news, both in this lab and in the scientific community as a whole. Take care!
Tuesday, December 22, 2009
Tuesday, December 15, 2009
WWDD (What Would Darwin Do?)
Sunday, December 13, 2009
On ecological speciation, tempo and mode of evolution
Phylogenies reveal new interpretation of speciation and the Red Queen
Chris Venditti1, Andrew Meade1 & Mark Pagel1,2
(Nature advance online publication)Evidence for Ecological Speciation and Its Alternative
Schluter Dolph
These two papers are interesting, because they reflect radically different views on the causes of speciation and the drivers of speciation processes. I therefore thought it would be interesting to discuss them with this in mind, and contrast their different underlying viewpoints against each other. Who is correct and who is wrong? Or are both correct, and if so, in what domains?
We will thus meet at 10.30 in "Darwin" on Wednesday 16 December. Any fika-volunteer?
Abstracts follow below:
Chris Venditti1, Andrew Meade1 & Mark Pagel1,2
Phylogenies reveal new interpretation of speciation and the Red Queen
Schluter Dolph
Sunday, December 6, 2009
No lab-meeting this week (9/12)
Friday, December 4, 2009
On scientific "peer-review"
Monday, November 30, 2009
New lab-publication about intralocus sexual conflict in polymorphic damselflies
These intersexual genetic correlations differ significantly between the different female morphs, the most striking pattern being higher intersexual genetic correlations ("more male-like") in the androchrome (male-mimicking) female morph. The paper can be found here, and the title is "Morph-specific intersexual genetic correlations in an intraspecific mimicry system". Enjoy!
New ads from Google
Monday, November 23, 2009
Lab-meeting on November 25: signalling sexual and species identity
1. We will start by discussing the Nature-paper by Billeter et al. of how Drosophila males and females signal sex and species identity using pheromones ("CHC:s").
Tom Gosden wrote about this paper in an earlier bloggpost, and it seems quite exciting also to those of us who are not particularly interested in pheromone communication. Signalling sex and species identity is clearly a general problem of interest to many evolutionary biologists, and not only those working with Drosophila. The paper can be downloaded here.
2. We will also give Anna Runemark som input on her "half-time seminar" that will take place next week at the Animal Ecology department meeting. Anna brings her laptop and some idéas of her presentation, and the rest of us provide feedback to help her.
Same time and place as usual: "Darwin"-room at 10.00, Wednesday November 25. Any fika-volunteer?
Saturday, November 14, 2009
An exciting week with the phenotype in the centre of focus: Thesis nailing, lab-meeting (18 November) and dissertation
Monday, November 2, 2009
New PhD-thesis in the lab: Fabrice Eroukhmanoff
Friday, October 30, 2009
Rapid adaptive divergence and FST-QST
Time for another study from the Svensson Lab:
In a recent study published (in early view) in Molecular Ecology, we (Erik Svensson, Anders Hargeby and myself) have quantified phenotypic and quantitative genetic divergence between two ecotypes of our favorite study organism, the aquatic isopod (Asellus aquaticus) in two lakes in southern Sweden. We have tried to assess the relative role of selection and genetic drift during rapid and parallel ecotype divergence events. We demonstrate that for seven quantitative traits, the average QST between ecotypes is significantly greater than the mean FST, which is clearly consistent with a role for divergent selection causing phenotypic and genetic differentiation of these ecotypes. However, some QST-values for traits linked to size-related morphology fall within the distribution of neutral FST-values, whereas it is not the case for pigmentation traits. Our study therefore underscores the need for caution when evolutionary inferences are made from FST-QST analysis.
For instance, many FST-QST studies have investigated large number of populations and traits, without prior ecological and historical knowledge of the system. This aspect is important because if, like it is in our case, you investigate a case of parallel evolution, you may use specific pairwise comparisons as "replicates", and others as “controls”. The hierarchical structure of the populations and their history might therefore be of importance.
Second, neutral markers may sometimes not be so neutral, thus it is important to compare the distributions of FST with the distributions of QST, and not their means, if one wants to infer the role of selection in the divergence process. All these issues have been reviewed in a very nice paper by Whitlock also published in Molecular Ecology in 2008 and that we have discussed in a previous lab-meeting.
A last point I would like to insist on is that of course, this kind of approach will never beat the advantages of directly measuring selection in the wild. However, it might also be tricky to determine is selection is driving divergence between two populations even when estimating selection in the wild, since it is often difficult to encompass all its components at once, for example linked to fecundity, mate choice, intrinsic survival, predation, etc. Thus, by using FST-QST comparisons, one will estimate the role of the “net” selection differential between populations and its role during divergence. And this is also an advantage.
Well, I hope it inspired you to read our paper…
Thursday, October 29, 2009
Smells like?
So a few CHC’s in D.melanogaster have been shown to control male-male mating interactions, influence male courting rates and act as a species barrier to other Drosophila males. Think about that next time you try a unisex eau de toilette.
Abstract:
Sunday, October 25, 2009
No lab-meeting the coming weeks, but some exciting symposia
15-15.30 Coffee
15.30-16.30 Why is Sex Determination in Reptiles so Variable? Integrating Development, Ecology & EvolutionTobias Uller
APPLIED ECOLOGICAL SCIENCE - WORKSHOP 27TH OF OCTOBER
Titles and presenters:
1. What can evolutionary ecologists contribute to medicine?
Insights and Inspiration from the World Health Summit
Dr. Tobias Uller, EGI, Oxford University
2. From selfish genes to group selection - implications for society
Prof. Erik Svensson, Lund University
3. Urban ecology
Dr. Caroline Isaksson, EGI, Oxford University
4. Attitudes and biodiversity
Dr. Johan Ahnström, Lund University
Coffee will be served during the afternoon.
Monday, October 19, 2009
Bayesian statistics for next Wednesday meeting
After that Erik and Maja will give a short presentation on what they have learnt in Uppsala.
Sunday, October 11, 2009
Labmeeting on hidden genetic variation 14 October 2009
Hidden genetic variation is genetic variation that is not normally expressed, e. g. genes that is contingent upon environmental conditions before they are expressed, and hence before they can be "seen" by natural or sexual selection and thus contribute to adaptive evolutionary change.
A well-known example of hidden genetic variation are so-called stress proteins or heat shock proteins, that function as molecular "chaperones" to protect cells during extreme environmental conditions, e. g. during high temperature conditions. How important is such hidden genetic variation in evolution? This what we should discuss, among several other topics.
I also hope that our new CAnMove-postdoc Sophia Engel (shared with Anders Hedenströms laboratory) will join in Wednesday, as she has now arrived to Lund. This would be an excellent opportunity to meet the rest of our lab and introduce her to the crowd.
Time and place as usual: "Darwin" at 10.00 on Wednesday (14/10). Any fika-volunteer?
Saturday, October 10, 2009
Pictures from the Okavango Delta and Botswana
Wednesday, October 7, 2009
Hello Svensson Lab!! Here's my travelogue:
Brains, Pain and Autumn Rain
Stockholm is one beautiful city. When I'm not at the Karolinska Institute learning the ropes on human behavioral studies, I am out wandering around the city's busy parks and waterways. It certainly gets dark quick up here.
In the lab, Martin Ingvar has set me under the direction and guidance of two Phd students, Karin Jensen and Fredrick Lindstedt, for a solid introduction to neuroscience. Karin defends her thesis in October while Fred is just beginning his doctoral studies. Erik will be happy to hear that Karin has recently published in PloS ONE, his fav journal.
Fred and I are tasked with designing a study that looks at the interaction between emotion-regulatory genes and pain perception. Over the weeks our colleagues have developed avoidance strategies as we search for 'naïve' subjects to test our methods on. We begin pretrials next week and we'll see if our protocol works. I can't say too much as our future subjects are people and they can google.
I've also become involved with an fMRI brain-imaging study of people who suffer from Fibromyalgia syndrome (FMS). FMS is a disease consisting of lasting chronic pain ( >3 months) that exists without any measurable peripheral tissue damage. Neuro-imaging studies have been essential in establishing how FMS sufferes differ from the general population in how they process pain. I'm learning that FMRI can be a great tool for connecting the dots between the biological, cognitive and psychological systems that determine behavior. Plus, hanging around the scanner means I get a pretty brain scan to take home to Mom (see pic!).
At the moment I am applying for graduate school as well as funding which has me reflecting on my time in Lund. I'm so grateful to have been a part of the Svensson lab- I learned so much!
See you guys in December,
Kram,
Lisa Orr
Tuesday, October 6, 2009
No lab-meeting this week but another opportunity to broaden your views
Last Sunday, the theme of this programme were the moralistic and the naturalistic fallacies. I was one of the three participants, together with sociologist Eva Kärfve from Lund University and philosophy professor Per Bauhn from Kalmar. You can listen to the programme here. It is in Swedish, though, but most of you will understand the discussion. Enjoy!
Wednesday, September 30, 2009
Write a blogpost about evolution, compete, get famous and win a ticket to an interesting conference!
In my opinion, blogging is an excellent new form of communication, that is here to stay. However, blogging is only one new form of communication, and it will certainly not replace all other forms of communication. But blogging is a new information channel, and it would be as stupid to dismiss this new communication channel today, as it would have been to be against the television in the 1940-ties or the phones about 100 years ago. How could one be against new ways of communicating science and other important issues?
Today, we have several interesting research blogs in the Ecology Building apart from this one: Anders Hedenströms "Animal Flight Lab" and the "CAnMove"-blog being two excellent examples of such interesting research group blogs. There is now also a general agreement among many scientists that "Public Outreach" (which blogs are one example of), can actually be beneficial to you also in your scientific career. Is anybody really surprised?
The negative views against blogging among some of my colleagues reminds me about the scepticism against "Open Access" (OA)-publishing a few years earlier, and the scepticism against PLoS ONE in particular. I am quite amazed about how extremely conservative many scientists are against new things: blogs, social media like Facebook or OA-publishing. These new means of communication are here to stay - and it does actually not matter if this-or-that less known second-grade researcher at Lund University says about these phenomena, as long as they work and accepted by the broader international scientific community.
It is after all the international arena that is important - not what less-informed self-proclaimed "experts" claim at stupid coffee-room discussions in the Ecology Building. It is therefore with great satisfaction I can tell the readers of this blog that PLoS ONE was recently awarded a prestigious price for the most innovative scientific journal in 2009. This award was provided by the very prestigious organisation ALPSP ("The Association for learned and Professional Society Publishers"). The motivation for providing this award to PLoS ONE was partly:
"in recognition of a truly innovative approach to any aspect of publication. Applications are judged on their originality and innovative qualities, together with their utility, benefit to their community and long term prospects. Any area of innovation is eligible – it could, for example, be a novel type of print or online publication or service, or even a radically different approach to a marketing campaign."
Part of PLoS ONE's and other PLoS-journals success is the approach to provide information about number of downloads and citation indices in conjunction with each published article, something that will hopefully make it even more attractive to publish in PLoS, as it is clearly an "added value" to have access to this information directly from the article -rather than having to go through a data-base like ISI (for instance). Inlinks, links to blogs and other articles citing the focal article will all contribute to increase the reader traffic to PLoS-articles in the near future. For instance, here you can see such information statistics for an article in PLoS ONE that Tom Gosden and I published two years ago, we have now more than 10 citations and almost 2000 downloads! Not bad, in my opinion.
But also scientific blogging is a growing activity, that becomes more and more important, both for journalists and for scientists like us who would like to communicate our results to the laymen and amongst ourselves. Now you actually have a nice opportunity to write a blogpost about evolution and win a price. You can read more about this competition here and on the blog "A blog around the clock".
Basically, if you write a blogpost about some evolution-theme, you could send in that blogpost (i. e. the URL) and participate in the competition of the best blogpost. The award to the winner is quite nice: you will get 750 US$ to cover the costs of attending a science communication conference: "Science Online 2010", that will take place in North Carolina in early 2010. The competition is funded by the "National Evolutionary Synthesis Centre" (NESCENT), a prestigious scientific centre in North Carolina, funded by the National Science Foundation.
This particular blog is a group blog, and not my private one, meaning that anyone one of us could send in a blogpost and participate in this competition, if you wish. Or we could nominate on of us, if we think that there is some particular blogpost that you found especially interesting. I would encourage you all to seriously consider this possibility, even though you should feel no pressure to participate if you do not wish to. However, I hope the general message goes through: blogging can be useful. Also for scientists interested in evolutionary biology. Don't listen to the nay-sayers! They are just loosers and yesterday's scientists. Just as they were wrong on OA-publishing and PLoS ONE, they will be wrong on blogs and Facebook. With historical hindsight, they will be laughed upon.
Sunday, September 27, 2009
Lab-meeting on population divergence in isopods and lizards
We will start with the lizard manuscript at 10.00, and continue with the isopod manuscript after that. I will send out these manuscripts by e-mail to the whole group today (Monday) provided that Anna and Fabrice send me the updated last versions first. If you do not get it by e-mail, please e-mail Anna (anna.runemark@zooekol.lu.se) and Fabrice (fabrice.eroukhmanoff@zooekol.lu.se) so that they can send you the manuscripts.
Time and place as usual: "Darwin" at 10.00 on September 30 (Wednesday). Any fika volunteer?
Monday, September 21, 2009
Lab-meeting on the ecology of (incomplete) speciation
Sunday, September 13, 2009
Lab-meeting on G-matrix divergence i isopods
This manuscript which deals with morphological variation and quantiative genetics of morphology, should also be of interest to Tina and Sanna, who have been working recently on phenotypic and genetic correlations of behavioural traits in these isopods.
You can get this manuscript by e-mailing me (erik.svensson@zooekol.lu.se) or Fabrice (fabrice.eroukhmanoff@zooekol.lu.se). If Fabrice sends me the last version, I will also send out this manuscript to the group tomorrow (Monday).
Time and place as usual: "Darwin-room" at 10.00 on Wednesday 16 September. Any fika volunteer?
Thursday, September 10, 2009
Relaxed selection and loss of non-beneficial traits
In the latest issue of Trends in Ecology & Evolution, there is a review and metaanalysis of the fascinating phenomen of trait loss after the disappearance of selection pressures maintaining the traits. Classical cases is the loss of vision among cave-dwelling fish or loss of flight ability or antipredator adaptations among birds and insects invading oceanic islands with few predators. This study is briefly reviewed at Science Daily, and one of the co-authors is Andrew P. Hendry, the external opponent of Fabrice Eroukhmanoff's Ph.D.-thesis on November 20 2009.
Fascinating questions to adress here is why do some traits disappear fast, while others take much longer time to decay? According to the results it seems as if two factors might be important in determining the speed by which traits are lost when no longer maintained by selection:
1/Traits that are energetically or nutrient-wise costly are more likely to disappear fast. Examples of such traits are the armour-plate reductions in marine sticklebacks, which disappear fast when these sticklebacks invade freshwater environments, where the minerals that are needed to produce these plates are scarce.
2/Traits that have a relatively simple genetic basis, and which are governed by one or a few loci are lost faster than traits governed by many traits. Examples of such traits include the loss of vision among cave-dwelling animals. Although many genes might influence vision, it might be sufficient with mutations in one or a few genes to cause blindness.
These interesting questions also apply to some of the study systems we are working in our lab, e. g. the Podarcis-lizards that Anna studies on the islets in Greece, where predators are few or the isopods that Fabrice have studied in Lake Krankesjön and Lake Tåkern which have invaded a new limnetic habitat (stonewort), where the isopoods seem to have evolved a suite of different anti-predator adaptations, perhaps as a response to a changed predator regime (invertebrates vs. fish) or perhaps even relaxed overall predation.
Wednesday, September 9, 2009
Is history always written by the victors?
I had planned to write a blogg post on my recent activities with a friend who was visiting us from Sweden. After a wonderful few weeks cavorting around Australia’s east coast including whale watching, snorkelling on the Great Barrier Reef, exploring the rainforests of Daintree (where we found a Hercules moth, see picture) and Springbrook national park (see pic of common tree snake eating what looks like a gecko), camping on the beach at Stradbroke Island and an ill-advised skydive onto a beach north of Brisbane (for pictures of some of these activities see this site) I felt I had enough to write about, even if it broke the recent run of excellent true scientific posts.
But my head was turned by a correspondence letter in this week’s nature about a retrospective book review of Lamarck’s Philosophie Zoologique (Zoological Philosophy) from 1809. Ignoring the small errors pointed out by the correspondence, the book review opened my eyes a little to the misrepresentative way Lamarck is viewed within main stream science (or at least by the english). I have been as guilty as many for lambasting the work of Lamarck (mainly as a way of mocking Fabrice and the French in general), based purely on summaries of his work I have read in undergraduate textbooks. So have we chosen to over look Lamarck’s main contributions to our field? Having only read what is mentioned in the articles above it would be wrong of me to draw any conclusions and opinions from this……but of course I will and I say yes.
So how does science remember those who have gone before? We are dealing with philosophy of history when we look back over the works of those who have preceded us. Even though much of the work is in print, and therefore assumed to be infallible, misreading and misquoting work is something we are all guilty of to some extent. Sometimes it is easier to cite a piece of work based on the general consensus of what was said rather than reading it yourself. So a lesson for us all, if you're fortunate enough for your work to be remembered, just hope that you're lucky enough that it is remembered favourably and that you're not French (just a joke for Fabrice)!
Sunday, September 6, 2009
Lab-meeting on intralocus sexual conflict on Wednesday 9 September 2009
It was interesting for me to closely have seen this "explosion" of a field, which I have been familiar with for quite a while, but which few (at least in Lund) understood a few years ago, or realized the importance of. I strongly suspect that the term "gender load", which I had difficulties in explaining in some talks I gave in Lund, will soon enter the mainstream language of evolutionary biology. Perhaps future historians of science will see the signs of a minor conceptual and scientific "revolution" here, as people are increasingly viewing the genome not as a peaceful and harmonic and well-functioning "unit", but rather as something is constantly selected in different directions, the end-result becoming a compromise between male and female fitness optima (see figure above).
For those of you want some additional background reading, I can also recommend Robert Cox and Ryan Calsbeek's recent metaanalysis of intralocus sexual conflict, which was published in American Naturalist earlier this year, and which you can find here. You could also download my own paper (co-published with Andrew McAdam and Barry Sinervo) about intralocus sexual conflict over immune defence and how it affects sex-specific signalling in lizards. This paper is in press in Evolution and can be found here.
I suggest that we all read the TREE-review, and those who wants can also study the two other papers as a general background and bring them to the lab-meeting. We meet the usual time: 10.00 on Wednesday morning in "Darwin". Any fika volunteer?
"Human" vs. "animal" evolution
They used an impressive dataset of 99 human populations, 210 animal populations and 848 animal species. Their main conclusions are that within-population variation in body height (but not body mass) is relatively low in humans, whereas among-population variation is more or less similar to what one might measure in animal populations. They interpret it as a sign for strong natural selection on body height in human populations which have become locally adapted.
This paper is, I am sure, probably going to be cited in the media, if it has not already been done, and will probably contribute to the growing success of PLoS ONE. Andrew Hendry has also been working on human influence on evolutionary rates of animals and more in particular human influence on beak size bimodality in finches. He is particularly interested in studying cases of rapid evolution and in the way ecology and evolution interacts on contemporary time scales. I am honored to have him as an opponent for my thesis defense that will take place on the 20th of November, and I can already tell you that Andrew will give a talk on these subjects on Thursday the 19th of November, at 13.00 in Blå Hallen at the Ecology Building.
If you are interested in contemporary evolution, if you have no idea what the term "eco-evolutionary dynamics" really means or simply if this PloS ONE paper has intrigued you, I recommend already now that you mark this date in your calendars, because you will probably don’t want to miss this talk.
Friday, September 4, 2009
Thoughts on ESEB and the Morphometrics Workshop
I returned from the ESEB meetings, plus a follow-up workshop on Geometric Morphometrics, last night. Boy am I tired!! I'm on my 3rd cup of coffee this morning and still feel sleepy; more than one good night's sleep may be needed for a full recovery.
Wednesday, September 2, 2009
Adaptation driven by novel mutations or from selection on standing genetic variation?
Our collegue Hopi Hoekstra at Harvard University in the US, who visited us in August last year, has a paper in one of the last issues of Science. You can read a brief report on the website Science Daily here.
At first I was not very excited about this paper, as it appears to be the usual story about the melanocortin receptor (MC1R) and how it affects coat colour patterns in various mice populations, a story that by know is sufficiently wellknown and established so one wonders what remains to be discovered.
MC1R is responsible for dark coat colour in mice that occur in dark habitats (see above), e. g. on the dark lava flows in Arizona, that Hopi Hoekstra has previously studied together with her colleague Michael Nachmann.
However, this new paper has a new twist: it appears as if selection has acted on a novel mutant in deer mice in Nebraska, and this novel that apparently appeared in the population shortly after the last Ice Age, about 8 000 years ago.
Catherine Linnen and Hopi have analyzed genetic variation among these different mice populations and estimated the age of the allele that causes light coat colour in the mice. Light coloured mice carry a certain allele at a gene called Agouti, and this allele is quite young as it shows evidence of a selective sweep through reduction in DNA sequence diversity around that particular allele. Linnen and Hoekstra have thus used the well-known statistical approach of coalescense analysis to infer the age of the novel mutation at the Agouti locus that is causing light coat colour.
This result is important, as it provides some contrast to recent suggestions that novel mutations might not be that important in cases of rapid evolutionary change, which have instead emphasize selection on standing genetic variation in rapid evolutionary change. For instance, rapid evolutionary change need not always to rely on standing genetic variation as suggested by the findings from other systems like sticklebacks. The alternative is instead that rapid adaptive change is driven by a process by which selection in novel environments "picks up" and favours alleles that already segregated in the ancestral population, rather than "waiting" for the emergence of rare novel beneficial mutations (that might take long time to appear).
This process is sometimes also called phenotype sorting, referring to how a polymorphic and variable base populations might become transformed in to a new (monomorphic and less variable) population through the selective increase and selective loss of already existing phenotypes, which are then "filtered" by selection in the novel environment. Something along these lines appears to also be the case in the freshwater isopods that we have studied in our group, and we discussed this earlier this year in a paper published in Journal of Evolutionary Biology, which you can find here.
In summary, the relative importance of selection acting on novel mutations vs. standing genetic variation is probably something that will be discussed a lot the coming years in evolutionary biology and ecology.
Monday, August 31, 2009
Goodbye Shawn and Lisa! No lab-meeting this week
Wednesday, August 26, 2009
Second conference day: Agents of selection and the ecology of selection
The second full conference day in Turin has been spent in the symposium that I organized (together with Alexis Chaine) entitled The phenotype-fitness map revisited: agents of selection and the importance of ecology in evolutionary studies. This symposium was, I would say, a HUGE success, and the room was crowded from the very beginning. It is clear to me that evolutionary biologists are increasingly realizing that they should not take ecology as "given" or treat it as a "black box" and only focus on DNA-sequence variation, which has been dominating these evolutionary conferences a lot the past decade.
Luckily, things are now changing and there is an increasing interest in the actual ecological causes of selection and their effects of evolutionary diversification. These ecological factors include inter- and intraspecific competition, predation, parasitism, social environments, to name only a few. Todays speakers included Craig Benkman, who gave an interesting overview of the crossbill radiation in North American Europe (see picture above!) and its ecological causes: the size and hardness of the cones of coniferous trees. Benkman showed that selection on cones by crossbills changes if there are also squirrels present in the area, a nice example of how interspecific competition can have a dramatic effect on evolutionary trajectories.
The other invited speaker was Stevan J. Arnold, a legendary evolutionary biologist and quantitative geneticist, who developed the statistical framework of estimating selection gradients in natural popualtions (together with Russel Lande). It was therefore very nice to see both Steve Arnold and Russ Lande sitting on the front row of this symposium, enjoying the fact that their landmark paper from 1983 (published in Evolution) still inspires workers today. Few papers in evolutionary biology has been cited as much as this landmark one.
Steve Arnold gave a talk about how the adaptive landscape model of microevolution can be extended to the macroevolutionary scale to understand phenomena like adaptive radiations. He presented some new models and a newly developed software (MIPoD: Microevolutionary Inference from Patterns of Divergence) that can estimate parameters like the strength of long-term stabilizing selection and its relationship to genetic drift and other evolutionary forces, using phylogenetic data, estimates of effective population sizes and phenotypic and genetic information from different evolving populations. He illustrated this new approach using his own collected empirical data on the number of vertebrae in gartern snake populations from different parts of North America.
Now, I will go and have a beer with my close college Tom van Doorn to prepare for tomorrow, which will include a trip to Mont Blanc in the afternoon. Hopefully, we will see some nice Alpine birds!
Tuesday, August 25, 2009
ESEB-meeting in Turin: impressions from first day
I am currently in Turin (Italy), participating in the European Evolutionary Biology Meeting, organized by European Society for the Study of Evolutionary Biology (ESEB). I travelled down to Italy with a dozen of my colleagues from the Ecology Department by train, a nice trip that took about 24 hours. We passed through the Alps and enjoyed the sight of the extensive grape fields in northern Italy before we reached our final destination. A nice experience that was also both climate-smart and environmentally friendly, compared to the usual flight trip.
What has happened this first day? Well, Hanna Kokko from University of Helsinkki gave an excellent keynote plenary about the need to incorporate ecology, particularly population dynamics, in evolutionary studies (and not only genetic factors). Being an ecologist myself, I could not agree more, and actually, tomorrow (Wednesday August 26) I am hosting a full-day symposium about the need to incorporate ecology, particularly information about selective agents (predators, parasites, inter- and intraspecific competitors etc.) and selective causes in studies of natural and sexual selection in the wild. Our two invited speakers tomorrow are Stevan J. Arnold and Craig Benkman, two well-known field evolutionary ecologists who have done excellent work in this spirit in natural populations of birds (crossbills) and amphibians (salamanders).
Back to Hanna Kokko. One of her most interesting points today was a critical re-evaluation of Bateman's principle, the idéa that differences in gamete size of males and females (i. e. eggs and sperm) is the main explanation for differences in reproductive strategies and sex-differences in parental care. This idéa has long been popular in evolutionary psychology and classical behavioural ecology, and it was taught to me as more or less a "truth" when I took courses in behavioural ecology and animal ecology in Lund in the late 80'ties and early 90'ties.
As many other popular idéas in behavioural ecology (a field with an unfortunate tendency of forming scientific "bandwagons") it was an oversimplification and Kokko convincingly argued that there are many other ecological factors than differences in gamete size that are likely to override these initial sex-differences and which are likely to be as important (or even more important) to explain sex differences in partental care. Among these factors are the operational sex ratio (OSR), which should (all else being equal) favor more male parental care when there are few females available and less mating opportunities, for a simple reason: males might then benefit more from providing parental care than try to hunt the few females that are available in the mating pool.
I suspect that Bateman's Principle will be start to become more critically questioned among evolutionary biologists in the future, although the hardcore dogmatic ones that remain (some of them in Lund) might not give up their pet idéa that easily and might be hard to convince. Paradigm shifts in the sense of science philosopher Thomas Kuhn sometimes need that some reactionary key figures retire, before new idéas can establish themselves, and this is also true for behavioural ecology and evolutionary biology.
Talking about pet idéas, another such (in Lund and at many other places) has been the so-called "good genes"-model of sexual selection. This popular hypothesis, which has actually quite limited empirical support in spite of its extreme popularity, was almost a dogma in the nineties in Lund and Uppsala and many other animal ecology departments. The idéa is that male secondary sexual ornaments (signals), like bright feathers and colour patterns, primarily evolve through the force of indirect selection for genetic fitness benefits of offspring.
Many workers have now pointed out, among them evolutionary geneticist William Rice, that the indirect fitness benefits are quite small and likely to be "swamped" by direct fitness costs (e. g. costs of mating, as shown in fruitflies) or direct fitness benefits (e. g. benefits of male parental care, which is probably present in most birds with parental care). Thus, even if indirect fitness exist, they are unlikely to be important in explaining the evolution of secondary sexual characters, which is of course frustrating for those bird behavioural ecologists who have invested a large part of their careers and prestige in to this particular scientific bandwagon which is no longer that fashionable anymore and actually contradicted by much new data and new theoretical models.
Recently, it has also been demonstrated in fruitflies, reed deer and some other animals that fitness benefits of alleles are sex-specific and that there exists intralocus sexual conflict in the genome: genes which have a positive fitness benefits on sons often have a detrimental fitness effect on daughters, which should further diminish the indirect fitness benefits of females mating to attractive males. This topic and other obstacles to the "good genes" were adressed in a symposium entitled Are “good genes” theories of sexual selection finally sinking into the sunset?. Well, one could hope so, or at least that people in behavioural ecology start to think more critically about this issue and that they do not take these "good genes" (important or not) as much as for granted as they have done in the past.