Thursday, December 22, 2011

Merry Christmas and Happy New Year 2012!

 Another year has soon passed, and I wish to say Merry Christmas and a Happy New Year to all of you involved in research in lab. This includes both those of you who are currently in Lund, and those of you who are elsewhere in the world, such as in exotic countries like Norway and Australia.

The pictures above come from the Christmas Meeting in the new Evolutionary Ecology Unit, which was held last week. After talks in the afternoon by several group members and other colleagues in the new unit, it was time for the traditional Swedish Christmas Table, or "Julbord" As you see, Jessica Abbott participated too, after several years of exile in Canada and Uppsala. Jessica will start her new position in Lund in January 2012, after receiving her "Junior Project Grant" from Vetenskapsrådet in 2011. Tina Karlsson also participated, and she will leave to start her postdoc in Finland (Helsinkki) in May 2012.

The year 2011 was an extremely successful year for our lab, in terms of succesful grant applications. Apart from Jessica obtaining a VR-grant and Tina getting a postdoc-grant from VR, Fabrice Eroukhmanoff obtained an EU/Marie Curie postdoc in December, and Machteld Verzijden got extension on her postdoc from the Wennergren Foundation. Considering the severe competition for grants these days, I am both amazed and proud of these achievements of you guys. And you should be as well, of course.

The year 2011 was also  successful in terms of publishing, with nice papers in leading journals, such as Animal Behaviour, BMC Evolutionary Biology, Heredity, Evolution, Journal of Evolutionary Biology, to name a few. We are clearly doing work that is interesting and relevant, and I have the feeling we are moving in the right direction to be even more succesful in the coming years.

Once again: Merry Christmas and enjoy the break! See you in 2012!

Tuesday, December 13, 2011

Congratulations to Fabrice Eroukhmanoff for obtaining postdoctoral EU-fellowship ("Marie Curie")

Former PhD-student Fabrice Eroukhmanoff, who is currently postdoc at CEES in Oslo (Norway) has apparently obtained a postdoctoral scholarship from the European Union through the "Marie Curie"-programme. As he recently obtained a two-year postdoctoral scholarship from the Swedish Research Council (VR), this means that he can stay longer in Oslo and be able to do more research, before possibly returning to Sweden.

On behalf of myself, as proud former advisor, and the rest of us, I wish to congratulate Fabrice for yet another impressive achievement. Well done!

Wednesday, December 7, 2011

Lab-meeting and some interesting evolutionary articles in Science

This week's lab-meeting will take place at an unusual time: Friday 9 December at 10.00 in "Argumentet". I hope you can make it, as Machteld and I will tell us a little bit about our impressions from the ASAB-meeting in London, where we recently participated. In addition, I would like to discuss two recent articles in Science which are of interest to evolutionary ecologists (and which are short reads). You will find more information about these papers below, including links and Abstracts.

First, there is this interesting study about negative frequency-dependent selection in voles: 

Negative Frequency-Dependent Selection of Sexually Antagonistic Alleles in Myodes glareolus


Second, there is this study on individual face recognition in paper wasps: 

Specialized Face Learning Is Associated with Individual Recognition in Paper Wasps


Monday, December 5, 2011

Increasing visitor traffic to our blog

The visitor statistics to this blog has been going steadily upwards since it was first launched in spring 2009 (see graph above), and last month we actually had more than 5000 hits. Although bloggers built-in visitor statistics does not separate automated searches from web-engines from individuals that are really interested in our stuff, and although it does not track "unique" visitors, I think these numbers reflect an ongoing and positive trend, and increasing awareness of our research and the blog. It is probably a safe educated guess that several hundred visitors per month read our blog and find it interesting and worthwhile to read.

Hopefully, this increase will continue in the near future, as it often takes several years to build up a new blog and "brand it". Hopefully, the blog will also help us to attract students, postdocs and other outside collaborators and also spread more efficiently information about our ongoing studies and publications.  Sofar, we have mainly used it to announce lab-meetings, but we are increasingly using it also as a vehicle to inform about recent meetings that we have participated in, as Maren did recently when she was at "Blodbadet" in Stockholm, as also Fabrice did after he went to a hybridization workshop in Scotland, and as I also I did myself when I recently visited the ASAB Winter Meeting with Machteld.

Blogs and social media do certainly not replace traditional means of scientific communication, such as peer-reviewed publications in international journals. But they are certainly an important complement, and I am more and more convinced that they can have a positive impact and "spill-over effects" on such vital things as citation rates of papers.

I would therefore encourage you all, once again, to post interesting things, short or long, on this blog, along these lines, including interesting talks you have been to, or interesting articles you have stumbled upon. Together, we might make this blog an excellent outlet for the dissemination of research, both our own and others.

Saturday, December 3, 2011

Some thoughts from ASAB:s winter meeting in London: remembering Mayr's and Tinbergen's legacies

Together with Machteld Verzijden from our lab, I recently attended the annual "winter meeting" for the Association for the Study of Animal Behaviour (ASAB), close to London Zoo. The theme for this year's meeting was "Why do animals mate with the "wrong" partner?", and you can find a list of the talks here. There were several interesting talks, including contributions from Marlene Zuk about "same-sex behaviour" and Karen Pfennig about adaptive hybridization in spadefoot toads. The most interesting talk, in my opinion, was however Tamra Mendelson, who pointed out the need for a clear operational definition of species recognition, and emphasized that it should be integrated with the need for a general theory of mate recognition.

Other contributions were more controversial, including a talk by Joan Roughgarden, about the evolution of cooperation and mutual affection, and Malin Ah-King from Uppsala University about the need for developing gender-neutral models of sexual selection. Malin Ah-King took as her starting point a model based on five demographic parameters that makes no assumptions about past evolutionary history of the two sexes and argued that the so-called "w-distribution" (distribution of male-female joint fitnesses) was crucial in determining the degree of mate acceptance and promiscuity. Although I see some validity in moving away from the evoutionary psychology tradition of stereotypic sex differences to better understand mating system evolution, the opposite approach, ignoring sex differences altogether seems to be a bit too drastic in my opinion. But I might have misunderstood some underlying assumptions of this model, of course.

Even more controversial was when Ah-King suggested that we should consider alternative explanations for why animals mate than the classical evolutionary one: that animals mate because natural selection favours reproduction and the transmission of genetic material across generations. King instead suggested that animals more often mate because of "pleasure", which to me seems to be making the classical mistake of confusing proximate ("mechanistic") and ultimate ("evolutionary") explanations of animal behaviour. 

As evolutionary biologist Ernst Mayr and ethologist Niko Tinbergen have taught us, proximate and ultimate explanations are not mutually exclusive, but rather complementary, and adress different "layers" in the explanation of behaviours and other traits. Thus, contrary to what Ah-King claimed, the two statements "animals mate because of pleasure" and "animals mate to maximize the transmission of their genes" are not contradicting each other. They can even be integrated by stating: "Animals have evolved pleasure of reproduction as an internal reward system because natural selection has favoured organisms which are efficient in spreading their genetic material".

This took very long time for many biologists to undertand, particularly for geneticists, physiologists and developmental biologists. There is a famous story about fly geneticist TH Morgan who, in the early twentieth century stated that: "Darwin thought that male birds had evolved bright plumage colouration because of sexual selection by female choice. We now know that this explanation was incorrect, and the reason why male birds have more bright plumage than females is because of difference in sex hormones".  It would be sad if the important conceptual insights about the crucial difference between proximate and ultimate explanations, so clearly explained by Mayr and Tinbergen were forgotten again. And yet, that is the impression I got after listening to Ah-King's talk.

Thursday, December 1, 2011

Hybridization and Speciation

Recently, I participated in a very interesting Frospects workshop in the UK about hybridization and speciation and organized by Roger Butlin and Mike Ritchie, under the coordination of Ulf Dieckman. Several invited experts such as Godfrey Hewitt, Richard Abbott, James Mallet or Karin Pfennig presented their views on hybridization and how it is (or should be) more and more recognized as a creative evolutionary force in many aspects including speciation (one of the classic examples being homoploid or polyploidy hybrid speciation). But another (among many) particularly interesting discussion that took place originated from an argument presented by evolutionary and behavioral ecologist Karin Pfennig. It deals with the possible outcomes of reinforcement and how it might induce reproductive isolation between allopatric and sympatric populations of the same species through divergence of mate preferences. It is thus very relevant to some of the systems we are working on, such as Calopteryx damselflies.

Indeed, in some cases, selection against heterospecific matings may incidentally result in individuals from conspecific populations which are either situated in sympatry or allopatry leading to the initiation of reproductive isolation between formerly conspecific populations (Pfennig & Ryan 2006 Proc. Roy. Soc. B). For example, Jaenike et al. (2006, PloS Biology) showed that, between two sympatric species of Drosophila, strong hybrid inviability could not only select discrimination of heterospecifics, but also incidentally lead to discrimination of conspecifics from allopatric populations. Anpther example, although a bit more complicated as it involves different sympatric populations instead of allopatric and sympatric ones can be found in Hoskins et al. (2006, Nature), but there the data on divergence in mating preferences is quite interesting.

Remarkably, we have actually kind of obtained a similar result in one of our previous study (Svensson et al. 2006 Evolution), where we found that strong divergent sexual selection was accompanied by a significant decrease of female response towards conspecifics from other populations. This is corroborated by another study yet from our group, that found reduced gene flow between some of these populations (Svensson et al. 2004 Heredity), like it has been found in other systems (Rice and Pfennig 2010). I had myself never really thought about it that way, and this opened my mind a lot I must say on what Erik and others of our group have done in the past. And what about learning then? Well, we know it is likely to play an important role in divergence of mate preferences in our system (Svensson et al. 2010 Evolution), and all things considered it might even facilitate this process, as mate choice may change faster and thus the constraining effects of gene flow in the early stages will then not be an issue anymore.

We all concluded that evaluating this type of scenario may be possible with existing data or systems. In particular, studies of reinforcement and reproductive character displacement often involve comparisons of reproductive traits between sympatry and allopatry. But I guess in our case, there might be ways to use existing data and design new experiements to test specifically this type of hypothesis and whether such a process can actually promote speciation or why conspecific populations never really speciate, only maintaining a moderate level of divergence (genetic constraints, learning etc.?). Maybe you guys are already long aware of this, but I still wanted to shareit, as it was new for me, and I hope you find this as interesting as I did, and that it stimulates some new ideas maybe?

Some useful refs:

Jaenike J, Dyer KA, Cornish C, Minhas MS (2006) Asymmetrical reinforcement and Wolbachia infection in Drosophila. Plos Biology 4, 1852-1862.Hoskin CJ, Higgie M, McDonald KR, Moritz C (2005) Reinforcement drives rapid allopatric speciation. Nature 437, 1353-1356.

Pfennig KS, Ryan MJ (2006) Reproductive character displacement generates reproductive isolation among conspecific populations: an artificial neural network study. Proceedings Of The Royal Society Of London Series B-Biological Sciences 273, 1361-1368.

Rice AM, Pfennig DW (2010) Does character displacement initiate speciation? Evidence of reduced gene flow between populations experiencing divergent selection. Journal of Evolutionary Biology.

Svensson EI, Eroukhmanoff F, Friberg M (2006) Effects of natural and sexual selection on adaptive population divergence and premating isolation in a damselfly. Evolution 60, 1242-1253.

Svensson EI, Kristoffersen L, Oskarsson K, Bensch S (2004) Molecular population divergence and sexual selection on morphology in the banded demoiselle (Calopteryx splendens). Heredity 93, 423-433.

Thursday, November 24, 2011

Congratulations to Tina for obtaining postdoctoral grant from The Swedish Research Council

Former PhD-student from our lab Kristina Karlsson-Green have just found out that she has been awarded a postdoctoral grant from "The Swedish Research Council" (VR), so that she can go to University of Helsinkki (Finland) for two  years and work with Junior Project Leader Dr. Anna-Liisa Laine, who is part of the famous "Metapopulation Ecology Research"-group lead by Professor Ilkka Hanski, who visited Lund and Sweden earlier this year when his research as a recipient of prestiguous "Crafoord Prize".

In Finland, Tina will work on a project with butterflies on the interface between sexual selection, parasites, host-pathogen interactions and trophic interactions. The study species will be the famous butterfly The Glanville Fritillary (Melitaea cinxia,; see picture above), who among its host plants also have Plantago lanceolata, which is infected by a fungal pathogen, which in turn has cascading effects at higher trophic interactions, such as those between the butterflies and parasitoids. This seems like an extremely exciting cutting-edge scientific project with links to community ecology, behavioural ecology and coevolutionary processes, and it will be very interesting to hear about the results from the planned studies.

Tina's success in obtaining one of these highly competitive postdoctoral research grant is mainly her own accomplishment, and shows her quality as an independent young scientist. Still, as former advisor, I feel very proud of her, as well as for my first PhD-student Jessica Abbott, who was able to obtain a "Junior Project Grant" earlier this month from VR.

Students and postdocs from this research lab are doing remarkably well in the stiff competition for grants and scholarships. Why this is so is up to others to analyze, and it is probably some kind of interaction effect between personalities in our group, as well as with other colleagues in our department. Whatever the reason(-s), I am very confident that these grants are not the last and that this positive trend  in grant success will continue in the future. The best thing we can do, and a good investment for the future, is to keep up with our regular lab-meetings and interesting scientific discussions about papers and science, encourage and stimulate each other, communicate our findings and joy on this blog and maintain a good spirit and positive attitude towards our work. In the end, I am convinced that these things are far more important than large grants.  Well done Tina!

Wednesday, November 23, 2011

Democracy on the biology department website.

My frustrations with the biology department website have come to a boil, and the safety valve is this blog. So here comes some steam... which might be put to some good use in powering change?

What brought my hissyfit on this time is that I was trying to advise someone who will be visiting Lund, who he might want to talk to while here. He does not know this department by heart, and, like everyone else, has a busy schedule, without oodles of time scouring the website.

Which is what you would need to figure out who all is here and what they are doing. Our department website is, as a matter of fact organized by the politics of research groups very much like ancient Greece was divvied up in city states. To find people in our group, first you'd first have to click on 'research' from the main page of the biology department, then on a tiny little link called 'research groups', then on another tiny little link called 'phenotypic evolution'. I'm not saying that's a bad way to describe what we do, but hardly the only one. Further more, if you'd be interested in finding, say, me, you'd have to know intimately what kind of research I'm doing in the first place.
Right now, this website is reflecting political associations, and if you look very carefully, with 20 years of history of this department in mind, you can see political strife, where people do and don't want to be put in a certain box (read research group names).
That, in my humble opinion, is not what a website is used for, or should be used for. Political associations within a department are NOT interesting to anyone outside this department, and should not be known intimately in order to be able to navigate this website. Which, as Erik pointed out, may be a slightly naive way of thinking about a website. Well....

Ok, that was my rant. Here comes the constructive part. Let's break out of the tyranny of the city states and have... democracy (yes, I have been reading up about ancient greek history, can you tell?). Let's be more fluid, let's stop playing hide and seek with visitors to the biology department website. I envision two ways of finding people/research:
1) By a person's name, which will link to their personal website.
2) By list of keywords which will link to a list of people's names who have indicated themselves that they want to be associated with those keywords. Yes, multiple. We all do diverse things. Let's celebrate diversity.... power to the people.. (ok, I get carried away..).

So if you were to surf around on the biology department website, and you'd click on 'research' you'd find 2 tabs: one labelled 'people', the other 'research subjects'. I would be listed on the people page with my straightforward name 'Machteld Verzijden', and on the research subjects page, I might be listed under a number of keywords, like 'evolution', 'behaviour','sexual selection','damselflies'... The research subjects page would show lots of keywords, maybe they'd be clickable themselves, then showing a list of names, or it could simply be a header with names of people under that word. Get creative, I think this could work well in a number of ways.

And so, the outsider visiting the department website would get an immediate overview of who is here (people site) and what kind of things we study (keyword site), and have several ways of finding people or research groups. This way, we don't have to remember who is (and who is not) associated with which small or large research group, the name of which might not make a lot of sense to outsiders. This way, no one will have to spent 1.5 hours finding where Anders Hedenström's webpage is, as was the case for Shawn, and me spending an equal amount of time where Jan-Åke Nilsson's page is located, without having to resort to mr Google. Also, if you don't know who is working in Lund, but you have a research interest, you might actually be able to find some people working in your area of interest.

There, glad that's off my chest. I'll get off my soap box now.

Monday, November 21, 2011

The 18th "Blodbadet" 2011

 I was invited to give a talk at the 18th Blodbadet, which is an annual meeting of the Zoology department at Stockholm University. The meeting took place at the Tovetorp research station, and included five invited speakers: Kerstin Johannesson (Gothenburg University), Alex Weiss (University of Edinburgh), Christopher Wheat (University of Helsinki) and John Bishop (Washington State University Vancouver) and myself (Lund University). PhD students and postdoctoral researchers from Stockholm and other Universities were also presenting their research, which made the 2.5 days of talks refreshingly diverse. The topics ranged from animal personalities, to parallel speciation, and the significance of eye spots as anti-predator behaviour and of course, a variety of talk on the evolution and ecology of damselflies and butterflies. I truly enjoyed the talks and meeting this diverse range of people, and left the meeting with lots of new ideas. 

Here is a photo that was taken at the meeting
Maren Wellenreuther

Sunday, November 20, 2011

On speciation in TREE

This coming Wednesday's lab-meeting (November 23), we will discuss two recent speciation-reviews, both published in Trends in Ecology & Evolution during the last year (2011). One is by Maria Servedio et al. and is entitled: "Magic traits in speciation: "magic" but not rare?" and can be downloaded here. The other one is by Roger Butlin and a number of co-authors and is entitled: "What do we need to know about speciation?" and can be downloaded here. The latter paper does also have an online discussion attached to it, where I and several others (including Maria Servedio) commented, and you might also want to check this discussion here, as well as a recent previous post on our blog here, and on the blog of Andrew Hendry and co-workers here.

Note that Hendry's group has written a criticism of Servedio's et al's article, which you can assess through the TREE webpage (unfortunately I do not have the links here, as there is problem with the university server at the moment).

Time and place as usual: "Argumentet" at 13.00 (Wednesday November 23, 2011).

Tuesday, November 15, 2011

Interesting interview with Richard Dawkins on the political implications of "The Selfish Gene" and the "God Delusion"

Here is an interesting interview with popular science writer and evolutionary biologist Richard Dawkins, famous for his book "The Selfish Gene" from 1976, which revolutionized the general public's view about the evolutionary process, in particular the role of gene selection, as opposed to naive group selection.I found this video as I was looking for material for an undergraduate course that I am teaching entitled "Human Biology & Evolution". 

It is worth watching, particularly since Richard Dawkins clearly explains what selfish genes are, and what they are not. In particular the crucial notion that selfish genes do not imply that individuals must be selfish, but rather the converse: selfish genes might often results in altruistic individuals. This crucial point has apparently been missed by the many right-winged libertarians and free-market ideologists, who wrote many letters to Richard Dawkins after the publication of his book to express their admiration and support. In this video, Richard Dawkins is very clear about his own view about such political idéas, which are strong in the right-wing segment of the US population: he does not support them at all.

As Dawkins states in the video above: "I have voted to the left in Britain in  my whole life". Selfish genes do thus by no means justify unregulated marked capitalism, although many wishful thinkers on the right side of the political spectrum have tried to exploit the title of his book for their own ideological purposes. As a matter of fact, Richard Dawkins have even stated that an alternative title of his book could very well have been "The Altruistic Organism".

It is important to be fair to Richard Dawkins, as there is actually some serious criticism that can be directed to both his idéa about the overall importance of gene selection, and his rather dogmatic dismissal of higher-level selection, such as at the level of groups, populations or species. Here, I think he is wrong, and there are many leading evolutionary biologists and population geneticists who would agree that group selection can indeed work in many ecological situations, including David Sloan Wilson and Michael J. Wade. 

There are many conceptual problems with Richard Dawkins strict separation between "replicators" (genes) and "vehicles" (organisms) that forms the basis of his whole argumentation that gene selection will always outpower higher-level selection, and some of these problems and logical pitfalls are discussed here.

Personally, I do als think that Dawkin's stance on religion is both unproductive and not very sophisticated, in terms of the nature of the criticism, as expressed in his too hyped book "The God Delusion". Apparently, Dawkinshas also recently stated that he partly regrets that he wrote this book (or should I say pamphlet?). The God that he describes in that book is more of a charicature of religion as he perceives it, than actually depicting the true beliefs of most religous people.

My own personal view, as an atheist, is again much closer to my fellow atheist David Sloan Wilson's view that religion has evolved for some reason, and hence can be treated as a problem that one can study in the light of evolutionary theory. That view strikes me as being a more intellectually fruitful and interesting approach towards understanding religion than just pointing fingers and treating it as a disease, which Dawkins tends to do.

What do we need to know about speciation? Interesting TREE-review and discussion at Cell Press

Some of you might already have seen this, but I wish to draw your attention to an interesting TREE-review entitled "What do we need to know about speciation", published in Trends in Ecology & Evolution, and authored by Roger Butlin and co-workers in the FroSpecs-network (an ESF-funded research network focussed on speciation research). As you know, FroSpecs funds speciation conferences, meetings and small symposia, including one in Jyväskylä (Finland) next year, and one organized by us after the ISBE-meeting in Lund in August 2012 about behaviour, adaptive and non-adaptive speciation and ecological and non-ecological speciation.

The review by Butlin et al. aims to identify the most important future questions in speciation research in the coming years, and the article is also accompanied by an online discussion, where I was invited to participate, together with several other biologists, including Mike Ritchie, Maria Servedio and Andrew Hendry, to name some of our friends and colleagues. I encourage you to follow both the discussion and read the original article. In terms of speciation discussions, I would also like to recommend an interesting (albeit long!) blog post about "magic traits" on the research blog of Andrew Hendry.

Friday, November 11, 2011

Lab-meeting on how to write a succesful application to VR: Part 2

On Wednesday November 16 (update: 13.00!), we will have a follow-up lab-meeting about strategies how to write a succesful application to VR, particularly in relation to the new form of grant directed to young researchers: "Junior Project Grants". This time, we  have invited two of the succesful grantees this year: Jessica Abbott, and Olof Hellgren.

Both these young scientists will participate in the lab-meeting and share their experiences about the application process and participate in the discussion. They will also tell us a little about their projects and what they want to do in the future.

I will start the discussion by re-iterating some of the general points and messages from the previous meeting, and give some reflections of this year's outcome and what it might mean for the future.To celebrate Olof and Jessica, some "bubbly" champagne-like drink will be served, and Machteld has promised to bring some "fika".

I would also like to point out an interesting blog post about how to be succesful in writing research grant on the blog "The Professor is in". I got the hint about this blog from Brazilian graduate student Marcos Robalinho Lima. The particular post is entitled "Dr. Karen's Foolproof Grant Template" and you can find it here.

Time and place: Wednesday November 16 at 13.00 at in "Argumentet".


Saturday, November 5, 2011

Dr. Jessica Abbott receives "Junior Project Grant" from the Swedish Research Council (VR) and moves to Lund

Some of the greatest moments of satisfaction in the life and career of scientists and teachers is when former PhD-students are succesful and able to obtain jobs and positions, especially these days with increasingly severe competition for research grants. It is therefore with great pleasure that I now note that Jessica Abbott, currently postdoc at the Evolutionary Biology Centre (EBC) in Uppsala, has received a so-called "Junior Project Grant" from the Swedish Research Council (VR).

As many regular readers of this blog probably already know, Jessica defended her PhD-thesis here in Lund in November 2006, with me as her main advisor. After her PhD-defence, she moved to Queens University (Canada) for a VR-funded postdoc in the laboratory of Adam Chippindale to work on intralocus sexual conflict over wing shape in fruitflies (Drosophila melanogaster). She continued working with fruitflies also during her second postdoc in Ted Morrow's lab in Uppsala, but now using more transcriptomic techniques, such as microarrays, to study the expression profile consequences of intralocus sexual conflict.

Jessica will join the Evolutionary Ecology Unit in the Biology Department, and start up her own independent research project on intralocus sexual conflict in simultaneous hermaphrodites, using experimental evolution approaches on marine flatworms (see picture above), in collaboration with Lucas Schärer. We will hopefully hear more about these plans in a few weeks, as Jessica will come to this year's Christmas Meeting and party in the Evolutionary Ecology Unit. Jessica has also promised to write a blogpost soon where she will inform us a bit more. She will also come to our weekly lab-meeting on November 16, to share her experience on how to obtain a Junior Project Grant from VR (more info in a forthcoming blogpost).

The fact that Jessica now will bee able to establish herself as an independent senior researcher is not only good for herself, but also for the rest of us, as a new intellectual force with novel research techniques and study organisms  will come to us in Lund. Jessica will thus join our lab soon and will of course be active at lab-meetings and (hopefully) also soon be able to recruit PhD-student(-s) and/or postdocs.

As Jessica now will become another Principal Investigator (PI), I think that time is now very mature to re-name this blog ("Erik Svensson Research Laboratory"), which is to focussed on only one person, to something more general, which captures both mine and Jessica's research, and also opens up for future recruitments and establishments of new PI:s.

Ideally, a new name for this blog should be long-lasting, general, independent of study organisms or techniques, yet still capture the essence of research interests among the PI:s, postdocs and PhD-students. It could very well be a name consisting of several words, even an acronym, as the case of some of our sister blogs at other universities, like the  Eco-Evo, Evo-Eco, which was started by Andrew Hendry at McGill University, but which is a true group blog for his co-workers, just like I want this one to become in the future.

I therefore congratulate Jessica once again, and declare the competition for a new blog name that captures current and future research interests of this group open! There is no deadline to come in with suggestions, and you could either tell me directly, or write in the comments below this blog posts. I have already one possible name in mind, which I have discussed with Jessica, but wanted everyone to have the chance to come in with suggestions before I decide. There is no jury, and I am the only judge. Good arguments will be considered, especially if they take in to account the factors that I listed above (generality, likely duration and the possibility of future recruits and new PI:s).

Thursday, November 3, 2011

The Impact of Inversion Polymorphisms on Evolution

Chromosomal inversions are widespread in nature and have been found in plants, mammals, birds and insects. A role of selection on the evolution of chromosomal inversions has been demonstrated through the pioneering work by Dobzhansky and co-workers on Drosophila pseudoobscura, but has since been found in several other species. Inversions are of particular interest in many species because they suppress recombination in heterokaryotypes and may therefore help to maintain positive epistatic interactions among groups of alleles at loci contained in the inversion. In this way, inversion can be seen as facilitating the formation of adaptive gene complexes, drivers of adaptation and speciation.
Traditionally, inversions on the species level have been identified cytologically through meiotic observations. Inversion polymorphisms within species can be identified through examination of the salivary glands of adults, where polytene chromosomes are located. 

Figure 1: A giant polytene chromosome in Drosophila

In these glands, inversion polymorphisms can be recognized by loops in polytene chromosomes, that reflect a chromosome pair consisting of a large inverted and a non-inverted chromosome. More recently, molecular techniques can be employed to score known inversion points, either through specific markers that span the breakpoint region or SNP’s in disequilibrium with the inversions. 

AN EXAMPLE: the white throated sparrow
A fascinating example of such an inversion polymorphism can be found in a North American songbird, the white throated sparrow. In this bird, a chromosomal inversion leads to two distinct color polymorphisms; some individuals have black and white head stripes and others have brown and tan head stripes. 

Figure 2: The white throated sparrow color morphs: black and white and brown and tan

This color variation corresponds perfectly to one of two alternative life history strategies. The black and white males sing often and are more aggressive than the plain males and are overall neither devoted mates nor caring fathers. Females are affected in a very similar way, with black and white striped females being more aggressive and polyandrous and less caring as mothers. Chromosomal staining methods revealed that white throated sparrows have a very large mirror-image end-to-end chromosomal rearrangement: roughly 1000 genes on chromosome number 2 have flipped around. In black and white birds, one copy of chromosome 2 is partly inverted, while both copies in brown and tan birds are uninverted. 

Figure 3: Example of paracentric and pericentric chromosomal inversions

The polymorphism is maintained by almost perfect negative assortative mating – each morph mates with its opposite. Dimorphic pairs have an advantageous balance between parental care and aggressive territorial defense. In fact, 95% of pairs are mixed-morphs. Negative assortment assures similar reproductive success, and populations consist of approximately half heterozygotes, which are black and white, and half homozygous recessives. This  structure is the predicted equilibrium if one homozygote is more fit than another. The double inversion ‘‘white–white’’ is nearly lethal. 
To read more about this go here

NEXT WEEK'S lab meeting: November 9th, 2011, 13:00

In next week’s lab meeting we will discuss two papers. The first is a review paper by Hoffmann and Rieseberg (2008) entitled ‘Revisiting the Impact of Inversions in Evolution: From Population Genetic Markers to Drivers of Adaptive Shifts and Speciation?’ The second paper is a by Gilburn and Day (1994) on seaweed flies, which I will be working on in New Zealand with Gregory Holwell from the University of Auckland. The seaweed fly article will use a population study to investigate the effect of stable and unstable environmental conditions on the Fisherian process and viability indicator mechanisms. The paper is entitled ‘Evolution of Female Choice in Seaweed Flies: Fisherian and Good Genes Mechanisms Operate in Different Populations‘ 

Any Fika volunteers?