First lab-meeting this autumn: on the remarkable diversity and evolution of sex determination systems

Posted by Erik Svensson

After field work and summer break it is time to start up this autumn's lab-meetings again. And what could be more interesting than an article about the remarkable diversity and evolution of sex determination systems? A recently published essay in the journal PLoS Biology, summarizes the current knowledge and state-of-the-art of research in this area. It should hopefully be an interesting read. Below, I attach the Abstract and a link to the paper, which is Open Access and downloadable. The figure above give you a taster about the content. Enjoy!

When: Tuesday, August 12 2014, 10.30

Where: "Argumentet", 2nd floor, Ecology Building.


Sex Determination: Why So Many Ways of Doing It? 

Doris Bachtrog Judith E. Mank, Catherine L. Peichel, Mark Kirkpatrick, Sarah P. Otto, Tia-Lynn Ashman, Matthew W. Hahn, Jun Kitano,Itay Mayrose, Ray Ming, Nicolas Perrin, Laura Ross, Nicole Valenzuela, Jana C. Vamosi, The Tree of Sex Consortium 

Published: July 01, 2014DOI: 10.1371/journal.pbio.1001899 

Abstract

Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination.

Greetings from Austin (Texas)

Posted by Erik Svensson

After about two weeks in Texas, around its capital Austin, I am heading home to Sweden again, after a very nice visit to my colleagues at Section for Integrative Biology at University of Texas. This department is certainly one of the strongest in ecology, evolution and behaviour in the US, and I can strongly recommend a visit here. Interestingly, they do not have any bird research at all, but most empirical work is on fish on insects, and the department is particularly strong in animal behaviour, sexual selection, neurobiology and evolutionary population genetics. This is the second time I visit, and I gave a talk already in spring 2003, nine years ago. Remarkably, almost all who attended my talk then were here this time as well, including Mark Kirkpatrick, Mike Ryan and legendary lizard evolutionary ecologist Eric Pianka.

I also met with some new folks, which have arrived since 2003, including PhD student Eben Gehring who works in the lab of Molly Cummings, and who does research on Ischnura-damselflies and evolutionary ecology professor Dan Bolnick, with whom I share many research interests, including the evolution of assortative mating and its consequences. Tonight, I am going to dinner with Scott Edwards, who is also visiting from Harvard this same week as I am here, and who will be the opponent of PhD-student Anna Runemark in our lab on May 25 next month.

Apart from Monday, this week, when I gave my talk, I have spent most time in the field, looking for and researching on Texas odonates. You can see one particularly stunning species that I saw here. Texas is especially species-rich, as half of North America's species occur here, more than 250 species, and several tropical elements from Mexico and Central America. As a comparision, Sweden has about 55 species, less than a fifth of Texas (although it should be said that Texas is slightly bigger than Sweden - everything is bigger in Texas, actually!). It is good to keep in mind that biodiversity is quite low in Europe, mainly due to the effects of past ice ages, and perhaps our faunas have not yet even been saturated, as re-colonziation from the last Ice Age might still be ongoing?

On the antagonistic relationship between sexual selection and assortative mating

Posted by Erik Svensson


It is time for lab-meeting again, and this week we are happy to welcome Machteld Verzijden back from Rutgers University, where she has been working with Jessica Ware. Let's start the lab-meeting with her telling us about her work and the progress made during the visit.

Note the new time: Wednesday March 28 at 13.30 (not 13.00!).


After this, I was thinking we should discuss the relationship between sexual selection and assortative mating, two processes that are often confused and mixed up, particularly in the field of sympatric speciation. Although these processes are by no means totally independent, they are not identical and their population genetic consequences are very different. Moreover, they can counteract each other and hence could be antagonistic.

To understand the finer details of the complex relationship between assortative mating and sexual selection, we'll have to leave the murky shallow waters of "Adaptive Dynamics" and instead to turn to a clear thinker and a population genetic theoretician who knows what he is talking about: Mark Kirkpatrick från Austin (Texas). I was thinking we should read a much-cited papers from Proceedings of the Royal Society, entitled "Sexual selection can constrain sympatric speciation". Below, you will find the Abstract and here is a downloadable link to the PDF:


Sexual selection can constrain sympatric speciation

1. Mark Kirkpatrick^* and 
2. Scott L. Nuismer†

Source: PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES  Volume: 271   Issue: 1540   Pages: 687-693   DOI:10.1098/rspb.2003.2645   Published: APR 7 2004

Abstract

Recent theory has suggested that sympatric speciation can occur quite easily when individuals that are ecologically similar mate assortatively. Although many of these models have assumed that individuals have equal mating success, in nature rare phenotypes may often suffer decreased mating success. Consequently, assortative mating may often generate stabilizing sexual selection. We show that this effect can substantially impede sympatric speciation. Our results emphasize the need for data on the strength of the stabilizing component of selection generated by mating in natural populations.

On "Evolutionary rescue", climate change and evolution of range limits

This week the lab-meeting will focus on  "Evolutionary rescue", which was a topic of a recent scientific conference involving several leading evolutionary biologists and ecologists in France, including leading population geneticist Mark Kirkpatrick who gave a talk entitled: "The evolution of a species’ range by beneficial mutations". 

The organisers of this interesting conference has been kind enough to put up videos on the internet of Mark's talk, which you can find here, as well as two other interesting talks by contributors. This is an excellent way of making it possible for others, like us, who could not take part in this meeting, and also a very environmentally-friendly way of spreading scientific information without necessarily travelling to every meeting you wish to attend.

I suggest that we meet the usual time (13.30 on Wednesday April 15 in "Argumentet") to listen to Mark's talk, and (if we have time), to one or two of the other talks. Thus, there is no need to read any paper before this lab-meeting, just come sharp and alert and be willing to discuss! Hopefully, we can arrange with Machteld's computer to be linked to the Powerpoint-projector so we can see the talk on a large screen.