Thursday, October 2, 2014

Sex differences in human disease genetics

Trends in Genetics' lovely image accompanying our paper.

Posted by Jessica Abbott

Just wanted to write a short post highlighting my new paper with Will Gilks and Ted Morrow. It's a review of the evidence for sex-specific genetic effects on disease risk in humans. However we also discuss the evolutionary origins of such sex-specific differences in genetic architecture, which we suggest is a result of the resolution of sexually antagonistic selection pressures.

I'm very happy to see this paper published, for a couple of reasons. For one thing, this review is something that Ted and I talked about for a long time, so it's great to see how it's taken shape. Will's expertise in human genetics and GWAS contributed a lot to the final product. For another, it seems to have been very timely, since the NIH in the United States just announced over 10 million USD in new funding to include sex and gender differences in ongoing clinical research. Publishing in a "proper" genetics journal such as Trends in Genetics also raises my profile an evolutionary geneticist, I think.

Check it out!

Gilks, W. P., Abbott, J. K., & Morrow, E. H. (2014) Sex differences in disease genetics: evidence, evolution and detection. Trends in Genetics, 30(10):453-463.

Abstract: Understanding the genetic architecture of disease is an enormous challenge, and should be guided by evolutionary principles. Recent studies in evolutionary genetics show that sexual selection can have a profound influence on the genetic architecture of complex traits. Here, we summarise data from heritability studies and genome-wide association studies (GWASs) showing that common genetic variation influences many diseases and medically relevant traits in a sex-dependent manner. In addition, we discuss how the discovery of sex-dependent effects in population samples is improved by joint interaction analysis (rather than separate-sex), as well as by recently developed software. Finally, we argue that although genetic variation that has sex-dependent effects on disease risk could be maintained by mutation–selection balance and genetic drift, recent evidence indicates that intra-locus sexual conflict could be a powerful influence on complex trait architecture, and maintain sex-dependent disease risk alleles in a population because they are beneficial to the opposite sex.

Wednesday, October 1, 2014

Talk by Katie Duryea about sexual selection in Anolis-lizards

Posted by Erik Svensson

This Tuesday (October 7 2014, note changed time!) we will listen to our new postdoc Katie Duryea, who will give an informal 1-hour summary of her PhD-thesis research on Anolis-lizards, which was performed at Dartmouth College in the laboratory of Ryan Calsbeek. Feel free to also invite some other folks outside our core lab-group, as Jessica and Tobias are away this Tuesday. Also, note that we will start at 09.00, rather than at 10.30, as we use to.  Here is the title:

"Sexual selection and sexual conflict in Anolis lizards: from molecules to populations."

And here is a short description by Katie about the content of her talk:  
"I will cover the  effects of male mating order on sperm precedence, the transcriptomics and molecular evolution of genes expressed during mating in female anoles, and a population study of sexual antagonism on male and female body size in anoles."

When: Tuesday October 7 at 09.00!!!
Where: "Argumentet", 2nd floor, Ecology Building 


Thursday, September 25, 2014

A second try to go the Himalayas

 Posted by Erik Svensson

Since we did not have time to discuss the paper on avian species diversity in eastern Himalaya last week, due to the fact that we enjoyed so much listening to Jessica's talk and drinking cava, we make a new try this coming week. Here is the paper by Trevor Price and his colleagues in Nature.

 For a short summary of the findings in the paper I also recomment this a brief comment about the study by Arne Mooers, in a "News & Views"-article in the same issue of Nature, which is also worth reading.

The picture above shows the national bird of Nepal, the charismatic Himalayan Monal, a pheasant that I was lucky to see myself during my bird watching tour to Nepal in 1991, along the slopes of the Anapurna Trekk. The paper interests me for personal reasons, as already as a young bird watcher in 1991, I wondered about the amazing species diversity and how it came about, before I was very knowledgeable in ecology and evolutionary theory.

Date and time: Tuesday September 30, 10.30
Where: "Argumentet", second floor (Ecology Building)

I will bring fika!

Friday, September 19, 2014

Lab-meeting on ERC-interview, PNAS-accept, niche-filling, supply and demand and avian species richness in the Himalayas

Morphological evolution.

Next week, we will listen to Jessica Abbott, giving her "practice talk" before her interview in Brussels (Belgium) for an ERC Junior Grant, which we certainly hope she will get this time (it is the second year in a row that Jessica has been shortlisted for this prestiguous grant). We should all try to give good feedback to Jessica so that her chances to get this grant are maximized!

We will also celebrate that Jessica, I, our two former postdocs Natsu and Yuma and Jostein Kjaerandsen got an accept on our paper on sexual selection on Wing Interference Patterns (WIP:s) in Drosophila melanogaster in Proc. Natl. Acad. Sci. USA. Jessica has promised to bring some nice "fika", and I will bring some "bubble" to celebrate this.

Finally, Jessica asked me to pick a short paper to discuss as well, and I have chosen a relatively recent paper on adaptive radiation, speciation and niche filling in the Himalayan bird fauna. I do this partly for personal reasons, as this is a fascinating and extremely species-rich region of the world where I travelled as a young student and avid bird watcher in 1991, just before the start of my PhD in 1992. I hope you will enjoy this beatiful paper (Abstract is provided below). You might also want to read the "News and Views" comment on this paper by Arne Mooers, which summarizes the main findings.

Date and time: Tuesday, September 23, 10.30
Where: "Argumentet", 2nd floor, Ecology Building. 
Trevor D. Price et al.

Niche filling slows the diversification of Himalayan songbirds

Nature 509, 222–225doi:10.1038/nature13272

Speciation generally involves a three-step process—range expansion, range fragmentation and the development of reproductive isolation between spatially separated populations1, 2. Speciation relies on cycling through these three steps and each may limit the rate at which new species form1, 3. We estimate phylogenetic relationships among all Himalayan songbirds to ask whether the development of reproductive isolation and ecological competition, both factors that limit range expansions4, set an ultimate limit on speciation. Based on a phylogeny for all 358 species distributed along the eastern elevational gradient, here we show that body size and shape differences evolved early in the radiation, with the elevational band occupied by a species evolving later. These results are consistent with competition for niche space limiting species accumulation5. Even the elevation dimension seems to be approaching ecological saturation, because the closest relatives both inside the assemblage and elsewhere in the Himalayas are on average separated by more than five million years, which is longer than it generally takes for reproductive isolation to be completed2, 3, 6; also, elevational distributions are well explained by resource availability, notably the abundance of arthropods, and not by differences in diversification rates in different elevational zones. Our results imply that speciation rate is ultimately set by niche filling (that is, ecological competition for resources), rather than by the rate of acquisition of reproductive isolation.

Thursday, September 11, 2014

How new colors evolve

Lately, we've been looking at macroevolutionary patterns and asking about the origin(s) and loss(es) of interesting traits. We've had exciting discussions about the lability of these traits and the problem of identifying cause and effect. So maybe it's a good time to look in more detail at one such trait and ask how does novelty arise? This is a bit old, but attempts to offer a compelling mechanism for the evolution of new pigments in Heliconius butterflies. What do you think?

Positive selection of a duplicated UV-sensitive visual pigment coincides with wing pigment evolution in Heliconius butterflies

Authors: Adriana D. Briscoe, Seth M Bybee, Gary D. Bernard, Furong Yuan, Marilou P. Sison-Mangus, Robert D. Reed, Andrew D. Warren, Jorge Llorente-Bousquets, and Chuan-Chin Chiao

Time: Tuesday September 16th at 10:30 in Argumentet

Abstract:The butterfly Heliconius erato can see from the UV to the red part of the light spectrum with color vision proven from 440 to 640 nm. Its eye is known to contain three visual pigments, rhodopsins, produced by an 11-cis-3-hydroxyretinal chromophore together with long wavelength (LWRh), blue (BRh) and UV (UVRh1) opsins. We now find that H. erato has a second UV opsin mRNA (UVRh2)—a previously undescribed duplication of this gene among Lepidoptera. To investigate its evolutionary origin, we screened eye cDNAs from 14 butterfly species in the subfamily Heliconiinae and found both copies only among Heliconius. Phylogeny-based tests of selection indicate positive selection of UVRh2 following duplication, and some of the positively selected sites correspond to vertebrate visual pigment spectral tuning residues. Epi-microspectrophotometry reveals two UV-absorbing rhodopsins in the H. erato eye with λmax = 355 nm and 398 nm. Along with the additional UV opsin, Heliconius have also evolved 3-hydroxy-DL-kynurenine (3-OHK)-based yellow wing pigments not found in close relatives. Visual models of how butterflies perceive wing color variation indicate this has resulted in an expansion of the number of distinguishable yellow colors on Heliconius wings. Functional diversification of the UV-sensitive visual pigments may help explain why the yellow wing pigments of Heliconius are so colorful in the UV range compared to the yellow pigments of close relatives lacking the UV opsin duplicate.

Friday, September 5, 2014

Parent-offspring conflict, placentas, fish!

Continuing the trend from last week of a phylogenetic comparative study published in Nature with a colorful tree graph and a little picture of an animal next to it, I suggest That we read:


The evolution of the placenta from a non-placental ancestor causes a shift of maternal investment from pre -to post-fertilization, creating a venue for parent-offspring conflicts during pregnancy 1 , 2 , 3 , 4 . Theory predicts That The Rise Of These conflicts Should drive a shift from a reliance on pre-copulatory female mate choice to polyandry in Conjunction with post-zygotic mechanisms of sexual selection 2 . This hypothesis has not yet been empirically tested. Here we apply comparative methods to test a key prediction of this hypothesis, Which Is that the evolution of placentation is Associated with Reduced pre-copulatory female mate choice. We exploit a unique quality of the fish family Poeciliidae livebearing: placentas have repeatedly evolved or been lost, creating Diversity Among pray be closely related lineages in the Presence or Absence of placentation 5 , 6 . We Show That post-zygotic maternal provisioning by means of a placenta is Associated with the Absence of bright coloration, courtship behavior and exaggerated ornamental display traits in males. Further More, we found That background of placental species have smaller bodies and longer genitalia, Which Facilitate sneak or coercive mating and, hence, circumvents female choice. Moreover, We demonstrate That post-zygotic maternal provisioning correlates with superfetation, a female reproductive adaptation That May resulted in polyandry through the formation of temporally overlapping, mixed-paternity litters. Our results suggest That The Emergence of prenatal Conflict During The evolution of the placenta correlates with a suite of phenotypic and behavioral male traits That is Associated with a Reduced reliance on pre-copulatory female mate choice.


Sunday, August 31, 2014

EXEB shrinks - but shows overcompensatory growth: introducing new members

Posted by Erik Svensson

EXEB is our own and dynamic research environment, and as such there is (and indeed should be!) a high turnover of new and old members, and a healthy balance between inflow (newcomers) and outflow (migrants). Recently, three co-workers have left us to take up new positions.

Our most recent outgoing migrants from EXEB include Tom Gosden, who has now moved back to Australia to start a DECRA Junior Research Position, Machteld Verzijden who has moved to Aarhus University for a new postdoc and Maren Wellenreuther, who has moved to New Zeeland to commence a position as Senior Scientist at the Plant & Food Research Institute (though Maren will be affiliated to Lund part-time for the coming couple of years). We thank Tom, Machteld and Maren for their time in Lund and wish them good luck in their new positions.

Here, we also welcome some new EXEB members, which are briefly introduced below. First, we are happy to welcome Tobias Uller, who is in the process of establishing himself in Lund as a faculty member at the Biology Department, after obtaining a prestiguous fellowship from The Wallenberg Foundation. This large grant enables him to build a research group in Lund. Tobias has research interests and competence that is largely complementary to already existing expertise within EXEB, and we are looking forward to integrate both him and his forthcoming PhD-students and postdocs to our research environment. His main interests is the role of developmental plasticity in evolution, and he will work with both invertebrates (Daphnia) and reptiles (lizards) to study these important questions.

Tobias Uller

We also welcome our new PhD-student Beatriz Willink, who is from Costa Rica and who has a research background as a herpetologist, with special interests in colour polymorphisms and sexual selection. Beatriz will work under my supervision and will focus on the macroevolutionary consequences of sexual selection and colour evolution in Coenagrionidae ("pond damselflies"), using a combination of field experiments, observations and comparative approaches. She obtained a scholarship from The World Bank to do her PhD in Lund and she has already integrated quite well in to the EXEB environment, as she has been here for one field season and several months.  

Beatriz Willink

Next, we welcome Viktor Nilsson-Örtman as a new incoming postdoc. Viktor recently obtained a postdoctoral research grant from The Swedish Research Council (VR). He will spend the first part of this three-year grant at the University of Toronto in the laboratory of Locke Rowe, before he joins Lund and EXEB. Viktor has a strong background in ecological developmental biology, working with latitudinal variation in larval growth rates of damselflies of the genus Enallagma. Viktors expertise on the larval aquatic life-stage will largely complement our ongoing research on adult odonates, and we are looking forward to bring him in to the EXEB environment. 

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                                                                      Viktor Nilsson-Örtman

Another postdoc who will join us now in late September 2014 is Katie Duryea from Dartmouth College (New Hampshire, USA), who did her PhD in the lab of Ryan Calsbeek, and who has a background as a herpetologist and Anolis-lizard biologist. Katie recently obtained a prestiguous outgoing postdoctoral fellowship from the National Science Foundation (NSF), which enables her to spend two years in Sweden and to join EXEB. Katie is interested in postcopulatory sexual selection and sperm competition, and she has a strong bioinformatic and molecular biology background, having worked also in the laboratories of Hopi Hoekstra at Harvard University and with Kelly Zammudio at Cornell University, prior to entering the PhD-programme at Dartmouth. During her postdoc in Lund, Katie will work on postcopulatory sexual selection in the polymorphic damselfly Ischnura elegans, taking advantage of soon available transcriptomic and genomic resources for this species, as well as our large outdoor cages at Stensoffa Field Station. 

Katie Duryea

Finally, we also welcome Rosa Sanchéz, who originally did her PhD at University of Vigo (Spain), and who is currently on her second postdoc in Barcelona, where she currently studies mechanisms of postzygotic isolation in mammals. However, Rosa has a solid background as an odonatologist, having worked in the laboratory of Adolfo Cordero during her PhD. Rosa will study the genomic signature of  hybridiziation between Ischnura elegans and its sister species I. graellsii in Spain. Last year, she obtained a Marie Curie Postdoctoral Fellowship from the EU, which enables her to come to Lund and join EXEB in spring 2015. 

´Rosa Sánchez

 Rosa Sanchéz