Lab meeting on non-adaptive plasticity and evolution of gene expression

For next week's lab meeting, let's discuss this recent Nature paper on plasticity and adaptive gene expression - topics that are of interest to many of us.

When: Sept 15, 10:00
Where: Argumentet
What: Paper discussion and Fika

Non-adaptive plasticity potentiates rapid adaptive evolution of gene expression in nature

• Cameron K. Ghalambor,
• Kim L. Hoke,
• Emily W. Ruell,
• Eva K. Fischer,
• David N. Reznick
• & Kimberly A. Hughes

Phenotypic plasticity is the capacity for an individual genotype to produce different phenotypes in response to environmental variation¹. Most traits are plastic, but the degree to which plasticity is adaptive or non-adaptive depends on whether environmentally induced phenotypes are closer or further away from the local optimum^2, 3, 4. Existing theories make conflicting predictions about whether plasticity constrains or facilitates adaptive evolution^{4, 5, 6, 7, 8, 9, 10, 11, 12}. Debate persists because few empirical studies have tested the relationship between initial plasticity and subsequent adaptive evolution in natural populations. Here we show that the direction of plasticity in gene expression is generally opposite to the direction of adaptive evolution. We experimentally transplanted Trinidadian guppies (Poecilia reticulata) adapted to living with cichlid predators to cichlid-free streams, and tested for evolutionary divergence in brain gene expression patterns after three to four generations. We find 135 transcripts that evolved parallel changes in expression within the replicated introduction populations. These changes are in the same direction exhibited in a native cichlid-free population, suggesting rapid adaptive evolution. We find 89% of these transcripts exhibited non-adaptive plastic changes in expression when the source population was reared in the absence of predators, as they are in the opposite direction to the evolved changes. By contrast, the remaining transcripts exhibiting adaptive plasticity show reduced population divergence. Furthermore, the most plastic transcripts in the source population evolved reduced plasticity in the introduction populations, suggesting strong selection against non-adaptive plasticity. These results support models predicting that adaptive plasticity constrains evolution^6, 7, 8, whereas non-adaptive plasticity potentiates evolution by increasing the strength of directional selection^11, 12. The role of non-adaptive plasticity in evolution has received relatively little attention; however, our results suggest that it may be an important mechanism that predicts evolutionary responses to new environments.

Dominance versus additivity

Posted by Jessica Abbott

X-chromosome-rated comic: The Dominant Gene, by Rather Humerus. From http://ratherhumerus.com/post/89836971148/tumblr-facebook-ratherhumerus

Sorry for being a bit late in choosing an article for next week's meeting. Don't worry, though, it's very short.

An important enterprise in genetics today is in trying to tie together molecular data with quantitative genetics. This paper uses theory to try to explain why a gene that behaves as dominant on the molecular level can still show up as part of the additive genetic variance for a trait, when investigated with quant gen.

Title: Heritability of heterozygosity offers a new way of understanding why dominant gene action contributes to additive genetic variance

Abstract: Whenever allele frequencies are unequal, nonadditive gene action contributes to additive genetic variance and therefore the resemblance between parents and offspring. The reason for this has not been easy to understand. Here, we present a new single-locus decomposition of additive genetic variance that may give greater intuition about this important result. We show that the contribution of dominant gene action to parent–offspring resemblance only depends on the degree to which the heterozygosity of parents and offspring covary. Thus, dominant gene action only contributes to additive genetic variance when heterozygosity is heritable. Under most circumstances this is the case because individuals with rare alleles are more likely to be heterozygous, and because they pass rare alleles to their offspring they also tend to have heterozygous offspring. When segregating alleles are at equal frequency there are no rare alleles, the heterozygosities of parents and offspring are uncorrelated and dominant gene action does not contribute to additive genetic variance.

Persistent directional selection on body size and a resolution to the paradox of stasis

Next week's lab meeting:

September 1st 2015, I am organizing the lab meeting at 10.00 in Argumentet.

Fika will be provided as usual. All are welcome!

Persistent directional selection on body size and a resolution to the paradox of stasis

Njal Rollinson & Locke Rowe

ABSTRACTDirectional selection on size is common but often fails to result in micro-evolution in thewild. Similarly, macro-evolutionary rates in size are low relative to the observed strength ofselection in nature. We show that many estimates of selection on size have been measured onjuveniles, not adults. Further, parents influence juvenile size by adjusting investment peroffspring. In light of these observations, we help resolve this paradox by suggesting that theobserved upward selection on size is balanced by selection against investment per offspring,resulting in little or no net selection gradient. We find that trade-offs between fecundity andjuvenile size are common, consistent with the notion of selection against investment peroffspring. We also find that median directional selection on size is positive for juveniles butno net directional selection exists for adult size. This is expected because parent-offspringconflict exists over size, and juvenile size is more strongly affected by investment peroffspring than adult size. These findings provide qualitative support for the hypothesis thatupward selection on size is balanced by selection against investment per offspring, whereparent-offspring conflict over size is embodied in the opposing signs of the two selectiongradients.

link

link

An exciting semester with interesting lab-meetings with EXEB

 Posted by Erik Svensson

As you know, Tobias Uller's group is growing fast, as he has recruited several new postdocs through his grant from The Wallenberg Foundation. Apart from being good for Tobias research, it also benefits the rest of us, as we can now look forward to several interesting lab-meetings this fall, where the new EXEB members will give talks and present results from their previous research.

Apart from these talks by new members, we will of course also keep to our traditional format of discussing scientific articles or - when preferred - giving inputs on talks, grant applications and manuscripts. The content of each lab-meeting will as usual be decided by the person responsible that data, who usually also brings "fika", introduces the paper(-s) to be discussed and so on.

The person responsible each Tuesday is also expected to announce the lab-meeting the week before (ideally on Thursday or Friday) by a short blog post, with relevant links to paper(-s) if it will be discussion about a paper. Otherwise, just a few words about the content of the forthcoming talk/activitiy.

Below is the schedule for the autumn, with name indicated at each date. Note that we from now on aim to start on Tuesdays at 10.00 - rather than 10.30 - and rather finish a bit earlier. Note also that we have some vacant slots (mainly in November), in case somebody would like to take care of more than one lab-meeting or invite somebody from the outside.

I have also taken the liberty to indicate whether the person responsible is expected to give a research talk, and in other cases I have just left it open for decision. Note that the first meeting talk will be this Tuesday (August 25) by Nathalie Feiner (see her recent blog post).

Autumn schedule (Tuesdays at 10.00 in "Argumentet")  

Tuesday August 25: Nathalie Feiner (talk):  "Anolis lizards, Hox clusters and transposable elements"

Tuesday, September 1: John Waller

Tuesday, September 8: Jessica Abbott


Tuesday, September 15: Katie Duryea


Tuesday, September 22: Anna Nordén


Tuesday, September 29: Beatriz Willink


Tuesday, October 6: Hanna Laakkonen (talk)

Tuesday, October 13: Erik Svensson


Tuesday, October 20: Reinder Radersma


Tuesday, October 27: Antonio Cordero (talk)


Tuesday, November 3: Tobias Uller


Tuesday, November 10: Weizhao Yang (talk)


Tuesday, November 17: VACANT


Tuesday, November 24: VACANT


Tuesday December 1: VACANT


Tuesday, December 8: Adam Hasik (talk)


Tuesday, December 15: VACANT

Lab-meeting by Nathalie Feiner on "evo-devo" and HOX-genes in Anolis lizards: September 25 (10.00)

Hej!

I have already been around since a few weeks now and it's time to introduce myself! I'm the latest (and last, for now) addition to the Uller group, namely a postdoc working on Anolis lizards.
My background is in comparative genomics, and I did a fair bit of developmental genetics in a variety of vertebrate animals. After my PhD, I turned my interest towards organismal biology, and I am now interested in understanding how evolution really works. I designed a project on the Anolis lizards, a famous example of an adaptive radiation, which aims to include ecological, developmental and phylogenetic aspects in order to fully comprehend their evolutionary history. In particular, I am interested in the relationship between developmental processes and the course of evolution – how can ontogenetic factors bias evolution and how strong is this influence? I would like to take the opportunity of next Tuesday's EXEB meeting and present my past work on Anolis lizards, Hox clusters and transposable elements (and what the hell they have to do with each other!).

Including Fika, of course!

Time: Tuesday, August 25, 10.00 (note changed time!) 
Place: "Argumentet", 2nd floor, Ecology Building

First lab-meeting for autumn 2015: ESEB summary and group selection

Posted by Erik Svensson 

It is time to kick off the EXEB labmeetings for this coming semester, and what would be better than do it this coming Tuesday (August 18)? Especially when several of us have been to the ESEB Congress and we can have a nice brief discussion about our impressions of where the field of evolutionary biology might be going.

In the same general spirit, I suggest we discuss a paper in Nature from last year on the prospects for group selection in a socially polymorphic spider system. This work has been performed by Jonathan Pruitt and Charles Goodnight, the latter being a long-term champion of group selection. 

As group selection has historically been a very controversial topic in evolutionary biology, I hope we will have a stimulating discussion about this paper. See also the "News & Views"-article in the same issue of Nature, which can be found here. 

Note different meeting time!

When: Tuesday August 18 at 10.00

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

Site-specific group selection drives locally adapted group compositions

Pruitt, JN (Pruitt, Jonathan N.)^{[ 1 ]} ; Goodnight, CJ (Goodnight, Charles J.)^{[ 2 ]}

NATURE 514: 359+ (2014)

 

Abstract

Group selection may be defined as selection caused by the differential extinction or proliferation of groups(1,2). The socially polymorphic spider Anelosimus studiosus exhibits a behavioural polymorphism in which females exhibit either a 'docile' or 'aggressive' behavioural phenotype(3,4). Natural colonies are composed of a mixture of related docile and aggressive individuals, and populations differ in colonies' characteristic docile: aggressive ratios(5,6). Using experimentally constructed colonies of known composition, here we demonstrate that population-level divergence in docile: aggressive ratios is driven by site-specific selection at the group level-certain ratios yield high survivorship at some sites but not others. Our data also indicate that colonies responded to the risk of extinction: perturbed colonies tended to adjust their composition over two generations to match the ratio characteristic of their native site, thus promoting their long-term survival in their natal habitat. However, colonies of displaced individuals continued to shift their compositions towards mixtures that would have promoted their survival had they remained at their home sites, regardless of their contemporary environment. Thus, the regulatory mechanisms that colonies use to adjust their composition appear to be locally adapted. Our data provide experimental evidence of group selection driving collective traits in wild populations.

Introducing new EXEB member: Antonio Cordero

Posted by Erik Svensson on behalf of Antonio Cordero

New postdoc: Antonio Cordero

I am a new postdoc in the research group of Tobias Uller. Broadly speaking, my work will aim to address important conceptual gaps concerning the role of developmental plasticity in ecology and evolution of reptilian systems. I recently completed my PhD at Iowa State University, USA, where I studied the developmental basis of phenotypic innovation and repeatability in turtles. My work integrated embryology, genetics, phylogenetics, and morphometrics. In Lund, I plan to continue using a multidisciplinary approach to address compelling questions in ecological and evolutionary developmental biology.