Friday, October 28, 2016

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

Lab meeting paper for Tuesday November 1st 2016 at 10.00. 


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.

Wednesday, October 19, 2016

On adaptive radiations and convergence

Next week I'd like to discuss a paper on the evolution of brain morphology in Neotropical monkeys. Have brains evolved towards shifting adaptive peaks? What ecological factors explain variation among present-day species? We'll see on Tuesday.

Brain shape convergence in the adaptive radiation of New World monkeys

Abstract: Primates constitute one of the most diverse mammalian clades, and a notable feature of their diversification is the evolution of brain morphology. However, the evolutionary processes and ecological factors behind these changes are largely unknown. In this work, we investigate brain shape diversification of New World monkeys during their adaptive radiation in relation to different ecological dimensions. Our results reveal that brain diversification in this clade can be explained by invoking a model of adaptive peak shifts to unique and shared optima, defined by a multidimensional ecological niche hypothesis. Particularly, we show that the evolution of convergent brain phenotypes may be related to ecological factors associated with group size (e.g., social complexity). Together, our results highlight the complexity of brain evolution and the ecological significance of brain shape changes during the evolutionary diversification of a primate clade.


Image result for tamarin monkey

Place & time : Argumentet 10:00 am

Fika as usual


Thursday, October 13, 2016

The role of peer review in today's science

It’s fun to discuss scientific papers, but it’s also interesting to think about how the scientific publication works. Peer review remains one of the most important steps ensuring the quality of science since it’s inception in the mid 1600s. The scientific landscape today however, is vastly different, as the number of both scientists and scientific articles are quickly expanding.  Is the peer review process lagging behind? What can be improved? We’re looking forward to hear your opinions. Fika will of course be provided.

-Alexander and Qinyang

Abstract:  Peer review is pivotal to science and academia, as it represents a widely accepted strategy for ensuring quality control in scientific research. Yet, the peer-review system is poorly adapted to recent changes in the discipline and current societal needs. We provide historical context for the cultural lag that governs peer review that has eventually led to the system’s current structural weaknesses (voluntary review, unstandardized review criteria, decentralized process). We argue that some current attempts to upgrade or otherwise modify the peer-review system are merely sticking-plaster solutions to these fundamental flaws, and therefore are unlikely to resolve them in the long term. We claim that for peer review to be relevant, effective, and contemporary with today’s publishing demands across scientific disciplines, its main components need to be redesigned. We propose directional changes that are likely to improve the quality, rigour, and timeliness of peer review, and thereby ensure that this critical process serves the community it was created for. 

Thursday, October 6, 2016

Visit by Ayana Martins from Brazil and talk about neutrality theory and speciation

Posted by Erik Svensson

As some of you know, I have developed an interest in non-ecological speciation mechanisms over the years, that is how reproductively isolation develops and are maintained between species that are only weakly ecologically niche differentiated (see our publications here and here). More recently I have also become more interested in the ecological side, manifested by the neutral theory of biodiversity and its implications, such as the role of ecological drift. 

Given these interests of mine, I am therefore happy to welcome Dr. Ayana Martins to the EXEB-meeting next week (Tuesday October 11, at 10.00), where she will give an informal talk about her theoretical research in this area. Ayana is thus primarily a theoretical evolutionary biologist, but she is also interested in empirical research in this field. Ayana will visit the department and my group next week to discuss some future collaborations,  and she will stay in Lund until early Thursday morning. Among her previous research, is an interesting paper about "ring species" in evolution.

We plan to go out for beers and something to eat on Tuesday evening (e. g. the new hamburger place "Tugg", see here!), and all EXEB-members who are interested in joining us or would like to talk to Ayana could contact me (email:

More info below, and of course "fika" will be provided. Welcome!

Is there a role for neutrality in speciation?

About Ayana: 
I have a bachelor degree in Biology (2006, University of Campinas, Brazil), a master degree in Genetics and Molecular Biology (2010) from the same institution and a doctor degree in Ecology (2014) from the University of São Paulo (Brazil). Currently, I am a post doctoral research fellow in the Institute of Physics Gleb Wataghin (University of Campinas). Since early May, I have been visiting the Swiss Federal Institute  of Aquatic Science and Technology (Eawag) in Switzerland to carry out part of my current research project. I work with  speciation models mostly addressing the roles of spatial structuring,  population expansion, genetic incompatibilities and non-random mate choice. More recently I have become interested in developing methods to test hypothesis with these models with empirical data


Neutral theories have had an important role in ecology and evolution not only  by providing novel ideas but also by serving as null models that allow hypothesis to be tested. In this context, the neutral theory of molecular evolution and the unified neutral theory of biodiversity are particularly relevant for understanding speciation since they provide predictions that can be tested at different levels of organization. While these two theories encompass processes that are conceptually related (e.g. genetic drift vs. ecological drift), much progress is needed before these two frameworks are formally integrated. In this talk, I will discuss the conditions for speciation under the assumption of ecological equivalence. I will focus on i) the interplay between spatial isolation and the number of loci resulting in genetic incompatibilities, and ii) how selection resulting from non-random mating schemes is related to neutrality on the level of individuals.