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: erik.svensson@biol.lu.se).

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

Abstract: 

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.

 

On sexual selection, non-ecological speciation and species coexistence

Next week's lab-meeting will focus on a topic that is closely connected to our coming ESF-funded workshop in August 2012 about non-ecological and non-adaptive speciation: The problem how weakly ecologically differentiated species might still coexist, in spite of being formed by sexual selection and when there are no or weak niche differences in between them. A recent paper in Nature presents a new model that aims to solve this problem (Abstract, link and authors posted below). You can download this paper here.

Time and place of lab-meeting as usual: "Argumentet" at 13.30, Wednesday May 16.

Sexual selection enables long-term coexistence despite ecological equivalence

• Leithen K. M’Gonigle,
• Rupert Mazzucco,
• Sarah P. Otto
• & Ulf Dieckmann

• Affiliations
• Contributions
• Corresponding author

Nature

 

484,

 

506–509

 

(26 April 2012)

 

doi:10.1038/nature10971

Received

 

09 August 2011 

Accepted

 

17 February 2012 

Published online

 

01 April 2012

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Empirical data indicate that sexual preferences are critical for maintaining species boundaries^{1, 2, 3, 4}, yet theoretical work has suggested that, on their own, they can have only a minimal role in maintaining biodiversity^{5, 6, 7, 8, 9}. This is because long-term coexistence within overlapping ranges is thought to be unlikely in the absence of ecological differentiation⁹. Here we challenge this widely held view by generalizing a standard model of sexual selection to include two ubiquitous features of populations with sexual selection: spatial variation in local carrying capacity, and mate-search costs in females. We show that, when these two features are combined, sexual preferences can single-handedly maintain coexistence, even when spatial variation in local carrying capacity is so slight that it might go unnoticed empirically. This theoretical study demonstrates that sexual selection alone can promote the long-term coexistence of ecologically equivalent species with overlapping ranges, and it thus provides a novel explanation for the maintenance of species diversity.

On speciation, the species problem and the role of species in evolution

This week's lab-meeting will be dedicated to the classical "species problem" in evolutionary biology and the role of species in ecology. We will start off with a brief presentation by Maren Wellenreuther about molecular identification of (putative) hybrid phenotypes between the two calopterygid damselflies (Calopteryx splendens and C. virgo) that she has been working on lately. I will also say a few words about my research trip to Texas, and the remarkable species diversity of odonates in this state (> 260 species in the state of Texas, about five times more than entire Sweden!).

Then, I was thinking we should discuss two recent idéa-articles, which should perhaps be a relatively easy read, and would hopefully be stimulating. One is on the state of the so-called "neutral theory" of species diversity in ecology, and the other is about species concepts and the ephemeral role of species in evolution. Phylogenetic comparative biologist Luke J. Harmon is co-author on both these papers, and one of the other authors is Rampall Etienne, who will be a plenary speaker at our ESF-funded meeting "The role of behaviour in non-adaptive and non-ecological speciation" in August this year. Here you can sign up to this meeting, which is free of charge and will take place on August 18 2012.

Our  lab-meeting  this coming week will take place on May 2, at 13.30 in the seminar room "Argumentet". Below, I provide the abstracts and links to these two interesting articles. You can download them here and here and also by clicking on the Abstract-links below. Enjoy!

The case for ecological neutral theory

• James Rosindell^1, 2, 3, , 
• Stephen P. Hubbell^4, 5, 
• Fangliang He^6, 7, 
• Luke J. Harmon^2, 8,
• Rampal S. Etienne⁹

• Ecological neutral theory has elicited strong opinions in recent years. Here, we review these opinions and strip away some unfortunate problems with semantics to reveal three major underlying questions. Only one of these relates to neutral theory and the importance of ecological drift, whereas the others involve the link between pattern and process, the tradeoff between simplicity and complexity in modeling, and the role of stochasticity and drift in ecology. We explain how neutral theory cannot be simultaneously used both as a null hypothesis and as an approximation. However, we also show how neutral theory always has a valuable use in one of these two roles, even though the real world is not neutral.

Trends Ecol. Evol. 27: 203-208.

Goldilocks Meets Santa Rosalia: An Ephemeral Speciation Model Explains Patterns of Diversification Across Time Scales

Erica Bree Rosenblum1, 2, 3  , Brice A. J. Sarver1, Joseph W. Brown1, Simone Des Roches1, Kayla M. Hardwick1, Tyler D. Hether1, Jonathan M. Eastman1, Matthew W. Pennell1 and Luke J. Harmon1, 3 

Understanding the rate at which new species form is a key question in studying the evolution of life on earth. Here we review our current understanding of speciation rates, focusing on studies based on the fossil record, phylogenies, and mathematical models. We find that speciation rates estimated from these different studies can be dramatically different: some studies find that new species form quickly and often, while others find that new species form much less frequently. We suggest that instead of being contradictory, differences in speciation rates across different scales can be reconciled by a common model. Under the “ephemeral speciation model”, speciation is very common and very rapid but the new species produced almost never persist. Evolutionary studies should therefore focus on not only the formation but also the persistence of new species.