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. 

Proposals for post-conference symposia after ISBE 2012

It will now be possible to send in proposals for so-called "Post-conference symposia" after the ISBE-meeting (August 12-17 2012) in Lund next year. Post-conference symposia are thematic, one-day long and are organized independently, the day after the regular ISBE-meeting, i. e. on August 18 2012. Already one such post-conference symposium has been decided to take place: our ESF-funded workshop on the role of behaviour in non-ecological and non-adaptive speciation, but there are certainly room for other topics.

It is now possible to send in a proposal here, and the deadline for such proposals will be sometime early next year (January or February 2012).

FroSpects-meeting on non-adaptive and non-ecological speciation in Lund August 18 2012

During the past decade, the ecological theory of adaptive radiation and adaptive speciation has been a main focus of interest in much speciation research. Much of current thinking in this area assumes that incipient species are formed as a direct or indirect result of niche-based ecological differences and divergent natural selection.

However, more recently it has been an increased interest also in non-ecological and non-adaptive speciation in groups like birds, fish, amphibians and insects. Some radiations are simply not very likely to result from divergent ecological selection, as species are often ecologically similar and show high degree of niche conservatism, yet speciation obviously happens also in these groups. Behavior might play a crucial role in driving speciation processes in these circumstances, including learned mate preferences, sexual selection and sexual conflict. These and related topics will be the focus of one-day scientific meeting at Lund University (Sweden) on August 18 2012.

On August 18 2012, we are therefore proud to organize this one-day meeting (free of charge) entitled "The Role of Behaviour in Non-adaptive and Non-ecological Speciation".

This meeting is funded by the European Science Foundation's (ESF) Frontier's of Speciation Research FroSpects, and will be one of several post-conference symposia the day after The International Behavioural Ecology Congress ("ISBE 2012") that will take place between August 12 and August 17 2012. 

Note that although the ESF-meeting is free of charge, the preceeding ISBE-congress is not. The meeting is open both for ISBE-participants and those who wish to only come for to the speciation meeting. Coffee and refreshments will be served on August 18, but participants will have to fund and organize travel, meals and ackomodation for themselves.

In addition to three excellent invited keynote speakers (Dr. Rampal S. Etienne, Prof. Kerry Shaw and Prof. John Wiens), we will also accept contributed talks (15 minutes, including 3 minutes of questions) to this meeting. Send an abstract (100-200 words) to Dr. Maren Wellenreuther (maren.wellenreuther@biol.lu.se), no later than April 2012.  More general questions about the meeting can be answered by Prof. Erik Svensson (erik.svensson@biol.lu.se).

Organizing committé:


Prof. Erik Svensson
Dr. Machteld Verzijden
Dr. Maren Wellenreuther
Ms. Anna Runemark