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.

 

First EXEB-meeting in 2016: on speciation, ecological opportunity and latitude

                                



















Crab spider (Misumenia vatia) with prey. Photo: Erik Svensson

Posted by Erik Svensson 

"Evolution in Sweden 2016" is now over, and in my opinion it was a great success. You can see photos from this meeting here, and we can also briefly summarize our general reflections about this meeting on the first EXEB-meeting, which I post information about below. 

On this first EXEB-meeting of 2016, I want to discuss a recent paper published as a "Presidential Adress" in American Naturalist by Dolph Schluter, entitled "Speciation, ecological opportunity and latitude". 

I saw Dolph give a talk about this last year at a speciation-meeting in California, and I think that he is a very thoughtful scientist who has stimulated my thinking and influenced many other ecologists and evolutionary biologists. Hopefully, we will have a good discussion about this paper. But as usual, we will start the meeting with some general reflections, summary of impressions of "Evolution in Sweden 2016" and we can also hear a bit from Tobias and Nathalie's trip to Australia, as well as mine, Katie's and John's trip to Argentina. I might even bring some pictures to show. 

Time: Tuesday, January 19, at 10.00

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

Abstract: Evolutionary hypotheses to explain the greater numbers of species in the tropics than the temperate zone include greater age and area, higher temperature and metabolic rates, and greater ecological opportunity. These ideas make contrasting predictions about the relationship between speciation processes and latitude, which I elaborate and evaluate. Available data suggest that per capita speciation rates are currently highest in the temperate zone and that diversification rates (speciation minus extinction) are similar between latitudes. In contrast, clades whose oldest analyzed dates precede the Eocene thermal maximum, when the extent of the tropics was much greater than today, tend to show highest speciation and diversification rates in the tropics. These findings are consistent with age and area, which is alone among hypotheses in predicting a time trend. Higher recent speciation rates in the temperate zone than the tropics suggest an additional response to high ecological opportunity associated with low species diversity. These broad patterns are compelling but provide limited insights into underlying mechanisms, arguing that studies of speciation processes along the latitudinal gradient will be vital. Using threespine stickleback in depauperate northern lakes as an example, I show how high ecological opportunity can lead to rapid speciation. The results support a role for ecological opportunity in speciation, but its importance in the evolution of the latitudinal gradient remains uncertain. I conclude that per capita evolutionary rates are no longer higher in the tropics than the temperate zone. Nevertheless, the vast numbers of species that have already accumulated in the tropics ensure that total rate of species production remains highest there. Thus, tropical evolutionary momentum helps to perpetuate the steep latitudinal biodiversity gradient.

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!

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

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, 222–225 (08 May 2014) doi: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.

More on speciation and extinction rates and latitudinal diversity gradients in amphibians

Common frog (Rana temporaria). Photo by Erik Svensson

Posted by Erik Svensson

It is spring time, and some of you have already noted the frogs that mate in the pond outside the Ecology Building. Then it seems highly timely to discuss some classical problems in ecology and evolutionary biology that have been subject to some previous lab-meetings, but which continue to fascinate many (including me): why are there more species in the tropics?

Is it because of evolutionary history, such as higher speciation rates in the tropics or lower extinction rates over millions of years? Or is it mainly due to ecological factors such as more energy through the sun and higher humidity in the tropics? Or a combination of ecological and evolutionary factors? What about the roles of niche conservatism and diversity dependence, and how do these affect tropical and temperate diversity?

We will discuss a recent paper  about this by Alexander Pyron and John Wiens about latitudinal diversity gradients in amphibians in relation to speciation, extinction and phylogeny. You can find the paper here, and it is a phylogenetic comparative study, and the abstract is appended below.

When: Tuesday, April  15, at 10.30
Where: "Argumentet", 2nd floor, Ecology Building.

Large-scale phylogenetic analyses reveal the causes of high tropical amphibian diversity

Abstract

Many groups show higher species richness in tropical regions but the underlying causes remain unclear. Despite many competing hypotheses to explain latitudinal diversity gradients, only three processes can directly change species richness across regions: speciation, extinction and dispersal. These processes can be addressed most powerfully using large-scale phylogenetic approaches, but most previous studies have focused on small groups and recent time scales, or did not separate speciation and extinction rates. We investigate the origins of high tropical diversity in amphibians, applying new phylogenetic comparative methods to a tree of 2871 species. Our results show that high tropical diversity is explained by higher speciation in the tropics, higher extinction in temperate regions and limited dispersal out of the tropics compared with colonization of the tropics from temperate regions. These patterns are strongly associated with climate-related variables such as temperature, precipitation and ecosystem energy. Results from models of diversity dependence in speciation rate suggest that temperate clades may have lower carrying capacities and may be more saturated (closer to carrying capacity) than tropical clades. Furthermore, we estimate strikingly low tropical extinction rates over geological time scales, in stark contrast to the dramatic losses of diversity occurring in tropical regions presently.

Lab-meeting on intraspecific assortative mating, disruptive selection and sympatric speciation

Posted by Erik Svensson on behalf of John Waller

This week's lab-meeting will continue on the theme of assorative mating and how it can possibly work together with disruptive selection to cause sympatric speciation. We will discuss two papers by Daniel Bolnick at University of Texas (Austin): one review paper in American Naturalist and one modelling paper in American Zoologist. Abstracts are found below.

Date: Tuesday March 25, 10.30
Place: "Argumentet", 2nd floor, Ecology Building

Assortative Mating in Animals

Yuexin Jiang, Daniel I. Bolnick and Mark Kirkpatrick

Abstract

Assortative mating occurs when there is a correlation (positive or negative) between male and female phenotypes or genotypes across mated pairs. To determine the typical strength and direction of assortative mating in animals, we carried out a meta-analysis of published measures of assortative mating for a variety of phenotypic and genotypic traits in a diverse set of animal taxa. We focused on the strength of assortment within populations, excluding reproductively isolated populations and species. We collected 1,116 published correlations between mated pairs from 254 species (360 unique species-trait combinations) in five phyla. The mean correlation between mates was 0.28, showing an overall tendency toward positive assortative mating within populations. Although 19% of the correlations were negative, simulations suggest that these could represent type I error and that negative assortative mating may be rare. We also find significant differences in the strength of assortment among major taxonomic groups and among trait categories. We discuss various possible reasons for the evolution of assortative mating and its implications for speciation.

Current Zoology    2012, 58(3): 484 - 492

Daniel I. BOLNICK, Mark KIRKPATRICK

The term 'assortative mating' has been applied to describe two very different phenomena: (1) the tendency for individuals to choose phenotypically similar mates from among conspecifics; or (2) the tendency to prefer conspecific over hete- rospecific mates (behavioral reproductive isolation). Both forms of assortative mating are widespread in nature, but the relationship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics incidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin’s Finches (Geospiza spp). We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating

Lab-meeting on learning, sexual selection and speciation: Invited talk by Tucker Gilman

Posted by Erik Svensson

On Tuesday next week (November 19 2014), we have an invited  speaker and collaborator of mine from University of Manchester: Dr. Tucker Gilman. Tucker is a theoretical evolutionary biologist who has recently become especially interested in the role of learned mate preferences in sexual selection and speciation (hence our collaboration). You can read more about his research and publications here.

Tucker will visit Lund next week for several days, and in case you would like to meet up with him and discuss science, send me an e-mail (erik.svensson@biol.lu.se). We can also perhaps arrange for a pub evening at "Inferno" if somebody is interested in this?

The lab-meeting will begin as usual at 10.30 with some informal chat and "fika" (any fika-volunteer?). Then, at 11.00 Tucker will give his talk, and if you know anybody outside the EXEB-environment who would be interested in attending, please invite them (and I will also send out an announcement). The title of Tuckers talk is:

"Learning to speciate: the role of peak shift in adaptive radiation."

Everybody should be most welcome to this exciting talk and lab-meeting!

P.S. I got the excellent news that Dr. Tom Gosden, a former PhD-student of mine, will return to Lund and the EXEB-lab in January 2014. Looking forward to it! D. S.

Updated information about lab-meeting on April 9: ERC, phylogenies and tropical diversification

This is an update about the coming lab-meeting on Tuesday April (10.30), as there was some mis-communication, and it turns out Lesley will not be able to attend the meeting due to a course in landscape genetics, and this is probably also the case for Rachel and Maren. The lab-meeting on Tuesday will start with  Jessica presenting her ERC-talk for the coming interview in Brussels, and she can then get final feedback from the lab-members that attend. Our new student Anais from Cataluna has also promised to bring some catalunian "fika", and we can try out the red wine she brought last week.

Then, we should discuss this paper that I originally suggested which deals with how the use of multiple phylogenies can be used to answer basic ecological and evolutionary questions about the niche conservatism and range expansions and test the classical "tropical conservatism" hypothesis. This paper is in press in Evolution, and is quite long, but in case you have time you can also read the shorter paper Lesley suggested that was published in Ecology Letters. 

Both these papers are thematically similar and demonstrate the power of a phylogenetic perspective and modern comparative methods to address fundamental problems and general processes in ecology and evolution. The titles and abstracts of both papers are posted below. Enjoy!

WHAT CAN MULTIPLE PHYLOGENIES SAY ABOUT THE LATITUDINAL DIVERSITY GRADIENT? A NEW LOOK AT THE TROPICAL CONSERVATISM, OUT OF THE TROPICS, AND DIVERSIFICATION RATE HYPOTHESES

1. Roland Jansson, 
2. Genoveva Rodríguez-Castañeda, 
3. Larisa E. Harding

We reviewed published phylogenies and selected 111 phylogenetic studies representing mammals, birds, insects, and flowering plants. We then mapped the latitudinal range of all taxa to test the relative importance of the tropical conservatism, out of the tropics, and diversification rate hypotheses in generating latitudinal diversity gradients. Most clades originated in the tropics, with diversity peaking in the zone of origin. Transitions of lineages between latitudinal zones occurred at 16–22% of the tree nodes. The most common type of transition was range expansions of tropical lineages to encompass also temperate latitudes. Thus, adaptation to new climatic conditions may not represent a major obstacle for many clades. These results contradict predictions of the tropical conservatism hypothesis (i.e., few clades colonizing extratropical latitudes), but support the out-of-the-tropics model (i.e., tropical originations and subsequent latitudinal range expansions). Our results suggest no difference in diversification between tropical and temperate sister lineages; thus, diversity of tropical clades was not explained by higher diversification rates in this zone. Moreover, lineages with latitudinal stasis diversified more compared to sister lineages entering a new latitudinal zone. This preserved preexisting diversity differences between latitudinal zones and can be considered a new mechanism for why diversity tends to peak in the zone of origin.

Species interactions constrain geographic range expansion over evolutionary time

Alex L. Pigot^*, 

Joseph A. Tobias

Whether biotic interactions limit geographic ranges has long been controversial, and traditional analyses of static distribution patterns have made little progress towards resolving this debate. Here, we use a novel phylogenetic approach to test whether biotic interactions constrain the transition to secondary sympatry following speciation. Applying this temporal framework to a diverse clade of passerine birds (Furnariidae), we reject models of geographic range overlap limited purely by dispersal or environmental constraints, and instead show that rates of secondary sympatry are positively associated with both the phylogenetic and morphological distance between species. Thus, transition rates to sympatry increase with time since divergence and accelerate as the ecological differences between species accumulate. Taken together, these results provide strong empirical evidence that biotic interactions – and primarily ecological competition – limit species distributions across large spatial and temporal scales. They also offer phylogenetic and trait-based metrics by which these interactions can be incorporated into ecological forecasting models.

Workshop on "Behaviour and Speciation" in Oslo

This is a quick greeting and update from Oslo (Norway), where I have participated in a very stimulating research workshop entitled "Behaviour and Speciation", funded by FroSpects and organized by Glenn-Peter Saetre at CEES (Oslo). There were a number of interesting talks by invited speakers, including from Ole Seehausen, Lee Dugatkin, Darren Irwin and Anna Qvarnström, to mention only a few. It was nice to meet friends and colleauges like Darren who I have not seen for ten years, i. e. since he was postdoc in Lund.

It was also nice to meet former PhD-student Fabrice Eroukhmanoff (see picture above), who seems to be doing very well in his new research group and who now works in transgressive hybridization in a homoploid hybrid species of Passer-sparrow and its effects on various phenotypic traits, including beak morphology and beak allometry. Fabrice, Glenn-Peter and several others from the "Sparrow-group" gave several interesting talks about the ongoing work in this fascinating system where genomic, phenotypic and ecological data are now being put together to reveal a complicated but interesting speciation history.

I am writing this post from Fabrice's apartment in Oslo, where I am staying two nights before continuing to North Carolina and the NESCent-meeting about "Environmental determinants of selection". I was of course also pleased to hear that EXEB lab-member in Lund Jessica Abbott have been shortlisted for interview in her application for a "Startup Grant" for junior researcher to the European Research Council (ERC). Well done! An impressive achievement to make it this far, irrespective of the outcome during the interview in Brussels in April, I think.

"Target Review" in Journal of Evolutionary Biology about hybridization and speciation and a comment

Posted by Erik Svensson

In the latest issue of Journal of Evolutionary Biology there is a so-called "Target Review" by a large group of evolutionary biologists entitled: "Hybridization and speciation".  This review, as well as the comments on it, are published "Open Acccess", meaning that anyone can read and download them, even if you are not in a university library. One of the co-authors of this multi-authored paper is by the way Fabrice Eroukhmanoff, former PhD-student in Lund and past member of the EXEB lab, and currently postdoc in Oslo (Norway).  Below is the Abstract:

Abstract

Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near-instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky–Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock-on effects on speciation both within and outside regions of hybridization.

The Target Review is, as usual for these types of invited reviews,  followed by a number of comments, some of them critical, by several evolutionary biologists, including myself. My comment can be found here and is entitled: "Beyond hybridization: diversity of interactions with heterospecifics, direct fitness consequences and the effects on mate preferences".  There are also contributions by Nick Barton, Servedio, Hermisson and Dorn, Seehausen, Björklund and Shaw and Mendelson, to mention only a few comments of what seems to be an interesting discussion around a controversial topic, namely the role of hybridization in speciation. Enjoy!

Our new paper about learning in sexual selection and speciation is now out in TREE

Our paper in Trends in Ecology & Evolution about the role of learning in sexual selection and speciation is now online, and you can find a link to it here. Soon the reprints will hopefully come, and then you can ask Machteld Verzijden for a copy (machteld.verzijden@biol.lu.se). Hopefully, this paper will stimulate increased interest and more experimental and observational studies in this fast moving field.

Below, you will find more details about the paper. Enjoy!

The impact of learning on sexual selection and speciation

• Machteld N. Verzijden 
• Carel ten Cate, 
• Maria R. Servedio, 
• Genevieve M. Kozak, 
• Jenny W. Boughman, 
• Erik I. Svensson

http://dx.doi.org/10.1016/j.tree.2012.05.007

Learning is widespread in nature, occurring in most animal taxa and in several different ecological contexts and, thus, might play a key role in evolutionary processes. Here, we review the accumulating empirical evidence for the involvement of learning in mate choice and the consequences for sexual selection and reproductive isolation. We distinguish two broad categories: learned mate preferences and learned traits under mate selection (such as bird song). We point out that the context of learning, namely how and when learning takes place, often makes a crucial difference to the predicted evolutionary outcome. Factors causing biases in learning and when one should expect the evolution of learning itself are also explored.

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. 

Welcome Lesley Lancaster, our new postdoc

I am pleased to welcome Lesley Lancaster, our new incoming postdoc, funded by BECC ("Biodiversity and Ecosystem Services in Changing Climate"). Lesley will arrive to Lund in late May or early June, and she will work with me and Bengt Hansson on the population genetics and ecology of range limit evolution, particularly using our favourite model organism: the damselfly Ischnura elegans ("Common Bluetail") as the main study object. Both Bengt and I are very excited about this project and about recruiting Lesley, who will bring with her new skills and perspectives from her previous research.

Currently, Lesley is a postdoctoral scholar at  the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara (California, USA), where she has been since 2009. Her main focus of research has been to reconstruct historical evolutionary processes of adaptation, speciation, extinction and migration using time-calibrated molecular phylogenies of various Californian plant clades. She is also interested in historical habitat tolerances of the unique California chaparral habitat. Her postdoctoral research has resulted in some interesting papers in BMC Evolutionary Biology and Systematic Biology.

Lesley's thesis research was on a quite different topic: maternal effects, reproductive strategies and evolutionary ecology of a colour polymorphic lizard (Uta stansburiana), where she worked in the laboratory of Barry Sinervo at University of California, Santa Cruz (UCSC). Her thesis work also resulted in a number of interesting and impressive publications in American Naturalist, Ecology Letters, Evolution and PNAS. 

Lesley is thus an extremely broad and well-rounded biologist and a very experienced postdoc, who has worked at quite different levels of biological organization, and moved her research focus from studies of individual behaviour and evolutionary ecology, to broader macroevolutionary and macroecological questions. It is for precisely these reasons we are excited to bring her in to Lund; she has both sufficient much in common with our already ongoing research,  yet has many complementary skills that will be of interest to us and our research.