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Data from: Fitness costs in spatially structured environments
Débarre, Florence — 2015-03-17 The clustering of individuals that results from limited dispersal is a double-edged sword: while it allows for local interactions to be mostly among related individuals, it also results in increased local competition. Here I show that, because they mitigate local competition, fitness costs such as reduced fecundity or reduced survival are less costly in spatially structured environments than in non spatial settings. I first present a simple demographic example to illustrate how spatial structure weakens selection against fitness costs. Then, I illustrate the importance of disentangling the evolution of a trait from the evolution of potential associated costs, using an example taken from a recent study investigating the effect of spatial structure on the evolution of host defense. In this example indeed, the differences between spatial and non-spatial selection gradients are due to differences in the fitness costs, thereby undermining interpretations of the results made in terms of the trait only. This illustrates the need to consider fitness costs as proper traits in both theoretical and empirical studies.
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Data from: Quantifying the effects of migration and mutation on adaptation and demography in spatially heterogeneous environments
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Débarre, Florence; Ronce, Ophélie; Gandon, Sylvain — 2013-01-10 How do mutation and gene flow influence population persistence, niche expansion, and local adaptation in spatially heterogeneous environments? In this article, we analyse a demographic and evolutionary model of adaptation to an environment containing two habitats in equal frequencies, and we bridge the gap between different theoretical frameworks. Qualitatively, our model yields four qualitative types of outcomes: (i) global extinction of the population (ii) adaptation to one habitat only, but also adaptation to both habitats with (iii) specialized phenotypes, or (iv) with generalized phenotypes; and we determine the conditions under which each equilibrium is reached. We derive new analytical approximations for the local densities and the distributions of traits in each habitat under a migration--selection--mutation balance, compute the equilibrium values of the means, variances and asymmetries of the local distributions of phenotypes, and contrast the effects of migration and mutation on the evolutionary outcome. We then check our analytical results by solving our model numerically, and also assess their robustness in the presence of demographic stochasticity. While increased migration results in a decrease in local adaptation, mutation in our model does not influence the values of the local mean traits. Yet, both migration and mutation can have dramatic effects on population size and even lead to metapopulation extinction when selection is strong. Niche expansion, the ability for the population to adapt to both habitats, can also be prevented by small migration rates and a reduced evolutionary potential characterised by rare mutation events of small effects; but niche expansion is otherwise the most likely outcome. Although our results are derived under the assumption of clonal reproduction, we finally show and discuss the links between our model and previous quantitative genetics models.
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Data from: Social evolution in structured populations
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Débarre, Florence; Hauert, Christoph; Doebeli, Michael — 2015-01-27 Understanding the evolution of social behaviours such as altruism and spite is a long-standing problem that has generated thousands of articles and heated debates. Previous theoretical studies showed that whether altruism and spite evolve may be contingent on seemingly artificial model features, such as which rule is chosen to update the population (e.g., Birth-Death or Death-Birth), and whether the benefits and costs of sociality affect fecundity or survival. Here we unify these features in a single comprehensive framework. We derive a general condition for social behaviour to be favoured over non-social behaviour, which is applicable in a large class of models for structured populations of fixed size. We recover previous results as special cases, and we are able to evaluate the relative effects of benefits and costs of social interactions on fecundity and survival. Our results highlight the crucial importance of identifying the relative scale at which competition occurs.
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Data from: The availability of research data declines rapidly with article age
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Vines, Timothy H.; Albert, Arianne Y. K.; Andrew, Rose L.; Débarre, Florence; Bock, Dan G.; Franklin, Michelle T.; Gilbert, Kimberly J.; Moore, Jean-Sébastien; Renaut, Sébastien; Rennison, Diana J. — 2014-11-05 Policies ensuring that research data are available on public archives are increasingly being implemented at the government, funding agency, and journal level. These policies are predicated on the idea that authors are poor stewards of their data, particularly over the long term, and indeed many studies have found that authors are often unable or unwilling to share their data. However, there are no systematic estimates of how the availability of research data changes with time since publication. We therefore requested datasets from a relatively homogenous set of 516 articles published between 2 and 22 years ago, and found that availability of the data was strongly affected by article age. For papers where the authors gave the status of their data, the odds of a dataset being extant fell by 17% per year. In addition, the odds that we could find a working email address for the first, last or corresponding author fell by 7% per year. Our results reinforce the notion that, in the long term, research data cannot be reliably preserved by individual researchers, and further demonstrate the urgent need for policies mandating data sharing via public archives.
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Data from: Refining the conditions for sympatric ecological speciation
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Débarre, Florence — 2012-09-12 Can speciation occur in a single population when different types of resources are available, in the absence of any geographical isolation, or any spatial or temporal variation in selection? The controversial topics of sympatric speciation and ecological speciation have already stimulated many theoretical studies, most of them agreeing on the fact that mechanisms generating disruptive selection, some level of assortment, and enough heterogeneity in the available resources, are critical for sympatric speciation to occur. Few studies, however, have combined the three factors and investigated their interactions. In this article, I analytically derive conditions for sympatric speciation in a general model where the distribution of resources can be uni- or bimodal, and where a parameter controls the range of resources that an individual can exploit. This approach bridges the gap between models of a unimodal continuum of resources and Levene-type models with discrete resources. I then test these conditions against simulation results from a recently published article (Thibert-Plante and Hendry 2011) and confirm that sympatric ecological speciation is favoured when (i) selection is disruptive (ie, individuals with an intermediate trait are at a local fitness minimum), (ii) resources are differentiated enough, and (iii) mating is assortative. I also discuss the role of mating preference functions, and the need (or lack thereof) for bimodality in resource distributions for diversification.

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(auteur : Débarre, Florence)

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