JCJC SVSE 7 - JCJC - SVSE 7 - Biodiversité, évolution, écologie et agronomie

Fragmented populations and dispersal syndromes: from genes to metapopulations dynamic – FRADISYN

The origins of dispersal, a crucial behavior for populations persistence in a fragmented landscape

Dispersal allows movements between small populations isolated by the human-induced fragmentation of the landscape. This project aims at studying the mechanisms of this spatial behavior resulting from the interactions between the environmental conditions and the internal factors of individuals.

Adaptive mechanisms reducing spatial isolation induced by habitat fragmentation

Habitat fragmentation change a large habitat into small habitat patches isolated which results in the decrease of species viability. Indeed, this isolation decreases movements between patches and therefore prevents almost extinct populations to be rescued. This project aims at understanding how dispersal between habitat patches happens. Specifically, individuals of a species vary in their phenotype creating different dispersal strategies. A better knowledge of the mechanisms producing this within-species variation would help understanding the dynamic of fragmented populations.

This project will be done in a recent experimental set-up connecting populations to measure dispersal in a fragmented landscape. This experimental approach allows us to measure a set of phenotypic traits, to collect genetic sample and to measure dispersal decisions on all individuals. We will be able to identify the phenotypic specializations of dispersers, such as behavioral types, and the genetic polymorphisms behind these specializations.

We identified disperser phenotypic attributes varying with factors inducing dispersal, such as longer tails in dispersers leaving a risky maternal environment or lower thermal preferences in dispersers leaving a warmer environment. These relationships between phenotype and dispersal decisions likely exist to reduce costs or increase benefits of dispersal.

These results are crucial in predicting consequences of fragmentation and global warming, because they show that individuals connecting patches following a global warming can have a specific phenotype and are clearly not a random subset of a population. The next step is to study genetic and environmental factors at the roots of dispersal syndromes in order to understand their influence in global changes.

Bestion E., Clobert J., and J. Cote. 2015. Dispersal response to climate change: scaling down to intraspecific variation. Ecology Letters. In press.

At birth, some juveniles prefer cooler temperatures than other juveniles. Using an experiment

Habitat loss and fragmentation are major threats affecting more than 85% of terrestrial threatened species and thus menacing biodiversity. For instance, 40% of original forest cover has been lost through human activity. The problem of habitat loss is made worse by the fragmentation of natural habitats, which results in smaller, more isolated sub-populations with reduced possibilities for dispersal. Fragmented populations follow a metapopulation dynamic dependent on local extinction, dispersal into locally extinct patches (colonization) and into extant patches (reinforcement). Reduced dispersal can hinder the recolonization of patches where sub-populations have become extinct, leading to stochastic local and ultimately global extinctions. Therefore, habitat fragmentation affects species occurrence through patch isolation. In FRADISYN, we study dispersal processes, the adaptive mechanisms allowing connectivity between patches and thus species to overcome this spatial isolation. We aim to integrate inter-individual variability in dispersal decisions, a recent advance in dispersal theory, into the dynamic of fragmented populations. Such inter-individual variability arises from the variability in phenotypic traits that shapes individual success in diverse ecological conditions and, in turn, should produce inter-individual differences in habitat selection. Those various associations between phenotypic traits and habitat preferences, named dispersal syndromes, should affect metapopulations dynamics. We predict that colonization and reinforcement involve individuals of different syndromes. Here, we aim to experimentally study, for the first time, the heterogeneity in dispersal syndromes, by exploring the relations between phenotypic traits and habitat preferences, the relationship between habitat preferences and fitness outcomes and the mechanisms producing and maintaining the heterogeneity in dispersal syndromes. Our project will use an integrative approach blending molecular, behavioral and modeling analyses. We will first quantify the relations between habitat preferences and behavioral types that are phenotypic traits likely to drive dispersal decisions. We will then study 1) the role of sequence polymorphism and expression of genes involved in neurochemicals in the production of those relations and 2) the heritability, consistency and effects on performance of established dispersal syndromes explaining their maintenance. Finally, we will integrate results from those tasks into metapopulation dynamic with experimental and modeling approaches. The success of FRADISYN requires a variety of knowledge brought by a team of young researchers from two labs (EDB and SEEM) and a unique and innovating experimental system of metapopulations available at SEEM. This project will merge the knowledge and skills from these two labs to develop the link between population, behavioral and evolutionary ecology. Given the importance of dispersal for species adaptability to changing environments, we need a more integrative comprehension of dispersal processes to understand how, after fragmentation, species can overcome isolation between patches to increase connectivity within the landscape. FRADISYN proposes a highly innovative approach that integrates explicitly within-species phenotypic variation into fragmented population dynamic models. We believe our results will be of wide interest for scientific communities and thus will be published in high ranking journals.

Project coordinator

Monsieur Julien Cote (Laboratoire Ecologie et Diversité Biologique) – julien.cote@univ-tlse3.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

UMR 5174 Laboratoire Ecologie et Diversité Biologique

Help of the ANR 239,995 euros
Beginning and duration of the scientific project: February 2013 - 48 Months

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