François Blanquart - Evolution of migration in a fluctuating environment

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Evolution of migration in a fluctuating environment

François Blanquart and Sylvain GandonJune 1st 2010

François Blanquart – Séminaire MEE 01.06.10

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Introduction

What is local adaptation?


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Introduction



W(home)

W(away)

W(away)

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Introduction


Local adaptation=W(home)-W(away)

Local adaptation>0 : populations are locally adapted

Migration decreases local adaptation

For this reason, when populations are locally adapted migration does not evolve (Balkau & Feldman 1973)


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Introduction

• Temporally changing selection (Morgan et al. 2005, Gandon 2002)

When selection changes in time migration may increase local adaptation


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Introduction

• Selection gradient changes in time frequently

François Blanquart – Séminaire MEE 01.06.10Siepielski et al.2009

years

selection gradient

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Introduction

Design a model to see how local adaptation and migration evolve when selection is heterogeneous in space and fluctuating in time

• Local adaptation in a fluctuating environment

• Evolution of migration


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Introduction

• The model– Metapopulation– Genetically explicit

• Life cycle– Individuals produce a large number of juveniles: fecundity selection– Populations are regulated– Juveniles migrate and settle in new demes


A M

selection

A and a

migration

M and m

4 genotypes -> pA, pM, D

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environment


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Higher migration: shorter lag, but more individuals are not locally adapted

Local adaptation in a fluctuating environment


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environmentHigher migration: shorter lag, but more individuals are not locally

adapted -> local adaptation peaks for an intermediate level of migration

Is it true for any shape of selection?


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environment


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environment

Local adaptation is maximized for an intermediate rate of migration, for a variety of fluctuating environments


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environment


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• Evolution of a modifier of migration and evolutionarily stable migration rate– The evolution of the modifier over one life cycle depends on indirect

selection, thus on the linkage disequilibrium

Linkage disequilibrium is generated by the interplay between local adaptation and migration


Fitness(A)>1

Fitness(a)<1

A a

Fitness(A)<1

Fitness(a)>1

M

many Am many am

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• Finding the evolutionarily stable migration rate (ESMR)– Quasi linkage equilibrium approximation

… migration is not selected for…because populations are locally adapted

– Explicit dynamics of the linkage disequilibrium…migration is selected for (ESMR is not 0) because of the lag in the

dynamics of the linkage disequilibrium


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Evolutionarily stable migration rate


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… with cost


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… different shapes of selection


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Conclusion and perspectives

• Local adaptation is maximal for an intermediate rate if migration, in a variety of fluctuating environments

• In spite of local adaptation, migration can be selected for in a changing environment


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• Host-parasite coevolution

François Blanquart – Séminaire MEE 01.06.10Sasaki et al. 2002

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• Migration: another strategy to adapt to a fluctuating environment

François Blanquart – Séminaire MEE 01.06.10Gandon & Otto 2007

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• Shape of selection?


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Thank you


François Blanquart - Evolution of migration in a fluctuating environment

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