Multilocus migration-selection models

(P 21305-N13, Austrian Science Fund, FWF, 01.01.2009 – 31.12.2012)

 

Abstract. Many natural populations are geographically structured and selection varies spatially due to environmental heterogeneity. Population subdivision is known to have numerous important evolutionary consequences. For instance, it has the capacity to maintain genetic variation, it may lead to ecological specialization and, eventually, to speciation. The effects of geographic structure, dispersal, and spatially varying selection are reasonably well understood only if a single locus is under selection. Most ecologically and evolutionary important traits, however, are quantitative and are determined by many gene loci.

            This project is devoted to the analysis of population-genetic models that describe evolution under the combined action of migration, recombination, and selection on multilocus genotypes. Such models are usually formulated in terms of systems of (nonlinear) difference or differential equations. There are two interrelated goals that shall be achieved. The first is the identification of conditions under which multilocus polymorphism can be maintained by a balance between migration and selection, especially when this is impossible in a panmictic population. The second is the identification of conditions that generate or enhance local adaptation and genetic diversification at multiple loci. Both goals require the determination of the pattern and amount of genetic variation at evolutionary equilibrium. This shall be achieved by concentrating research on three ecologically motivated scenarios: a spatially heterogeneous environment but no population structure (the Levene model), antagonistic directional selection in a population distributed over two demes connected by migration, and stabilizing selection on a quantitative trait, where the optimum may vary among demes.

Methodologically, this shall be achieved by applying techniques from the theory of dynamical systems to explore the equilibrium, stability, and bifurcation structure of the underlying models. Comprehensive computational studies will complement the analytical work.

 

Persons funded by this project:

·        Stephan Peischl: PhD student from 01.01.2009 – 30.04.2010,  Postdoc from 01.05.2010 – 30.09.2010

·        Ada Akerman: research stipend from 01.01.2009 – 31.01.2009, PhD student from 01.02.2010 – 31.12.2012

·        Sebastian Novak: PhD student from 01.10.2010 – 31.12.2010

·        Peter Kepplinger: research stipend from 01.12.2010 – 30.6.2011

·        Simon Aeschbacher: Postdoc from 01.10.2011-15.12.2012

 

Publications

1.     Peer reviewed

·        Aeschbacher S, Beaumont MA, Futschik A (2013) Approximate Bayesian computation for modular inference problems with many parameters: the example of migration rates. Molecular Ecology 22, 987–1002, doi: 10.1111/mec.12165

·        Akerman A, Bürger R (2013) The consequences of gene flow for local adaptation and differentiation: a two-locus two-deme model. J. Math. Biol. (online), doi: 10.1007/s00285-013-0660-z

·        Bank C, Bürger R, Hermisson J (2012) The limits to parapatric speciation: Dobzhansky-Muller incompatibilities in a continent-island model. Genetics 191, 845–863, pdf

·        Bürger R (2010) Evolution and polymorphism in the multilocus Levene model with no or weak epistasis. Theoret. Popul. Biol. 78, 123-138, pdf

·        Bürger R (2011) Some mathematical models in evolutionary genetics. In: The Mathematics of Darwin’s Legacy, pp. 67-89, FACC Chalub and JF Rodrigues (eds), Birkhäuser, Basel, pdf

·        Bürger R, Akerman A (2011) The effects of linkage and gene flow on local adaptation: A two-locus continent-island model. Theoret. Popul. Biol. 80, 272-288, pdf

·        Jones AG, Bürger R, Arnold SJ, Hohenlohe PA, Uyeda JC (2012) The effects of stochastic and episodic movement of the optimum on the evolution of the G-matrix and the response of the trait mean to selection. J. Evol. Biol. 25, 2210–2231, pdf

·        Novak S (2011) The number of equilibria in the diallelic Levene model with multiple demes. Theoret. Popul. Biol. 79, 97-101, doi:10.1016/j.tpb.2010.12.002

·        Peischl S (2010) Dominance and the maintenance of polymorphism in multiallelic migration-selection models with two demes. Theor. Popul. Biol.78, 12-25, doi:10.1016/j.tpb.2010.03.006

·        Schneider K, Peischl S (2011) Evolution of assortative mating in a population expressing dominance. PLoS ONE 6(4): e16821, doi:10.1371/journal.pone.0016821

·     Akerman A, Bürger R (2013): The consequences of gene flow for local adaptation and differentiation: a two-locus two-deme model. J. Math. Biol., pdf, doi: 10.1007/s00285-013-0660-z

·     Urban MC, Bürger R, Bolnick DI (2013): Asymmetric selection and the evolution of extraordinary defences. Nature Communications 4:2085, DOI: 10.1038/ncomms3085

 

2.     Preprints and manuscripts in preparation

·        Aeschbacher S, Bürger R (2013): Invasion properties of beneficial mutations in a two-locus continent-island model. To be submitted

 

3.      Diploma and PhD thesis

·        Akerman A (2010) A two-locus two-allele migration-selection model. Diploma thesis, University of Vienna, pdf

·        Peischl S (2010) Mathematical models of frequency-dependent selection with dominance. PhD thesis, University of Vienna, pdf