Density-regulated population dynamics and conditional dispersal alter the fate of mutations occurring at the front of an expanding population

Abstract

There is an increasing recognition that the interplay between ecological and evolutionary processes shapes the genetic footprint of populations during and after range expansions. However, more complex ecological processes regularly considered within spatial ecology remain unexplored in models describing the population genetics of range expansion. In this study we integrate flexible descriptions of population growth and competition as well as conditional dispersal into a model that simulates the fate of mutations occurring at the wave front of an expanding population. Our results show that the survival and distribution of a mutation is not only affected by its bias (that is, whether it is deleterious, neutral or beneficial) but also by the mode of local density regulation and conditional dispersal of the simulated populations. It is in particular the chance of a mutation to establish at the front of advance and 'surf' to high frequencies that critically depends on the investigated ecological processes. This is because of the influence of these processes on demographic stochasticity in the system and the differential responses of deleterious, neutral and beneficial mutations to this stochasticity. Generally, deleterious mutations rely more on chance and thus profit the most from ecological processes that enhance demographic stochasticity during the period of establishment. Our study emphasizes the importance of incorporating more ecological realism into evolutionary models to better understand the consequences of shifting geographic ranges for the genetic structure of populations and to find efficient adaptation strategies to mitigate these effects.

Community dynamics under environmental change: How can next generation mechanistic models improve projections of species distributions?

“…in demographic rates (Swab et al, 2015)), local adaptation (Atkins and Travis, 2010;Bocedi et al, 2013;Bourne et al, 2014), evolution (e.g. changes in genetic variety along the gradient from core to range margin Cobben et al, 2011;Hill et al, 2011), enhancement of dispersal traits Thomas et al, 2001) and habitat as well as host plant switch (Thomas et al, 2001)), intraspecific density dependence Münkemüller et al, 2011) and interspecific interactions (Brooker et al, 2007;Kissling et al, 2010;Menendez et al, 2008;Münkemüller et al, 2009;Singer et al, 2013;Svenning et al, 2014).…”

Mutation surfing and the evolution of dispersal during range expansions

“…, 2006) and nonneutral (Travis et al. , 2007; Burton & Travis, 2008b; Münkemüller et al. , in press) mutations arising at expanding range margins.…”

Range expansion and retraction along a moving contact zone has no effect on the genetic diversity of two passerine birds

“…Under a short distance dispersal scenario, neutral mutations forming at the range edge can either stay near their place of origin or 'surf ' along with the expansion front, resulting in genetic differentiation. This hypothesized concept of 'allele surfing' (Edmonds et al 2004, Klopfstein et al 2006, Travis et al 2010, Münkemüller et al 2011 was confirmed by lab experiments on prokaryotes (Hallatschek et al 2007) as well as by empirical genetic studies (Gassert et al 2013). While short distance dispersal and allele surfing can lead to a depletion of genetic diversity at the expansion front, long-distance-dispersal (LDD) might lead to Disentangling the factors shaping species distributions remains a central goal in biogeography, ecology and evolutionary biology.…”

“…Recently, a series of theoretical studies have simulated the effects on genetic diversity at expanding (Fayard et al , Ray and Excoffier , Travis et al , Münkemüller et al ) and receding (Leblois et al , Arenas et al ) range edges. At expanding range edges the propensity of individuals to disperse may have contrasting effects on the genetic structure.…”