From nature to the laboratory: the impact of founder effects on adaptation

Abstract

Most founding events entail a reduction in population size, which in turn leads to genetic drift effects that can deplete alleles. Besides reducing neutral genetic variability, founder effects can in principle shift additive genetic variance for phenotypes that underlie fitness. This could then lead to different rates of adaptation among populations that have undergone a population size bottleneck as well as an environmental change, even when these populations have a common evolutionary history. Thus, theory suggests that there should be an association between observable genetic variability for both neutral markers and phenotypes related to fitness. Here, we test this scenario by monitoring the early evolutionary dynamics of six laboratory foundations derived from founders taken from the same source natural population of Drosophila subobscura. Each foundation was in turn three‐fold replicated. During their first few generations, these six foundations showed an abrupt increase in their genetic differentiation, within and between foundations. The eighteen populations that were monitored also differed in their patterns of phenotypic adaptation according to their immediately ancestral founding sample. Differences in early genetic variability and in effective population size were found to predict differences in the rate of adaptation during the first 21 generations of laboratory evolution. We show that evolution in a novel environment is strongly contingent not only on the initial composition of a newly founded population but also on the stochastic changes that occur during the first generations of colonization. Such effects make laboratory populations poor guides to the evolutionary genetic properties of their ancestral wild populations.

Toxicity and Cross-Resistance of Insecticides to Cry2Ab-Resistant and Cry2Ab-Susceptible <I>Helicoverpa armigera</I> and <I>Helicoverpa punctigera</I> (Lepidoptera: Noctuidae)

“…A signiÞcant limitation of laboratory rearing of small populations is genetic bottlenecking through founder effect and genetic drift which can result in signiÞcant reduction in genetic variation (Santos et al 2012). Based on results from our bioassays, the laboratoryreared reference strain (GR) appears to be distinct from the reference strain previously described as having full susceptibility to broad-spectrum insecticides (Forrester et al 1993, Gunning et al 1996a.…”

Fitness and Field Performance of a Mass-Reared Biological Control Agent,Rhinoncomimus latipes(Coleoptera: Curculionidae)

“…Insects have been mass reared over many generations for a variety of reasons, including biological control (Mackauer 1976, Nunney 2003, van Lenteren 2003, sterile insect release (Gilchrist et al 2012, Sorensen et al 2012, Weldon et al 2013, and basic studies of genetics and evolution (Hoffmann et al 2001, Santos et al 2012. Insect populations subjected to many generations of artiÞcial selection in the laboratory may change genetically in ways that improve their performance in the rearing facility but reduce their performance in the Þeld (Mackauer 1976, Nunney 2003, van Lenteren 2003, Chambers 1977, Sorensen et al 2012.…”

History, chance and selection during phenotypic and genomic experimental evolution: replaying the tape of life at different levels

“…We found that all populations adapt during the first generations, though at different rates (Simões et al, 2008a). We have also studied the evolutionary dynamics of several neutral molecular markers in these foundations (Simões et al, 2008b, 2010; Santos et al, 2012, 2013). The joint analyses of molecular markers and life-history traits showed that most differences in adaptive rates were due to sampling effects during the early stages of colonization (Santos et al, 2012).…”

“…We have also studied the evolutionary dynamics of several neutral molecular markers in these foundations (Simões et al, 2008b, 2010; Santos et al, 2012, 2013). The joint analyses of molecular markers and life-history traits showed that most differences in adaptive rates were due to sampling effects during the early stages of colonization (Santos et al, 2012). These results illustrate that evolution in a novel environment may be strongly contingent: not only on the initial composition of a newly founded population, but also on the stochastic changes that occur during the first generations of colonization.…”

“…Fly samples were collected from historically differentiated wild populations in three European locations: Groningen (Netherlands), Montpellier (France), and Adraga (Portugal), minimizing sampling effects (cf. Santos et al, 2012) both by increasing the number of founders and by maintaining females (and all their descendants) in separate vials during the first generations. With this set up, the following questions were considered: (1) Will populations that have a different history converge to the same adaptive peak?…”