Browsing by Author "Donohue, K"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Gene-flow through space and time: dispersal, dormancy and adaptation to changing environments
    (Evolutionary Ecology, 2015-11-01) Rubio de Casas, R; Donohue, K; Venable, DL; Cheptou, P-O
    © 2015, Springer International Publishing Switzerland.Dispersal through space or time (via dormancy) determines gene flow and influences demography. Because of their functional similarities, a covariation between dispersal and dormancy is expected. Dispersal and dormancy are anatomically linked in plants, because they both depend on attributes of the seed, albeit this anatomical association is rarely considered when analyzing interactions between dispersal and dormancy. In this paper, we investigate the extent to which dispersal and dormancy can be expected to correlate and how each might influence adaptation to novel environments such as those brought on by climate change. We review the theoretical and empirical literature on the subject with a focus on seed plants. We find that although a negative correlation between dispersal and dormancy has been theoretically anticipated, several models predict deviations from this expectation under scenarios of environmental heterogeneity. The empirical evidence does not support any specific covariation pattern, likely because the interaction between dispersal and dormancy is affected by multiple environmental and developmental constraints. From a climate change perspective, the effects of dispersal and dormancy on population structure are not equivalent: dormancy-mediated gene flow is intrinsically asymmetric (from the past towards the future) whereas spatial dispersal is not necessarily directional. As a result, selection on traits linked to dormancy and dispersal might differ qualitatively. In particular, gene flow through dormancy can only be adaptive if future environmental conditions are similar to those of the past, or if it contributes to novel allelic combinations. We conclude that, in spite of a long tradition of research, we are unable to anticipate a universal relationship between dispersal and dormancy. More work is needed to predict the relative contributions of spatial dispersal and dormancy to gene flow and adaptation to novel environments.
  • Thumbnail Image
    ItemOpen Access
    The scale of population structure in Arabidopsis thaliana.
    (PLoS Genet, 2010-02-12) Platt, A; Horton, M; Huang, Y; Li, Y; Anastasio, A; Mulyati, W; Agren, J; Bossdorf, O; Byers, D; Donohue, K; Dunning, M; Holub, E; Hudson, A; Le Corre, V; Loudet, O; Rivero, L; Scholl, R; Nordborg, M; Bergelson, J; Borevitz, JO
    The population structure of an organism reflects its evolutionary history and influences its evolutionary trajectory. It constrains the combination of genetic diversity and reveals patterns of past gene flow. Understanding it is a prerequisite for detecting genomic regions under selection, predicting the effect of population disturbances, or modeling gene flow. This paper examines the detailed global population structure of Arabidopsis thaliana. Using a set of 5,707 plants collected from around the globe and genotyped at 149 SNPs, we show that while A. thaliana as a species self-fertilizes 97% of the time, there is considerable variation among local groups. This level of outcrossing greatly limits observed heterozygosity but is sufficient to generate considerable local haplotypic diversity. We also find that in its native Eurasian range A. thaliana exhibits continuous isolation by distance at every geographic scale without natural breaks corresponding to classical notions of populations. By contrast, in North America, where it exists as an exotic species, A. thaliana exhibits little or no population structure at a continental scale but local isolation by distance that extends hundreds of km. This suggests a pattern for the development of isolation by distance that can establish itself shortly after an organism fills a new habitat range. It also raises questions about the general applicability of many standard population genetics models. Any model based on discrete clusters of interchangeable individuals will be an uneasy fit to organisms like A. thaliana which exhibit continuous isolation by distance on many scales.