Quantitative genetic effects of bottlenecks: experimental evidence from a wild plant species, Nigella degenii.
Understanding the genetic consequences of changes in population size is fundamental in a variety of contexts, such as adaptation and conservation biology. In the study presented here, we have performed a replicated experiment with the plant Nigella degenii to explore the quantitative genetic effects of a single-founder bottleneck. In agreement with additive theory, the bottleneck reduced the mean (co)variance within lines and caused stochastic, line-specific changes in the genetic (co)variance structure. However, a significant portion of the (co)variance structure was conserved, and 2 characters-leaf and flower (sepal) size-turned out to be positively correlated in all data sets, indicating a potential for correlated evolution in these characters, even after a severe bottleneck. The hierarchical partitioning of genetic variance for flower size was in good agreement with predictions from additive theory, whereas the remaining characters showed an excess of within-line variance and a deficiency of among-line variance. The latter discrepancies were most likely a result of selection, given the small proportion of lines (23%) that remained viable until the end of the experiment. Our results suggest that bottlenecked populations of N. degenii generally have a lower adaptive potential than the ancestral population but also highlight the idiosyncratic nature of bottleneck effects.
Andersson
Stefan
S
Department of Ecology, Section of Plant Ecology and Systematics, Lund University, Sölvegatan 37, Lund SE-223 62, Sweden. stefan.andersson@ekol.lu.se
Ellmer
Maarten
M
Jorgensen
Tove H
TH
Palmé
Anna
A
D000220:Adaptation, Biological / Q000235:genetics; D035264:Flowers / Q000235:genetics; D040961:Genetic Drift; D014644:Genetic Variation; D008957:Models, Genetic; D031844:Nigella / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics; D011157:Population Dynamics; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic