Résumé
Local adaptation is a key process for the maintenance of genetic diversity
and population diversification. A better understanding of the mechanisms
that allow (or prevent) local adaptation constitutes a key in apprehending
how and at what spatial scale it occurs. The production of resting stages
is found in many taxa and reflects an adaptation to outlast adverse
environmental conditions. Daphnia magna (Crustacea) can alternate between
asexual and sexual reproduction, the latter being linked to dormancy, as
resting stages can only be produced sexually. In this species, on a
continental scale, resting stage production is locally adapted, i.e. it is
induced when the photoperiod indicates the imminence of habitat
deterioration. Here, we aimed to explore whether selection is strong
enough to maintain local adaptation at a scale of a few kilometers. We
assessed life history traits of 64 D. magna clones originating from 11
populations of a meta-population with permanent and intermittent pool
habitats. We found large within- and between-population variation for all
dormancy-related traits, but no evidence for the hypothesised higher
resting stage production in animals from intermittent habitats. We discuss
how gene flow, founder events or other forms of selection might interfere
with the process of local adaptation.