Data from: Evolutionary rescue of freshwater copepods during historical lake acidification

The persistence of populations facing severe environmental disturbance can
be enabled by natural selection on heritable phenotypic variation - a
process known as evolutionary rescue. Few studies have documented this
process in complex natural settings and the long-term outcome of
evolutionary rescue. Here, we used copepod resting eggs of Leptodiaptomus
minutus from three time periods of lake ecological history, spanning ≈ 200
generations (100 years) in two populations impacted by historical
acidification. Whole-genome sequencing of the resting eggs revealed
significant allele-frequency shifts associated with acidification followed
by pH recovery. We used a resurrection ecology approach to retrace
adaptive shifts concomitant with environmental transitions. Copepods from
the pre-acidification period were sensitive to acidity, whereas those from
the acidification period were adapted to acidic pH. This tolerance was
subsequently lost during pH recovery, implying an adaptive reversal.
Demographic models indicated a decline during the acidification process,
followed by population recovery based on historical data, suggesting that
selection led to evolutionary rescue. This study fills a critical
knowledge gap about the long-term implications of evolutionary rescue in
the wild.