Data for: Predicting the contribution of single trait evolution to rescuing a plant population from demographic impacts of climate change

Evolutionary adaptation can allow a population to persist in the face of a
new environmental challenge. With many populations now threatened by
environmental change, it is important to understand whether this process
of evolutionary rescue is feasible under natural conditions, yet work on
this topic has been largely theoretical. We used unique long-term data to
parameterize deterministic and stochastic models of the contribution of
one trait to evolutionary rescue using field estimates for the subalpine
plant Ipomopsis aggregata and hybrids with its close relative I.
tenuituba. In the absence of evolution or plasticity, the two studied
populations are projected to go locally extinct due to earlier snowmelt
under climate change, which imposes drought conditions. Phenotypic
selection on specific leaf area (SLA) was estimated in 12 years and
multiple populations. Those data on selection and its environmental
sensitivity to annual snowmelt timing in the spring were combined with
previous data on heritability of the trait, phenotypic plasticity of the
trait, and the impact of snowmelt timing on mean absolute fitness.
Selection favored low values of SLA (thicker leaves). The evolutionary
response to selection on that single trait was insufficient to allow
evolutionary rescue by itself, but in combination with phenotypic
plasticity it promoted evolutionary rescue in one of the two populations.
The number of years until population size would stop declining and begin
to rise again was heavily dependent upon stochastic environmental changes
in snowmelt timing around the trend line. Our study illustrates how field
estimates of quantitative genetic parameters can be used to predict the
likelihood of evolutionary rescue. Although a complete set of parameter
estimates are generally unavailable, it may also be possible to predict
the general likelihood of evolutionary rescue based on published ranges
for phenotypic selection and heritability and the extent to which early
snowmelt impacts fitness.