Data from: Sand lizard (Lacerta agilis) phenology in a warming world

Background: Present-day climate change has altered the phenology (the
timing of periodic life cycle events) of many plant and animal populations
worldwide. Some of these changes have been adaptive, leading to an
increase in population fitness, whereas others have been associated with
fitness decline. Representing short-term responses to an altered weather
regime, hitherto observed changes are largely explained by phenotypic
plasticity. However, to track climatically induced shifts in optimal
phenotype as climate change proceeds, evolutionary capacity in key
limiting climate- and fitness-related traits is likely to be crucial. In
order to produce realistic predictions about the effects of climate change
on species and populations, a main target for conservation biologists is
thus to assess the potential of natural populations to respond by these
two mechanisms. In this study we use a large 15-year dataset on an
ectotherm model, the Swedish sand lizard (Lacerta agilis), to investigate
how higher spring temperature is likely to affect oviposition timing in a
high latitude population, a trait strongly linked to offspring fitness and
survival. Results: With an interest in both the short- and potential
long-term effect of rising temperatures, we applied a random regression
model, which yields estimates of population-level plasticity and
among-individual variation in the average, as well as the plastic,
response to temperature. Population plasticity represents capacity for
short-term adjustments whereas variation among individuals in a
fitness-related trait indicates an opportunity for natural selection and
hence for evolutionary adaptation. The analysis revealed both
population-level plasticity and individual-level variation in average
laying date. In contrast, we found no evidence for variation among females
in their plastic responses to spring temperature, which could demonstrate
a similarity in responses amongst females, but may also be due to a lack
of statistical power to detect such an effect. Conclusion: Our findings
indicate that climate warming may have positive fitness effects in this
lizard population through an advancement of oviposition date. This
prediction is consistent over shorter and potentially also longer time
scales as the analysis revealed both population-level plasticity and
individual-level variation in average laying date. However, the genetic
basis for this variation would have to be examined in order to predict an
evolutionary response.