Exploring links between climatic predictability and the evolution of within- and transgenerational plasticity

In variable environments, phenotypic plasticity can increase fitness by
providing tight environment-phenotype matching. However, adaptive
plasticity is expected to evolve only when the future selective
environment can be predicted based on the prevailing conditions. That is,
the juvenile environment should be predictive of the adult environment
(within-generation plasticity) or the parental environment should be
predictive of the offspring environment (transgenerational plasticity).
Moreover, environmental predictability can also shape transient responses
such as stress responses in an adaptive direction. Here, we test links
between environmental predictability and the evolution of adaptive
plasticity by combining time series analyses and a common garden
experiment using temperature as a stressor in a temperate butterfly
(Melitaea cinxia). Time series analyses revealed that across-season
fluctuations in temperature over 48 years are overall predictable.
However, within the growing season, temperature fluctuations showed high
heterogeneity across years with low autocorrelations and the timing of
temperature peaks was asynchronous. Most life-history traits showed strong
within-generation plasticity for temperature and traits such as body size
and growth rate broke the temperature-size rule. Evidence for
transgenerational plasticity, however, was weak and detected for only two
traits each in an adaptive and non-adaptive direction. We suggest that the
low predictability of temperature fluctuations within the growing season
likely disfavours the evolution of adaptive transgenerational plasticity
but instead favours strong within-generation plasticity.