Data from: Evolutionary dynamics of the leaf phenological cycle in an oak metapopulation along an elevation gradient

It has been predicted that environmental changes will radically alter the
selective pressures on phenological traits. Long-lived species, such as
trees, will be particularly affected, as they may need to undergo major
adaptive change over only one or a few generations. The traits describing
the annual life cycle of trees are generally highly evolvable, but nothing
is known about the strength of their genetic correlations. Tight
correlations can impose strong evolutionary constraints, potentially
hampering the adaptation of multivariate phenological phenotypes. In this
study, we investigated the evolutionary, genetic and environmental
components of the timing of leaf unfolding and senescence within an oak
metapopulation along an elevation gradient. Population divergence,
estimated from in situ and common garden data, was compared to
expectations under neutral selection, based on microsatellite markers.
This approach made it possible (1) to evaluate the influence of genetic
correlation on multivariate local adaptation to elevation and (2) to
identify traits probably exposed to past selective pressures due to the
colder climate at high elevation. The genetic correlation was positive but
very weak, indicating that genetic constraints did not shape the local
adaptation pattern for leaf phenology. Both spring and fall (leaf
unfolding and senescence, respectively) phenology timings were involved in
local adaptation, but leaf unfolding was probably the trait most exposed
to climate change-induced selection. Our data indicated that genetic
variation makes a much smaller contribution to adaptation than the
considerable plastic variation displayed by a tree during its lifetime.
The evolutionary potential of leaf phenology is, therefore, probably not
the most critical aspect for short-term population survival in a changing
climate.