Quantifying eco-evolutionary contributions to trait divergence in spatially structured systems

Ecological and evolutionary processes can occur at similar time scales,
and hence influence one another. There has been much progress in
developing metrics that quantify contributions of ecological and
evolutionary components to trait change over time. However, many empirical
evolutionary ecology studies document trait differentiation among
populations structured in space. In both time and space, the observed
differentiation in trait values among populations and communities can be
the result of interactions between non-evolutionary (phenotypic
plasticity, changes in the relative abundance of species) and evolutionary
(genetic differentiation among populations) processes. However, the tools
developed so far to quantify ecological and evolutionary contributions to
trait changes are implicitly addressing temporal dynamics because they
require directionality of change from an ancestral to a derived state.
Identifying directionality from one site to another in spatial studies of
eco-evolutionary dynamics is not always possible and often not meaningful.
We suggest three modifications to existing partitioning metrics so they
allow quantifying ecological and evolutionary contributions to changes in
population and community trait values across spatial locations in
landscapes. Applying these spatially modified metrics to published
empirical examples shows how these metrics can be used to generate new
empirical insights and to facilitate future comparative analyses. The
possibility to apply eco-evolutionary partitioning metrics to populations
and communities in natural landscapes is critical as it will broaden our
capacity to quantify eco-evolutionary interactions as they occur in
nature.