Data from: Experimental evidence for an eco-evolutionary coupling between local adaptation and intraspecific competition

Determining how adaptive evolution can be coupled to ecological processes
is key for developing a more integrative understanding of the demographic
factors that regulate populations. Intraspecific competition is an
especially important ecological process because it generates negative
density dependence in demographic rates. Although ecological factors are
most often investigated to determine the strength of density dependence,
evolutionary processes such as local adaptation could also feed back to
shape variation in the strength of density dependence among populations.
Using an experimental approach with damselflies, a predaceous aquatic
insect, we find evidence that both density-dependent intraspecific
competition and local adaptation can reduce per capita growth rates. In
some cases, the effects of local adaptation on reducing per capita growth
rates exceeded the ecological competitive effects of a doubling of
density. However, we also found that these ecological and evolutionary
properties of populations are coupled, and we offer two interpretations of
the causes underlying this pattern: (1) the strength of density-dependent
competition depends on the extent of local adaptation, or (2) the extent
of local adaptation is shaped by the strength of density-dependent
competition. Regardless of the underlying causal pathway, these results
show how eco-evolutionary dynamics can affect a key demographic process
regulating populations.