Code and data for: The difficulty of predicting evolutionary change in response to novel ecological interactions: a field experiment with Anolis lizards

Determining whether and how evolution is predictable is an important goal,
particularly as anthropogenic disturbances lead to novel species
interactions that could modify selective pressures. Here, we use a
multi-generation field experiment with brown anole lizards (Anolis sagrei)
to test hypotheses about the predictability of evolution. We manipulated
the presence and absence of predators and competitors across 16 islands in
the Bahamas with preexisting brown anole populations. Before the
experiment and again after roughly five generations, we measured traits
related to locomotory performance and habitat use of brown anoles and used
ddRAD sequencing to estimate genome-wide changes in allele frequencies.
Although previous work showed that predators and competitors had
consistent effects on brown anole behavior, diet, and population sizes, we
found that evolutionary change at both phenotypic and genomic levels was
difficult to forecast. Phenotypic changes were contingent on sex and
habitat use, whereas genetic change was unpredictable and not measurably
correlated with phenotypic changes, experimental treatments, or other
environmental factors. Our work shows how differences in ecological
context can alter evolutionary outcomes over short timescales and
underscores the difficulty of forecasting evolutionary responses to
multi-species interactions in natural conditions, even in a well-studied
system with ample ecological information.