Rapid evolution of life history traits in response to warming, predation and competition: a meta-analysis

Although studies quantifying evolutionary change in response to the
selective pressures that organisms face in the wild have demonstrated that
organisms can evolve rapidly, we lack a systematic assessment of the
frequency, magnitude and direction of rapid evolutionary change across
taxa. To address this gap, we conducted a meta-analysis of 58 studies that
document the effects of warming, predation or competition on the evolution
of body size, development rate or fecundity in natural or experimental
animal populations. We tested whether there was a consistent effect of any
selective agent on any trait, whether the direction of these effects align
with theoretical predictions, and whether the three agents select in
opposing directions on any trait. Overall, we found weak effects of all
three selective agents on trait evolution: none of our nine trait by
selective agent combinations had an overall effect that differed from
zero, only 31% of studies had a significant within-study effect, and
attributes of the included studies generally did not account for
between-study variation in results. One notable exception was that
predation targeting adults consistently resulted in the evolutoin of
smaller prey body size. We discuss potential causes of these generally
weak responses and consider how our results inform the ongoing development
of eco-evolutionary research.