DOI: 10.5061/dryad.xgxd254hh
title: Rapid evolution of life history traits in response to warming, predation and competition: a meta-analysis

description: 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.
description: In August 2020, we searched the Web of Science for papers that
 included (“evolution” OR “adaptation”) AND (“temperature” OR “warming” OR
 “thermal” OR “predators” OR “predation” or “competition” or “competitors”)
 in the title. This returned 595 results, all of which were assessed for
 inclusion (detailed search methods in Supporting Information). We then
 searched 20 previous reviews and meta-analyses on related topics for
 additional studies that met our inclusion criteria (see list in Supporting
 Information). Finally, we searched all of the studies that met our
 inclusion criteria for further studies to include. We
 used the following criteria to determine inclusion in our meta-analysis.
 Studies had to: (1) quantify evolutionary change in response to one or
 more of our three focal selective agents (temperature, predation,
 competition) (2) compare at least one group that we could use as a control
 group (e.g. lower temperature, no predation, no competition) to at least
 one group that we could use as a treatment group (e.g. higher temperature,
 predator present, competitor present) (3) measure at least one of our
 three focal life history traits (body size, development rate, fecundity)
 in both the control and treatment group, and (4) seperate evolutionary
 change from maternal effects and plasticity by growing individuals under
 common conditions for at least one generation (i.e., a common
 garden). We included both “experimental” studies in
 which the selective agent was imposed by the researcher either in the lab
 or in the field (e.g., experimentally imposed presence or absence of a
 predator) and “natural” studies in which the selective agent varied
 naturally across space or time (e.g., comparison of streams with predators
 to streams without). We excluded studies that focused on evidence from the
 fossil record, but placed no other restrictions on study duration and
 instead included the number of generations of selection in our models to
 determine whether this affected the outcome of evolution (see Data
 Analysis). We restricted competition studies to those that focused on
 resource competition (i.e., no mate competition). We also excluded studies
 for which it was not clear that the selective agent of interest was the
 principal factor driving trait change (e.g., studies that assessed trait
 change across latitudinal or urbanization gradients as a proxy for
 temperature change). Our inclusion criteria resulted in the exclusion of
 rapid evolution studies that focused on the effects of other environmental
 variables (e.g., drought, CO<sub>2</sub>), other biotic
 interactions (e.g., disease, mutualisms), or other anthropogenic changes
 (e.g., fish harvesting, habitat fragmentation). Our criteria also excluded
 studies that used population growth rate rather than life history traits
 as the response, that did not separate plastic from heritable responses,
 that used selective mortality or selection gradients as the response, or
 that imposed artificial selection. Details of our study selection criteria
 are provided in the Supporting Information. Our
 selection criteria resulted in a dataset of 58 studies focused on
 animals. The 58 remaining studies encompassed 33 focal species (14 aquatic
 and 19 terrestrial) spanning 15 orders (Fig. S1). All but two of the
 included studies were conducted with ectothermic organisms (the exceptions
 were studies with rabbits (Williams & Moore 1989) and mice
 (Barnett & Dickson 1984)). Many of the 58 studies measured
 multiple life history traits, included multiple focal species, or assessed
 the effect of multiple selective agents, and thus our final dataset
 included 124 unique effect sizes (data points).
description: See "Explanations" tab in excel file.