DOI: 10.5061/dryad.w6m905qn7
title: Data from: Competitive history shapes rapid evolution in a seasonal climate

description: Eco-evolutionary dynamics will play a critical role in determining
 species’ fates as climatic conditions change. Unfortunately, we have
 little understanding of how rapid evolutionary responses to climate play
 out when species are embedded in the competitive communities that
 they inhabit in nature. We tested the effects of rapid evolution
 in response to interspecific competition on subsequent ecological and
 evolutionary trajectories in a seasonally changing climate using a
 field-based evolution experiment with Drosophila melanogaster. Populations
 of D. melanogaster were either exposed, or not exposed, to interspecific
 competition with an invasive competitor, Zaprionus indianus, over the
 summer. We then quantified these populations’ ecological trajectories
 (abundances) and evolutionary trajectories (heritable phenotypic change)
 when exposed to a cooling fall climate. We found that competition with Z.
 indianus in the summer affected the subsequent evolutionary trajectory of
 D. melanogaster populations in the fall, after all interspecific
 competition had ceased. Specifically, flies with a history of
 interspecific competition evolved under fall conditions to be larger, have
 lower cold fecundity and faster development than flies without a history
 of interspecific competition. Surprisingly, this divergent fall
 evolutionary trajectory occurred in the absence of any detectible effect
 of the summer competitive environment on phenotypic evolution over the
 summer or population dynamics in the fall. This study demonstrates that
 competitive interactions can leave a legacy that shapes evolutionary
 responses to climate even after competition has ceased, and more broadly,
 that evolution in response to one selective pressure can fundamentally
 alter evolution in response to subsequent agents of selection.
description: We tested how rapid evolution in response to interspecific
 competition influences ecological and evolutionary dynamics in a seasonal
 climate using a large-scale experimental evolution study in the field with
 the vinegar fly <i>Drosophila melanogaster</i> and its
 invasive competitor <i>Zaprionus indianus</i>. We conducted
 our experimental evolution study with replicate fly populations on caged
 peach trees planted in an experimental orchard that mimics our focal
 species’ primary Northeastern U.S. habitat. These field mesocosms
 experience natural temperature fluctuations and contain many of the
 predators and microbes that co-occur with local natural populations of
 <i>D. melanogaster</i>. To examine the consequences of rapid
 evolution in response to interspecific competition on ecological and
 evolutionary dynamics in the fall, we first allowed replicate populations
 of <i>D. melanogaster</i> to grow and evolve in the presence
 or absence of <i>Z. indianus</i> for ~6 generations over the
 summer (Fig. 1). At the end of summer, we removed <i>Z.
 indianus</i>, equalized abundances of <i>D.
 melanogaster</i> across populations, and allowed these populations
 with or without a history of interspecific competition to continue their
 ecological and evolutionary dynamics throughout the fall (~3 generations).
 We quantified the ecological (population dynamic) consequences of the
 summer competitive environment with weekly censuses of fly abundance
 through the fall, after all competition with <i>Z. indianus
 </i>had ceased. We quantified the evolutionary consequences of our
 treatments by measuring ten key phenotypes on <i>D.
 melanogaster</i> collected at the end of summer and end of the fall
 and then reared for two generations in a common garden to remove any
 plastic responses to treatments or field conditions. The ten phenotypes
 were: body size (female and male), early life fecundity (warm [25°C] and
 cold [15°C] conditions) and larval development speed and egg viability,
 each under three different conditions (Behrman<i> et al.</i>
 2015; Rudman<i> et al.</i> 2019) (details in SI Appendix). The
 three conditions for larval development speed and egg viability were (1)
 cold (15°C) low density (50 eggs), (2) warm (25°C) low density and (3)
 warm high density (500 eggs).