Ecological pleiotropy and indirect effects alter the potential for evolutionary rescue

Abstract

Invading predators can negatively affect naïve prey populations due to a lack of evolved defenses. Many species therefore may be at risk of extinction due to overexploitation by exotic predators. Yet the strong selective effect of predation might drive evolution of imperiled prey toward more resistant forms, potentially allowing the prey to persist. We evaluated the potential for evolutionary rescue in an imperiled prey using Gillespie eco‐evolutionary models (GEMs). We focused on a system parameterized for protists where changes in prey body size may influence intrinsic rate of population growth, space clearance rate (initial slope of the functional response), and the energetic benefit to predators. Our results show that the likelihood of rescue depends on (a) whether multiple parameters connected to the same evolving trait (i.e., ecological pleiotropy) combine to magnify selection, (b) whether the evolving trait causes negative indirect effects on the predator population by altering the energy gain per prey, (c) whether heritable trait variation is sufficient to foster rapid evolution, and (d) whether prey abundances are stable enough to avoid very rapid extinction. We also show that when evolution fosters rescue by increasing the prey equilibrium abundance, invasive predator populations also can be rescued, potentially leading to additional negative effects on other species. Thus, ecological pleiotropy, indirect effects, and system dynamics may be important factors influencing the potential for evolutionary rescue for both imperiled prey and invading predators. These results suggest that bolstering trait variation may be key to fostering evolutionary rescue, but also that the myriad direct and indirect effects of trait change could either make rescue outcomes unpredictable or, if they occur, cause rescue to have side effects such as bolstering the populations of invasive species.

Functional responses are maximized at intermediate temperatures

“…Effects of body mass are among the most studied of these factors, with strong evidence showing that consumer mass, resource mass, or consumer:resource mass ratio affect both space clearance rate and handling times. Typically, space clearance rate increases and handling time decreases as consumer size or consumer:resource mass ratio increases (Gergs and Ratte , Vucic‐Pestic et al , DeLong and Vasseur , Rall et al , Kalinoski and DeLong , Hirt et al , Uiterwaal and DeLong , DeLong and Belmaker ). This is generally attributed to the increased ability of larger consumers to cover ground, detect resources from farther away, and successfully attack resources (McGill and Mittelbach ).…”

Exploring evolution of maximum growth rates in plankton

“…Conversely, in an environment where conditions are severe more frequently, as expected under climate change ( Doney et al ., 2012 ; Thornton et al ., 2014 ), μ mRT evolves downwards ( Figs. 5 , 9 and 10B and F ); evolution under climate change would then decrease production but enhance the prevention of extinction through evolutionary rescue ( Bell, 2013 ; DeLong and Belmaker, 2019 ).…”

Prey diversity constrains the adaptive potential of predator foraging traits

“…We use GEMs, implemented in Matlab, to conduct our simulations. GEMs are a simple modification of the standard Gillespie algorithm (DeLong and Gibert 2016, DeLong and Belmaker 2019). In short, GEMs transform the rate terms of ODEs into discrete ‘events,' such as births and death by predation, and use these events to update population sizes and trait distributions through time.…”