More Like this

1. Changes in prey body size differentially reduces predation risk across predator and prey abundances

   https://doi.org/10.1111/oik.09933  

   Hammill, Edd; Hancey, Kayla; Cortez, Michael (April 2023, Oikos)

   Subject Editor: Gregor Kalinkat Editor-in-Chief: Dries Bonte (Ed.)

   Trophic interactions underpin the structure of ecological communities by describing the rates at which consumers exploit their resources. The rates at which predators consume their prey are influenced by prey traits, with many species inducing defensive modifications to prey traits following the threat of predation. Here we use different clonal lines of the protist Paramecium being consumed by Stenostomum predators to highlight how differences in prey traits impact rates of predation. Clonal lines differed in their body width traits, and in their ability to induce changes in body width. By using a factorial cross of predator and prey abundances for different clonal lines we demonstrate how evolutionary or induced alterations in prey traits can impact the relative threat of predation. Our experiments show how interference among predators impacts predation rate, and how increased body width increased predator handling times. Given that reductions in the strength of interspecific interactions are associated with increased levels of overall community stability, our results indicate how individual level changes may scale up to impact whole communities 

   more » « less
2. Evolution of population dynamics following invasion by a non‐native predator

   https://doi.org/10.1002/ece3.9348  

   Einum, Sigurd; Ullern, Emil R.; Walsh, Matthew; Burton, Tim (September 2022, Ecology and Evolution)

   Abstract Invasive predatory species are frequently observed to cause evolutionary responses in prey phenotypes, which in turn may lead to evolutionary shifts in the population dynamics of prey. Research has provided a link between rates of predation and the evolution of prey population growth in the lab, but studies from natural populations are rare. Here, we tested for evolutionary changes in population dynamics parameters of zooplanktonDaphnia pulicariafollowing invasion by the predatorBythotrephes longimanusinto Lake Kegonsa, Wisconsin, US. We used a resurrection ecological approach, whereby clones from pre‐ and post‐invasive periods were hatched from eggs obtained in sediment cores and were used in a 3‐month growth experiment. Based on these data, we estimated intrinsic population growth rates (r), the shape of density dependence (θ) and carrying capacities (K) using theta‐logistic models. We found that post‐invasionDaphniamaintained a higherrandKunder these controlled, predation‐free laboratory conditions. Evidence for changes inθwas weaker. Whereas previous experimental evolution studies of predator–prey interactions have demonstrated that genotypes that have evolved under predation have inferior competitive ability when the predator is absent, this was not the case for theDaphnia. Given that our study was conducted in a laboratory environment and the possibility for genotype‐by‐environment interactions, extrapolating these apparent counterintuitive results to the wild should be done with caution. However, barring such complications, we discuss how selection for reduced predator exposure, either temporally or spatially, may have led to the observed changes. This scenario suggests that complexities in ecological interactions represents a challenge when predicting the evolutionary responses of population dynamics to changes in predation pressure in natural systems. 

   more » « less
3. Predators drive selection for adaptive plasticity in prey defense behavior

   https://doi.org/10.1093/evolut/qpaf004  

   Boys, Wade_A; Lanzer, Tara_L; Ping, Taylor_S; Siepielski, Adam_M; Caruso, ed., Christina; Morlon, ed., Hélène (January 2025, Evolution)

   Abstract Plasticity to reduce activity is a common way prey evade predators. However, by reducing activity prey often experience lower individual growth rates because they encounter their own prey less often. To overcome this cost, natural selection should not simply favor individuals generating stronger plasticity to reduce activity rates but also selection to resume activity once the threat of predation subsides. If such plasticity is adaptive, it should vary under environmental conditions that generate stronger selection for greater plasticity, such as predator density. Using a mesocosm experiment and observational study with a damselfly-prey/fish-predator system, we show that fish predation exerts selection for greater plasticity in activity rates of damselflies. Such selection allows damselfly activity levels to initially decrease and then rebound when the threat of predation dissipates, potentially helping to ameliorate a hypothesized growth penalty from activity reductions. We also find that the extent of plasticity in activity to the threat of fish predation increases, albeit slightly (r2 = 0.04%–0.063%), as fish densities increase across natural lakes, consistent with the idea that the magnitude of plasticity is shaped by environmental conditions underlying selection. Collectively, these results demonstrate how selection acts to drive adaptive plasticity in a common predator avoidance strategy. 

   more » « less
4. The far-reaching effects of genetic process in a keystone predator species, grey wolves

   https://doi.org/10.1126/sciadv.adc8724  

   Hoy, Sarah R.; Hedrick, Philip W.; Peterson, Rolf O.; Vucetich, Leah M.; Brzeski, Kristin E.; Vucetich, John A. (August 2023, Science Advances)

   Although detrimental genetic processes are known to adversely affect the viability of populations, little is known about how detrimental genetic processes in a keystone species can affect the functioning of ecosystems. Here, we assessed how changes in the genetic characteristics of a keystone predator, grey wolves, affected the ecosystem of Isle Royale National Park over two decades. Changes in the genetic characteristic of the wolf population associated with a genetic rescue event, followed by high levels of inbreeding, led to a rise and then fall in predation rates on moose, the primary prey of wolves and dominant mammalian herbivore in this system. Those changes in predation rate led to large fluctuations in moose abundance, which in turn affected browse rates on balsam fir, the dominant forage for moose during winter and an important boreal forest species. Thus, forest dynamics can be traced back to changes in the genetic characteristics of a predator population. 

   more » « less
5. Reactive anti-predator behavioral strategy shaped by predator characteristics

   https://doi.org/10.1371/journal.pone.0256147  

   Palmer, Meredith S.; Packer, Craig (August 2021, PLOS ONE)

   Yue, Bi-Song (Ed.)

   Large mammalian herbivores use a diverse array of strategies to survive predator encounters including flight, grouping, vigilance, warning signals, and fitness indicators. While anti-predator strategies appear to be driven by specific predator traits, no prior studies have rigorously evaluated whether predator hunting characteristics predict reactive anti-predator responses. We experimentally investigated behavioral decisions made by free-ranging impala, wildebeest, and zebra during encounters with model predators with different functional traits. We hypothesized that the choice of response would be driven by a predator’s hunting style (i.e., ambush vs. coursing) while the intensity at which the behavior was performed would correlate with predator traits that contribute to the prey’s relative risk (i.e., each predator’s prey preference, prey-specific capture success, and local predator density). We found that the choice and intensity of anti-predator behaviors were both shaped by hunting style and relative risk factors. All prey species directed longer periods of vigilance towards predators with higher capture success. The decision to flee was the only behavior choice driven by predator characteristics (capture success and hunting style) while intensity of vigilance, frequency of alarm-calling, and flight latency were modulated based on predator hunting strategy and relative risk level. Impala regulated only the intensity of their behaviors, while zebra and wildebeest changed both type and intensity of response based on predator traits. Zebra and impala reacted to multiple components of predation threat, while wildebeest responded solely to capture success. Overall, our findings suggest that certain behaviors potentially facilitate survival under specific contexts and that prey responses may reflect the perceived level of predation risk, suggesting that adaptive functions to reactive anti-predator behaviors may reflect potential trade-offs to their use. The strong influence of prey species identity and social and environmental context suggest that these factors may interact with predator traits to determine the optimal response to immediate predation threat. 

   more » « less