Change in prey genotype frequency rescues predator from extinction

Abstract

Indirect evolutionary rescue (IER) is a mechanism where a non-evolving species is saved from extinction in an otherwise lethal environment by evolution in an interacting species. This process has been described in a predator–prey model, where extinction of the predator is prevented by a shift in the frequency of defended towards undefended prey when reduced predator densities lower selection for defended prey. We test here how increased mortality and the initial frequencies of the prey types affect IER. Combining the analysis of model simulations and experiments with rotifers feeding on algae we show IER in the presence of increased predator mortality. We found that IER was dependent on the ability of the prey to evolve as well as on the frequency of the defended prey. High initial frequencies of defended prey resulted in predator extinction despite the possibility for prey evolution, as the increase in undefended prey was delayed too much to allow predator rescue. This frequency dependency for IER was more pronounced for higher predator mortalities. Our findings can help informing the development of conservation and management strategies that consider evolutionary responses in communities to environmental changes.

Tracking the frequency of phytoplankton clonal lineages using multispectral image flow cytometry and neural networks

“…Evolutionary rescue studies, in which an increase in the frequency of a genotype rescues a population from extinction in a detrimental environment, could go beyond observing a u‐shaped change in population size (Carlson et al., 2014; Gomulkiewicz & Holt, 1995) by also showing changes in frequency of lineages within the rescued population. This requires that the phenotype of the lineage is known, and that the lineage is at low frequencies at the start of the experiment (Hermann & Becks, 2022), as training data are required. With recent advances in anomaly detection in ML, this may also be possible for unknown phenotypes by implementing tools for anomaly detection (Pang et al., 2021; Ruff et al., 2021).…”

“…This is particularly important for microbial and plankton systems where reproduction is often clonal and evolutionary dynamics are strongly affected by clonal interference, genetic hitchhiking and constraints arising from linkage (Lang et al, 2013). Current methods for tracking clonal lineages in microbial and plankton systems include re-isolation of individuals and classification based on morphology with and without regrowth of clonal cultures (da Silva & Bell, 1996;Hermann & Becks, 2022), genotyping of individual isolates (Werner & Mergenhagen, 1998), inferring frequencies from trait means in a population (Becks et al, 2012), using fluorescent markers, quantitative PCR and digital droplet PCR when lineage-specific sequences are known (Carrasco et al, 2007;Koch et al, 2016;Meyer et al, 2006). These methods are often labour intensive (e.g.…”

Temporal changes in the role of species sorting and evolution determine community dynamics

“…Our study suggests that the temporal dynamics of the relative roles of ecology and evolution may be driven by the presence of phenotypic/trait variation in the direction of selection, and that evolution becomes more important in the absence of variation within the species pool. Consequently, identifying the conditions under which we can predict the convergence of ecological and evolutionary timescales requires an understanding of the direction of selection and the variation in traits (Hermann et al, 2024;Hermann & Becks, 2022;Scheuerl et al, 2019) and/or the underlying genetics under selection (Barbour et al, 2022;Blanchet et al, 2023;Pantel & Becks, 2023;Yamamichi, 2022).…”

Geographic variation in evolutionary rescue in a predator-prey system under climate change: an example with aphids and ladybird beetles

“…In our system, if only the prey evolves in response to climate change, predators will not be rescued. The “indirect evolutionary rescue” (IER) mechanism does not not seem to occur, whereby a non-evolving predator can be rescued from extinction solely due to the evolution of its prey (Yamamichi and Miner, 2015; Hermann and Becks, 2022). The IER mechanism assumes the defense cost for prey against predation relies on the predator density.…”