Garreau, A. | Search bioRxiv

bioRxiv2023

Thermal environment and ecological interactions modulate the importance of evolution in response to warming

Understanding the interaction between evolutionary history, the current abiotic environment, and biotic interactions is critical for a more nuanced understanding of the response of communities to anthropogenic stressors. We leveraged a long term experiment manipulating temperature in mesocosms containing communities of phytoplankton and zooplankton to examine how evolution in response to long-term community warming affects consumer-resource dynamics at different temperatures. We showed that the evolution in response to warming depends on both the current thermal environment, as well as the presence of interactions between consumers and resources. We also demonstrated that evolution influences the outcomes of current ecological dynamics. For each consumer-resource pair, the effects of evolution were temperature-dependent, but both the effects and the temperature dependence itself additionally depended upon the identity of evolving species in each pair. Evolution resulted on a win-win situation for the first resource species: across all temperatures, this resource was more fit and the consumer was less successful, with fitness gains peaking at intermediate temperatures. For this resource species our results supported the "hotter is better" hypothesis, especially at moderate or intermediate temperatures, while "hotter is worse" for the consumer. In the second species pair, patterns were more complex. Warm-origin populations of both the second resource and the consumer generally failed to show improved fitness. Overall, our results show that evolution altered resource and consumer fitness, but these effects were dependent on the current combination of abiotic and biotic conditions.

ecology↗

bioRxiv2020

Intraspecific diversity loss in a predator species alters prey community structure and ecosystem functions

AO_SCPLOWBSTRACTC_SCPLOWLoss in intraspecific diversity can alter ecosystem functions, but the underlying mechanisms are still elusive, and intraspecific biodiversity-ecosystem function relationships (iBEF) have been restrained to primary producers. Here, we manipulated genetic and functional richness of a fish consumer (Phoxinus phoxinus), to test whether iBEF relationships exist in consumer species, and whether they are more likely sustained by genetic or functional richness. We found that both genotypic and functional richness affected ecosystem functioning, either independently or in interaction. Loss in genotypic richness reduced benthic invertebrate diversity consistently across functional richness treatments, whereas it reduced zooplankton diversity only when functional richness was high. Finally, both losses in genotypic and functional richness altered essential functions (e.g. decomposition) through trophic cascades. We concluded that iBEF relationships lead to substantial top-down effects on entire food chains. The loss of genotypic richness impacted ecological properties as much as the loss of functional richness, probably because it sustains "cryptic" functional diversity.

ecology↗