Brans, K. I. | bioRxiv Science

bioRxiv2025

Eco-evolutionary feedback of adaptive evolution to a pesticide worsens the impact of a pesticide switch in a pivotal freshwater non-target species

Pest management often requires the switches of insecticides, sequentially exposing non-target populations to different compounds. In a two-phased experiment, we assessed whether exposure to the pesticide chlorpyrifos induces rapid evolution in the non-target species Daphnia magna, and quantified the response of control and pre-exposed populations to a second exposure to the same pesticide, another pesticide with the same mode of action (malathion), or a pesticide with another mode of action (deltamethrin). Chlorpyrifos selection induced rapid shifts in genotype composition and reduced genotype richness, and strongly influenced population development following the second exposure. Chlorpyrifos-selected populations outperformed control populations when subsequently exposed to chlorpyrifos and malathion, but underperformed when exposed to deltamethrin. Our results highlight an eco-evolutionary feedback in which rapid adaptive responses to a pesticide worsens the response when exposed to a different type of pesticide in non-target species, increasing vulnerability to common agricultural practices.

ecology↗

bioRxiv2023

Regional and fine-scale local adaptation in salinity tolerance in Daphnia inhabiting contrasting clusters of inland saline waters

Understanding the spatial scales at which organisms can adapt to strong natural and human-induced environmental gradients is important. Salinisation is a key threat to biodiversity, ecosystem functioning, and the provision of ecosystem services of freshwater systems. Clusters of naturally saline habitats represent ideal test cases to study the extent and scale of local adaptation to salinisation. We studied local adaptation of the water flea Daphnia magna, a key component of pond food webs, to salinity in two contrasting landscapes - a dense cluster of sodic bomb crater ponds and a larger-scale cluster of soda pans. We show regional differentiation in salinity tolerance reflecting the higher salinity levels of soda pans versus bomb crater ponds. We found local adaptation to differences in salinity levels at the scale of tens of metres among bomb crater pond populations but not among geographically more distant soda pan populations. More saline bomb crater ponds showed an upward shift of the minimum salt tolerance observed across clones and a consequent gradual loss of less tolerant clones in a nested pattern. Our results show evolutionary adaptation to salinity gradients at different spatial scales and fine-tuned local adaptation in neighbouring habitat patches in a natural landscape.

evolutionary biology↗