Evolutionary and plastic responses of freshwater invertebrates to climate change: realized patterns and future potential

TLDR

Many studies document temperature‑driven phenological and body‑size shifts in freshwater invertebrates, but evidence that these changes are genetically based, adaptive, and causally linked to climate change is scarce, with only a few replicated common‑garden experiments providing proof. The study integrates evidence for evolutionary and plastic trait changes in situ in freshwater invertebrates in response to climate change. The authors synthesize data from in‑situ observations, experimental thermal evolution, and common‑garden warming studies to assess evolutionary and plastic responses. The synthesis reveals limited adaptive, plastic, or genetic changes to hydroperiod reduction and salinity increase, while thermal evolution and common‑garden experiments suggest that phenotypic plasticity, evolution of plasticity, and genetic photoperiod adjustments contribute to observed phenotypic shifts, with photoperiod changes potentially dominating phenology.

Abstract

Abstract We integrated the evidence for evolutionary and plastic trait changes in situ in response to climate change in freshwater invertebrates (aquatic insects and zooplankton). The synthesis on the trait changes in response to the expected reductions in hydroperiod and increases in salinity indicated little evidence for adaptive, plastic, and genetic trait changes and for local adaptation. With respect to responses to temperature, there are many studies on temporal trait changes in phenology and body size in the wild that are believed to be driven by temperature increases, but there is a general lack of rigorous demonstration whether these trait changes are genetically based, adaptive, and causally driven by climate change. Current proof for genetic trait changes under climate change in freshwater invertebrates stems from a limited set of common garden experiments replicated in time. Experimental thermal evolution experiments and common garden warming experiments associated with space‐for‐time substitutions along latitudinal gradients indicate that besides genetic changes, also phenotypic plasticity and evolution of plasticity are likely to contribute to the observed phenotypic changes under climate change in aquatic invertebrates. Apart from plastic and genetic thermal adjustments, also genetic photoperiod adjustments are widespread and may even dominate the observed phenological shifts.