Urban Environments Promote Adaptation to Multiple Stressors

Abstract

Anthropogenic activities have drastically changed environmental conditions worldwide, negatively impacting biodiversity and ecosystem services. At the same time, the majority of the human population lives in urban areas that are greatly altered from natural habitats. Nevertheless, many species thrive in these urban environments. To improve our knowledge of evolution and adaptation in these anthropogenically impacted habitats, we conducted the widest series of stress experiments to date with three marine taxa: one mussel and two gammarid species. We compared intraspecific populations from protected and human-altered habitats to determine their tolerance to salinity, temperature and partial pressure of CO₂ in water (pCO₂) regimes. Populations from impacted habitats typically outperformed protected habitat populations, with individuals from the most impacted habitat being the most robust. We propose that urban populations are adapting to life in disturbed environments-this adaptation concurrently promotes more resilient rescue populations but potentially confers increased invasion risk from non-native species.

Keywords: aquatic ecosystem; environmental change; land use; pCO2; salinity; temperature.

FIGURE 1

Sampling locations used in the study, where individuals of species populations were collected. Schleimünde served as the protected site, whereas Falckenstein beach, Kiel canal and downtown Kiel served as human‐altered sites.

FIGURE 2

Percentage mortality for Mytilus sp. from protected and human‐altered habitats for the temperature‐pCO₂ experiment (left) and the temperature‐salinity experiment (right).

FIGURE 3

Percentage mortality for Gammarus locusta from protected and human‐altered habitats for the temperature‐pCO₂ experiment (left) and the temperature‐salinity experiment (right).

FIGURE 4

Percentage mortality for Gammarus salinus from protected and human‐altered habitats for the temperature‐pCO₂ experiment (left) and the temperature‐salinity experiment (right).