Evolutionary responses of marine organisms to urbanized seascapes

Abstract

Many of the world's major cities are located in coastal zones, resulting in urban and industrial impacts on adjacent marine ecosystems. These pressures, which include pollutants, sewage, runoff and debris, temperature increases, hardened shorelines/structures, and light and acoustic pollution, have resulted in new evolutionary landscapes for coastal marine organisms. Marine environmental changes influenced by urbanization may create new selective regimes or may influence neutral evolution via impacts on gene flow or partitioning of genetic diversity across seascapes. While some urban selective pressures, such as hardened surfaces, are similar to those experienced by terrestrial species, others, such as oxidative stress, are specific to aquatic environments. Moreover, spatial and temporal scales of evolutionary responses may differ in the ocean due to the spatial extent of selective pressures and greater capacity for dispersal/gene flow. Here, we present a conceptual framework and synthesis of current research on evolutionary responses of marine organisms to urban pressures. We review urban impacts on genetic diversity and gene flow and examine evidence that marine species are adapting, or are predicted to adapt, to urbanization over rapid evolutionary time frames. Our findings indicate that in the majority of studies, urban stressors are correlated with reduced genetic diversity. Genetic structure is often increased in urbanized settings, but artificial structures can also act as stepping stones for some hard‐surface specialists, promoting range expansion. Most evidence for rapid adaptation to urban stressors comes from studies of heritable tolerance to pollutants in a relatively small number of species; however, the majority of marine ecotoxicology studies do not test directly for heritability. Finally, we highlight current gaps in our understanding of evolutionary processes in marine urban environments and present a framework for future research to address these gaps.

Holistic Impact Evaluation of Human Activities on the Coastal Fish Biodiversity in the Chinese Coastal Environment

“…For instance, excessive Zn significantly changes the expression of fish-related developmental genes, thereby changing the sequence diversity of fish. Here, we found that fish sequence diversity had stronger association with environmental factors than the other two diversity facets in the YLJK, which also showed that estuarine pollution from urbanized settings may primarily affect the sequence diversity of fish . Actually, the no breeding areas can be regarded as a diversity protection measure of the coastal governments.…”

Cities of the Anthropocene: urban sustainability in an eco-evolutionary perspective

“…Examples of mechanisms that link GBI and eco-evolutionary dynamics are the effects of climate change, heat islands, pests and herbivory, which drive evolutionary changes in photosynthetic, tree growth and plant defence traits that affect the ability of trees to capture carbon or mitigate air pollution [82,110]. Other examples include the effects of urban heat islands on zooplankton (which might determine urban water pollution) [84], the adaptation of wetland vegetation (which may affect nutrient cycling and flood mitigation) [126] and the adaptation of marine algae and invertebrates to pollutants (which may affect marine ecosystem function and food webs) [110,127]. Because evolutionary changes in species traits may have substantial consequences on ecosystem functions, it is crucial to understand and incorporate evolutionary processes into the design and implementation of GBI (figure 3).…”

Urban evolution comes into its own: Emerging themes and future directions of a burgeoning field

“…Alter et al. (2020) raise several emerging themes in urban marine research, echoing themes in terrestrial research—impacts of pollutants, convergence in trait shifts, spatial heterogeneity, the implications of genetic structure, and provide a conceptual framework for guiding future studies on urban evolution in marine systems.…”

“…this emerging and understudied area of urban evolutionary study,Alter et al (2020) present a synthesis of the myriad ways urbanization influences marine organisms from a broad swath of taxa including macroalgae, invertebrates, and fishes. The marine environment is impacted by urbanization in similar or analogous ways as terrestrial environments.…”