Adaptive capabilities and fitness consequences associated with pollution exposure in fish

Abstract

Many fish populations are exposed to harmful levels of chemical pollution and selection pressures associated with these exposures have led to the evolution of tolerance. Our understanding of the physiological basis for these adaptations is limited, but they are likely to include processes involved with the absorption, distribution, metabolism and/or excretion of the target chemical. Other potential adaptive mechanisms include enhancements in antioxidant responses, an increased capacity for DNA and/or tissue repair and alterations to the life cycle of fish that enable earlier reproduction. Analysis of single-nucleotide polymorphism frequencies has shown that tolerance to hydrocarbon pollutants in both marine and estuarine fish species involves alteration in the expression of the xenobiotic metabolism enzyme CYP1A. In this review, we present novel data showing also that variants of the CYP1A gene have been under selection in guppies living in Trinidadian rivers heavily polluted with crude oil. Potential costs associated with these adaptations could reduce fitness in unpolluted water conditions. Integrating knowledge of local adaptation to pollution is an important future consideration in conservation practices such as for successful restocking, and improving connectivity within river systems.This article is part of the themed issue ‘Human influences on evolution, and the ecological and societal consequences’.

Human influences on evolution, and the ecological and societal consequences

“…urbanization [27]), strong abiotic stressors (e.g. pollution [23,24]) and strong biotic stressors (e.g. invasive predators/parasites [34] and emerging diseases [38]).…”

“…The evolution of such enemies is correspondingly very common, rapid and dramatic [79][80][81][82][83][84]. Another context where genetic changes might be especially important is pollution-because the selection pressures often involve novel chemicals for which existing adaptive plasticity is unlikely [3,23]. Regardless of the context, the relative contributions of plasticity and genetic change should vary through time.…”

“…Introductions can also increase or decrease biodiversity by altering patterns of gene flow, hybridization and gene flow within and among species [94,98]. Other contexts that merit special mention are fragmentation, which imposes strong selection and increases evolutionary independence [27,91], and urbanization and pollution, which create especially novel environments [3,23,25,99].…”

Endocrine disruption in aquatic systems: up‐scaling research to address ecological consequences

“…Varying levels of resistance were found across several populations. Adaptation has also been observed within fish assemblages (Hamilton et al, 2016b). Both the Atlantic tomcod (Microgadus tomcod Walbaum) and the Atlantic killifish (Fundulus heteroclitus L.) can adapt to polycyclic aromatic hydrocarbon (PAH) and PCB exposure in natural systems (Clark et al, 2010;Wirgin et al, 2011), but through different mechanisms.…”

Turning natural adaptations to oncogenic factors into an ally in the war against cancer

“…For example, large amounts of standing genetic diversity may be an important factor facilitating rapid adaptations, as observed in the Atlantic killifish (Reid et al., , ). Distinguishing between physiological acclimation and evolutionary heritable changes is also crucial (e.g., Fisker, Sørensen, Damgaard, Pedersen, & Holmstrup, ; Hamilton, Rolshausen, Webster, & Tyler, ; Mousseau & Møller, ). Moreover, we need to determine the extent to which species, when naturally or artificially exposed to EOF, are selected (i) to better handle toxic compounds in the body, (ii) to limit their fitness impact through an adjustment of life‐history traits, and/or (iii) to select mechanisms that limit the occurrence and progression of EOF‐induced diseases, like cancer.…”