Abstract:The ability of populations to rapidly adapt to new environments will determine their future in an increasingly human-modified world. Although meta-analyses do frequently uncover signatures of local adaptation, they also reveal many exceptions. We suggest that particular constraints on local adaptation might arise when organisms are exposed to novel stressors, such as anthropogenic pollution. To inform this possibility, we studied the extent to which guppies (Poecilia reticulata) show local adaptation to oil po… Show more
“…No differences in survival and growth were found over a 6-day period. However, guppies from an unpolluted river in the north had a small, but significant, reduction in survival and growth in the polluted river [27]. The small difference in survival in that study provided little evidence for adaptation.…”
Section: The Trinidad Guppy (Poecilia Reticulata) As a Model To Studymentioning
confidence: 82%
“…Figure 1.Distribution of alleles for a DNA microsatellite within the CYP1A gene for guppies living in four rivers in Trinidad. The Vance and Morne rivers are unconnected by freshwater and have stretches that are heavily contaminated with crude oil, described in [27]. Within each polluted river, data are pooled for populations from unpolluted and polluted stretches as no frequency differences were observed.…”
Section: The Trinidad Guppy (Poecilia Reticulata) As a Model To Studymentioning
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’.
“…No differences in survival and growth were found over a 6-day period. However, guppies from an unpolluted river in the north had a small, but significant, reduction in survival and growth in the polluted river [27]. The small difference in survival in that study provided little evidence for adaptation.…”
Section: The Trinidad Guppy (Poecilia Reticulata) As a Model To Studymentioning
confidence: 82%
“…Figure 1.Distribution of alleles for a DNA microsatellite within the CYP1A gene for guppies living in four rivers in Trinidad. The Vance and Morne rivers are unconnected by freshwater and have stretches that are heavily contaminated with crude oil, described in [27]. Within each polluted river, data are pooled for populations from unpolluted and polluted stretches as no frequency differences were observed.…”
Section: The Trinidad Guppy (Poecilia Reticulata) As a Model To Studymentioning
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’.
“…However, local adaptation to pollution may be weak if chronic stress levels lead to small populations and/or there is high gene flow between different sites (Rolshausen et al. ), which may be the case in the stream ecosystems we studied. Although it is highly likely that both ecological and evolutionary processes determine community structure, we cannot disentangle these factors as we only assessed structural differences in communities, not phenotypic or genetic changes in responding taxa.…”
Human land uses and population growth represent major global threats to biodiversity and ecosystem services. Understanding how biological communities respond to multiple drivers of human‐induced environmental change is fundamental for conserving ecosystems and remediating degraded habitats. Here, we used a replicated ‘real‐world experiment’ to study the responses of invertebrate communities to wastewater perturbations across a land‐use intensity gradient in 12 Swiss streams. We used different taxonomy and trait‐based community descriptors to establish the most sensitive indicators detecting impacts and to help elucidate potential causal mechanisms of change. First, we predicted that streams in catchments adversely impacted by human land‐uses would be less impaired by wastewater inputs because their invertebrate communities should be dominated by pollution‐tolerant taxa (‘environmental context’). Second, we predicted that the negative effects of wastewater on stream invertebrate communities should be larger in streams that receive proportionally more wastewater (‘magnitude of disturbance’). In support of the ‘environmental context’ hypothesis, we found that change in the Saprobic Index (a trait‐based indicator of tolerance to organic pollution) was associated with upstream community composition; communities in catchments with intensive agricultural land uses (e.g., arable cropping and pasture) were generally more resistant to eutrophication associated with wastewater inputs. We also found support for the ‘magnitude of disturbance’ hypothesis. The SPEAR Index (a trait‐based indicator of sensitivity to pesticides) was more sensitive to the relative input of effluent, suggesting that toxic influences of wastewater scale with dilution. Whilst freshwater pollution continues to be a major environmental problem, our findings highlight that the same anthropogenic pressure (i.e., inputs of wastewater) may induce different ecological responses depending on the environmental context and community metrics used. Thus, remediation strategies aiming to improve stream ecological status (e.g., rehabilitating degraded reaches) need to consider upstream anthropogenic influences and the most appropriate indicators of restoration success.
“…The selection experiments in this study used similar approaches as prior studies, with similar starting population size (hundreds of copepods). Difficulties in inducing an evolutionary response to crude oil was also found in populations of Trinidad guppies, where populations from oil‐polluted tributaries showed little evidence of local adaptation in survival and growth (Rolshausen et al., 2015). …”
Section: Discussionmentioning
confidence: 99%
“…In an older study, imposing crude oil exposure for 2–10 days in marine gastropods revealed allele frequency shifts at two allozyme loci, suggesting an evolutionary response to crude oil, though the functional implications of these allele frequency shifts are unclear (Nevo & Lavie, 1989). In a comparison between populations of the Trinidad guppy Poecilia reticulate in oil‐polluted versus unpolluted streams, populations in oil‐polluted habitats showed little evidence for adaptation to oil pollution, but were actually maladapted to their local environment (Rolshausen et al., 2015). An intriguing comparative study found that the Gulf killifish Fundulus grandis at an oil‐contaminated site in the Gulf of Mexico exhibited changes in genome expression and larval CYP1A enzyme expression (a biomarker for PAH exposure) that was divergent from fish from uncontaminated sites, 1–4 months after the oil spill (Whitehead, Dubansky, et al.…”
The BP Deepwater Horizon Oil Disaster was the most catastrophic offshore oil spill in U.S. history, yet we still have a poor understanding of how organisms could evolve in response to the toxic effects of crude oil. This study offers a rare analysis of how fitness‐related traits could evolve rapidly in response to crude oil toxicity. We examined evolutionary responses of populations of the common copepod Eurytemora affinis residing in the Gulf of Mexico, by comparing crude oil tolerance of populations collected before versus after the Deepwater Horizon oil spill of 2010. In addition, we imposed laboratory selection for crude oil tolerance for ~8 generations, using an E. affinis population collected from before the oil spill. We found evolutionary increases in crude oil tolerance in the wild population following the oil spill, relative to the population collected before the oil spill. The post‐oil spill population showed increased survival and rapid development time in the presence of crude oil. In contrast, evolutionary responses following laboratory selection were less clear; though, development time from metamorphosis to adult in the presence of crude oil did become more rapid after selection. We did find that the wild population, used in both experiments, harbored significant genetic variation in crude oil tolerance, upon which selection could act. Thus, our study indicated that crude oil tolerance could evolve, but perhaps not on the relatively short time scale of the laboratory selection experiment. This study contributes novel insights into evolutionary responses to crude oil, in directly examining fitness‐related traits before and after an oil spill, and in observing evolutionary responses following laboratory selection.
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