Connectivity mediates the spatial ecological impacts of a glyphosate-based herbicide in experimental metaecosystems.

Metacommunity ecology has shown that connectivity is important for the persistence of a species locally and across connected ecosystems, however we do not know if ecological effects in freshwater ecosystems exposed to biocides leaking from agriculture depend on metaecosystem connectivity. We experimentally replicated metaecosystems in the laboratory using gradostats as a model system. We tested the effects of connectivity, in terms of node distance from the pollutant-source, flow rate, and a glyphosate-based herbicide, on phytoplankton productivity, diversity and stability. Gradostats were composed of interconnected equally spaced nodes where resources and phytoplankton move directionally along a gradient of increasing distance from the source of the polluting herbicide. We hypothesised that ecological effects would be stronger in the node situated closer to the point of herbicide input, but that flow would suppress phytoplankton populations in distant nodes. Overall, RoundUp impacted phytoplankton productivity and stability by reducing algal biomass and abundances. This occurred especially in the node closest to the diluted herbicide point-source and under high flow, where species abundances were heavily suppressed by the effects of the rapidly flowing herbicide. At low flow on the other hand, distant nodes where buffered from the effects of the slow-moving herbicide. No differences in beta and gamma diversity among replicate metaecosystems was found; however, a significant loss of alpha diversity in all metaecosystems occurred through time until the end of the experiment. Together, these results point to the importance of considering aquatic connectivity in management plans for monitoring and mitigating unintended ecological consequences of agrochemical runoff.

Phenotype-environment mismatch in metapopulations-Implications for the maintenance of maladaptation at the regional scale.

Maladaptation is widespread in natural populations. However, maladaptation has most often been associated with absolute population decline in local habitats rather than on a spectrum of relative fitness variation that can assist natural populations in their persistence at larger regional scales. We report results from a field experiment that tested for relative maladaptation between-pond habitats with spatial heterogeneity and (a)symmetric selection in pH. In the experiment, we quantified relative maladaptation in a copepod metapopulation as a mismatch between the mean population phenotype and the optimal trait value that would maximize mean population fitness under either stable or fluctuating pH environmental conditions. To complement the field experiment, we constructed a metapopulation model that addressed both relative (distance from the optimum) and absolute (negative population growth) maladaptation, with the aim of forecasting maladaptation to pH at the regional scale in relation to spatial structure (environmental heterogeneity and connectivity) and temporal environmental fluctuations. The results from our experiment indicated that maladaptation to pH at the regional scale depended on the asymmetry of the fitness surface at the local level. The results from our metapopulation model revealed how dispersal and (a)symmetric selection can operate on the fitness surface to maintain maladaptive phenotype-environment mismatch at local and regional scales in a metapopulation. Environmental stochasticity resulted in the maintenance of maladaptation that was robust to dispersal, but also revealed an interaction between the asymmetry in selection and environmental correlation. Our findings emphasize the importance of maladaptation for planning conservation strategies that can support adaptive potential in fragmented and changing landscapes.

Conservation through the lens of (mal)adaptation: Concepts and meta-analysis.

Evolutionary approaches are gaining popularity in conservation science, with diverse strategies applied in efforts to support adaptive population outcomes. Yet conservation strategies differ in the type of adaptive outcomes they promote as conservation goals. For instance, strategies based on genetic or demographic rescue implicitly target adaptive population states whereas strategies utilizing transgenerational plasticity or evolutionary rescue implicitly target adaptive processes. These two goals are somewhat polar: adaptive state strategies optimize current population fitness, which should reduce phenotypic and/or genetic variance, reducing adaptability in changing or uncertain environments; adaptive process strategies increase genetic variance, causing maladaptation in the short term, but increase adaptability over the long term. Maladaptation refers to suboptimal population fitness, adaptation refers to optimal population fitness, and (mal)adaptation refers to the continuum of fitness variation from maladaptation to adaptation. Here, we present a conceptual classification for conservation that implicitly considers (mal)adaptation in the short-term and long-term outcomes of conservation strategies. We describe cases of how (mal)adaptation is implicated in traditional conservation strategies, as well as strategies that have potential as a conservation tool but are relatively underutilized. We use a meta-analysis of a small number of available studies to evaluate whether the different conservation strategies employed are better suited toward increasing population fitness across multiple generations. We found weakly increasing adaptation over time for transgenerational plasticity, genetic rescue, and evolutionary rescue. Demographic rescue was generally maladaptive, both immediately after conservation intervention and after several generations. Interspecific hybridization was adaptive only in the F1 generation, but then rapidly leads to maladaptation. Management decisions that are made to support the process of adaptation must adequately account for (mal)adaptation as a potential outcome and even as a tool to bolster adaptive capacity to changing conditions.