Abstract-Maintaining the viability of populations of plants and animals is a key focus for environmental regulation. Population-level responses integrate the cumulative effects of chemical stressors on individuals as those individuals interact with and are affected by their conspecifics, competitors, predators, prey, habitat, and other biotic and abiotic factors. Models of population-level effects of contaminants can integrate information from lower levels of biological organization and feed that information into higher-level community and ecosystem models. As individual-level endpoints are used to predict population responses, this requires that biological responses at lower levels of organization be translated into a form that is usable by the population modeler. In the current study, we describe how mechanistic data, as captured in adverse outcome pathways (AOPs), can be translated into modeling focused on population-level risk assessments. First, we describe the regulatory context surrounding population modeling, risk assessment and the emerging role of AOPs. Then we present a succinct overview of different approaches to population modeling and discuss the types of data needed for these models. We describe how different key biological processes measured at the level of the individual serve as the linkage, or bridge, between AOPs and predictions of population status, including consideration of community-level interactions and genetic adaptation. Several case examples illustrate the potential for use of AOPs in population modeling and predictive ecotoxicology. Finally, we make recommendations for focusing toxicity studies to produce the quantitative data needed to define AOPs and to facilitate their incorporation into population modeling. Environ. Toxicol. Chem. 2011;30:64-76. # 2010 SETAC

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Nine out of 57 bovine and caprine microsatellites investigated have proved polymorphic in roe deer populations from Central Europe. The polymorphism of four to nine microsatellites (with two to 16 alleles each) has been screened in 492 roe deer from 27 sample locations in Germany, the Netherlands and France, and 10 allozyme loci have been investigated in 118 roe deer from Germany. These studies have revealed a genetically homogeneous population, but with a local scatter of allele frequencies. The mean genetic distance among sample pairs, and the overall fixation index for the 27 population samples were D=0.1638 and GST=0.0972 for four microsatellite loci, and D=0.0598 and GST=0.1459 for 10 allozyme loci. No isolation‐by‐distance was observed. Roe deer from isolated habitats could be distinguished by various measures of genetic variability. The expected heterozygosity and the allelic diversity were higher in male than in female roe deer, but mean genetic distances and fixation indices were higher in females. The fixation indices of pairs of adjacent samples, and the genetic distance among these samples correlated highly significantly with the density of human settlement, measured by the percentage of land surface covered by roads and villages. The utility of allozymes and microsatellites for population genetic studies in cervids are compared.

Nine out of 57 bovine and caprine microsatellites investigated have proved polymorphic in roe deer populations from Central Europe. The polymorphism of four to nine microsatellites (with two to 16 alleles each) has been screened in 492 roe deer from 27 sample locations in Germany, the Netherlands and France, and 10 allozyme loci have been investigated in 118 roe deer from Germany. These studies have revealed a genetically homogeneous population, but with a local scatter of allele frequencies. The mean genetic distance among sample pairs, and the overall fixation index for the 27 population samples were D=0.1638 and GST=0.0972 for four microsatellite loci, and D=0.0598 and GST=0.1459 for 10 allozyme loci. No isolation-by-distance was observed. Roe deer from isolated habitats could be distinguished by various measures of genetic variability. The expected heterozygosity and the allelic diversity were higher in male than in female roe deer, but mean genetic distances and fixation indices were higher in females. The fixation indices of pairs of adjacent samples, and the genetic distance among these samples correlated highly significantly with the density of human settlement, measured by the percentage of land surface covered by roads and villages. The utility of allozymes and microsatellites for population genetic studies in cervids are compared.

In the last few years, the interest in using ecological population models as a tool for pesticide risk assessment has increased rapidly. Practical guidance, however, on how to perform a risk assessment with a population model is still lacking. It is still unclear which endpoint (population density, population growth, etc.) is the most sensitive indicator of population-level effects and how risk can be evaluated at the population level. Moreover, a main added value of model-based risk assessments, which is an understanding of the mechanisms involved in alternative exposure scenarios, so far has received little attention. We therefore used an example model to compare commonly used endpoints and alternative exposure scenarios. The model is a structurally realistic, but relatively simple, individual-based, spatially explicit model for the common shrew (Sorex araneus), which was selected because it has been tested and validated extensively. We show that population density is more sensitive for detecting population-level effects in the short term (months) than population growth rate. Population viability measured by extinction risk can also be a relevant endpoint, because it is especially sensitive for small populations. We show that landscape structure and the timing of pesticide application (population structure at the time of application) can have a great impact on population recovery, and we analyze statistical tests for use in population-level risk assessments. Our results demonstrate which factors and insights should be taken into account in population-level risk assessments.