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Conservation translocations are widely used to recover threatened species, but can pose risks to recipient ecosystems, particularly in the case of conservation introductions. Because of limited data and uncertainty, risk assessments for such projects often rely on extrapolated evidence and expert opinion, further complicating decision making. The Environmental Impact Classification for Alien Taxa (EICAT) serves to classify the realised impacts of invasive species. We developed a protocol combining EICAT and formal expert elicitation to predict these impacts. We applied our protocol to the extinct-in-the-wild sihek (Guam kingfisher; Todiramphus cinnamominus ), for which introduction outside the known historical range is being considered. We elicited from multiple experts probability estimates of impact levels across four impact mechanisms and five candidate release sites. We aggregated estimates using simulation-based and Bayesian approaches, with and without accounting for expert confidence. Experts generally agreed that sihek introduction might impact the recipient ecosystem through predation, competition, and disease, although they disagreed about the likely impact levels. Releases to Palmyra Atoll were considered to pose the lowest risk across candidate sites, so this site was selected for further detailed ecological assessments and risk mitigation efforts. EICAT, with its standardized impact mechanisms and definitions, helped reduce the linguistic uncertainty and subjectivity common to expert-based assessments. Expressing judgments as probabilities allowed us to evaluate uncertainty transparently and to assess the weight of expert confidence on the overall risk estimation. Formal quantitative elicitation and aggregation then allowed a transparent evaluation of results, facilitating communication with stakeholders and decision-makers.

1. A population's effective size (Ne) is a key parameter that shapes rates of inbreeding and loss of genetic diversity, thereby influencing evolutionary processes and population viability. However, estimating Ne, and identifying key demographic mechanisms that underlie the Ne to census population size (N) ratio, remains challenging, especially for small populations with overlapping generations and substantial environmental and demographic stochasticity and hence dynamic age-structure. 2. A sophisticated demographic method of estimating Ne/N, which uses Fisher's reproductive value to account for dynamic age-structure, has been formulated. However, this method requires detailed individual- and population-level data on sex- and age-specific reproduction and survival, and has rarely been implemented. 3. Here, we use the reproductive value method and detailed demographic data to estimate Ne/N for a small and apparently isolated red-billed chough (Pyrrhocorax pyrrhocorax) population of high conservation concern. We additionally calculated two single-sample molecular genetic estimates of Ne to corroborate the demographic estimate and examine evidence for unobserved immigration and gene flow. 4. The demographic estimate of Ne/N was 0.21, reflecting a high total demographic variance $\\left( {\\sigma _{dg}^2} \\right)$ of 0.71. Females and males made similar overall contributions to $\\sigma _{dg}^2$. However, contributions varied among sex-age classes, with greater contributions from 3 year-old females than males, but greater contributions from ≥5 year-old males than females. 5. The demographic estimate of Ne was ~30, suggesting that rates of increase of inbreeding and loss of genetic variation per generation will be relatively high. Molecular genetic estimates of Ne computed from linkage disequilibrium and approximate Bayesian computation were approximately 50 and 30, respectively, providing no evidence of substantial unobserved immigration which could bias demographic estimates of Ne. 6. Our analyses identify key sex-age classes contributing to demographic variance and thus decreasing Ne/N in a small age-structured population inhabiting a variable environment. They thereby demonstrate how assessments of Ne can incorporate stochastic sex- and age-specific demography and elucidate key demographic processes affecting a population's evolutionary trajectory and viability. Furthermore, our analyses show that Ne for the focal chough population is critically small, implying that management to re-establish genetic connectivity may be required to ensure population viability.

Small, declining populations can face simultaneous, interacting, ecological and genetic threats to viability. Conservation management strategies designed to tackle such threats independently may then prove ineffective. Population viability analyses that evaluate the efficacy of management strategies implemented independently versus simultaneously are then essential to the design of effective management plans, yet such quantitative evaluations are typically lacking. We used stochastic individual‐based models, parameterised with high‐quality multi‐year demographic and genetic data, to evaluate the efficacy of independent or simultaneous ecological (supplementary feeding) and genetic (translocations to alleviate inbreeding) management strategies for a red‐billed chough (Pyrrhocorax pyrrhocorax) population of major conservation concern. This population is experiencing ecological threats from food limitation and genetic threats from escalating inbreeding. Conservation managers therefore face a dilemma: supplementary feeding may be ineffective if inbreeding is limiting stochastic population growth rate (λs), while translocations may be ineffective if food is limiting. Model simulations suggested that the focal population will decline to extinction relatively rapidly with no conservation management (mean λs ≈ 0.86) and with genetic management alone (λs ≈ 0.90). Ecological management alone reduced, but did not halt the population decline (λs ≈ 0.93). However, simultaneous genetic and ecological management yielded population stability (λs ≈ 1), with genetic rescue lasting ~25 years. These outcomes arose because the capacity for translocations to alleviate inbreeding depression is limited by food availability, while supplementary feeding cannot achieve population viability in the presence of accumulating inbreeding. However, supplementary feeding improved environmental quality enough to allow expression of variance in fitness and thus inbreeding depression, meaning that reductions in inbreeding following translocations can increase λs. Synthesis and applications. Our analyses suggest that simultaneous management of ecological and genetic threats will be critical to ensuring viability of Scotland's chough population; neither strategy independently is likely to achieve population persistence and may consequently waste conservation resources. Managers of other resource‐limited, inbred populations should consider that the efficacy of strategies designed to alleviate ecological and genetic threats may be interdependent, such that holistic management is essential to ensure population viability. Our analyses suggest that simultaneous management of ecological and genetic threats will be critical to ensuring viability of Scotland's chough population; neither strategy independently is likely to achieve population persistence and may consequently waste conservation resources. Managers of other resource‐limited, inbred populations should consider that the efficacy of strategies designed to alleviate ecological and genetic threats may be interdependent, such that holistic management is essential to ensure population viability.

Deleterious recessive alleles that are masked in outbred populations are predicted to be expressed in small, inbred populations, reducing both individual fitness and population viability. However, there are few definitive examples of phenotypic expression of lethal recessive alleles under inbreeding conditions in wild populations. Studies that demonstrate the action of such alleles, and infer their distribution and dynamics, are required to understand their potential impact on population viability and inform management responses. The Scottish population of red‐billed choughs (Pyrrhocorax pyrrhocorax), which currently totals <60 breeding pairs and is of major conservation concern, has recently been affected by lethal blindness in nestlings. We used family data to show that the pattern of occurrence of blindness within and across affected families that produced blind nestlings was exactly 0·25, matching that expected given a single‐locus autosomal lethal recessive allele. Furthermore, the observed distribution of blind nestlings within affected families did not differ from that expected given Mendelian inheritance of such an allele. Relatedness estimates showed that individuals from affected families were not more closely related to each other than they were to individuals from unaffected families that did not produce blind nestlings. Blind individuals tended to be less heterozygous than non‐blind individuals, as expected if blindness was caused by the expression of a recessive allele under inbreeding. However, there was no difference in the variance in heterozygosity estimates, suggesting that some blind individuals were relatively outbred. These results suggest carriers of the blindness allele may be widely distributed across contemporary families rather than restricted to a single family lineage, implying that the allele has persisted across multiple generations. Blindness occurred at low frequency (affecting 1·6% of observed nestlings since 1981). However, affected families had larger initial brood sizes than unaffected families. Such high fecundity of carriers of a lethal recessive allele might reflect overdominance, potentially reducing purging and increasing allele persistence probability. We thereby demonstrate the phenotypic expression of a lethal recessive allele in a wild population of conservation concern, and provide a general framework for inferring allele distribution and persistence and informing management responses.

1. Deleterious recessive alíeles that are masked in outbred populations are predicted to be expressed in small, inbred populations, reducing both individual fitness and population viability. However, there are few definitive examples of phenotypic expression of lethal recessive alleles under inbreeding conditions in wild populations. Studies that demonstrate the action of such alleles, and infer their distribution and dynamics, are required to understand their potential impact on population viability and inform management responses. 2. The Scottish population of red-billed choughs (Pyrrhocorax pyrrhocorax), which currently totals < 60 breeding pairs and is of major conservation concern, has recently been affected by lethal blindness in nestlings. We used family data to show that the pattern of occurrence of blindness within and across affected families that produced blind nestlings was exactly 0·25, matching that expected given a single-locus autosomal lethal recessive allele. Furthermore, the observed distribution of blind nestlings within affected families did not differ from that expected given Mendelian inheritance of such an allele. 3. Relatedness estimates showed that individuals from affected families were not more closely related to each other than they were to individuals from unaffected families that did not produce blind nestlings. Blind individuals tended to be less heterozygous than non-blind individuals, as expected if blindness was caused by the expression of a recessive alíele under inbreeding. However, there was no difference in the variance in heterozygosity estimates, suggesting that some blind individuals were relatively outbred. These results suggest carriers of the blindness alíele may be widely distributed across contemporary families rather than restricted to a single family lineage, implying that the allele has persisted across multiple generations. 4. Blindness occurred at low frequency (affecting 1·6% of observed nestlings since 1981). However, affected families had larger initial brood sizes than unaffected families. Such high fecundity of carriers of a lethal recessive allele might reflect overdominance, potentially reducing purging and increasing allele persistence probability. 5. We thereby demonstrate the phenotypic expression of a lethal recessive allele in a wild population of conservation concern, and provide a general framework for inferring allele distribution and persistence and informing management responses.

Small, isolated populations can be at risk from genetic threats. In particular, inbreeding depression can threaten population viability, however the contribution of large-effect alleles to inbreeding depression in natural populations is largely unknown. Quantification of genetic threats requires estimation of the effective population size (Ne), which can be challenging given age-structure. Further, identification of large-effect alleles and estimation of Ne requires knowledge of a population's genetic mating system, which can itself be difficult to determine in populations with low genetic diversity. In this study, I quantified genetic threats to the small, isolated Scottish population of red-billed choughs (Pyrrhocorax pyrrhocorax), which is of high conservation concern, heightened by the recent occurrence of lethal blindness in nestlings. I first estimated extra-pair parentage rates to be low in Scottish choughs (~5% extra-pair offspring). I quantified inheritance patterns of blindness and found that the pattern of occurrence matched that expected for a single-locus recessive allele. Heterozygous carriers of the blindness allele are likely to be widely distributed in the population, limiting management options. Further, affected families had relatively larger broods than unaffected families, suggesting the blindness allele could persist in the population. Using a candidate gene approach, no consistent polymorphisms were found between blind and non-blind individuals in candidate gene amplicons and therefore a diagnostic marker for blindness could not be developed. I used demographic and genetic data to estimate Ne for Scottish choughs. Both demographic and genetic estimators suggested Ne is critically small (Ne≈30), such that future rates of loss of genetic variation will be high. The small Ne was largely due to high demographic variance, with high contributions to demographic variance from younger females and older males. Overall, this study adds to our understanding of genetic threats to small, wild populations and can thus inform management of threatened populations.

Early life exposures can increase the risk of developing chronic diseases including nonalcoholic fatty liver disease. Maternal high-fat diet increases susceptibility to development of steatosis in the offspring. We determined the effect of maternal high-fat diet exposure in utero and during lactation on offspring liver histopathology, particularly fibrosis. Female C57Bl/6J mice were fed a control or high-fat diet (HFD) for 8 weeks and bred with lean males. Nursing dams were continued on the same diet with offspring sacrificed during the perinatal period or maintained on either control or high-fat diet for 12 weeks. Increased hepatocyte proliferation and stellate cell activation were observed in the liver of HFD-exposed pups. Offspring exposed to perinatal high-fat diet and high-fat diet postweaning showed extensive hepatosteatosis compared to offspring on high-fat diet after perinatal control diet. Offspring exposed to perinatal high-fat diet and then placed on control diet for 12 weeks developed steatosis and pericellular fibrosis. Importantly, we found that exposure to perinatal high-fat diet unexpectedly promotes more rapid disease progression of nonalcoholic fatty liver disease, with a sustained fibrotic phenotype, only in adult offspring fed a postweaning control diet.