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Genetic diversity among and within populations of all species is necessary for people and nature to survive and thrive in a changing world. Over the past three years, commitments for conserving genetic diversity have become more ambitious and specific under the Convention on Biological Diversity's (CBD) draft post-2020 global biodiversity framework (GBF). This Perspective article comments on how goals and targets of the GBF have evolved, the improvements that are still needed, lessons learned from this process, and connections between goals and targets and the actions and reporting that will be needed to maintain, protect, manage and monitor genetic diversity. It is possible and necessary that the GBF strives to maintain genetic diversity within and among populations of all species, to restore genetic connectivity, and to develop national genetic conservation strategies, and to report on these using proposed, feasible indicators. ispartof: CONSERVATION GENETICS vol:24 issue:2 pages:181-191 ispartof: location:Netherlands status: published

Conservation research has historically been conducted at the macro level, focusing on animals and plants and their role in the wider ecosystem. However, there is a growing appreciation of the importance of microbial communities in conservation. Most microbiome research in conservation thus far has used amplicon sequencing methods to assess the taxonomic composition of microbial communities and inferred functional capabilities from these data. However, as manipulation of the microbiome as a conservation tool becomes more and more feasible, there is a growing need to understand the direct functional consequences of shifts in microbiome composition. This review outlines the latest advances in microbiome research from a functional perspective and how these data can be used to inform conservation strategies. This review will also consider some of the challenges faced when studying the microbiomes of wild animals and how they can be overcome by careful study design and sampling methods. Environmental changes brought about by climate change or direct human actions have the potential to alter the taxonomic composition of microbiomes in wild populations. Understanding how taxonomic shifts affect the function of microbial communities is important for identifying species most threatened by potential disruption to their microbiome. Preservation or even restoration of these functions has the potential to be a powerful tool in conservation biology and a shift towards functional characterisation of gut microbiome diversity will be an important first step.

Background While recent advances in genomics has enabled vast improvements in the quantification of genome-wide diversity and the identification of adaptive and deleterious alleles in model species, wildlife and non-model species have largely not reaped the same benefits. This has been attributed to the resources and infrastructure required to develop essential genomic datasets such as reference genomes. In the absence of a high-quality reference genome, cross-species alignments can provide reliable, cost-effective methods for single nucleotide variant (SNV) discovery. Here, we demonstrated the utility of cross-species genome alignment methods in gaining insights into population structure and functional genomic features in cheetah (Acinonyx jubatas), snow leopard (Panthera uncia) and Sumatran tiger (Panthera tigris sumatrae), relative to the domestic cat (Felis catus). Results Alignment of big cats to the domestic cat reference assembly yielded nearly complete sequence coverage of the reference genome. From this, 38,839,061 variants in cheetah, 15,504,143 in snow leopard and 13,414,953 in Sumatran tiger were discovered and annotated. This method was able to delineate population structure but limited in its ability to adequately detect rare variants. Enrichment analysis of fixed and species-specific SNVs revealed insights into adaptive traits, evolutionary history and the pathogenesis of heritable diseases. Conclusions The high degree of synteny among felid genomes enabled the successful application of the domestic cat reference in high-quality SNV detection. The datasets presented here provide a useful resource for future studies into population dynamics, evolutionary history and genetic and disease management of big cats. This cross-species method of variant discovery provides genomic context for identifying annotated gene regions essential to understanding adaptive and deleterious variants that can improve conservation outcomes.

Classic Mendelian inheritance is the bedrock of population genetics and underpins pedigree-based management of animal populations. However, assumptions of Mendelian inheritance might not be upheld in conservation breeding programmes if early viability selection occurs, even when efforts are made to equalise genetic contributions of breeders. To test this possibility, we investigated deviations from Mendelian proportions in a captive metapopulation of the endangered Tasmanian devil. This marsupial population is ideal for addressing evolutionary questions in conservation due to its large size, range of enclosure types (varying in environmental conditions), good genomic resources (which aid interpretation), and the species' biology. Devil mothers give birth to more offspring than they can nurse in the pouch, providing the potential for intense viability selection amongst embryos. We used data from 140 known sire-dam-offspring triads to isolate within-family selection from population-level mechanisms (such as mate choice or inbreeding), and compared observed offspring genotypes at 123 targeted SNPs to neutral (i.e., Mendelian) expectations. We found lower offspring heterozygosity than expected, and subtle patterns that varied across a gradient of management intensity from zoo-like enclosures to semi-wild environments for some loci. Meiotic drive or maternal-foetal incompatibilities are consistent with our results, although we cannot statistically confirm these mechanisms. We found some evidence that maternal genotype affects annual litter size, suggesting that family-level patterns are driven by differential offspring mortality before birth or during early development. Our results show that deviations from Mendelian inheritance can occur in conservation programmes, despite best-practice management to prevent selection.

Conservation breeding programs such as zoos play a major role in preventing extinction, but their sustainability may be impeded by neutral and adaptive population genetic change. These changes are difficult to detect for a single species or context, and impact global conservation efforts. We analyse pedigree data from 15 vertebrate species – over 30,000 individuals – to examine offspring survival over generations of captive breeding. Even accounting for inbreeding, we find that the impacts of increasing generations in captivity are highly variable across species, with some showing substantial increases or decreases in offspring survival over generations. We find further differences between dam and sire effects in first- versus multi-generational analysis. Crucially, our multispecies analysis reveals that responses to captivity could not be predicted from species’ evolutionary (phylogenetic) relationships. Even under best-practice captive management, generational fitness changes that cannot be explained by known processes (such as inbreeding depression), are occurring., Captive breeding could prevent species extinctions, but selection for captivity may decrease fitness. Here the authors analyse pedigree data on 15 long-running vertebrate breeding programs and find generational fitness changes that processes such as inbreeding depression cannot explain.

Species’ declines around the globe have reached such a rapid rate that without the implementation of extreme conservation methods, we are likely to witness the next mass extinction. Translocation is a popular and growing conservation technique, especially to islands. However, despite the widespread use of this method, the long-term genetic outlook of populations established on islands (namely those with small carrying capacity, and isolated from other populations) is often poorly quantified, and there are conflicting data supporting the relative roles of evolutionary processes such as drift, balancing selection, directional selection and genetic purging. Taking examples from avian translocations, this paper reviews recent data on the genetic dynamics of island populations established for conservation purposes. The goal of conservation genetics is to preserve species’ adaptive potential for the long term. In general, population bottlenecks cause losses of genetic diversity, but there is mixed evidence for the importance of other evolutionary processes, such as maintenance of genetic diversity by balancing selection. There is a clear need for long-term studies that test for associations between genetic change and success of populations established via translocation to conservation islands, and for integration of these observations with ecological and climate data. Combining data types into the future will provide a holistic view on the interactions between the role selection plays, how island populations established by translocations may respond, and how this information can improve conservation strategy.

Biodiversity underlies ecosystem resilience, ecosystem function, sustainable economies, and human well-being. Understanding how biodiversity sustains ecosystems under anthropogenic stressors and global environmental change will require new ways of deriving and applying biodiversity data. A major challenge is that biodiversity data and knowledge are scattered, biased, collected with numerous methods, and stored in inconsistent ways. The Group on Earth Observations Biodiversity Observation Network (GEO BON) has developed the Essential Biodiversity Variables (EBVs) as fundamental metrics to help aggregate, harmonize, and interpret biodiversity observation data from diverse sources. Mapping and analyzing EBVs can help to evaluate how aspects of biodiversity are distributed geographically and how they change over time. EBVs are also intended to serve as inputs and validation to forecast the status and trends of biodiversity, and to support policy and decision making. Here, we assess the feasibility of implementing Genetic Composition EBVs (Genetic EBVs), which are metrics of within-species genetic variation. We review and bring together numerous areas of the field of genetics and evaluate how each contributes to global and regional genetic biodiversity monitoring with respect to theory, sampling logistics, metadata, archiving, data aggregation, modeling, and technological advances. We propose four Genetic EBVs: (i) Genetic Diversity; (ii) Genetic Differentiation; (iii) Inbreeding; and (iv) Effective Population Size (Ne ). We rank Genetic EBVs according to their relevance, sensitivity to change, generalizability, scalability, feasibility and data availability. We outline the workflow for generating genetic data underlying the Genetic EBVs, and review advances and needs in archiving genetic composition data and metadata. We discuss how Genetic EBVs can be operationalized by visualizing EBVs in space and time across species and by forecasting Genetic EBVs beyond current observations using various modeling approaches. Our review then explores challenges of aggregation, standardization, and costs of operationalizing the Genetic EBVs, as well as future directions and opportunities to maximize their uptake globally in research and policy. The collection, annotation, and availability of genetic data has made major advances in the past decade, each of which contributes to the practical and standardized framework for large-scale genetic observation reporting. Rapid advances in DNA sequencing technology present new opportunities, but also challenges for operationalizing Genetic EBVs for biodiversity monitoring regionally and globally. With these advances, genetic composition monitoring is starting to be integrated into global conservation policy, which can help support the foundation of all biodiversity and species' long-term persistence in the face of environmental change. We conclude with a summary of concrete steps for researchers and policy makers for advancing operationalization of Genetic EBVs. The technical and analytical foundations of Genetic EBVs are well developed, and conservation practitioners should anticipate their increasing application as efforts emerge to scale up genetic biodiversity monitoring regionally and globally. ispartof: BIOLOGICAL REVIEWS vol:97 issue:4 pages:1511-1538 ispartof: location:England status: published

The increased availability of genomic resources for many species has expanded perspectives on problems in conservation by helping to design management strategies for threatened species. Tasmanian devils (Sarcophilus harrisii) are an iconic and endangered marsupial with an intensively managed breeding program aimed at preventing extinction in the wild caused by devil facial tumour disease. Between 2015 and 2017, 85 devils from this program were released to three sites in Tasmania to support wild populations. Of these, 26 were known to have been killed by vehicles shortly after release. A previous analysis indicated that increased generations in captivity was a positive predictor of vehicle strike, with possible behavioural change hypothesised. Here we use 39 resequenced devil genomes to characterise diversity at 35 behaviour-associated genes, which contained 826 single nucleotide polymorphisms (24 were non-synonymous). We tested for a predictor of survival by examining three genes (AVPR1B, OXT and SLC6A4) in 62 released devils with known fates (survived, N = 39; died, N = 23), and genome-wide associations via reduced-representation sequencing (1727 single nucleotide polymorphisms [SNPs]), in 55 devils with known fates (survived, N = 38; died, N = 17). Overall, there was little evidence of an association between genetic profile and probability of being struck by a vehicle. Despite previous evidence of low genetic diversity in devils, the 35 behaviour-associated genes contained variation that may influence their functions. Our dataset can be used for future research into devil behavioural ecology, and adds to the increasing body of research applying genomics to conservation problems.

Captive breeding for conservation is widely used to prevent extinction, however these programs face many challenges due to small population size, founder effects, lack of migration and potential adaptation to captivity. Together these influence how selection, genetic drift and gene flow shape the genetic makeup of small populations, so examining these in a captive setting is valuable for appropriate biodiversity management. We have quantified the effects of selection, drift and gene flow in 503 individuals across five generations from the Tasmanian devil insurance population. To determine whether different processes were acting in different settings, we separately analysed animals housed under individual-based management, versus those that were released to an island site. We found that a greater proportion of alleles were lost over time in the smaller island population than in captivity and propose that genetic drift is the most likely process influencing this result. We found that the captive population became more heterozygous over time, while the island population stayed constant. Our molecular measure of inbreeding found a decrease over generations in captivity that is not captured by pedigree-based analysis. As management of breeding interactions only takes place in the captive population, our results are consistent with gene flow through managed breeding in captivity minimising inbreeding over time. Gene flow was also evident through changes to population structure in the captive population. Our findings serve as an example of how conservation managers can assess the impact of evolutionary processes on managed populations and adapt management practices if required.

Inter-individual variation at genes known to play a role in reproduction may impact reproductive fitness. The Tasmanian devil is an endangered Australian marsupial with low genetic diversity. Recent work has shown concerning declines in productivity in both wild and captive populations over time. Understanding whether functional diversity exists at reproductive genes in the Tasmanian devil is a key first step in identifying genes that may influence productivity. We characterised single nucleotide polymorphisms (SNPs) at 214 genes involved in reproduction in 37 Tasmanian devils. Twenty genes contained non-synonymous substitutions, with genes involved in embryogenesis, fertilisation and hormonal regulation of reproduction displaying greater numbers of nonsynonymous SNPs than synonymous SNPs. Two genes, ADAMTS9 and NANOG, showed putative signatures of balancing selection indicating that natural selection is maintaining diversity at these genes despite the species exhibiting low overall levels of genetic diversity. We will use this information in future to examine the interplay between reproductive gene variation and reproductive fitness in Tasmanian devil populations.

Establishing populations of endangered species in captivity is becoming an increasingly common component of species recovery programs for insurance against extinction, and/or for reintroductions. It is important for the success of these efforts that captive populations are genetically representative of wild source populations, and that genetic diversity is maintained over time. Our study presents SNP data from wild and captive populations of the critically endangered Australian orange-bellied parrot (Neophema chrysogaster). We examine the genetic effects of a decision made in the 2010/2011 breeding season to recruit half of the juvenile cohort (n = 21), from a wild population in decline, to supplement an existing captive program. We report that heterozygosity among wild birds decreased in the years after this action. Following multiple releases of captive-reared birds back into the wild (occurring annually since 2013), captive and wild populations have attained similar overall levels of heterozygosity, and genetic differentiation between these populations is low. Parentage analyses confirm that captive-bred released individuals have successfully paired with wild birds and produced offspring. Our study suggests that translocation of wild individuals into captivity, from wild populations in decline, can potentially have deleterious lasting impacts on genetic diversity levels in these populations. However, our data also confirm that in captivity, founder diversity can be successfully preserved over time, and addition of wild founders can improve captive population health. The genetic diversity retained in captive populations can also be reintroduced to wild populations at a later date, provided that captive-release individuals are able to reproductively contribute to their recipient population.

Conservation breeding programs, such as fenced reserves, conserve species by removing populations from key threatening processes and providing supplementary resources to support species preservation. This form of management often has the eventual aim to reintroduce individuals back to their native habitat. A key issue with captive management is the small breeding pool, due to generally small population sizes and limited migration, which may lead to inbreeding and consequent inbreeding depression. We investigated inbreeding and its potential fitness consequences in a large, free-ranging, captive population of an Australian marsupial, the long-nosed potoroo (Potorous tridactylus), a species that has been recently impacted by severe bushfire. We used reduced-representation sequencing to genotype single nucleotide polymorphisms and reconstruct a pedigree for the population. We detected low levels of inbreeding in our partial pedigree that incorporated 50.7% (34/67) of sampled individuals. Inbreeding depression was investigated using heterozygosity–fitness correlations of six fitness measurements, but we found no evidence of inbreeding depression in the population despite strong molecular evidence for inter-individual variation in inbreeding coefficient. Our findings suggest that the potoroo population at Tidbinbilla Nature Reserve (TNR) maintains a high level of diversity. As the population is descendant of animals from divergent sources, the TNR population also helps conservationists to learn more about potential consequences of admixture, and plan recovery strategies for the species. For TNR potoroos, we suggest that current management protocols have been effective at maintaining diversity to date. More generally, our results show how modern molecular techniques can efficiently characterise the genetic profile of a free-ranging, captive population to help inform management guidelines for wild recovery.

How innovations such as vision, flight and pregnancy evolve is a central question in evolutionary biology. Examination of transitional (intermediate) forms of these traits can help address this question, but these intermediate phenotypes are very rare in extant species. Here we explore the biology and evolution of transitional forms of pregnancy that are midway between the ancestral state of oviparity (egg-laying) and the derived state, viviparity (live birth). Transitional forms of pregnancy occur in only three vertebrates, all of which are lizard species that also display intraspecific variation in reproductive phenotype. In these lizards (Lerista bougainvillii, Saiphos equalis, and Zootoca vivipara), geographic variation of three reproductive forms occurs within a single species: oviparity, viviparity, and a transitional form of pregnancy. This phenomenon offers the valuable prospect of watching ‘evolution in action’. In these species, it is possible to conduct comparative research using different reproductive forms that are not confounded by speciation, and are of relatively recent origin. We identify major proximate and ultimate questions that can be addressed in these species, and the genetic and genomic tools that can help us understand how transitional forms of pregnancy are produced, despite predicted fitness costs. We argue that these taxa represent an excellent prospect for understanding the major evolutionary shift between egg-laying and live birth, which is a fundamental innovation in the history of animals.

A correction to this paper has been published: https://doi.org/10.1007/s10592-021-01376-9

Top carnivores are essential for maintaining ecosystem stability and biodiversity. Yet, carnivores are declining globally and current

Recent advances in molecular genetics have enabled a great deal of information about species to be obtained from analysis of non-invasively collected samples such as scat. Scat provides genetic information via residual host DNA on the outside of the scat, via characterising the genetic makeup of intestinal microbes that are present in the scat, or by examining the DNA remnants of prey items that have passed through the animal’s digestive tract. In this review, we provide a case study to demonstrate how these approaches are being used to better understand the threatened Tasmanian devil in the landscape, and to support the species’ conservation. Scat analysis enables us to quantify the genetic diversity of remote populations, where trapping is logistically challenging. We are beginning to learn how conservation management impacts the microbiome of threatened species, and investigate how various management strategies may be impacting the diverse array of bacteria and viruses that devils, like all animal species, are host to. We are using scat samples to better understand the interaction between devils and other animals in their environment by learning more about what they eat. We explore the strengths and challenges of these approaches by comparing our work to that conducted in other species. Finally, we provide specific examples of how our results are being integrated into conservation strategy for the devil.

Quantifying fitness of wild organisms from genomic data alone is a challenging frontier

Reduced-representation sequencing methods have wide utility in conservation genetics of non-model species. Several methods are now available that reduce genome complexity to examine a wide range of markers in a large number of individuals. We produced two datasets collected using different laboratory techniques, comprising a common set of samples from the greater bilby (Macrotis lagotis). We examined the impact of differing data filtering thresholds on downstream population inferences. We found that choice of restriction enzyme and data filtering thresholds, especially the rate of allowable missing data, impacted our ability to detect population structure. Estimates of FST were robust to alterations in laboratory and bioinformatic protocols while principal coordinates and STRUCTURE analyses showed variation according to the number of loci and percent missing data. We advise researchers using reduced-representation sequencing in conservation projects to examine a range of data thresholds, and follow these through to downstream population inferences. Multiple measures of population differentiation should be used in order to fully understand how data filtering thresholds influence the final dataset, paying particular attention to the impact of allowable missing data. Our results indicate that failure to follow these checks could impact conclusions drawn, and conservation management decisions made.

Mate choice contributes to driving evolutionary processes when animals choose breeding partners that confer genetic advantages to offspring, such as increased immunocompetence. The major histocompatibility complex (MHC) is an important group of immunological molecules, as MHC antigens bind and present foreign peptides to T-cells. Recent studies suggest that mates may be selected based on their MHC profile, leading to an association between an individual’s MHC diversity and their breeding success. In conservation, it may be important to consider mate choice in captive breeding programs, as this mechanism may improve reproductive rates. We investigated the reproductive success of Tasmanian devils in a group housing facility to determine whether increased MHC-based heterozygosity led individuals to secure more mating partners and produce more offspring. We also compared the breeding success of captive females to a wild devil population. MHC diversity was quantified using 12 MHC-linked microsatellite markers, including 11 previously characterized markers and one newly identified marker. Our analyses revealed that there was no relationship between MHC-linked heterozygosity and reproductive success either in captivity or the wild. The results of this study suggest that, for Tasmanian devils, MHC-based heterozygosity does not produce greater breeding success and that no specific changes to current captive management strategies are required with respect to preserving MHC diversity.

Captive animals are commonly housed in groups to make efficient use of limited resources and allow for natural social behaviour. Captive management relies on accurate pedigrees to estimate various population genetic parameters, such as genetic contributions of breeders, but pedigrees of group-housed offspring can be uncertain. Pedigree analysis software incorporates genetic information from multiple putative parents (“MULT”). Molecular pedigree reconstruction to resolve pedigree uncertainties can be costly. We quantify the need for molecular parentage assignment by comparing predicted offspring contributions (based on uncertain “MULT” pedigrees) to contributions obtained from a molecular genetic pedigree reconstruction. Parentage of 81 insurance population Tasmanian devils (Sarcophilus harrisii) born in free-range enclosures from 2011 to 2017 was resolved using 891 single nucleotide polymorphisms. We observed large discrepancies between the MULT pedigree and molecular pedigree data, revealing both overestimates and underestimates of genetic contributions of individuals, and different pedigree-based effective population sizes (102 vs. 158 respectively). The molecular data revealed that reproductive skew (proportion of adults that failed to breed) was high for both sexes. Over half of the wild-born individuals in our dataset were found to have not bred. If undetected, variation in breeding success undermines the utility of pedigree management and may threaten the success of captive breeding. Molecular techniques are increasingly cost-effective, and our data demonstrate that they are critical to devil management. Where feasible, we recommend molecular management of group-housed species in captivity to avoid inaccurate estimates of genetic diversity and to identify non-breeding individuals, in particular founders, for targeted breeding.

Molecular markers are a useful tool allowing conservation and population managers to shed light on genetic processes affecting threatened populations. However, as technological advancements in molecular techniques continue to evolve, conservationists are frequently faced with new genetic markers, each with nuanced variation in their characteristics as well as advantages and disadvantages for informing various questions. We used a well-studied population of Tasmanian devils (Sarcophilus harrisii) from Maria Island, Tasmania, to illustrate the issues associated with combining multiple genetic data sets and to help answer a question posed by many population managers: which data set will provide the most precise and accurate estimates of the population processes we are trying to measure? We analysed individual heterozygosity (as internal relatedness, IR) of 96 individuals, calculated using four genetic marker types (putatively neutral microsatellites, major histocompatibility complex-linked microsatellites, reduced representation sequencing, and candidate region resequencing). We found no correlation in IR values across marker types, suggesting that various genetic markers reflect different aspects of genomic diversity. In addition, some marker types were more informative than others for conservation decision-making. Reduced representation sequencing provided the highest precision (lowest error) for estimating population-level genetic diversity, and most closely reflected genome-wide heterozygosity both theoretically and empirically. Within the conservation context, our results highlight important considerations when choosing a molecular technique for wildlife genetics.

The major histocompatibility complex (MHC) plays a critical role in the vertebrate immune system. Accurate MHC typing is critical to understanding not only host fitness and disease susceptibility, but also the mechanisms underlying host-pathogen co-evolution. However, due to the high degree of gene duplication and diversification of MHC genes, it is often technically challenging to accurately characterise MHC genetic diversity in non-model species. Here we conducted a systematic review to identify common issues associated with current widely used MHC typing approaches. Then to overcome these challenges, we developed a long-read based MHC typing method along with a new analysis pipeline. Our approach enables the sequencing of fully phased MHC alleles spanning all key functional domains and the separation of highly similar alleles as well as the removal of technical artefacts such as PCR heteroduplexes and chimeras. Using this approach, we performed population-scale MHC typing in the Tasmanian devil (Sarcophilus harrisii), revealing previously undiscovered MHC functional diversity in this endangered species. Our new method provides a better solution for addressing research questions that require high MHC typing accuracy. Since the method is not limited by species or the number of genes analysed, it will be applicable for studying not only the MHC but also other complex gene families.

ispartof: CONSERVATION GENETICS vol:22 issue:4 pages:533-536 status: published

Conservation introductions to islands and fenced enclosures are increasing as in situ mitigations fail to keep pace with population declines. Few studies consider the potential loss of genetic diversity and increased inbreeding if released individuals breed disproportionately. As funding is limited and post-release monitoring expensive for conservation programs, understanding how sampling effort influences estimates of reproductive variance is useful. To investigate this relationship, we used a well-studied population of Tasmanian devils (Sarcophilus harrisii) introduced to Maria Island, Tasmania, Australia. Pedigree reconstruction based on molecular data revealed high variance in number of offspring per breeder and high proportions of unsuccessful individuals. Computational subsampling of 20%, 40%, 60%, and 80% of observed offspring resulted in inaccurate estimates of reproductive variance compared to the pedigree reconstructed with all sampled individuals. With decreased sampling effort, the proportion of inferred unsuccessful individuals was overestimated and the variance in number of offspring per breeder was underestimated. To accurately estimate reproductive variance, we recommend sampling as many individuals as logistically possible during the early stages of population establishment. Further, we recommend careful selection of colonizing individuals as they may be disproportionately represented in subsequent generations. Within the conservation management context, our results highlight important considerations for sample collection and post-release monitoring during population establishment.

Extinction risk is increasing for a range of species due to a variety of threats, including disease. Emerging infectious diseases can cause severe declines in wild animal populations, increasing population fragmentation and reducing gene flow. Small, isolated, host populations may lose adaptive potential and become more susceptible to extinction due to other threats. Management of the genetic consequences of disease-induced population decline is often necessary. Whilst disease threats need to be addressed, they can be difficult to mitigate. Actions implemented to conserve the Tasmanian devil (Sarcophilus harrisii), which has suffered decline to the deadly devil facial tumour disease (DFTD), exemplify how genetic management can be used to reduce extinction risk in populations threatened by disease. Supplementation is an emerging conservation technique that may benefit populations threatened by disease by enabling gene flow and conserving their adaptive potential through genetic restoration. Other candidate species may benefit from genetic management via supplementation but concerns regarding outbreeding depression may prevent widespread incorporation of this technique into wildlife disease management. However, existing knowledge can be used to identify populations that would benefit from supplementation where risk of outbreeding depression is low. For populations threatened by disease and, in situations where disease eradication is not an option, wildlife managers should consider genetic management to buffer the host species against inbreeding and loss of genetic diversity.

ispartof: BIOLOGICAL CONSERVATION vol:253 status: published

Understanding how inbreeding affects endangered species in conservation breeding programs is essential for their recovery. The Hawaiian Crow ('Alalā) (Corvus hawaiiensis) is one of the world's most endangered birds. It went extinct in the wild in 2002, and, until recent release efforts starting in 2016, nearly all of the population remained under human care for conservation breeding. Using pedigree inbreeding coefficients (F), we evaluated the effects of inbreeding on Hawaiian Crow offspring survival and reproductive success. We used regression tree analysis to identify the level of inbreeding (i.e., inbreeding threshold) that explains a substantial decrease in 'Alalā offspring survival to recruitment. Similar to a previous study of inbreeding in 'Alalā, we found that inbreeding had a negative impact on offspring survival but that parental (vs. artificial) egg incubation improved offspring survival to recruitment. Furthermore, we found that inbreeding did not substantially affect offspring reproductive success, based on the assumption that offspring that survive to adulthood breed with distantly related mates. Our novel application of regression tree analysis showed that offspring with inbreeding levels exceeding F = 0.098 were 69% less likely to survive to recruitment than more outbred offspring, providing a specific threshold value for ongoing population management. Our results emphasize the importance of assessing inbreeding depression across all life history stages, confirm the importance of prioritizing parental over artificial egg incubation in avian conservation breeding programs, and demonstrate the utility of regression tree analysis as a tool for identifying inbreeding thresholds, if present, in any pedigree-managed population.Moverse de las Tendencias a los Referentes Mediante el Análisis de Árbol de Regresión para Encontrar los Umbrales de Endogamia de una Ave en Peligro Crítico Resumen Es necesario entender cómo afecta la endogamia a las especies en peligro que se encuentran en programas de reproducción para la conservación para la recuperación exitosa de estas especies. El cuervo hawaiano (‘Alalā) (Corvus hawaiiensis) es una de las especies de ave que se encuentra en mayor peligro de extinción en todo el mundo. Esta especie se extinguió en vida libre en el 2002 y no fue hasta los recientes esfuerzos de liberación que iniciaron en 2016 que casi toda la población permaneció bajo cuidado humano en programas de reproducción para la conservación. Usamos los coeficientes de linaje endogámico (F) para evaluar los efectos de la endogamia sobre el éxito reproductivo y de supervivencia de la descendencia de los cuervos hawaianos. Usamos un análisis de árbol de regresión para identificar el nivel de endogamia (es decir, el umbral de endogamia) que explicara una disminución sustancial en la supervivencia de la descendencia de ‘Alalā hasta el reclutamiento. Similar a un estudio previo de la endogamia en los ‘Alalā, descubrimos que la endogamia tuvo un impacto negativo sobre la supervivencia de la descendencia pero que la incubación parental (vs. la artificial) de huevos mejoró la supervivencia de la descendencia hasta el reclutamiento. Además, encontramos que la endogamia no afectó de manera importante al éxito reproductivo de la descendencia, esto basado en la suposición de que los descendientes que sobreviven hasta la edad adulta se reproducen con parejas cuya relación familiar es lejana. Nuestra aplicación novedosa del análisis de árbol de regresión mostró que la descendencia con niveles de endogamia que exceden F = 0.098 tuvieron 69% menos de probabilidad de sobrevivir hasta el reclutamiento que aquella progenie con menor endogamia, lo que proporciona un valor específico de umbral para el manejo continuo de la población. Nuestros resultados resaltan la importancia de la evaluación de la depresión endogámica en todas las etapas de la historia de vida, confirman la importancia de priorizar la incubación parental de huevos sobre la artificial en los programas de conservación de aves y demuestran la utilidad del análisis de árbol de regresión como herramienta para identificar los umbrales de endogamia, cuando presentes, en cualquier población manejada por linaje.

The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come.\ud\ud Previous article in issue