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Genetics in conservation management: Revised recommendations for the 50/500 rules, Red List criteria and population viability analyses
... Many species worldwide currently exhibit highly fragmented distributions due to the widespread loss of natural habitats and anthropogenic pressures (Frankham et al., 2014;Gross, 2019). The resulting demographic effects are of concern to conservation biologist because small and isolated populations tend to suffer from genetic impoverishment, limiting their evolutionary potential and thus increasing the probability of extinction (Fagan and Holmes, 2006;Forester et al., 2022). ...
... Recent visual surveys estimate ~63-150 individuals in Colombia, ~94-150 in Ecuador and >300 in Peru, while the largest populations are found in the south of the continent with the species reaching a total of 6700 individuals (Naveda-Rodríguez et al., 2016;Vargas et al., 2018a;SERFOR, 2022;BirdLife International, 2023). However, traditional methods such as population census are poor predictors of genetic diversity patterns and effective population sizes (Willoughby et al., 2015), which are critical to informing management plans for small populations with increased extinction risks (Frankham et al., 2014). Moreover, regional conservation efforts aimed at curbing the species' demographic decline have mainly relied on assisted translocations using condors of undeclared origin or from distant regions (Plaza and Lambertucci, 2020). ...
... If true, the mean effective to census population size ratio in Ecuador is much higher (~0.35-0.5) than usual estimates (0.1-0.2) for wildlife management (Frankham et al., 2014). Although this could be related to the extremely low reproductive rate and long generational time of condors, it may also be exacerbated by the high mortality rate of immature individuals in the region (Koenen et al., 2000;Restrepo-Cardona et al., 2022), suggesting severe risks of low recruitment in the population. ...
Determining the conservation status of long-lived and highly mobile species is particularly challenging due to their long generational time and the spatio-temporal scale at which they interact with their landscape. Vultures are not only extremely vagile and long-lived but are also some of the most threatened species globally. However, the genetic status and connectivity patterns of most vulture species of the southern hemisphere remain poorly understood. Herein, we studied the patterns of neutral genetic variability in both the captive and remnant wild populations of Andean condors (Vultur gryphus) from the equatorial Andes and assessed their movement dynamic to infer current connectivity, as well as identify conservation corridors in one of the most critical areas for the conservation of the species. We found that the demographic collapse of condors in the region has severely affected their effective population size, which might lead to an extinction vortex in the near future. However, our results indicated that the captive population still harbors substantial genetic variation that could be harnessed to strengthen wild populations. Although our landscape resistance models revealed that the northern Andean corridor provides a continuum of suitable habitat for condors, our connectivity assessment identified important spatial disruptions, likely driven by anthropogenic processes. We discuss the implications of our findings to the conservation plan of Andean condors, while highlighting the importance of integrating multiple data sources to identify extinction risks in other species exhibiting high dispersal capabilities and long generational times.
... However, the species remains at risk of extinction due to human activities other than weir construction [35]. The effective population size was determined to be 177 (122-296), which is higher than the effective population size of 100 required to maintain the size of the population in the short term but far less than the effective population size of 1000 required over the long term [36]. In conservation genetics, a small population size potentially accelerates extinction processes by extinction factors [37]. ...
... In conservation genetics, a small population size potentially accelerates extinction processes by extinction factors [37]. One important genetic factor that can affect extinc-tion risk at small population sizes is inbreeding depression [36]. Based on this rationale, it can be assumed that the long-term sustainability of M. rapidus is at risk [36,37]. ...
... One important genetic factor that can affect extinc-tion risk at small population sizes is inbreeding depression [36]. Based on this rationale, it can be assumed that the long-term sustainability of M. rapidus is at risk [36,37]. In addition, the low but significant (p < 0.001) inbreeding index of the entire population (0.044) indicated that genetic drift in the population could lead to rapid loss of genetic diversity. ...
Microphysogobio rapidus, an endemic cyprinid fish species found exclusively in Korea, has been identified in only two tributaries of the Nakdong River. The species predominantly occupies the near-gravel bottom waters within shallow sections of the middle and lower reaches of the river, characterized by swift currents. M. rapidus is currently recognized as a critically endangered species due to its distinct habitat preference, as well as the negative impacts of stream dam development and water environment pollution. In this study, we used 10 microsatellite markers to examine the genetic diversity of M. rapidus in the upper Nam (UN), lower Nam (LN), and Deokcheon Rivers (DC) in Korea, with a specific focus on assessment of the impact of dam development. Fish sampled from the UN and LN showed a greater average number of alleles and allelic richness (A = 18.3–18.4, AR = 13.8) compared to those from DC (A = 11.8, AR = 11.5). The observed heterozygosity among the fish examined ranged from HO = 0.748 (LN) to 0.766 (DC). All three fish groups exhibited a significant departure from Hardy–Weinberg equilibrium (HWE) (p < 0.05). Despite having the largest effective population size (Ne = 175 and 157, respectively), the fish sampled from UN and LN showed the highest inbreeding coefficients (FIS = 0.056–0.053, respectively), which were highly significant (p < 0.01). In contrast, the fish sampled from DC exhibited the smallest effective population size (Ne = 61) and showed an inbreeding coefficient close to zero (p > 0.05). BOTTLENECK analysis and estimated M-ratio values (0.341–0.372) revealed indications of past population size reduction in all fish groups examined. No significant genetic differentiation (FST
... Estimates of N e were <100 for 5 of the nine population genetic clusters, suggesting that they are below the recommended threshold for short-term persistence, and potentially at future risk of inbreeding depression (Frankham et al. 2014). Only three genetic clusters (New Jersey/Long Island, New York, Connecticut/Monomoy, and the Great Marsh complex of Massachuestts/New Hamphsire/Maine) have breeding populations large enough for likely long-term persistence (N e > 1,000), according to recommendations of Frankham et al. (2014). ...
... Estimates of N e were <100 for 5 of the nine population genetic clusters, suggesting that they are below the recommended threshold for short-term persistence, and potentially at future risk of inbreeding depression (Frankham et al. 2014). Only three genetic clusters (New Jersey/Long Island, New York, Connecticut/Monomoy, and the Great Marsh complex of Massachuestts/New Hamphsire/Maine) have breeding populations large enough for likely long-term persistence (N e > 1,000), according to recommendations of Frankham et al. (2014). The low precision in the estimates for larger populations, often with confidence intervals extending to infinity, is typical and may suggest that additional samples and/or loci are needed to better estimate N e in the larger populations (Neel et al. 2013) For comparison with our genetic data, we also calculated N e based on prior estimates of patch-level abundance (Wiest et al., 2019) and a conservative ratio of N e to census size of 0.2 (Supplementary Material Table 8; Frankham 1995, Frankham et al. 2014). ...
... Only three genetic clusters (New Jersey/Long Island, New York, Connecticut/Monomoy, and the Great Marsh complex of Massachuestts/New Hamphsire/Maine) have breeding populations large enough for likely long-term persistence (N e > 1,000), according to recommendations of Frankham et al. (2014). The low precision in the estimates for larger populations, often with confidence intervals extending to infinity, is typical and may suggest that additional samples and/or loci are needed to better estimate N e in the larger populations (Neel et al. 2013) For comparison with our genetic data, we also calculated N e based on prior estimates of patch-level abundance (Wiest et al., 2019) and a conservative ratio of N e to census size of 0.2 (Supplementary Material Table 8; Frankham 1995, Frankham et al. 2014). The estimates of N e from abundance tended to be lower than our genetic estimates of N e . ...
Determining factors that shape a species’ population genetic structure is beneficial for identifying effective conservation practices. We assessed population structure and genetic diversity for Saltmarsh Sparrow (Ammospiza caudacuta), an imperiled tidal marsh specialist, using 13 microsatellite markers and 964 individuals sampled from 24 marshes across the breeding range. We show that Saltmarsh Sparrow populations are structured regionally by isolation-by-distance, with gene flow occurring among marshes within ~110–135 km of one another. Isolation-by-resistance and isolation-by-environment also shape genetic variation; several habitat and landscape features are associated with genetic diversity and genetic divergence among populations. Human development in the surrounding landscape isolates breeding marshes, reducing genetic diversity and increasing population genetic divergence, while surrounding marshland and patch habitat quality (proportion high marsh and sea-level-rise trend) have the opposite effect. The distance of the breeding marsh to the Atlantic Ocean also influences genetic variation, with marshes farther inland being more divergent than coastal marshes. In northern marshes, hybridization with Nelson’s Sparrow (A. nelsoni) strongly influences Saltmarsh Sparrow genetic variation, by increasing genetic diversity in the population; this has a concomitant effect of increasing genetic differentiation of marshes with high levels of introgression. From a conservation perspective, we found that the majority of population clusters have low effective population sizes, suggesting a lack of resiliency. To conserve the representative breadth of genetic and ecological diversity and to ensure redundancy of populations, it will be important to protect a diversity of marsh types across the latitudinal gradient of the species range, including multiple inland, coastal and urban populations, which we have shown to exhibit signals of genetic differentiation. It will also require maintaining connectivity at a regional level, by promoting high marsh habitat at the scale of gene flow (~130 km), while also ensuring “stepping stone” populations across the range.
... Geographically isolated populations increase rates of inbreeding. Importantly, inbreeding causes inbreeding depression; to avoid this, an N e value of > 100 (N < 5 generations) has been suggested 75 . In the present study, the N e value was < 100 in the UC and CG groups; thus, efforts to avoid inbreeding depression are needed. ...
... Frankham et al. 75 suggested that N e > 1000 is needed to maintain evolutionary potential; in all populations of P. nigra, N e was in the range of 52-301. The species is unlikely to become extinct in the near future but may lose its ability to evolve over time, thus limiting its long-term survival 75 . ...
... Frankham et al. 75 suggested that N e > 1000 is needed to maintain evolutionary potential; in all populations of P. nigra, N e was in the range of 52-301. The species is unlikely to become extinct in the near future but may lose its ability to evolve over time, thus limiting its long-term survival 75 . Therefore, conservation and restoration efforts are suggested for specific populations, as well as all resident populations to maintain their evolutionary potential. ...
The black shinner Pseudopungtungia nigra Mori, 1935 is an endangered fish endemic to Korea. It lives in the narrow basin of the Geumgang River, Mangyeonggang River, and Ungcheoncheon Stream, which flow into the West Sea of Korea. One population of P. nigra in Ungcheoncheon Stream has been locally exterminated once; it is now inhabiting the upper reaches of the dam through a restoration program. Efforts to identify and understand the genetic structure of these populations are important for conservation planning. Here, we analyzed genetic diversity using 21 microsatellite markers for 9 populations. The mean number of alleles ranged from 4.4 to 8.1, mean allelic richness ranged from 4.6 to 7.8, mean observed heterozygosity ranged from 0.519 to 0.702, and mean expected heterozygosity ranged from 0.540 to 0.763. All groups had recent and historical bottlenecks (P < 0.05, M-ratio < 0.68). Three groups [YD (2019), OC and UC] had significant inbreeding index values, suggesting that they were engaged in inbreeding. We observed a moderate level of genetic differentiation between MG and the rest of the population (FST = 0.135 to 0.168, P < 0.05). The genetic structure exhibited a fitting constant K = 2, along with separation between MG and the remaining populations. With respect to genetic flow, YD (2019), OC, CG, and ND shifted to the UC population (0.263 to 0.278). The genetic flow of each population was transferred only within the population; there was no gene flow among populations, except for the Ungcheoncheon Stream population. This study shows that the Ungcheoncheon Stream population needs conservation efforts to increase its genetic diversity, and the Geumgang River populations needs a conservation plan that considers the possibility of conservation and evolution through gene exchange among the populations.
... Given our sample sizes and the resulting wide confidence intervals associated with our N e estimates, caution should be used to not overinterpret our findings. That said, point estimates were relatively consistent among analyses at near or above 500 fish, suggesting that Blue Suckers in the Wabash River are not in immediate threat of extirpation from genetic impoverishment and inbreeding depression (Rieman and Allendorf, 2001;Frankham et al., 2014). While upper confidence interval limits (4,492 fish) suggest a minimum impact of genetic drift on genetic variation (Do et al., 2014), lower limits (318 fish) strongly suggest future monitoring of genetic diversity would be prudent to ensure the conservation of Blue Suckers throughout the Wabash River system (Frankham et al., 2014). ...
... That said, point estimates were relatively consistent among analyses at near or above 500 fish, suggesting that Blue Suckers in the Wabash River are not in immediate threat of extirpation from genetic impoverishment and inbreeding depression (Rieman and Allendorf, 2001;Frankham et al., 2014). While upper confidence interval limits (4,492 fish) suggest a minimum impact of genetic drift on genetic variation (Do et al., 2014), lower limits (318 fish) strongly suggest future monitoring of genetic diversity would be prudent to ensure the conservation of Blue Suckers throughout the Wabash River system (Frankham et al., 2014). ...
Widespread losses in river connectivity and habitat degradation have led to rapid declines in migratory freshwater fishes. Large, connected tributary systems are likely critical to the conservation of fluvial species when they provide access to life-cycle-dependent habitats. The Blue Sucker (Cycleptus elongatus) is a large-bodied migratory catostomid, endemic to the large rivers of North America and declining in abundance across much of its range. Blue Suckers occupying the Wabash River (Illinois/Indiana, USA), a large tributary within the Mississippi River basin, may be one of few remaining robust populations of this species. To understand the characteristics of a successful Blue Sucker population, we analyzed data from ten years of electrofishing surveys conducted in the lower Wabash River (2010-2019, n ¼ 563 Blue Suckers). We found Blue Sucker presence probability increased at sites with snags and with increasing surface water velocity. The length-weight regression was comparable to other populations, and the mean relative weight was 94.27. Maturation was estimated to occur at a minimum of 422 mm total length, around 2-3 years of age. We found support for variable individual spawning preparedness evidenced by inconsistent gonadal development among pre-winter adults and found support for intermittent reproductive success evidenced by a multi-modal population age structure. Genetic analysis supported the presence of a panmictic population throughout the Wabash River system, with no barrier to separate this population from the greater Mississippi River basin metapopulation. The effective population size was estimated to be 632.8 (95% CI ¼ 318.4-4,492.2), indicating the population is not at immediate risk of inbreeding depression but should continue to be monitored. The characteristics of this resilient lower Wabash River Blue Sucker population can inform the management and conservation of this imperiled species throughout its range.
... It is suggested that such cases may be associated with longterm adaptations for persistence in small populations on naturally fragmented landscape features, such as those that are expressed in old, climatically buffered, infertile landscapes (OCBILs) of limited distribution (Hopper, 2009). However, regardless of the genetic effects, demographic risk remains, and recent research suggests 250 may be well below an appropriate population size for many taxa (Frankham et al., 2014). Thus, while we consider the 250 threshold to be a practical indicator of population persistence for the purposes of this process, it does not necessarily indicate that populations below this threshold will not persist. ...
... To that end, as and when taxon or population specific evidence becomes available, the numeric threshold can be altered for a given taxon to operate using a number of individuals more appropriate for that taxon. Alternatively, if desired, a more conservative threshold could be utilised: e.g., 1,000 as suggested in Frankham et al., (2014). In practice, more conservative thresholds, while desirable, are often not possible -few CR and EN flora have anywhere close to such numbers, and adoption of a threshold of 250 individuals is far more practical for the appropriate allocation of resources in these cases. ...
A large number of Australia’s plants are in danger of extinction. Plant translocations have become increasingly important in threatened flora conservation programs. They can, however, be costly and there are trade-offs inherent in deciding which conservation actions to invest in. Here we develop a decision-support process to rapidly identify when translocations are likely to be preferable to the status quo of managing threats in situ.
... Genetics plays a prominent role in conservation biology, particularly for investigating and developing solutions to problems of inbreeding and taxonomic uncertainty (Frankham 1995;Kohn et al. 2006; Avise 2012; Frankham et al. 2014). Conservation biology studies aim to sample with minimal impacts on the individual or population, particularly when working with rare or endangered species (Morin et al. 1993; Taberlet and Luikart 1999;Riddle et al. 2003; Lefort et al. 2014). ...
... demonstrated, it can also be di cult to obtain tissue from smaller live amastrids. Because of their rarity and the need to maximize genetic variation in captive breeding programs to ensure population health (reviewed byFrankham et al. 2014), it is especially important that individuals are not killed for DNA sampling. This study not only con rmed FTA sampling as a viable non-lethal DNA sampling method for this family, its successful use for amplifying and sequencing markers makes conservation studies requiring wide scale genetic sampling feasible. ...
Sampling the DNA of rare animal species should have minimal impacts on individual health. This can be accomplished through non-lethal/non-invasive sampling. Few of these methods have been developed for invertebrates, including the Mollusca, which are in global decline. Tissue clipping the foot is a common non-lethal method for gastropods. However, it causes permanent damage and is inappropriate for smaller snails. This study used Flinders Technology Associates (FTA) cards to sample DNA from snail mucus for species of different sizes and habitat types, and across evolutionarily distant lineages. In a survival assay, the death rate of individuals sampled with FTA cards (12.1%) was greater than in the controls (3.7%), but the difference was not significant. Of 224 individuals representing 27 snail species (17 Hawaiian native, ten non-native) sampled using both FTA cards and tissue clipping, 80.4% of FTA samples and 91.6% of tissue samples amplified for COI, a significant difference. COI sequencing success did not differ significantly between the two methods. For individuals that failed to produce a COI sequence, an attempt was made to sequence 16S. For 16S, amplification and sequencing rates did not differ significantly between FTA and tissue samples. Habitat type and shell size did not affect FTA sampling success. Phylogenetically basal taxa exhibited lower success rates, but this may have been because of difficulty in sampling operculate taxa, and not because of identity. These results indicate that the FTA sampling is a viable non-lethal alternative to tissue clipping and can be used for diverse gastropods.
... Specifically, population increases may obscure declines in genetic diversity that may undermine population persistence. This reinforces the importance of incorporating realistic processes of genetic inheritance and gene flow in modelling small populations 27,38 . ...
... Thus, the subspecies lacks reservoirs of genetic variation in captivity, unlike other species, e.g. the Amur tiger 52 . Evidence suggests that existing subpopulations may not meet minimum viable population size thresholds 38 . Even for one of the largest single populations of tigers globally (Western-Ghats, India 18 ), one study suggests an unrealistic amount of population growth and size would be required to prevent loss in genetic diversity. ...
Isolation of wildlife populations represents a key conservation challenge in the twenty-first century. This may necessitate consideration of translocations to ensure population viability. We investigated the potential population and genetic trajectory of a small, isolated tiger (Panthera tigris) population in Thailand’s Dong Phayayen-Khao Yai forest complex across a range of scenarios. Using an individual-based, spatially-explicit population modelling approach, we simulate population and genetic trajectories and evaluate the relative impact of translocations from a related population. Population and genetic trajectories in our study were most sensitive to sex and number of individuals translocated and translocation frequency. Translocation of females produced consistently higher population, allelic richness, and heterozygosity compared to equal numbers of males. Despite population increases, declines in allelic richness and heterozygosity across simulations were stark, with simulations predicting a mean decline of allelic richness and heterozygosity of 46.5% and 53.5% without intervention, respectively. Translocations of four females every generation or every other generation were required to prevent substantial heterozygosity declines. While translocations could increase population size, they may fail to prevent long-term loss of genetic diversity in small populations unless applied frequently. This reinforces the importance of incorporating realistic processes of genetic inheritance and gene flow in modelling small populations.
... eventual genetic erosion (Aguilar et al., 2008). This is especially true given the small Ne values (Table 1), leaving these populations susceptible to reduced population viability (Frankham et al., 2014). The calculated Ne values as well as most of the confidence intervals of the Mojave milkweed populations were less than the 50/500 rule, where in the short term an Ne ≥ 50 reduces inbreeding depression and a long-term Ne ≥ 500 maintains evolutionary potential (Jamieson & Allendorf, 2012). ...
... The distinct population structure of Mojave milkweed in the Ivanpah Valley, coupled with the small effective population size of each individual population, may lead to eventual genetic erosion (Aguilar et al., 2008). This is especially true given the small Ne values (Table 1), leaving these populations susceptible to reduced population viability (Frankham et al., 2014). The observed Ne values of each of the Mojave milkweed populations were much less than the 50/500 rule, where in the short term, an Ne of 50 reduces inbreeding depression and a longterm Ne of 500 maintains evolutionary potential (Jamieson & Allendorf, 2012). ...
Abstract A rapid renewable energy transition has facilitated the development of large, ground‐mounted solar energy facilities worldwide. Deserts, and other sensitive aridland ecosystems, are the second most common land‐cover type for solar energy development globally. Thus, it is necessary to understand existing diversity within environmentally sensitive desert plant populations to understand spatiotemporal effects of solar energy siting and design. Overall, few population genomic studies of desert plants exist, and much of their biology is unknown. To help fill this knowledge gap, we sampled Mojave milkweed (Asclepias nyctaginifolia) in and around the Ivanpah Solar Electric Generating Station (ISEGS) in the Mojave Desert of California to understand the species' population structure, standing genetic variation, and how that intersects with solar development. We performed Restriction‐site Associated Sequencing (RADseq) and discovered 9942 single nucleotide polymorphisms (SNPs). Using these data, we found clear population structure over small spatial scales, suggesting each site sampled comprised a genetically distinct population of Mojave milkweed. While mowing, in lieu of blading, the vegetation across the solar energy facility's footprint prevented the immediate loss of the ISEGS Mojave milkweed population, we show that the effects of land‐cover change, especially those impacting desert washes, may impact long‐term genetic diversity and persistence. Potential implications of this include a risk of overall loss of genetic diversity, or even hastened extirpation. These findings highlight the need to consider the genetic diversity of impacted species when predicting the impact and necessary conservation measures of large‐scale land‐cover changes on species with small population sizes.
... To formulate scientific and effective conservation strategies and measures for endangered species, it is necessary to understand its genetic diversity, spatial distribution, and relationship with environmental factors, and establish conservation units or select populations with high genetic diversity for in situ or ex situ conservation [13][14][15]. ...
... It can be inferred that CM was widely and continuously distributed in north and northeast China in the past, this speculation is also supported by our study of the Max-Ent species distribution model combined with 38 environmental variables to analyze the suitable geographical range of CM in China in the past and future (The data has not yet been published). All CM can be considered a huge population connected by large gene flow, and the historical gene flow occurred according to the steppingstone model, short distance gene flow without interference can make continuously distributed population can reach a dynamic balance during a long evolutionary process, but once disturbance occurs, such as excessive collection, environmental change, orogeny in geological history, extreme weather, accidental event and so on, it will accelerate the genetic differentiation and formation of genetic structure of species [13], for example, due to a variety of reasons, forests in Northeast China have been extensively cut down historically, and some woodland has been replaced by farmland, which has had a certain impact on the species in the original habitat under the forest, including CM. Genetic differentiation detected among CM populations is one of evidence that these populations have been subjected to extensive human disturbance and habitat fragmentation in recent times. Various exogenous disturbances can upset this balance and reduce the genetic diversity of species and aggravate genetic differentiation between populations [56]. ...
Background
Genetic diversity, genetic structure, and gene flow in plant populations and their influencing factors are important in conservation biology. Cypripedium macranthos is one of the few wild orchids with high ornamental value in northern China. However, over the past decade, excessive collection, trading, tourism development, habitat fragmentation, deceptive pollination, and seed germination difficulties have all caused a sharp decline in the number of C. macranthos individuals and its population. In order to propose a scientific and effective conservation strategy, the genetic diversity, genetic structure and gene flow of the current CM population are urgent scientific issues to be clarified.
Results
Here, 99 individuals of C. macranthos from north and northeast China were analyzed to evaluate the genetic diversity, gene flow among populations, and genetic structure by genotyping-by-sequencing. More than 68.44 Gb high-quality clean reads and 41,154 SNPs were obtained. Our data based on bioinformatics methods revealed that C. macranthos has lower genetic diversity, high levels of historical gene flow, and moderate-to-high genetic differentiation between populations. The gene migration model revealed that the direction of gene flow was mainly from northeast populations to north populations in China. The results of genetic structure analysis showed that 11 C. macranthos populations can be considered as two groups, and further divided into four subgroups. Moreover, the Mantel test detected no significant “Isolation by Distance” between populations.
Conclusions
Our study demonstrates that the present genetic diversity and genetic structure of C. macranthos populations were mainly caused by biological characteristics, human interference, habitat fragmentation, and restricted gene flow. Finally, constructive measures, which can provide a basis for the proposal of conservation strategies, have been suggested.
... Given these results, our estimates of effective population size were generally low in all populations (mean = 47.6) and indicate populations may potentially be susceptible to inbreeding depression over time (i.e. N e < 100; Frankham et al., 2014). We stress that cautious interpretation of these results is required, ...
Translocation programmes are increasingly being informed by genetic data to monitor and enhance conservation outcomes for both natural and established populations. These data provide a window into contemporary patterns of genetic diversity, structure and relatedness that can guide managers in how to best source animals for their translocation programmes. The inclusion of historical samples, where possible, strengthens monitoring by allowing assessment of changes in genetic diversity over time and by providing a benchmark for future improvements in diversity via management practices. Here, we used reduced representation sequencing (ddRADseq) data to report on the current genetic health of three remnant and seven translocated boodie ( Bettongia lesueur ) populations, now extinct on the Australian mainland. In addition, we used exon capture data from seven historical mainland specimens and a subset of contemporary samples to compare pre‐decline and current diversity. Both data sets showed the significant impact of population founder source (whether multiple or single) on the genetic diversity of translocated populations. Populations founded by animals from multiple sources showed significantly higher genetic diversity than the natural remnant and single‐source translocation populations, and we show that by mixing the most divergent populations, exon capture heterozygosity was restored to levels close to that observed in pre‐decline mainland samples. Relatedness estimates were surprisingly low across all contemporary populations and there was limited evidence of inbreeding. Our results show that a strategy of genetic mixing has led to successful conservation outcomes for the species in terms of increasing genetic diversity and provides strong rationale for mixing as a management strategy.
... The maintenance of genetic diversity has been understood to be vitally important for biodiversity conservation for some time [120,121]. Genetic considerations must be made at multiple stages within the translocation process by the selection of appropriate source populations, determination of founder group sizes to capture representative genetic variation and ongoing monitoring and management to ensure its persistence [122]. Nowhere is the need to consider genetics greater than in conservation translocations [123]. ...
Conservation translocations have become increasingly popular for ‘rewilding’ areas that have lost their native fauna. These multispecies translocations are complex and need to consider the requirements of each individual species as well as the influence of likely interactions among them. The Dirk Hartog Island National Park Ecological Restoration Project, Return to 1616, aspires to restore ecological function to Western Australia’s largest island. Since 2012, pest animals have been eradicated, and conservation translocations of seven fauna species have been undertaken, with a further six planned. Here, we present a synthesis of the innovative approaches undertaken in restoring the former faunal assemblage of Dirk Hartog Island and the key learnings gathered as the project has progressed.
... Some studies indicate that an effective population size of more than 50 is needed to avoid inbreeding depression, whereas others suggest that a Ne greater than 500 is required to sustain a population's evolutionary potential (Harmon and Braude, 2010). However, a Ne of 1000 is more realistic for maintaining the population's long-term adaptive potential as per the revised recommendations (Frankham et al., 2014). ...
Due to environmental change and anthropogenic activities, global biodiversity has suffered an unprecedented loss, and the world is now heading toward the sixth mass extinction event. This urges the need to step up our efforts to promote the sustainable use of animal genetic resources and plan effective strategies for their conservation. Although habitat preservation and restoration are the primary means of conserving biodiversity, genomic technologies offer a variety of novel tools for identifying biodiversity hotspots and thus, support conservation efforts. Conservation genomics is a broad area of science that encompasses the application of genomic data from thousands or tens of thousands of genome-wide markers to address important conservation biology concerns. Genomic approaches have revolutionized the way we understand and manage animal populations, providing tools to identify and preserve unique genetic variants and alleles responsible for adaptive genetic variation, reducing the deleterious consequences of inbreeding, and increasing the adaptive potential of threatened species. The advancement of genomic technologies, particularly comparative genomic approaches, and the increased accessibility of genomic resources in the form of genome-enabled taxa for non-model organisms, provides a distinct advantage in defining conservation units over traditional genetics approaches. The objective of this review is to provide an exhaustive overview of the concept of conservation genomics, discuss the rationale behind the transition from conservation genetics to genomic approaches, and emphasize the potential applications of genomic techniques for conservation purposes. We also highlight interesting case studies in both livestock and wildlife species where genomic techniques have been used to accomplish conservation goals. Finally, we address some challenges and future perspectives in this field.
... Additional support for this hypothesis comes from the fact that preliminary screening of microsatellite markers in five ponds from our study area showed a large proportion of them to be monomorphic, although they were shown to be polymorphic in central Iberian populations. However, effective population sizes seem to be high, suggesting populations are not threatened by inbreeding depression and retain their evolutionary potential (Frankham et al. 2014), provided functional connectivity is maintained. Fig. 2 Map of ancestry proportions for each Pleurodeles waltl deme, based on TESS analyses for K = 2 to K = 7, using the neutral SNP dataset ...
Context
Functional connectivity across fragmented habitat patches is essential for the conservation of animal populations in humanized landscapes. Given their low dispersal capacity, amphibians in the Mediterranean region are threatened by habitat fragmentation and loss due to changes in land use, including agricultural intensification.
Objectives
We assessed patterns of functional connectivity of a Near Threatened Mediterranean amphibian, the sharp ribbed newt (Pleurodeles waltl), in an agricultural landscape matrix in NW Spain subject to different intensification regimes.
Methods
We sampled newts in 17 ponds embedded in a terrestrial habitat matrix dominated by agricultural land uses. Genome-wide molecular markers (1390 SNPs) were used to assess patterns of genetic diversity and gene flow among ponds. We tested the role of landscape features on functional connectivity using isolation by resistance models incorporating information on Normalized Difference Vegetation Index (NDVI) data.
Results
We found low levels of genetic diversity in all sampled populations. Global FST estimates and cluster analyses revealed shallow but significant genetic structure in the study area, with NDVI-based resistance models showing that open areas (rainfed crops and grasslands) offer lower resistance to gene flow and thus promote functional connectivity among demes.
Conclusions
Our study highlights the important role of landscape features, such as open areas resulting from traditional rainfed agriculture, in promoting functional connectivity between amphibian populations in Mediterranean agrosystems. Conservation policies must adopt a functional network strategy and protect groups of inter-connected temporary ponds across the traditional agricultural matrix to efficiently preserve their associated biotic communities.
... De tidigare internationellt etablerade bevarandegenetiska riktlinjerna som anger att populationer inte ska understiga 50 och 500 individer på kortare respektive längre sikt har på senare tid börjat ifrågasättas. Det har i stället föreslagits att högre riktvärden på 100 och 1 000 borde tillämpas (Frankham et al. 2014). Framför allt om arternas evolutionära potential ska kunna uppnås i genetiskt isolerade populationer. ...
Technical Report about salmon (Salmo salar) population status in Piteälven, Sweden.
Report in Swedish only.
... In this study, except for the HDC and HSNC populations, whose N e were difficult to measure, the remaining ten populations showed considerably low effective population sizes (N e < 100). Frankham et al. suggested that N e should be >100 to avoid inbreeding depression [58]. However, all populations have a median N e of ≤100; therefore, they will likely suffer from inbreeding depression. ...
The spotted sleeper, Odontobutis interrupta, is a fish species endemic to Korea and shows potential as an aquaculture species. Nevertheless, the population size of this species has declined significantly in recent years. To characterize the population structure and genetic diversity of O. interrupta in Korea, we analyzed four microsatellite loci in twelve populations from four major river systems. The provenance of the population was investigated to discern the origin of the translocated populations. The genetic diversity of the microsatellite ranged from 0.440 to 0.756, showing a high level of diversity similar to that of other freshwater fishes. However, mitochondrial DNA analysis exhibited low genetic diversity (Hd: 0.000–0.674, π: 0.00000–0.00159). The FST values of microsatellites and mitochondrial DNA ranged from 0.096 to 0.498 and −0.046 to 0.951, suggesting genetic admixture among populations. All populations exhibited an effective population size of <100; therefore, preservation efforts to prevent inbreeding depression would be required. The genetic structure could be divided into unique genotypes from the Seomjingang and Geumgang Rivers. However, genetic admixture was observed in all populations, rendering it impossible to distinguish them. Our findings provide fundamental but significant genetic insights pursuant to devising conservation strategies for O. interrupta.
... The (Flury et al., 2010;Li and Kim, 2015;Jemaa et al., 2019). Although the standard value for stable Ne is debatable, there is a consensus that Ne ≤ 50 is insufficient to avert inbreeding depression and retain fitness within a short period, while Ne ≥ 100 is considered stable to limit total fitness loss to less than 10% (Frankham et al., 2014). Using 0.05 as the maximum value of the recombination rate, the lowest Ne < 50 were recorded in Väne, Fjällnära and Bohuskulla, respectively. ...
The indigenous cattle populations are on the decline globally with the continuous improvement of genetic gains in commercial breeds. Due to their unique adaptive features to the local ecosystem, traditional cattle breeds are pools of valuable genetic resources that could help combat the impact of climate change in the near future.
However, besides the census population sizes, it is crucial to
assess the impacts of genetic drift to design strategic breeding programmes to improve genetic diversity and safeguard the breeds against genetic erosion.
This study estimated the effective population sizes (Ne) of nine Swedish native cattle breeds from 147 individuals genotyped with GenSeek GGP Bovine 150K and 33 samples from whole genome sequence data using the observed linkage disequilibrium spectrum. Demographic trajectories of up to 200 generations ago were also inferred to match the decline observed to a series of events that have shaped the breeds’ current status.
The estimated result showed that two breeds (Bohuskulla and Väne) have Ne values within Ne ≤ 50, indicating critical status. Also, four are in the endangered zone (Ringamålako, Fjällnara, Swedish Polled, and Swedish Red Polled) with Ne ≤ 100, and only three breeds (Holstein Friesian, Swedish Red Cattle, and Swedish Mountain Cattle) are considered stable to limit total fitness loss up to 10% with Ne ≥ 100. Also, a general dramatic decline was observed between the 12th to 15th
generations across all breeds, which suggests that the reduction in the population of Swedish native cattle breeds began with breed formation.
While maintaining high Ne is critical for the conservation of indigenous cattle, using the pedigree method or demographic might not provide accurate estimates due to several limitations. These include overlapping generations and a lack of pedigree information. Therefore, besides preventing inbreeding, Ne estimates from genomic data should be adopted in the breeding and conservation strategies of Swedish native cattle breeds. They are non-dependent on pedigree information and
demographic data.
Keywords: Swedish native cattle, effective population size, genetic drift, cattle demographic trajectories, native cattle conservation
... Aspectos teóricos relacionados à conservação genética em populações naturais A conservação de populações de espécies arbóreas depende primordialmente da existência de alta diversidade genética contida dentro das populações, ou seja, as árvores adultas devem ser geneticamente variáveis. Populações com um número grande de indivíduos ->1.000 árvores não aparentadas (Frankham et al., 2014) -em florestas contínuas (ou pouco fragmentadas) são as condições primordiais para que essas estejam geneticamente conservadas (Young et al., 1996). A fragmentação de florestas, devido ao desmatamento, ocasiona a redução de tamanhos populacionais efetivos e o aumento da distância entre árvores remanescentes, resultando em menor probabilidade de uma árvore receber pólen de outros indivíduos e em maior chance de receber pólen da própria árvore ou de árvore aparentada. ...
... Captive breeding programs typically operate with smaller populations than would be ideal to maintain long-term population viability [22,23]. The retention of genetic diversity is therefore the focus, targeting an effective population size (N e ) of at least 500 [24], a threshold used by the Convention on Biological Diversity (CBD) [25] to describe a healthy population. Lack of diversity leads to disproportionate heritable disease burden, for example inbreeding depression in Italian wildcats [26]. ...
This paper asks the question: can genomic information recover a species that is already on the pathway to extinction due to genetic swamping from a related and more numerous population? We show that whole genome sequencing can be used to identify and remove hybrid segments of DNA, when used as part of the breeding policy in a captive breeding program. The proposed policy uses a generalised measure of kinship or heterozygosity accounting for local ancestry, that is, whether a specific genetic location was inherited from from the target of conservation. We then show that optimising these measures would minimise undesired ancestry whilst also controlling undesired kinship or heterozygosity respectively, in a simulated breeding population. The process is applied to real data representing the hybridized Scottish wildcat breeding population, with the result that it should be possible to breed out the domestic cat ancestry. The ability to reverse introgression is a powerful new tool brought about from both sequencing and computational advances in ancestry estimation. Since it works best when applied early in the process, important decisions need to be made about which genetically distinct populations should benefit from it and which should be left to reform into a single population.
... This can be achieved by either focusing on which are the predators of a given prey species, using species-specific assays, or by assessing the diet composition of a predator species using sequencing. Genetic technologies are being used to examine what genes are important for adaptive divergence, for past and present evolution in aquatic species (Brennan et al. 2018;2019), and what population sizes should be considered as critically endangering long-term conservation (Frankham, Bradshaw and Brook 2014). New species, new stocks and potentially new genes with beneficial traits can be identified using genetic screening (Nature 2022). ...
... N eGD is however of more relevance for long term than for short term conservation since it approximates the additive genetic variance effective size N eAV (Franklin 1980;Hössjer et al. 2016). This is important since the frequently used conservation guideline for long term survival, that stipulates that N e should be larger than 500 (Franklin 1980;Jamieson and Allendorf 2012) or larger than 1000 (Frankham et al. 2014;Pérez-Pereira et al. 2022), relates to N eAV (Ryman et al. 2019). However, since N eGD (and N eAV ) is difficult to estimate in practice, it is important to assess how well it is approximated by N eV . ...
The variance effective population size ([Formula: see text]) is frequently used to quantify the expected rate at which a population's allele frequencies change over time. The purpose of this paper is to find expressions for the global [Formula: see text] of a spatially structured population that are of interest for conservation of species. Since [Formula: see text] depends on allele frequency change, we start by dividing the cause of allele frequency change into genetic drift within subpopulations (I) and a second component mainly due to migration between subpopulations (II). We investigate in detail how these two components depend on the way in which subpopulations are weighted as well as their dependence on parameters of the model such a migration rates, and local effective and census sizes. It is shown that under certain conditions the impact of II is eliminated, and [Formula: see text] of the metapopulation is maximized, when subpopulations are weighted proportionally to their long term reproductive contributions. This maximal [Formula: see text] is the sought for global effective size, since it approximates the gene diversity effective size [Formula: see text], a quantifier of the rate of loss of genetic diversity that is relevant for conservation of species and populations. We also propose two novel versions of [Formula: see text], one of which (the backward version of [Formula: see text]) is most stable, exists for most populations, and is closer to [Formula: see text] than the classical notion of [Formula: see text]. Expressions for the optimal length of the time interval for measuring genetic change are developed, that make it possible to estimate any version of [Formula: see text] with maximal accuracy.
... Effective population size is a crucial parameter in conservation genetics because it provides insight into species' long-term adaptive potential and extinction risk. Several benchmark values of N e have been proposed to prevent detrimental effects of inbreeding (inbreeding N e of 50-100) and to prevent loss of quantitative variation and maintain adaptive potential (N eV of 500-1000) (Franklin, 1980;Frankham et al., 2014). Our observed LD N e values in RGSM were not small enough to suggest immediate risks from inbreeding. ...
Human water use combined with a recent megadrought have reduced river and stream flow through the southwest United States and led to periodic drying of formerly perennial river segments. Reductions in snowmelt runoff and increased extent of drying collectively threaten short‐lived, obligate aquatic species, including the endangered Rio Grande silvery minnow ( Hybognathus amarus ). This species is subject to boom‐and‐bust population dynamics, under which large fluctuations in abundance are expected to lower estimates of effective population size and erode genetic diversity over time. Rates of diversity loss are also affected by additions of hatchery‐origin fish used to supplement the wild population. We used demographic and genetic data from wild and hatchery individuals to examine the relationship of genetic diversity and effective population size to abundance over the last two decades. Genetic diversity was low during the early 2000s, but diversity and demographic metrics stabilized after the hatchery program was initiated and environmental conditions improved. Yet, from 2017 onward, allelic diversity declined (Cohen's d = 1.34) and remained low despite hatchery stocking and brief wild population recovery. Across the time series, single‐sample estimates of effective population size based on linkage disequilibrium (LD N e ) were positively associated ( r = 0.53) with wild abundance and total abundance, but as the proportion of hatchery‐origin spawners increased, LD N e declined ( r = −0.55). Megadrought limited wild spawner abundance and precluded refreshment of hatchery brood stocks with wild fish; hence, we predict a riverine population increasingly dominated by hatchery‐origin individuals and accelerated loss of genetic diversity despite supplementation. We recommend an adaptive and accelerated management plan that integrates river flow management and hatchery operations to slow the pace of genetic diversity loss exacerbated by megadrought.
... Endangered species are commonly subject to have limited genetic diversity in the population. Populations with low genetic variation are often less able to adapt to environmental changes, more susceptible to inbreeding, and at greater risk of local extinction (Frankham et al., 2010(Frankham et al., , 2014. For endangered species conservation, an understanding of the current effective population size (N e ), distribution of genetic variation within population and the history of population differentiation is required to assess genetic threats to population persistence (Di Santo et al., 2022). ...
i>Hibiscus hamabo (Malvaceae) is a deciduous shrub mainly found in northeast Asia, including China, Japan, and Korea. Due to its limited distribution on Jejudo Island and at several sites in Jeollanam-do in Korea, H. hamabo has been designated as an endangered species by the Ministry of the Environment and has been the subject of several restoration programs. In this study, we quantified genetic variations using double-digestion restrictionassociated DNA sequencing technology in 96 individuals of H. hamabo from 13 distinct populations in Korea. We determined 3,352 genome-wide single nucleotide polymorphism loci after stringent filtering processes and analyzed the level of genetic variation within and among populations as well as the population differentiation and genetic ancestry with various assumptions pertaining to the population origin. Our results indicated weak differentiations among populations surveyed in this study but clearly suggested that most of the H. hamabo populations maintain a relatively high level of genetic diversity as evidence of frequent genetic exchanges among populations via outcrossing or sequential gene flows. For a more detailed analysis of the origin of Korean H. hamabo and its demographic history, it will be necessary to expand sampling in China and Japan.
... This study shows that Galapagos bullhead sharks produce genetic and biogeographic signatures comparable to many terrestrial organisms in oceanic archipelagos and contrasting those commonly found in pelagic elasmobranchs and marine taxa with larval dispersal. Isolated marine populations with small effective population sizes and low genetic diversity are at high risk of extinction because they have reduced adaptive potential and lack replenishment from adjacent locations (Frankham et al. 2014;Ryman et al. 2019). This highlights the importance of preserving shallow marine habitat to protect marine island populations (Vieira et al. 2019). ...
Oceanic islands play a central role in the study of evolution and island biogeography. The Galapagos Islands are one of the most studied oceanic archipelagos but research has almost exclusively focused on terrestrial organisms compared to marine species. Here we used the Galapagos bullhead shark ( Heterodontus quoyi ) and single nucleotide polymorphisms (SNPs) to examine evolutionary processes and their consequences for genetic divergence and island biogeography in a shallow-water marine species without larval dispersal. The sequential separation of individual islands from a central island cluster gradually established different ocean depths between islands that pose barriers to dispersal in H. quoyi . Isolation by resistance analysis suggested that ocean bathymetry and historical sea level fluctuations modified genetic connectivity. These processes resulted in at least three genetic clusters that exhibit low genetic diversity and effective population sizes that scale with island size and the level of geographic isolation. Our results exemplify that island formation and climatic cycles shape genetic divergence and biogeography of coastal marine organisms with limited dispersal comparable to terrestrial taxa. Because similar scenarios exist in oceanic islands around the globe our research provides a new perspective on marine evolution and biogeography with implications for the conservation of island biodiversity.
... The "50/500" rule-of-thumb suggests that an Ne ≥ 50 is needed for avoiding inbreeding depression in the short-term, and an Ne ≥ 500 for retaining evolutionary potential in the long-term (Franklin, 1980). Other authors have proposed to update this rule to 100/1000 (Frankham, Bradshaw, & Brook, 2014), or to 70/1000 (Caballero et al., (2017)). Regarding metapopulations, Laikre et al. (2016) established that both Ne Meta and Ne Rx should achieve 500. ...
The Iberian lynx has shown a favourable demographic trajectory in the last decade as a result of the conservation measures adopted which are still ongoing. However, the viability of the species is still compromised by genetic factors. Here, we used the GESP software that predicts the effective population size (Ne) and inbreeding accumulation (Δf) over time in metapopulations, to find realistic scenarios that guarantee the genetic viability of this species. We proposed as genetic targets that Ne of the metapopulation (Ne Meta) should exceed 500 in 20 generations (long term), whereas Δf of the subpopulations (Δf x) should not exceed 0.05 in five generations (short term). The current Iberian lynx metapopulation configuration, with the expected subpopulations sizes at carrying capacity (5 subpops.; Ne 1 = 100, Ne 2,3,4,5 = 25), does not reach the long-term goal, with a Ne Meta~1 50 in 20 generations. The results indicate that the long-term genetic viability of the metapopula-tion requires an increase in the subpopulation size of 50-200%, the creation of at least 8 new subpopulations, and migration rates close to 0.1 between neighbouring subpopulations, comprising 2165 effective individuals (ca. 1100 breeding females). In addition, a minimum migration rate of 0.05 into the smallest subpopulations of Ne = 25 (i.e. 1.25 migrants/generation) is needed to avoid excessive inbreeding accumulation (short-term goal). Larger subpopulations are preferable to several smaller subpopulations with the same number of effective individuals, even when the latter are well connected. Although these requirements seem challenging to achieve in the short-medium term, the study provides key information for informed decision making by environmental managers and policymakers. The conclusions drawn here apply to other carnivores in need of conservation.
... Extensive simulation and population genetic modeling is needed to place time points on genetic divergence. Finally, it is believed that the minimum effective population size necessary for viable isolated populations may be approximately 100 individuals to avoid inbreeding depression and approximately 1,000 to maintain adaptive potential into the long term (Frankham et al. 2014). As such, effective population sizes in these four river sections of the Alabama River should be monitored going forward. ...
Objective
We used two approaches, fish hard‐part microchemistry and genetics, to quantify effects of low‐use lock‐and‐dam structures on riverine fish movement. Each approach varied in temporal scope, with microchemistry addressing effects within a lifetime and genetics addressing effects across generations.
Methods
Water samples and individuals of two species (Paddlefish Polyodon spathula and Smallmouth Buffalo Ictiobus bubalus ) were collected from four river sections that were separated by three low‐use lock‐and‐dam structures on the Alabama River. Quarterly water samples were collected from 15 sites during 2017–2018, and concentrations of Sr, Ba, Mn, Mg, and Ca were quantified using mass spectrometry.
Result
Water elemental signatures were spatially variable but temporally consistent. The Sr:Ca ratios in fish hard parts differed significantly among river sections for both species. Additionally, discriminant function analyses classified fish to their river capture section with accuracy between 55% and 74% for Paddlefish (errors nearly always assigned individuals to adjacent river sections) and 37–47% for Smallmouth Buffalo. Population genetic analyses included fish from each river section, as well as from Alabama River tributaries and a neighboring watershed. Genotyping‐by‐sequence techniques identified 1,889 and 3,737 single nucleotide polymorphisms postfiltering in Paddlefish and Smallmouth Buffalo, respectively, which we used to estimate population diversity indices and conduct differentiation analyses. Analysis of molecular variance, discriminant analysis of principal components, Bayesian clustering, and pairwise comparisons of F ST values indicated no strong evidence for genetic divergence in either species among river sections.
Conclusion
Within‐lifespan results based on hard‐part microchemistry suggested a potential for population isolation. However, longer‐term genetic effects were not apparent, possibly because the life span of these large and relatively long‐lived species means that few generations have passed since dam construction, and there could be sufficient mixing or population connectivity to prevent genetic divergence across river sections, particularly at the most downstream structure.
... Upper bounds on the 95% jackknife confidence intervals associated with each estimate were infinite for every population except in the Onion River. In the Onion River, Knife River, and Kimball Creek populations, the lower bounds of these intervals were below thresholds frequently used to identify the most at-risk populations (N E = 50 and 100; Frankham et al., 2014aFrankham et al., , 2014bFranklin, 1980;Franklin et al., 2014;Jamieson and Allendorf, 2012), though point estimates for every population were above these thresholds. ...
Knowledge of population-level relationships and how these relationships pertain to different life history forms is critical to developing effective management plans for native trout, char, and salmon. In the Lake Superior basin, identifying effective restoration strategies for coaster brook trout (Salvelinus fontinalis), a lake-inhabiting form of brook trout, is hampered by limited information on genetic connectivity and source-sink dynamics among brook trout populations. Here, we infer these relationships by surveying 8,178 single nucleotide polymorphisms in 234 brook trout from seven rivers along the Minnesota shoreline with Lake Superior, including from reaches above and below natural waterfalls that prevent upstream movement. We identified well-differentiated above-barrier populations that supply brook trout to below-barrier reaches. We also compared within-river brook trout to 26 coaster brook trout from Lake Superior. We identified at least four source populations for these coaster brook trout, three of which were located within rivers. Additionally, we estimated N E for within-river populations and detected a decline across recent generations, with the most recent estimates approaching critical thresholds. Finally, comparisons with 94 domestic brook trout representing nine hatchery strains revealed a lack of domestic introgression into wild populations, demonstrating the importance of natural reproduction to population persistence. Our results offer novel insights into sources of coaster brook trout and highlight the role of within-river populations in supporting the coaster life history. Management efforts focused on instream restoration may be more important to rehabilitating coaster brook trout than previously thought and are urgently needed given the population-level conservation status reported here.
... As evidence of the reasonably good conservation status of the historical populations, all had N e above the minimum threshold (N e = 95) for retaining 90% of genetic diversity over 100 years [76], and several showed N e values close to or well over the threshold (N e = 1000), below which long-term maintenance of evolutionary potential is uncertain [92]. Considering other N e estimates from the study area [76], which included three of the studied rivers (Cares, Sella, and Narcea), it is established that the decline in effective population size between the 1990s and 2007-2008 already started between the 1950s and the 1990s, probably due to marine overfishing and climate-driven environmental changes in both freshwater and marine habitats. ...
Atlantic salmon Salmo salar supports highly valuable commercial and recreational fisheries in Europe, but its stocks are currently overexploited and threatened by climate change. Its southernmost populations (in northern Spain) play a key role in conserving the species’ original genetic diversity, which is endangered due to decades-long (1970s to 1990s) massive stocking with non-native stocks. Their decline is well documented, but the effect of stock transfer and conservation efforts is unclear. Nine microsatellite loci were amplified from archival samples (scales from 1958–1959) from eight Spanish rivers to analyse the species’ natural genetic dynamics before its decline started. Allelic richness was high in the historical populations (the 1950s) and above most contemporary estimates. Private alleles were found in most rivers, indicating high local uniqueness and relative isolation among river basins. Some alleles are regional markers since they are rare or absent from contemporary northern European populations. Effective population size suggested good conservation status, with higher values than those estimated for contemporary populations. Strong population structure and genetic differentiation between rivers were found, with limited gene flow, restricted to geographically close populations. Our estimates of historical genetic diversity and structure from southernmost salmon populations are a powerful benchmark to guide conservation programs.
... Identification of a minimum viable population size is of interest to guide management for individual populations, the most fundamental level at which conservation decisions are made. Although controversial [81,87], the 50/500 [88] rule sets a lower limit for N e from a genetic perspective for the short-term avoidance of inbreeding depression and long-term risk of genetic drift, respectively. Except for a few notable exceptions, census sizes of Blanding's Turtle populations tend to number in the tens to hundreds of adults [6,78]. ...
The Blanding’s Turtle (Emydoidea blandingii) is a species in need of conservation across much of its geographic range. A key aspect to conserving a species is understanding the genetic diversity and population structure across the landscape. Several researchers have focused on E. blandingii genetic diversity in the northeastern United States, Canada, and parts of the Midwestern United States; however, little investigation has been carried out on localities within the Great Lakes region of Indiana, Michigan, and Ohio. Understanding genetic trends within this region will assist with conservation planning by documenting levels of genetic variation within and among localities and developing hypotheses that have led to the observed patterns. We used 14 microsatellite loci to characterize the genetic diversity of E. blandingii in 16 localities in Indiana, Ohio, and southeast Michigan (with one northwestern locality). Overall, genetic diversity within localities tended to be high and little differentiation was observed among sample localities. No consistent evidence of bottlenecks was detected, and effective population size (Ne) estimates were generally high, but likely biased by sample size. A minimum of two clusters, and as many as seven clusters in a hierarchical analysis, were identified using three methods for grouping individuals (STRUCTURE, TESS3r, and sPCA). A correlation between geographic distance and genetic differentiation (isolation by distance) was observed. The long lifespan and historic gene flow of E. blandingii is likely responsible for the observed genetic diversity and lack of differentiation between localities. This should not suggest that populations are secure in the Great Lakes Region. Modeling aimed at estimating future genetic variation in populations under realistic demographic scenarios indicates that many localities in the region are likely to be vulnerable to genetic loss in the next 200 years.
... T. swinderianus populations locked in different mountain blocks, therefore, experience geographic isolation and barriers to gene flow and could result in morphological differentiation as observed in the cranial morphometry in our study. Studies elsewhere indicated that a loss of functional connectivity between landscapes reduces gene flow between populations and may lead to genetic variations [49][50][51]. ...
Evolutionary information on the greater cane rat (Thryonomys swinderianus) in the Eastern and Southern African regions is scarce, making population management and conservation of the species challenging. We studied T. swinderianus populations from two spatially isolated Eastern Arc Mountains in Tanzania to link molecular and geometric–morphological evidence to characterize these populations’ diversity. Fecal samples (n = 50) and skulls (n = 99) of T. swinderianus were collected from Udzungwa (north and south) and Uluguru mountains (urban and rural sites) and analyzed using molecular and geomorphometry techniques. Molecular analysis grouped the population into three distinct clades based on the location where the samples were collected, while the morphometric method was not able to distinctively separate the populations. Both methods revealed that the population obeyed the isolation by distance model with higher genetic distance between the Udzungwa and Uluguru populations and lower distance between Uluguru urban and rural populations. Both Mahalanobis and Procrustes distances in skull landmarks between the Udzungwa and Uluguru populations were significantly higher across the dorsal, ventral, and lateral views of the skulls, suggesting strongly that molecular and morphometric methods applied together can be useful in characterizing the population traits of the least known species. Our study suggests genetic and morphometric methods could complement each other in understanding the evolutionary biology and within-species diversity of vertebrate species that do not exhibit strong intra-species differentiation.
... Estimating the effective population size (N E ), as well as identifying the factors that drive changes in N E , is important for evaluating population viability and developing appropriate management strategies for conservation biology (Frankham et al., 2014;Laikre et al., 2016;Trask et al., 2017). N E is a parameter of fundamental importance in population genetics and conservation biology, and it affects the magnitude of genetic drift and the efficacy of natural selection in populations (Araki et al., 2007;Charlesworth, 2009;Wang et al., 2016). ...
Mangrove forests, which occur in the intertidal regions of tropical and sub-tropical zones, have high ecological and economic values. They have rapidly reduced over the past decades due to various reasons. Reforestation is a common strategy for the conservation of mangroves, but information on the renewal capacity and viability of these artificial mangrove populations is still lacking. Here, we estimated the effective population size (NE) of an artificial population of Kandelia obovata (Rhizophoraceae) and explored the effects of intrinsic and extrinsic factors on changes in NE to evaluate population viability and develop appropriate management strategies for mangrove forests. This population consisted of three ecologically and genetically differentiated groups that had experienced a major low-temperature event during the winter of 2015–2016 and varied in cold resistance. We first detected population bottlenecks and estimated contemporary values of NE for different groups using microsatellite data. Next, we performed paternity analyses for seedlings and propagules to explore variations in the reproductive success of individuals within the three groups before and after the low-temperature event. Lastly, we simulated four scenarios to characterize the effects of low temperature, mating system, and variance in reproductive success on changes in NE in a hypothetical metapopulation based on empirical estimates. Our results show that groups with moderate or poor cold resistance experienced local bottlenecks, and shifts in effective breeders occurred following the low-temperature event, which indicates that low temperature has an effect on not only population size but also reproductive success. Furthermore, our simulations revealed that changes in NE are jointly affected by reproductive success, mating system, and environmental conditions. These findings enhance our understanding of the multiple factors that affect NE, and provide key information that will aid the reforestation and management of mangrove forests, especially when they are introduced to high-latitude areas.
... The contemporary Ne estimates of O. henryi were much lower than the numbers generally suggested in the 50/500 rule. A Ne of 50 is recommended to avoid short-term inbreeding depression, and a Ne of 500 to maintain the long-term evolutionary potential of a species [45,46]. The demographic analysis also revealed the sustained declining trend of Ne since the LGP. ...
Background:
The evergreen broadleaved forest (EBLF) is an iconic vegetation type of East Asia, and it contributes fundamentally to biodiversity-based ecosystem functioning and services. However, the native habitat of EBLFs keeps on decreasing due to anthropogenic activities. Ormosia henryi is a valuable rare woody species in EBLFs that is particularly sensitive to habitat loss. In this study, ten natural populations of O. henryi in southern China were sampled, and then genotyping by sequencing (GBS) was applied to elucidate the standing genetic variation and population structure of this endangered species.
Results:
In ten O. henryi populations, 64,158 high-quality SNPs were generated by GBS. Based on these markers, a relatively low level of genetic diversity was found with the expected heterozygosity (He) ranging from 0.2371 to 0.2901. Pairwise FST between populations varied from 0.0213 to 0.1652, indicating a moderate level of genetic differentiation. However, contemporary gene flow between populations were rare. Assignment test and principal component analysis (PCA) both supported that O. henryi populations in southern China could be divided into four genetic groups, and prominent genetic admixture was found in those populations located in southern Jiangxi Province. Mantel tests and multiple matrix regression with randomization (MMRR) analyses suggested that isolation by distance (IBD) could be the possible reason for describing the current population genetic structure. In addition, the effective population size (Ne) of O. henryi was extremely small, and showed a continuous declining trend since the Last Glacial Period.
Conclusions:
Our results indicate that the endangered status of O. henryi is seriously underestimated. Artificial conservation measures should be applied as soon as possible to prevent O. henryi from the fate of extinction. Further studies are needed to elucidate the mechanism that leading to the continuous loss of genetic diversity in O. henryi and help to develop a better conservation strategy.
... In Ghana,Hagan et al. (2013) also reported that the effective population size of the local chickens in the Coastal Savannah, Rain Forest, and Guinea Savannah were found to be 13.3, 11.3 and 12.9, and 0.038 (3.8%), respectively, which were lesser than the result of the current study, and they obtained similar levels of inbreeding coe cients in three of Ghana's agroecologies: Coastal (0.038 or 3.8%), Forest (0.044 or 4.4%), and Guinea (0.039 or 3.9%), which were higher than the result obtained in this study. The effective population size (Ne) of local chickens in all agro-ecologies was within the minimum acceptable level of 100-1000 under the conservation rule(Frankham et al., 2014), and the rate of inbreeding coe cient (ΔF) was lower than the maximum acceptable level of 0.063(Armstrong, 2006). This indicates the existence of genetic variability among local chicken ecotypes and within individuals of each local chicken ecotype. ...
A survey was conducted in Western Tigray, Northern Ethiopia to assess flock composition, ownership, and gender roles in chicken production and factors affecting chicken product consumption. Multi-stage sampling procedures were employed to select three districts, nine sample peasant associations, and 385 respondents. A pretested, structured questionnaire and focused group discussion were employed to generate data. All survey data were analyzed using SPSS software. Chicken flock size per household is significantly different among the three agro ecologies. The overall mean chicken flock size per household was 24. 35 ± 10. 69. The effective population size Ne and the rate of inbreeding (∆F) were 1263. 69, and 0.04, respectively. Chicken and egg consumption is influenced by cultural and religious festivals, farmer status, agroecology, breed, plumage colour, shank type, comb type, feather distribution, and age. In all agro ecologies, the average annual chicken and egg consumption per household was higher among large-scale farmers than among small-scale farmers. The average annual chicken consumption per household was 7.76 ± 0.68 and 20.79 ± 0.68 for small and large-scale farmers, respectively. Similarly, the average annual egg consumption was 67.52 ± 3.13 and 182.27 ± 3.13 for small and large-scale farmers, respectively. The ranking indices of consumption preferences according to plumage colours indicated uniform preferences for chicken plumage colours for consumption across the agro ecologies. Chickens with red (1st ), greyish (2nd ), and multicoloured (3rd ) plumage colours were the most preferred for consumption, while chickens with full white and black colours were used for mystical purposes in the study. Every family member participated in taking care of chickens, Even though the level of responsibility varied among family members. Husband and wife involved in decision-making of chicken product utilization even though their degrees of involvement varied across the three agro ecologies. Information on flock composition, factors affecting chicken product consumption, ownership, and gender roles are prerequisites for the design and implementation of successful chicken breeding strategies.
The genetic effective size (Ne) is arguably one of the most important characteristics of a population as it impacts the rate of loss of genetic diversity. Genetic estimators of (Ne) increasingly popular tools in population and conservation genetic studies. Yet there are very few methods that can estimate the Ne from data from a single population and without extensive information about the genetics of the population, such as a linkage map, or a reference genome of the species of interest.
We present ONeSAMP 3.0, an algorithm for estimating Ne from single nucleotide polymorphism (SNP) data collected from a single population sample using Approximate Bayesian Computation and local linear regression.
We demonstrate the utility of this approach using simulated Wright-Fisher populations, and empirical data from five endangered Channel Island fox ( Urocyon littoralis ) populations to evaluate the performance of ONeSAMP 3.0 compared to a commonly used Ne estimator. Our results show that ONeSAMP 3.0 is robust to the number of individual samples and number of loci included in and appears accurate even if the range of true Ne values is large.
This method is broadly applicable to natural populations and is flexible enough that future versions could easily include summary statistics appropriate for a suite of biological and sampling conditions. ONeSAMP 3.0 is publicly available under the GNU license at https://github.com/AaronHong1024/ONeSAMP_3 and also available with Bioconda ( https://bioconda.github.io/index.html ).
Small, fragmented or isolated populations are at risk of population decline due to fitness costs associated with inbreeding and genetic drift. The King Island scrubtit Acanthornis magna greeniana is a critically endangered endemic subspecies of the nominate Tasmanian scrubtit A. m. magna, with an estimated population of <100 individuals persisting in three patches of swamp forest. The Tasmanian scrubtit is widespread in wet forests on mainland Tasmania. We sequenced the scrubtit genome using PacBio HiFi and undertook a population genomics study of the King Island and Tasmanian scrubtit using a double-digest restriction site-associated DNA (ddRAD) dataset of 5,239 SNP loci. The genome was 1.48 Gb long, comprising 1,518 contigs with an N50 of 7.715 Mb. King Island scrubtits formed one of four overall genetic clusters, but separated into three distinct subpopulations when analysed separately. Pairwise FST values were greater among the King Island scrubtit subpopulations than among most Tasmanian scrubtit subpopulations. Genetic diversity was lower and inbreeding coefficients were higher in the King Island scrubtit than all except one of the Tasmanian scrubtit subpopulations. We observed crown baldness in 8/15 King Island scrubtits, but 0/55 Tasmanian scrubtits. Six loci were significantly associated with baldness, including one within the DOCK11 gene which is linked to early feather development. Contemporary gene flow between King Island scrubtit subpopulations is unlikely, with further field monitoring required to quantify the fitness consequences of its small effective size, low genetic diversity and high inbreeding. Evidence-based conservation actions can then be implemented before the taxon goes extinct.
Reproductive strategy and population status are crucial factors to understand species adaptation mechanism and to make suitable conservation decisions. In the present study, we investigated the reproductive strategy of the silver carp (Hypophthalmichthys molitrix) using microsatellite markers and sibship analysis on 476 offspring born in 2017 from the middle and lower reaches of Yangtze River in China. The results revealed that silver carp adopts a promiscuous genetic mating system with a balanced sex ratio 1:1 in the breeding population. Inferred partner numbers ranged from 1 to 4 for each parent, with more than half of the males (50.96%) and females (55.12%) mating with multiple partners. Sibship assignment revealed that reproductive success was relatively even among individuals for both sexes. The effective population size (Neadj) and census population size (Nc) in the middle and lower reaches of the Yangtze River in 2017 were 2686 and 8104, respectively, with a relatively high Neadj/ Nc ratio 0.33. The even reproductive success and relatively high ratio value of Neadj/ Nc suggest the absence of the sweepstakes reproductive success (SRS, the strategy offspring only from a few parents) in silver carp, which help maintain a relatively high genetic diversity in population. According to the result of larval (egg) resource survey, we estimated the census population of the silver carp in Yichang section, the main spawning ground, in 2017 to be 6498, which is approximately 58.71% of the historical record. Therefore, we recommend that conservation efforts for silver carp should be strengthened, especially focused on protecting the Yichang spawning ground to help restore its population.
This chapter presents an overview of technologies for freshwater fish conservation, emphasizing the neotropical species. The reproductive success and recruitment of populations are discussed based on changes in habitat. How the decline in fish populations indirectly affects the food chain is discussed from the perspective of the ecological functions of each species. A critical analysis of fish stocking is presented, including special breeding techniques and stocking guidelines designed to be genetically favorable to breeding programs. New technologies that can improve the reproductive success of threatened species and minimize the impact of aquaculture on native fish species are reviewed. Some recommendations to mitigate harmful habitat changes for reproductive success, impacts of non-native species introduction, and a guideline for fish stocking are presented. Finally, limitations and perspectives of fish biotechnology are discussed.KeywordsFish reproductionHabitat changesFish assemblingExotic speciesFish biotechnology
The Southern Rocky Mountain Boreal Toad ( Anaxyrus boreas boreas) is an ex situ managed species which relies heavily on the use of assisted reproductive technologies to augment existing in situ populations. Despite the use of ARTs to manipulate reproduction of this species, the ex situ program continues to face challenges with annual reproduction. Human chorionic gonadotropin (hCG) at 10 IU/gbw singly or in combination with 0.4 ug/gbw GnRH-A have been successfully reported for this species, however, with a number of other available hormones, it is not clear if these are the most effective protocols for this species. Moreover, there is no information on how exogenous hormone administration is affected by other factors such as seasonality. Therefore, in the first part of this study, we compare the efficacy of the 10 IU/g hCG and 0.4 Lg/g Gonadotropin Releasing Hormone agonist (GnRH-A) administered singly or in combination, as well as GnRH-Apd + Amphiplex (0.4 Lg/g GnRH-A + 10 Lg/g Metoclopramide [MET] - a dopamine antagonist), or 10 Lg/g MET alone. Spermiation responses and sperm viability were compared across treatments with hormonal curves then correlated to seasonality. The results of this study suggest that the optimal hormonal stimulation protocol, across all treatments, in terms of sperm quality was 10 IU/g hCG + 0.4 Lg/g GnRH-A. Further optimization is required, in particular the exploration of higher doses of GnRH-A. Lastly, we observed that the effect of seasonality influenced the hormonal efficacy and magnitude of the spermiation response. As was expected, quality and concentration parameters were affected by the month in which hormone administration occurred.
HIGHLIGHTS
Spermiation in the Southern Rocky Mountain Boreal toad, Anaxyrus boreas boreas, is elicited most effectively by hCG singly or in combination with GnRH-A.
Spermiation responses lasted up to 96 hours post injection (hpi) though quantity and quality parameters were highest in the first 12 hpi.
Total motility, forward progressive motility and percentage live cells all indicated A. b. boreas sperm quality was in a good range.
Acrosome integrity requires more research as it was comparatively lower than expected.
Responses to hormone inductions are seasonally affected in this species but suggest semi-discontinuous cycling.
Ex situ breeding should perform better sperm assessments before designing breeding strategies.
The designation of units for conservation has been a necessary but challenging objective since conservation efforts began. Most species are divided, typically by environment, into populations with independent evolutionary trajectories. There are practical conservation objectives for defining these boundaries. Separate genetic clusters provide future evolutionary potential as environments change, and individuals in isolated populations may lose fitness when population size is reduced. The history of the effort to define units is briefly reviewed here, but I focus on finding a process that may facilitate uniform and effective application at a time when conservation urgency is great. I propose a refinement of the designated unit concept, distinguishing between conservation units (CUs) and evolutionarily sustaining conservation units (ESCUs).
Foskett Spring in Oregon's desert harbors a historically threatened population of Western Speckled Dace ( Rhinichthys klamathensis ). Though recently delisted, the dace's recruitment depends upon regular removal of encroaching vegetation. Previous studies assumed that Foskett Dace separated from others in the Warner Valley about 10,000 years ago, thereby framing an enigma about the population's surprising ability to persist for so long in a tiny habitat easily overrun by plants. To investigate the phenomenon of persistence and the effectiveness of interventions to augment population size, we assessed genetic diversity among daces inhabiting Foskett Spring, a refuge at Dace Spring, and three nearby streams. Analysis revealed a robust effective population size (Ne) of nearly 5,000 within Foskett Spring, though Ne in the Dace Spring refuge is just 10% of that value. Heterozygosity is slightly lower than expected based on random mating at all five sites, indicating mild inbreeding, but not at a level of concern. These results confirm the genetic health of Foskett Dace. Unexpectedly, genetic differentiation reveals closer similarity between Foskett Dace and a newly discovered population from Nevada's Coleman Creek than between Foskett Dace and dace elsewhere in Oregon. Demographic modeling inferred Coleman Creek as the ancestral source of Foskett Dace just 600 years ago, much more recently than previously suspected and coincident with the arrival of large herbivores whose grazing may have maintained open water suitable for reproduction. These results solve the enigma of persistence by greatly shortening the duration over which Foskett Dace have inhabited their isolated spring.
Background
Corybas taliensis is an endemic species of sky islands in the Pan-Tibetan Plateau region of China. Its habitat is fragile and volatile, and it is likely that the species is threatened. However, it is difficult to determine the conservation priority or unit without knowing the genetic background and the distribution of this species. In this study, we used double digest restriction-site associated DNA-sequencing (ddRAD-seq) to investigate the conservation genomics of C. taliensis. At the same time, we modeled the present and future (2030 and 2090) suitable habitats for C. taliensis using the maximum-entropy (MaxEnt) model.
Results
The results suggested that the related C. fanjingshanensis belongs to C. taliensis and should not be considered a separate species. All the sampling locations were divided into three genetic groups: Sichuan & Guizhou population (SG population), Hengduan Mountains population (HD population) and Himalaya population (HM population), and there was complex gene flow between the sampling locations of HD population. MT was distinct genetically from other sampling locations due to the special environment in Motuo. The genetic diversity (π, He) of C. taliensis was relatively high, but its contemporary effective population size (Ne) was small. C. taliensis might be currently affected by inbreeding depression, while its large population density may be able to reduce the effect. The areas of suitable habitats in higher mountains are not predicted to change significantly in the future, and these suitable habitats is predicted to spread to other higher mountains under future climate change. However, suitable habitats in relatively low altitude mountains may disappear in the future. Which indicated that C. taliensis will be caught in a ‘summit trap’ in low altitude areas. On the contrary, the high altitude of Himalaya and Hengduan Mountains regions play as ‘biological refuges’ for C. taliensis.
Conclusions
These results not only provide a new understanding of the genetic background and potential resource distribution of C. taliensis, but also lay the foundation for its conservation and management.
THE BIRDS OF SAUDI ARABIA are extraordinary. In total, 499 species have been recorded in the Kingdom. This incredible diversity includes some of the most beautiful birds on earth, some of the most fascinating, some of the most bizarre, some of the most migratory, some of the rarest, some of the smallest, some of the largest, and some of the fastest birds on earth. Indeed, the birds of Saudi Arabia should be world famous.
Breeding habitat loss and depletion of genetic diversity can have critically negative impacts on species, and especially so for habitat specialists. The Aquatic Warbler Acrocephalus paludicola is a threatened European songbird that breeds in fens, which have been lost and fragmented over centuries. We used microsatellite loci to perform a spatial and longitudinal comparison, comparing samples collected recently (contemporary) with those obtained about two decades earlier (historical) from c. 25% of the breeding range (Biebrza and Polesie) of the Aquatic Warbler. With these data we explored changes in genetic diversity, expansions and reductions of population size, population structure, and gene flow. Allelic richness, expected heterozygosity, the number of effective and private alleles, and effective population size (NE ≈ 200) were low and comparable across time and space. We detected a genetic bottleneck in contemporary Biebrza, and a less certain bottleneck in both historical and contemporary Polesie. Across space, Biebrza and Polesie were not genetically differentiated in either period. All the historical samples clustered together, but in the contemporary samples a small part of Polesie clustered separately (FST = 0.011). Across time, Biebrza and Polesie showed low but significant differentiation (FST = 0.026–0.064), and historical and contemporary groups clustered apart. A principal coordinate analysis on genetic distance detected three groups, which spanned sampling locations. In the temporal comparison, the contemporary group and contemporary Biebrza had elevated mean within-group pairwise relatedness. We did not recover signals for sex-biased dispersal, asymmetric gene flow or isolation-by-distance using the molecular data. Our results suggest that the studied populations show: (1) impoverished genetic diversity, (2) a change in allele frequencies over the two decades studied and (3) high gene flow between distant breeding sites, implying high resilience to habitat fragmentation that should facilitate the success of recolonising restored habitat patches by Aquatic Warblers.
Anthropogenically-driven environmental changes over the past two centuries have led to severe biodiversity loss, most prominently in the form of loss of populations and individuals. Better tools are needed to assess the magnitude of these wildlife population declines. Anecdotal evidence suggests European bat populations have suffered substantial declines in the past few centuries. However, there is little empirical evidence of these declines that can be used to put more recent population changes into historic context and set appropriate targets for species recovery.
This study is a collaboration between academics and conservation practitioners to develop molecular approaches capable of providing quantitative evidence of historic population changes and their drivers that can inform the assessment of conservation status and conservation management. We generated a genomic dataset for the Western barbastelle, Barbastella barbastellus, a globally Near Threatened and regionally Vulnerable bat species, including colonies from across the species’ British and Iberian ranges. We used a combination of landscape genetics and approximate Bayesian computation model-based inference of demographic history to identify both evidence of population size changes and possible drivers of these changes.
We found that levels of genetic diversity increased and inbreeding decreased with increasing broadleaf woodland cover around the colony location. Genetic connectivity was impeded by artificial lights and facilitated by the combination of rivers and broadleaf woodland cover.
The demographic history analysis showed that both the northern and southern British barbastelle populations have declined by 99% over the past 330-548 years. These declines may have been triggered by loss of large oak trees and native woodlands due to shipbuilding during the early colonial period.
Synthesis and applications. Genomic approaches can be applied to provide a better understanding of the conservation status of threatened species, within historic and contemporary context, and inform their conservation management. This study shows how we can bridge the implementation gap and promote the application of genomics in conservation management through co-designing studies with conservation practitioners and co-developing applied management targets and recommendations.
Habitat fragmentation affects the survival of wildlife and is a main threat to biodiversity. Corridors are frequently used to alleviate habitat fragmentation. However, corridors are costly and often ineffective in practice. Endangered species in montane regions are particularly affected by habitat fragmentation and therefore require economic and efficient conservation strategies. We propose a stepping stone strategy (SSS) to deal with habitat fragmentation threatening an endangered primate, the black-and-white snub-nosed monkeys (Rhinopithecus bieti). We selected the southern range of R. bieti as the study area, which covers 3,580 km2. We evaluated the habitat status and formulated an SSS based on the dispersal ability of an adult male R. bieti. Six sustainable habitat patches and 340 natural stepping stones were detected. Thirteen artificial stepping stones are needed to establish weak connectivity of habitats. Forty-four stepping stones are proposed as key stepping stones for attaining strong connectivity. The SSS is projected to incur substantially less pecuniary investment than the corridor strategy (0.06 million versus 5.65 million, USD). We conclude that 5 steps are needed for the SSS: (a) assessing the status of habitats to plan restorative intervention activities, (b) designing artificial stepping stones to weakly link sustainable habitats, (c) proposing corridors to allow for a stable connection between sustainable habitats, (d) identifying key stepping stones to establish small protected area, and (e) recovery of fragmented habitat and reinstatement of sustainable habitat. Our study suggests that SSS is a cost-effective and practical way for maintaining connectivity and supporting habitat recovery for endangered wildlife in montane regions.
A new method is developed to estimate the contemporary effective population size ( Ne ) from linkage disequilibrium between SNPs without information on their location, which is the usual scenario in non-model species. The general theory of linkage disequilibrium is extended to include the contribution of full-sibs to the measure of LD, leading naturally to the estimation of Ne in monogamous and polygamous mating systems, as well as in multiparous species and non-random distributions of full-sib family size due to selection or other causes. The prediction of confidence intervals for Ne estimates was solved using a small artificial neural network trained on a dataset of over 105 simulation results. The method, implemented in a user-friendly and fast software ( currentNe ) is able to estimate Ne even in problematic scenarios with large population sizes or small sample sizes, and provides confidence intervals that are more consistent than parametric methods or resampling.
Translocations of freshwater species have become a widespread conservation strategy to mitigate the impacts of habitat fragmentation, yet they are not often rigorously monitored using animal movement data to determine their success. We demonstrate the value of monitoring pre- and post-translocation movements and home-range sizes of a fully-aquatic, benthic stream salamander, the eastern hellbender (Cryptobranchus a. alleganiensis) to determine translocation success. We studied the home range sizes, movements, and habitat use of individuals (n = 27) in two self-sustaining populations (S1 & S2) for one year, and then subsequently collected similar data from a subset of these individuals (n = 17) that were translocated into two nearby streams (T1 & T2) with dam-isolated, declining populations in the Blue Ridge Ecoregion of Tennessee. We collected 1,571 location data points (869 pre-translocation and 715 post-translocation) from four study sites, and evaluated effects of mass, sex, and pre-translocation home range size/sedentariness, as well as habitat covariates on home range size and movements. Hellbender home range sizes increased from pre-translocation estimates at both sites, but response depended primarily on physical characteristics of release sites. Home range and fine-scale movement metrics indicated that hellbenders translocated from S1 to T1 settled in more quickly, had greater site fidelity, and smaller home ranges than hellbenders translocated from S2 to T2. Hellbender movements were influenced by cover rock size and density rather than individual characteristics. Study-long survival rates of translocated hellbenders increased from S1 to T1 (80% to 100%) and decreased from S2 to T2 (76% to 33%). Monitoring pre- and post-translocation movements was a valuable method for evaluating short-term translocation success in a freshwater environment. For future hellbender translocations, managers should prioritize selecting suitable release sites with contiguous boulder-dense areas (1-2 per m2), adequate prey (crayfish) densities (>1/m2), and habitats with low risk of predation.
Unraveling the factors that determine the rate of adaptation is a major question in evolutionary biology. One key parameter is the effect of a new mutation on fitness, which invariably depends on the environment and genetic background. The fate of a mutation also depends on population size, which determines the amount of drift it will experience. Here, we manipulate both population size and genotype composition and follow adaptation of 23 distinct Escherichia coli genotypes. These have previously accumulated mutations under intense genetic drift and encompass a substantial fitness variation. A simple rule is uncovered: the net fitness change is negatively correlated with the fitness of the genotype in which new mutations appear—a signature of epistasis. We find that Fisher's geometrical model can account for the observed patterns of fitness change and infer the parameters of this model that best fit the data, using Approximate Bayesian Computation. We estimate a genomic mutation rate of 0.01 per generation for fitness altering mutations, albeit with a large confidence interval, a mean fitness effect of mutations of −0.01, and an effective number of traits nine in mutS−
E. coli. This framework can be extended to confront a broader range of models with data and test different classes of fitness landscape models.
Wild populations face threats both from deterministic factors, e.g., habitat loss, overexploitation, pollution, and introduced species, and from stochastic events of a demographic, genetic, and environmental nature, including catastrophes. Inbreeding reduces reproductive fitness in naturally outbreeding species, but its role in extinctions of wild populations is controversial. To evaluate critically the role of inbreeding in extinction, we conducted realistic population viability analyses of 20 threatened species, with and without inbreeding depression, using initial population sizes of 50, 250, and 1000. Inbreeding markedly decreased median times to extinction by 28.5, 30.5, and 25% for initial populations of 50, 250, and 1000, respectively, and the impacts were similar across major taxa. The major variable explaining differences among species was initial population growth rate, whereas the impact of inbreeding was least in species with negative growth rates. These results demonstrate that the prospects for survival of threatened species will usually be seriously overestimated if genetic factors are disregarded, and that inappropriate recovery plans may be instituted if inbreeding depression is ignored. Copyright © 2002 by the author(s). Published here under licence by The Resilience Alliance.
Effective population size (Ne) controls both the rate of random genetic drift and the effectiveness of selection and migration, but it is difficult to estimate in nature. In particular, for species with overlapping generations, it is easier to estimate the effective number of breeders in one reproductive cycle (Nb) than Ne per generation. We empirically evaluated the relationship between life history and ratios of Ne, Nb and adult census size (N) using a recently developed model (agene) and published vital rates for 63 iteroparous animals and plants. Nb/Ne varied a surprising sixfold across species and, contrary to expectations, Nb was larger than Ne in over half the species. Up to two-thirds of the variance in Nb/Ne and up to half the variance in Ne/N was explained by just two life-history traits (age at maturity and adult lifespan) that have long interested both ecologists and evolutionary biologists. These results provide novel insights into, and demonstrate a close general linkage between, demographic and evolutionary processes across diverse taxa. For the first time, our results also make it possible to interpret rapidly accumulating estimates of Nb in the context of the rich body of evolutionary theory based on Ne per generation.
Understanding the functional impacts of pollinator species losses on plant populations is critical given ongoing pollinator declines. Simulation models of pollination networks suggest that plant communities will be resilient to losing many or even most of the pollinator species in an ecosystem. These predictions, however, have not been tested empirically and implicitly assume that pollination efficacy is unaffected by interactions with interspecific competitors. By contrast, ecological theory and data from a wide range of ecosystems show that interspecific competition can drive variation in ecological specialization over short timescales via behavioral or morphological plasticity, although the potential implications of such changes in specialization for ecosystem functioning remain unexplored. We conducted manipulative field experiments in which we temporarily removed single pollinator species from study plots in subalpine meadows, to test the hypothesis that interactions between pollinator species can shape individual species' functional roles via changes in foraging specialization. We show that loss of a single pollinator species reduces floral fidelity (short-term specialization) in the remaining pollinators, with significant implications for ecosystem functioning in terms of reduced plant reproduction, even when potentially effective pollinators remained in the system. Our results suggest that ongoing pollinator declines may have more serious negative implications for plant communities than is currently assumed. More broadly, we show that the individual functional contributions of species can be dynamic and shaped by the community of interspecific competitors, thereby documenting a distinct mechanism for how biodiversity can drive ecosystem functioning, with potential relevance to a wide range of taxa and systems.
We use an individual-based eco-genetic model to examine the demographic and evolutionary consequences of selective mortality on a species with parental care, the smallmouth bass Micropterus dolomieu. Our analyses are grounded in a long-term (1936-2003) empirical study of the dynamics of two populations that differ widely in both density and life history. The model we construct extends previous approaches by including phenotypic plasticity in age and size at maturation, by permitting density-dependent somatic growth, and by analyzing how costs associated with parental care alter model predictions. We show that, first, additional mortality on age-0 individuals applied for 100 years causes reduced population abundance and biomass, faster somatic growth rates, and phenotypic plasticity toward slightly larger sizes at maturation. Second, mortality on individuals above a minimum size limit, also applied for 100 years, has a small influence on population abundance and somatic growth, causes a reduction of biomass, and substantial evolution of the probabilistic maturation reaction norm, leading to younger ages and smaller sizes at maturation. Third, the incorporation of body-size-dependent survival costs associated with parental care (i.e., by reducing the number of small breeding adults at high population densities, increasing the mortality of parents that breed at small body sizes, or increasing the mortality of offspring originating from small-sized parents) reduces the amount of evolution predicted to occur within 100 years. Together, these results underscore that selective harvest can cause both phenotypically plastic responses and rapid evolution; however, the rate and magnitude of the evolved changes are sensitive to a species' life history characteristics.
The extent of larval dispersal on coral reefs has important implications for the persistence of coral reef metapopulations, their resilience and recovery from an increasing array of threats, and the success of protective measures. This article highlights a recent dramatic increase in research effort and a growing diversity of approaches to the study of larval retention within (self-recruitment) and dispersal among (connectivity) isolated coral reef populations. Historically, researchers were motivated by alternative hypotheses concerning the processes limiting populations and structuring coral reef assemblages, whereas the recent impetus has come largely from the need to incorporate dispersal information into the design of no-take marine protected area (MPA) networks. Although the majority of studies continue to rely on population genetic approaches to make inferences about dispersal, a wide range of techniques are now being employed, from small-scale larval tagging and paternity analyses, to large-scale biophysical circulation models. Multiple approaches are increasingly being applied to cross validate and provide more realistic estimates of larval dispersal. The vast majority of empirical studies have focused on corals and fishes, where evidence for both extremely local scale patterns of self-recruitment and ecologically significant connectivity among reefs at scales of tens of kilometers (and in some cases hundreds of kilometers) is accumulating. Levels of larval retention and the spatial extent of connectivity in both corals and fishes appear to be largely independent of larval duration or reef size, but may be strongly influenced by geographic setting. It is argued that high levels of both self-recruitment and larval import can contribute to the resilience of reef populations and MPA networks, but these benefits will erode in degrading reef environments.
IUCN categories of threat (Endangered, Vulnerable, Rare, Indeterminate, and others) are widely used in "Red lists' of endangered species and have become an important tool in conservation action at international, national, regional and thematic levels. The authors present proposals to redefine categories in terms of the probability of extinction within a specific time period, based on the theory of extinction times for single populations and on meaningful time scales for conservation action. Three categories are proposed (critical, endangered, vulnerable) with decreasing levels of threat over increasing time scales for species estimated to have at least a 10% probability of extinction within 100 yr. -from Authors
Whether introduced species invasions pose a major threat to biodiversity is hotly debated. Much of this debate is fueled by recent findings that competition from introduced organisms has driven remarkably few plant species to extinction. Instead, native plant species in invaded ecosystems are often found in refugia: patchy, marginal habitats unsuitable to their nonnative competitors. However, whether the colonization and extinction dynamics of these refugia allow long-term native persistence is uncertain. Of particular concern is the possibility that invasive plants may induce an extinction debt in the native flora, where persistence over the short term masks deterministic extinction trajectories. We examined how invader impacts on landscape structure influence native plant persistence by combining recently developed quantitative techniques for evaluating metapopulation persistence with field measurements of an invaded plant community. We found that European grass invasion of an edaphically heterogeneous California landscape has greatly decreased the likelihood of the persistence of native metapopulations. It does so via two main pathways: (i) decreasing the size of native refugia, which reduces seed production and increases local extinction, and (ii) eroding the dispersal permeability of the matrix between refugia, which reduces their connectivity. Even when native plant extinction is the deterministic outcome of invasion, the time to extinction can be on the order of hundreds of years. We conclude that the relatively short time since invasion in many parts of the world is insufficient to observe the full impact of plant invasions on native biodiversity.
Background
Effective population sizes of 140 populations (including 60 dog breeds, 40 sheep breeds, 20 cattle breeds and 20 horse breeds) were computed using pedigree information and six different computation methods. Simple demographical information (number of breeding males and females), variance of progeny size, or evolution of identity by descent probabilities based on coancestry or inbreeding were used as well as identity by descent rate between two successive generations or individual identity by descent rate.
Results
Depending on breed and method, effective population sizes ranged from 15 to 133 056, computation method and interaction between computation method and species showing a significant effect on effective population size (P < 0.0001). On average, methods based on number of breeding males and females and variance of progeny size produced larger values (4425 and 356, respectively), than those based on identity by descent probabilities (average values between 93 and 203). Since breeding practices and genetic substructure within dog breeds increased inbreeding, methods taking into account the evolution of inbreeding produced lower effective population sizes than those taking into account evolution of coancestry. The correlation level between the simplest method (number of breeding males and females, requiring no genealogical information) and the most sophisticated one ranged from 0.44 to 0.60 according to species.
Conclusions
When choosing a method to compute effective population size, particular attention should be paid to the species and the specific genetic structure of the population studied.
With an ecological-evolutionary perspective increasingly applied toward the conservation and management of endangered or exploited species, the genetic estimation of effective population size (N(e)) has proliferated. Based on a comprehensive analysis of empirical literature from the past two decades, we asked: (i) how often do studies link N(e) to the adult census population size (N)? (ii) To what extent is N(e) correctly linked to N? (iii) How readily is uncertainty accounted for in both N(e) and N when quantifying N(e)/N ratios? and (iv) how frequently and to what degree might errors in the estimation of N(e) or N affect inferences of N(e)/N ratios? We found that only 20% of available N(e) estimates (508 of 2617; 233 studies) explicitly attempted to link N(e) and N; of these, only 31% (160 of 508) correctly linked N(e) and N. Moreover, only 7% (41 of 508) of N(e)/N ratios (correctly linked or not) reported confidence intervals for both N(e) and N; for those cases where confidence intervals were reported for N(e) only, 31% of N(e)/N ratios overlapped with 1, of which more than half also reached below N(e)/N = 0.01. Uncertainty in N(e)/N ratios thus sometimes spanned at least two orders of magnitude. We conclude that the estimation of N(e)/N ratios in natural populations could be significantly improved, discuss several options for doing so, and briefly outline some future research directions.
We investigated inbreeding depression and genetic load in a small (N(e) ∼ 100) population of the Glanville fritillary butterfly (Melitaea cinxia), which has been completely isolated on a small island [Pikku Tytärsaari (PT)] in the Baltic Sea for at least 75 y. As a reference, we studied conspecific populations from the well-studied metapopulation in the Åland Islands (ÅL), 400 km away. A large population in Saaremaa, Estonia, was used as a reference for estimating genetic diversity and N(e). We investigated 58 traits related to behavior, development, morphology, reproductive performance, and metabolism. The PT population exhibited high genetic load (L = 1 - W(PT)/W(ÅL)) in a range of fitness-related traits including adult weight (L = 0.12), flight metabolic rate (L = 0.53), egg viability (L = 0.37), and lifetime production of eggs in an outdoor population cage (L = 0.70). These results imply extensive fixation of deleterious recessive mutations, supported by greatly reduced diversity in microsatellite markers and immediate recovery (heterosis) of egg viability and flight metabolic rate in crosses with other populations. There was no significant inbreeding depression in most traits due to one generation of full-sib mating. Resting metabolic rate was significantly elevated in PT males, which may be related to their short lifespan (L = 0.25). The demographic history and the effective size of the PT population place it in the part of the parameter space in which models predict mutation accumulation. This population exemplifies the increasingly common situation in fragmented landscapes, in which small and completely isolated populations are vulnerable to extinction due to high genetic load.
It has been proposed that inbreeding contributes to the decline and
eventual extinction of small and isolated populations,. There is ample
evidence of fitness reduction due to inbreeding (inbreeding depression)
in captivity and from a few experimental, and observational field
studies,, but no field studies on natural populations have been
conducted to test the proposed effect on extinction. It has been argued
that in natural populations the impact of inbreeding depression on
population survival will be insignificant in comparison to that of
demographic and environmental stochasticity,. We have now studied the
effect of inbreeding on local extinction in a large metapopulation of
the Glanville fritillary butterfly (Melitaea cinxia). We found that
extinction risk increased significantly with decreasing heterozygosity,
an indication of inbreeding, even after accounting for the effects of
the relevant ecological factors. Larval survival, adult longevity and
egg-hatching rate were found to be adversely affected by inbreeding and
appear to be the fitness components underlying the relationship between
inbreeding and extinction. To our knowledge, this is the first
demonstration of an effect of inbreeding on the extinction of natural
populations. Our results are particularly relevant to the increasing
number of species with small local populations due to habitat loss and
fragmentation.
Fitness and adaptation are fundamental characteristics of plant and animal species, enabling them to survive in their environment and to adapt to the inevitable changes in this environment. This is true for both the genetic resources of natural ecosystems as well as those used in agricultural production.
Extensive genetic variation exists between varieties/breeds in a species and amongst individuals within breeds. This variation has developed over very long periods of time. A major ongoing challenge is how to best utilize this variation to meet short-term demands whilst also conserving it for longer-term possible use.
Many animal breeding programs have led to increased performance for production traits but this has often been accompanied by reduced fitness. In addition, the global use of genetic resources prompts the question whether introduced genotypes are adapted to local production systems. Understanding the genetic nature of fitness and adaptation will enable us to better manage genetic resources allowing us to make efficient and sustainable decisions for the improvement or breeding of these resources.
This book had an ambitious goal in bringing together a sample of the world’s leading scientists in animal breeding and evolutionary genetics to exchange knowledge to advance our understanding of these vital issues.
We established replicated experimental populations of the annual plant Clarkia pulchella to evaluate the existence of a causal relationship between loss of genetic variation and population survival probability. Two treatments differing in the relatedness of the founders, and thus in the genetic effective population size (Ne ), were maintained as isolated populations in a natural environment. After three generations, the low Ne treatment had significantly lower germination and survival rates than did the high Ne treatment. These lower germination and survival rates led to decreased mean fitness in the low Ne populations: estimated mean fitness in the low Ne populations was only 21% of the estimated mean fitness in the high Ne populations. This inbreeding depression led to a reduction in population survival: at the conclusion of the experiment, 75% of the high Ne populations were still extant, whereas only 31% of the low Ne populations had survived. Decreased genetic effective population size, which leads to both inbreeding and the loss of alleles by genetic drift, increased the probability of population extinction over that expected from demographic and environmental stochasticity alone. This demonstrates that the genetic effective population size can strongly affect the probability of population persistence.
The ratio of the effective population size to adult (or census) population size (N-e/N) is an indicator of the extent of genetic variation expected in a population. It has been suggested that this ratio may be quite low for highly fecund species in which there is a sweepstakes-like chance of reproductive success, known as the Hedgecock effect. Here I show theoretically how the ratio may be quite small when there are only a few successful breeders (N-b) and that in this case, the N-e/N ratio is approximately N-b/N. In other words, high variance in reproductive success within a generation can result in a very low effective population size in an organism with large numbers of adults and consequently a very low N-e/N ratio. This finding appears robust when there is a large proportion of families with exactly two progeny or when there is random variation in progeny numbers among these families.
Fitness and rates of extinction were compared among populations of the housefly, Musca domestica L., kept either at constant effective sizes of 50, 500 or 1500 or passed through extreme founder events reducing effective size to 5. Populations were maintained for 24 generations, which for small to medium-sized mammals would be less than the 200 years suggested by Soule et al. (1986) as necessary for maintaining viable populations of endangered species. The results demonstrate that effective population sizes have to be greater than the 50 individuals suggested by Franklin (1980) to retain fitness and escape extinction, even in the short term. In contrast to populations of constant size that exhibited monotonic decreases in fitness through time, populations established with few founders rebounded from initial inbreeding depression. However, they were less adaptable to environmental stress than constant size populations, suggesting that populations founded with few numbers may do well within a single environment but may do far less well if they are reintroduced to natural environments or exposed to rapid environmental changes.
A characteristic of modern landscapes worldwide is that continuous habitats have become, largely due to human activities, mosaics of remnant habitat fragments embedded in an urban or agricultural matrix (see Chapter 9 by Leberg and colleagues). Landscape fragmentation can have distinct ecological (e.g., species extinction), demographic (e.g., lowered reproduction and elevated mortality), and genetic (e.g., less genetic diversity and increased inbreeding) consequences. In northern temperate regions, human impacts on natural landscapes date back several thousand years but, in most tropical landscapes, widespread human disturbance is more recent, with the heaviest impacts occurring during the last fifty years. Disturbance and fragmentation of once continuous habitats can have immediate, short-term, and long-term consequences for the management and conservation of genetic diversity within tropical plant species. Immediate consequences Landscape fragmentation has immediate consequences for the levels and distribution of genetic diversity that are not dependent on population genetic processes acting across subsequent generations. Three factors can have immediate effects on the genetic composition of fragmented populations: 1) the proportion of the original population that is removed, 2) the number of individuals that survive in each fragment, and 3) patterns of genetic variation present within natural populations prior to fragmentation (e.g., clusters of related individuals).
We established replicated experimental populations of the annual plant Clarkia pulchella to evaluate the existence of a causal relationship between loss of genetic variation and population survival probability. Two treatments differing in the relatedness of the founders, and thus in the genetic effective population size (Ne), were maintained as isolated populations in a natural environment. After three generations, the low Ne treatment had significantly lower germination and survival rates than did the high Ne treatment. These lower germination and survival rates led to decreased mean fitness in the low Ne populations: estimated mean fitness in the low Ne populations was only 21% of the estimated mean fitness in the high Ne populations. This inbreeding depression led to a reduction in population survival: at the conclusion of the experiment, 75% of the high Ne populations were still extant, whereas only 31% of the low Ne populations had survived. Decreased genetic effective population size, which leads to both inbreeding and the loss of alleles by genetic drift, increased the probability of population extinction over that expected from demographic and environmental stochasticity alone. This demonstrates that the genetic effective population size can strongly affect the probability of population persistence.
Cited By (since 1996):107, Export Date: 26 November 2013, Source: Scopus
Cited By (since 1996):88, Export Date: 26 November 2013, Source: Scopus
ZnO films were deposited by dc sputtering technique on glass and Pt/Si substrates. The effect of growth parameters is investigated on sheet resistance and noise. The 1/f noise normalized for bias, frequency and unit area, Cus is proportional with the sheet resistance Rsh. We found that the noise results correlate strongly with the crystalline structure of ZnO. For comparison, we have also studied the ZnO films structural properties.
Use of population viability analyses (PVAs) in endangered species recovery planning has been met with both support and criticism. Previous reviews promote use of PVA for setting scientifically based, measurable, and objective recovery criteria and recommend improvements to increase the framework's utility. However, others have questioned the value of PVA models for setting recovery criteria and assert that PVAs are more appropriate for understanding relative trade-offs between alternative management actions. We reviewed 258 final recovery plans for 642 plants listed under the U.S. Endangered Species Act to determine the number of plans that used or recommended PVA in recovery planning. We also reviewed 223 publications that describe plant PVAs to assess how these models were designed and whether those designs reflected previous recommendations for improvement of PVAs. Twenty-four percent of listed species had recovery plans that used or recommended PVA. In publications, the typical model was a matrix population model parameterized with ≤5 years of demographic data that did not consider stochasticity, genetics, density dependence, seed banks, vegetative reproduction, dormancy, threats, or management strategies. Population growth rates for different populations of the same species or for the same population at different points in time were often statistically different or varied by >10%. Therefore, PVAs parameterized with underlying vital rates that vary to this degree may not accurately predict recovery objectives across a species' entire distribution or over longer time scales. We assert that PVA, although an important tool as part of an adaptive-management program, can help to determine quantitative recovery criteria only if more long-term data sets that capture spatiotemporal variability in vital rates become available. Lacking this, there is a strong need for viable and comprehensive methods for determining quantitative, science-based recovery criteria for endangered species with minimal data availability. Uso Actual y Potencial del Análisis de Viabilidad Poblacional para la Recuperación de Especies de Plantas Enlistadas en el Acta de Especies En Peligro de E.U.A.
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Preservation of wild populations implies their persistence, but biological persistence is a relative term. This paper outlines
criteria for what constitutes successful preservation and the methods available for determining population sizes and their
area requirements to meet these criteria.