| 1. |
- Bertola, Laura D., et al.
(författare)
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A pragmatic approach for integrating molecular tools into biodiversity conservation
- 2024
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Ingår i: Conservation science and practice. - 2578-4854. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Molecular tools are increasingly applied for assessing and monitoring biodiversity and informing conservation action. While recent developments in genetic and genomic methods provide greater sensitivity in analysis and the capacity to address new questions, they are not equally available to all practitioners: There is considerable bias across institutions and countries in access to technologies, funding, and training. Consequently, in many cases, more accessible traditional genetic data (e.g., microsatellites) are still utilized for making conservation decisions. Conservation approaches need to be pragmatic by tackling clearly defined management questions and using the most appropriate methods available, while maximizing the use of limited resources. Here we present some key questions to consider when applying the molecular toolbox for accessible and actionable conservation management. Finally, we highlight a number of important steps to be addressed in a collaborative way, which can facilitate the broad integration of molecular data into conservation. Molecular tools are increasingly applied in conservation management; however, they are not equally available to all practitioners. We here provide key questions when establishing a conservation genetic study and highlight important steps which need to be addressed when these tools are globally applied.image
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| 2. |
- Andersson, Anastasia, 1987-, et al.
(författare)
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Monitoring genetic diversity with new indicators applied to an alpine freshwater top predator
- 2022
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 31:24, s. 6422-6439
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity is the basis for population adaptation and long-term survival, yet rarely considered in biodiversity monitoring. One key issue is the need for useful and straightforward indicators of genetic diversity. We monitored genetic diversity over 40 years (1970–2010) in metapopulations of brown trout (Salmo trutta) inhabiting 27 small mountain lakes representing 10 lake systems in central Sweden using >1200 fish per time point. We tested six newly proposed indicators; three were designed for broad, international use in the UN Convention on Biological Diversity (CBD) and are currently applied in several countries. The other three were recently elaborated for national use by a Swedish science-management effort and applied for the first time here. The Swedish indicators use molecular genetic data to monitor genetic diversity within and between populations (indicators ΔH and ΔFST, respectively) and assess the effective population size (Ne-indicator). We identified 29 genetically distinct populations, all retained over time. Twelve of the 27 lakes harboured more than one population indicating that brown trout biodiversity hidden as cryptic, sympatric populations are more common than recognized. The Ne indicator showed values below the threshold (Ne ≤ 500) in 20 populations with five showing Ne < 100. Statistically significant genetic diversity reductions occurred in several populations. Metapopulation structure appears to buffer against diversity loss; applying the indicators to metapopulations suggest mostly acceptable rates of change in all but one system. The CBD indicators agreed with the Swedish ones but provided less detail. All these indicators are appropriate for managers to initiate monitoring of genetic biodiversity.
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| 3. |
- Dussex, Nicolas, et al.
(författare)
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Range-wide and temporal genomic analyses reveal the consequences of near-extinction in Swedish moose
- 2023
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Ingår i: Communications Biology. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Ungulate species have experienced severe declines over the past centuries through overharvesting and habitat loss. Even if many game species have recovered thanks to strict hunting regulation, the genome-wide impacts of overharvesting are still unclear. Here, we examine the temporal and geographical differences in genome-wide diversity in moose (Alces alces) over its whole range in Sweden by sequencing 87 modern and historical genomes. We found limited impact of the 1900s near-extinction event but local variation in inbreeding and load in modern populations, as well as suggestion of a risk of future reduction in genetic diversity and gene flow. Furthermore, we found candidate genes for local adaptation, and rapid temporal allele frequency shifts involving coding genes since the 1980s, possibly due to selective harvesting. Our results highlight that genomic changes potentially impacting fitness can occur over short time scales and underline the need to track both deleterious and selectively advantageous genomic variation.
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| 4. |
- Hoban, Sean, et al.
(författare)
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Genetic diversity goals and targets have improved, but remain insufficient for clear implementation of the post-2020 global biodiversity framework
- 2023
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 24:2, s. 181-191
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity among and within populations of all species is necessary for people and nature to survive and thrive in a changing world. Over the past three years, commitments for conserving genetic diversity have become more ambitious and specific under the Convention on Biological Diversity’s (CBD) draft post-2020 global biodiversity framework (GBF). This Perspective article comments on how goals and targets of the GBF have evolved, the improvements that are still needed, lessons learned from this process, and connections between goals and targets and the actions and reporting that will be needed to maintain, protect, manage and monitor genetic diversity. It is possible and necessary that the GBF strives to maintain genetic diversity within and among populations of all species, to restore genetic connectivity, and to develop national genetic conservation strategies, and to report on these using proposed, feasible indicators.
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| 5. |
- Hoban, Sean, et al.
(författare)
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Monitoring status and trends in genetic diversity for the Convention on Biological Diversity : An ongoing assessment of genetic indicators in nine countries
- 2023
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Ingår i: Conservation Letters. - 1755-263X. ; 16:3
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Tidskriftsartikel (refereegranskat)abstract
- Recent scientific evidence shows that genetic diversity must be maintained, managed, and monitored to protect biodiversity and nature's contributions to people. Three genetic diversity indicators, two of which do not require DNA-based assessment, have been proposed for reporting to the Convention on Biological Diversity and other conservation and policy initiatives. These indicators allow an approximation of the status and trends of genetic diversity to inform policy, using existing demographic and geographic information. Application of these indicators has been initiated and here we describe ongoing efforts in calculating these indicators with examples. We specifically describe a project underway to apply these indicators in nine countries, provide example calculations, address concerns of policy makers and implementation challenges, and describe a roadmap for further development and deployment, incorporating feedback from the broader community. We also present guidance documents and data collection tools for calculating indicators. We demonstrate that Parties can successfully and cost-effectively report these genetic diversity indicators with existing biodiversity observation data, and, in doing so, better conserve the Earth's biodiversity.
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| 6. |
- Hoban, Sean, et al.
(författare)
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Too simple, too complex, or just right? Advantages, challenges, and guidance for indicators of genetic diversity
- 2024
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Ingår i: BioScience. - 0006-3568 .- 1525-3244.
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Tidskriftsartikel (refereegranskat)abstract
- Measuring genetic diversity of wild species using DNA-based data remains resource intensive and time consuming for nearly all species. However, genetic assessments are needed for global conservation commitments, including the Convention on Biological Diversity, and for governments and managers to evaluate conservation progress, as well as prioritizing species and populations to preserve and recover genetic diversity (e.g., via genetic rescue). Recently, indicators were developed for tracking and reporting genetic diversity status and trends for hundreds of species. The indicators quantify two simple proxies of within-population and among-population genetic diversity and adaptive potential: small effective population size (Ne < 500) and the loss of genetically distinct populations. The indicators must balance scientific credibility, practicality, and simplicity. In the present article, we summarize the advantages of these pragmatic indicators, address critiques by scientists for simplifying assumptions and by policymakers for complexity, and propose potential solutions and next steps. We aim to support practitioners putting indicators into policy, action, legislation, and reporting.
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| 7. |
- Hössjer, Ola, 1964-, et al.
(författare)
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Assessment of the Global Variance Effective Size of Subdivided Populations, and Its Relation to Other Effective Sizes
- 2023
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Ingår i: Acta Biotheoretica. - 0001-5342 .- 1572-8358. ; 71:3
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Tidskriftsartikel (refereegranskat)abstract
- The variance effective population size (N-eV) 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 N-eV of a spatially structured population that are of interest for conservation of species. Since N-eV 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 N-eV of the metapopulation is maximized, when subpopulations are weighted proportionally to their long term reproductive contributions. This maximal N-eV is the sought for global effective size, since it approximates the gene diversity effective size N-eGD, 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 N-eV, one of which (the backward version of N-eV) is most stable, exists for most populations, and is closer to N-eGD than the classical notion of N-eV. Expressions for the optimal length of the time interval for measuring genetic change are developed, that make it possible to estimate any version of N-eV with maximal accuracy.
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| 8. |
- Jansson, Mija, 1979-, et al.
(författare)
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mPed : a computer program for converting pedigree data to a format used by the PMx-software for conservation genetic analysis
- 2013
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Ingår i: Conservation Genetics Resources. - : Springer Science and Business Media LLC. - 1877-7252 .- 1877-7260. ; 5:3, s. 651-653
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Tidskriftsartikel (refereegranskat)abstract
- There is a growing need for conservation genetic management of animal populations when individual relatedness data (pedigrees) are available. Such data can be used to monitor rates of inbreeding and loss of genetic diversity. Traditionally, pedigree analysis for conservationmanagement has focused on zoo populations of threatened wild animals; available software has been developed in that context. Population Management x (PMx) is a free software for estimating genetic parameters including inbreeding, kinship, founder allele contribution and survival. PMx is an accessory program to the zoo studbook platform Single Population Analysis and Records Keeping System (SPARKS) and is not easily applied outside this platform, but such use is of interest for various domestic breeds or wild populations. We developed a converter program (mPed) for making pedigrees of any studbook format fitting the input requirements of PMx. mPed can be downloaded free at www.popgen.su.se/mped.php
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| 9. |
- Kershaw, Francine, et al.
(författare)
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The Coalition for Conservation Genetics : Working across organizations to build capacity and achieve change in policy and practice
- 2022
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Ingår i: Conservation Science and Practice. - : Wiley. - 2578-4854. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- The Coalition for Conservation Genetics (CCG) brings together four eminent organizations with the shared goal of improving the integration of genetic information into conservation policy and practice. We provide a historical context of conservation genetics as a field and reflect on current barriers to conserving genetic diversity, highlighting the need for collaboration across traditional divides, international partnerships, and coordinated advocacy. We then introduce the CCG and illustrate through examples how a coalition approach can leverage complementary expertise and improve the organizational impact at multiple levels. The CCG has proven particularly successful at implementing large synthesis-type projects, training early-career scientists, and advising policy makers. Achievements to date highlight the potential for the CCG to make effective contributions to practical conservation policy and management that no one “parent” organization could achieve on its own. Finally, we reflect on the lessons learned through forming the CCG, and our vision for the future.
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| 10. |
- Kurland, Sara, 1989-, et al.
(författare)
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Effects of subpopulation extinction on effective size (Ne) of metapopulations
- 2023
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 24:4, s. 417-433
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Tidskriftsartikel (refereegranskat)abstract
- Population extinction is ubiquitous in all taxa. Such extirpations can reduce intraspecific diversity, but the extent to which genetic diversity of surviving populations are affected remains largely unclear. A key concept in this context is the effective population size (Ne), which quantifies the rate at which genetic diversity within populations is lost. Ne was developed for single, isolated populations while many natural populations are instead connected to other populations via gene flow. Recent analytical approaches and software permit modelling of Ne of interconnected populations (metapopulations). Here, we apply such tools to investigate how extinction of subpopulations affects Ne of the metapopulation (NeMeta) and of separate surviving subpopulations (NeRx) under different rates and patterns of genetic exchange between subpopulations. We assess extinction effects before and at migration-drift equilibrium. We find that the effect of extinction on NeMeta increases with reduced connectivity, suggesting that stepping stone models of migration are more impacted than island-migration models when the same number of subpopulations are lost. Furthermore, in stepping stone models, after extinction and before a new equilibrium has been reached, NeRx can vary drastically among surviving subpopulations and depends on their initial spatial position relative to extinct ones. Our results demonstrate that extinctions can have far more complex effects on the retention of intraspecific diversity than typically recognized. Metapopulation dynamics need heightened consideration in sustainable management and conservation, e.g., in monitoring genetic diversity, and are relevant to a wide range of species in the ongoing extinction crisis.
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| 11. |
- Kurland, Sara, et al.
(författare)
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Genomic dynamics of brown trout populations released to a novel environment
- 2022
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Population translocations occur for a variety of reasons, from displacement due to climate change to human-induced transfers. Such actions have adverse effects on genetic variation and understanding their microevolutionary consequences requires monitoring. Here, we return to an experimental release of brown trout (Salmo trutta) in order to monitor the genomic effects of population translocations. In 1979, fish from each of two genetically (F-ST = 0.16) and ecologically separate populations were simultaneously released, at one point in time, to a lake system previously void of brown trout. Here, whole-genome sequencing of pooled DNA (Pool-seq) is used to characterize diversity within and divergence between the introduced populations and fish inhabiting two lakes downstream of the release sites, sampled 30 years later (c. 5 generations). Present results suggest that while extensive hybridization has occurred, the two introduced populations are unequally represented in the lakes downstream of the release sites. One population, which is ecologically resident in its original habitat, mainly contributes to the lake closest to the release site. The other population, migratory in its natal habitat, is genetically more represented in the lake further downstream. Genomic regions putatively under directional selection in the new habitat are identified, where allele frequencies in both established populations are more similar to the introduced population stemming from a resident population than the migratory one. Results suggest that the microevolutionary consequences of population translocations, for example, hybridization and adaptation, can be rapid and that Pool-seq can be used as an initial tool to monitor genome-wide effects.
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| 12. |
- Kurland, Sara, 1989-, et al.
(författare)
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New indicators for monitoring genetic diversity applied to alpine brown trout populations using whole genome sequence data
- 2024
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Ingår i: Molecular Ecology. - : John Wiley & Sons. - 0962-1083 .- 1365-294X. ; 33:2
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Tidskriftsartikel (refereegranskat)abstract
- International policy recently adopted commitments to maintain genetic diversity in wild populations to secure their adaptive potential, including metrics to monitor temporal trends in genetic diversity – so-called indicators. A national programme for assessing trends in genetic diversity was recently initiated in Sweden. Relating to this effort, we systematically assess contemporary genome-wide temporal trends (40 years) in wild populations using the newly adopted indicators and whole genome sequencing (WGS). We use pooled and individual WGS data from brown trout (Salmo trutta) in eight alpine lakes in protected areas. Observed temporal trends in diversity metrics (nucleotide diversity, Watterson's ϴ and heterozygosity) lie within proposed acceptable threshold values for six of the lakes, but with consistently low values in lakes above the tree line and declines observed in these northern-most lakes. Local effective population size is low in all lakes, highlighting the importance of continued protection of interconnected systems to allow genetic connectivity for long-term viability of these populations. Inbreeding (FROH) spans 10%–30% and is mostly represented by ancient (<1 Mb) runs of homozygosity, with observations of little change in mutational load. We also investigate adaptive dynamics over evolutionarily short time frames (a few generations); identifying putative parallel selection across all lakes within a gene pertaining to skin pigmentation as well as candidates of selection unique to specific lakes and lake systems involved in reproduction and immunity. We demonstrate the utility of WGS for systematic monitoring of natural populations, a priority concern if genetic diversity is to be protected.
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| 13. |
- Laikre, Linda, 1960-
(författare)
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Genetic diversity is overlooked in international conservation policy implementation.
- 2010
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 11, s. 349-354
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Tidskriftsartikel (refereegranskat)abstract
- The importance of genetic variation for maintaining biological diversity and evolutionary processes has been recognized by researchers for decades. This realization has prompted agreements by world leaders toconserve genetic diversity, and this is an explicit goal of the Convention on Biological Diversity (CBD). Nevertheless, very limited action has been taken to protect genetic diversity on a global scale. International conservation efforts to halt biodiversity loss focus on habitats and species,whereas little or no attention is paid to gene level variation. By this year, 2010, world leaders have agreed that a significant reduction of the rate of biodiversity loss should have been achieved. However, gene level diversity is still not monitored, indicators that can help identify threats to genetic variation are missing, and there is no strategy for how genetic aspects can be included in biodiversity targets beyond 2010. Important findings and conclusions from decades of conservation genetic research are not translated into concrete conservation action in the arena of international policy development. There is an urgent need for conservation geneticists worldwide to become involved in policy and practical conservation work beyond the universities and research institutions.
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| 14. |
- Laikre, Linda, 1960-, et al.
(författare)
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Planned cull endangers Swedish wolf population
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 377:6602
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Tidskriftsartikel (refereegranskat)abstract
- In May, the Swedish Parliament announced a goal to reduce the Swedish wolf population from about 400 to about 200 individuals (1). This action further threatens this highly endangered population, which is genetically isolated and inbred. Scientific advice for improvements has not been implemented (2, 3).The Swedish Parliament proposed this drastic cull at a time when biodiversity is a global focus. The 50-year anniversary of the first UN conference on the environment was celebrated in June, and the UN Convention on Biological Diversity (CBD) will soon finalize its global biodiversity framework for 2020 to 2050. Sweden’s actions are inconsistent with the country’s obligations under the CBD and European Union law.Few wild populations are as well studied as the Scandinavian wolf. Genetic monitoring has provided a full pedigree since the population was reestablished in the 1980s after extinction, and the data confirm persisting genetic isolation (4–6). Hunting, conducted both legally and illegally, has prevented population expansion and the influx of genetic variation.Three founders comprised the population’s genetic origin until 2007, and only three more wolves have subsequently contributed genetically to the present population (6). The genetic base is thus extremely narrow, and genomic erosion has been confirmed (7, 8). The average level of inbreeding is similar to the level found in the offspring of two full siblings (6). Inbreeding in this population has been shown to reduce litter size (4). Also, high frequencies of anatomical defects (9) and male reproductive disorders (10) have been observed.To make this population viable, population size and immigration must increase. So far, the population has been too small, and limited immigration followed by inbreeding could lead to extinction, similar to the Isle Royale wolf population (11). The goal should be to recreate a well-connected metapopulation spanning Scandinavia and Finland with a genetically effective population size of over 500, in line with the proposed CBD indicator (12). Considerably more genetic exchange than the current one-migrant-per-generation aim is needed (3).
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| 15. |
- O'Brien, David, et al.
(författare)
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Bringing together approaches to reporting on within species genetic diversity
- 2022
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 59:9, s. 2227-2233
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity is one of the three main levels of biodiversity recognised in the Convention on Biological Diversity (CBD). Fundamental for species adaptation to environmental change, genetic diversity is nonetheless under-reported within global and national indicators. When it is reported, the focus is often narrow and confined to domesticated or other commercial species.Several approaches have recently been developed to address this shortfall in reporting on genetic diversity of wild species. While multiplicity of approaches is helpful in any development process, it can also lead to confusion among policy makers and heighten a perception that conservation genetics is too abstract to be of use to organisations and governments.As the developers of five of the different approaches, we have come together to explain how various approaches relate to each other and propose a scorecard, as a unifying reporting mechanism for genetic diversity.Policy implications. We believe the proposed combined approach captures the strengths of its components and is practical for all nations and subnational governments. It is scalable and can be used to evaluate species conservation projects as well as genetic conservation projects.
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| 16. |
- Pearman, Peter B., et al.
(författare)
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Monitoring of species' genetic diversity in Europe varies greatly and overlooks potential climate change impacts
- 2024
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Ingår i: Nature Ecology & Evolution. - 2397-334X. ; 8, s. 267-281
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Tidskriftsartikel (refereegranskat)abstract
- Genetic monitoring of populations currently attracts interest in the context of the Convention on Biological Diversity but needs long-term planning and investments. However, genetic diversity has been largely neglected in biodiversity monitoring, and when addressed, it is treated separately, detached from other conservation issues, such as habitat alteration due to climate change. We report an accounting of efforts to monitor population genetic diversity in Europe (genetic monitoring effort, GME), the evaluation of which can help guide future capacity building and collaboration towards areas most in need of expanded monitoring. Overlaying GME with areas where the ranges of selected species of conservation interest approach current and future climate niche limits helps identify whether GME coincides with anticipated climate change effects on biodiversity. Our analysis suggests that country area, financial resources and conservation policy influence GME, high values of which only partially match species' joint patterns of limits to suitable climatic conditions. Populations at trailing climatic niche margins probably hold genetic diversity that is important for adaptation to changing climate. Our results illuminate the need in Europe for expanded investment in genetic monitoring across climate gradients occupied by focal species, a need arguably greatest in southeastern European countries. This need could be met in part by expanding the European Union's Birds and Habitats Directives to fully address the conservation and monitoring of genetic diversity. Comparing data on genetic monitoring efforts across Europe with the distributions of areas at species' climatic niche margins, the authors show that monitoring efforts should be expanded to populations at trailing niche margins to include genetic variation that may prove important for adaptation to ongoing climate warming.
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| 17. |
- Pearman, Peter B., et al.
(författare)
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Monitoring of species' genetic diversity in Europe varies greatly and overlooks potential climate change impacts
- 2024
-
Ingår i: Nature Ecology & Evolution. - : Springer Nature. - 2397-334X. ; 8:2, s. 267-281
-
Tidskriftsartikel (refereegranskat)abstract
- Genetic monitoring of populations currently attracts interest in the context of the Convention on Biological Diversity but needs long-term planning and investments. However, genetic diversity has been largely neglected in biodiversity monitoring, and when addressed, it is treated separately, detached from other conservation issues, such as habitat alteration due to climate change. We report an accounting of efforts to monitor population genetic diversity in Europe (genetic monitoring effort, GME), the evaluation of which can help guide future capacity building and collaboration towards areas most in need of expanded monitoring. Overlaying GME with areas where the ranges of selected species of conservation interest approach current and future climate niche limits helps identify whether GME coincides with anticipated climate change effects on biodiversity. Our analysis suggests that country area, financial resources and conservation policy influence GME, high values of which only partially match species' joint patterns of limits to suitable climatic conditions. Populations at trailing climatic niche margins probably hold genetic diversity that is important for adaptation to changing climate. Our results illuminate the need in Europe for expanded investment in genetic monitoring across climate gradients occupied by focal species, a need arguably greatest in southeastern European countries. This need could be met in part by expanding the European Union's Birds and Habitats Directives to fully address the conservation and monitoring of genetic diversity. Comparing data on genetic monitoring efforts across Europe with the distributions of areas at species' climatic niche margins, the authors show that monitoring efforts should be expanded to populations at trailing niche margins to include genetic variation that may prove important for adaptation to ongoing climate warming.
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| 18. |
- Robuchon, Marine, et al.
(författare)
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Conserving species' evolutionary potential and history : Opportunities under the Kunming–Montreal Global Biodiversity Framework
- 2023
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Ingår i: Conservation Science and Practice. - 2578-4854. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity (GD) and phylogenetic diversity (PD) respectively represent species' evolutionary potential and history, and support most of the biodiversity benefits to humanity. Yet, these two biodiversity facets have been overlooked in previous biodiversity policies. As the Parties to the Convention on Biological Diversity (CBD) adopted the Kunming–Montreal Global Biodiversity Framework (GBF) in December 2022, we analyze how GD and PD are considered in this new framework and discuss how their incorporation in the GBF could strengthen their conservation. Although the inclusion of certain indicators could be elevated, both GD and PD are an integral part of the recently adopted GBF. This represents a significant improvement compared to the CBD strategic plan 2011–2020 and an unprecedented opportunity to bring species' evolutionary potential and history to the core of public biodiversity policies. We urge the scientific community to leverage this opportunity to actually improve the conservation of species' evolutionary potential and history.
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| 19. |
- Ryman, Nils, 1943-, et al.
(författare)
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Variance effective population size is affected by census size in sub-structured populations
- 2023
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Ingår i: Molecular Ecology Resources. - 1755-098X .- 1755-0998. ; 23:6, s. 1334-1347
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Tidskriftsartikel (refereegranskat)abstract
- Measurement of allele frequency shifts between temporally spaced samples has long been used for assessment of effective population size (N-e), and this 'temporal method' provides estimates of N-e referred to as variance effective size (N-eV). We show that N-eV of a local population that belongs to a sub-structured population (a metapopulation) is determined not only by genetic drift and migration rate (m), but also by the census size (N-c). The realized N-eV of a local population can either increase or decrease with increasing m, depending on the relationship between N-e and N-c in isolation. This is shown by explicit mathematical expressions for the factors affecting N-eV derived for an island model of migration. We verify analytical results using high-resolution computer simulations, and show that the phenomenon is not restricted to the island model migration pattern. The effect of N-c on the realized N-eV of a local subpopulation is most pronounced at high migration rates. We show that N-c only affects local N-eV, whereas N-eV for the metapopulation as a whole, inbreeding (N-eI), and linkage disequilibrium (N-eLD) effective size are all independent of N-c. Our results provide a possible explanation to the large variation of N-e/N-c ratios reported in the literature, where N-e is frequently estimated by N-eV. They are also important for the interpretation of empirical N-e estimates in genetic management where local N-eV is often used as a substitute for inbreeding effective size, and we suggest an increased focus on metapopulation N-eV as a proxy for N-eI.
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| 20. |
- Saha, Atal, et al.
(författare)
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Monitoring genome-wide diversity over contemporary time with new indicators applied to Arctic charr populations
- 2024
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Ingår i: Conservation Genetics. - 1566-0621 .- 1572-9737. ; 25, s. 513-531
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity is fundamental to the adaptive potential and survival of species. Although its importance has long been recognized in science, it has a history of neglect within policy, until now. The new Global Biodiversity Framework recently adopted by the Convention on Biological Diversity, states that genetic diversity must be maintained at levels assuring adaptive potential of populations, and includes metrics for systematic monitoring of genetic diversity in so called indicators. Similarly, indicators for genetic diversity are being developed at national levels. Here, we apply new indicators for Swedish national use to one of the northernmost salmonid fishes, the Arctic charr (Salvelinus alpinus). We sequence whole genomes to monitor genetic diversity over four decades in three landlocked populations inhabiting protected alpine lakes in central Sweden. We find levels of genetic diversity, inbreeding and load to differ among lakes but remain stable over time. Effective population sizes are generally small (< 500), suggesting a limited ability to maintain adaptive variability if genetic exchange with nearby populations became eliminated. We identify genomic regions potentially shaped by selection; SNPs exhibiting population divergence exceeding expectations under drift and a putative selective sweep acting within one lake to which the competitive brown trout (Salmo trutta) was introduced during the sampling period. Identified genes appear involved in immunity and salinity tolerance. Present results suggest that genetically vulnerable populations of Arctic charr have maintained neutral and putatively adaptive genetic diversity despite small effective sizes, attesting the importance of continued protection and assurance of gene flow among populations.
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| 21. |
- Thurfjell, Henrik, et al.
(författare)
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Practical application of indicators for genetic diversity in CBD post-2020 global biodiversity framework implementation
- 2022
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X .- 1872-7034. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity is a key aspect of biological variation for the adaptability and survival of populations of species and must be monitored to assure maintenance. We used data from the Swedish Red List 2020 and from published reviews to apply three indicators for genetic diversity proposed for the post-2020 Global Biodiversity Framework of the Convention on Biological Diversity (CBD). We studied a wide range of taxonomic groups, and made more detailed indicator assessments for mammals and herptiles.For indicator 1, the proportion of populations with effective population size Ne > 500, 33% of 22,557 investigated species had a population size estimate that could be used as a proxy for Ne. For herptiles and mammals, 70% and 49% of populations of species, respectively, likely had Ne > 500.Data for evaluation of indicator 2, the proportion of remaining populations or historical range, was available for 20% of all species evaluated for the Red List. Meanwhile, 32% of the herptile and 84% of the mammal populations are maintaining their populations and range.For indicator 3, the number of species or populations in which genetic diversity is monitored using DNA-based methods, there are genetic studies on 3% of all species, and 0.3% are beeing monitored genetically. In contrast, 68% of mammals and 29% of herptiles are studied using DNA, and 8% of mammals and 24% of herptiles are genetically monitored.We conclude that the Red List provides data that are suitable for evaluating the genetic indicators, but the data quality can be improved. We also show that the genetic indicators capture conservation issues of genetic erosion that the Red List misses.There is a synergy in estimating the genetic indicators in parallel with the Red Listing process. We propose that indicator values could be included in national Red Listing as a new category - “genetically threatened”, based on the genetic indicators.
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