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Clarke SH, Lawrence ER, Matte JM, Gallagher BK, Salisbury SJ, Michaelides SN, Koumrouyan R, Ruzzante DE, Grant JWA, Fraser DJ. Global assessment of effective population sizes: Consistent taxonomic differences in meeting the 50/500 rule. Mol Ecol 2024; 33:e17353. [PMID: 38613250 DOI: 10.1111/mec.17353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 04/01/2024] [Accepted: 04/03/2024] [Indexed: 04/14/2024]
Abstract
Effective population size (Ne) is a particularly useful metric for conservation as it affects genetic drift, inbreeding and adaptive potential within populations. Current guidelines recommend a minimum Ne of 50 and 500 to avoid short-term inbreeding and to preserve long-term adaptive potential respectively. However, the extent to which wild populations reach these thresholds globally has not been investigated, nor has the relationship between Ne and human activities. Through a quantitative review, we generated a dataset with 4610 georeferenced Ne estimates from 3829 populations, extracted from 723 articles. These data show that certain taxonomic groups are less likely to meet 50/500 thresholds and are disproportionately impacted by human activities; plant, mammal and amphibian populations had a <54% probability of reachingN ̂ e = 50 and a <9% probability of reachingN ̂ e = 500. Populations listed as being of conservation concern according to the IUCN Red List had a smaller medianN ̂ e than unlisted populations, and this was consistent across all taxonomic groups.N ̂ e was reduced in areas with a greater Global Human Footprint, especially for amphibians, birds and mammals, however relationships varied between taxa. We also highlight several considerations for future works, including the role that gene flow and subpopulation structure plays in the estimation ofN ̂ e in wild populations, and the need for finer-scale taxonomic analyses. Our findings provide guidance for more specific thresholds based on Ne and help prioritise assessment of populations from taxa most at risk of failing to meet conservation thresholds.
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Affiliation(s)
- Shannon H Clarke
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | | | - Jean-Michel Matte
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Brian K Gallagher
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Sarah J Salisbury
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | | | - Ramela Koumrouyan
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Daniel E Ruzzante
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - James W A Grant
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Dylan J Fraser
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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2
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Waples RS. Practical application of the linkage disequilibrium method for estimating contemporary effective population size: A review. Mol Ecol Resour 2024; 24:e13879. [PMID: 37873672 DOI: 10.1111/1755-0998.13879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/26/2023] [Accepted: 09/29/2023] [Indexed: 10/25/2023]
Abstract
The method to estimate contemporary effective population size (Ne ) based on patterns of linkage disequilibrium (LD) at unlinked loci has been widely applied to natural and managed populations. The underlying model makes many simplifying assumptions, most of which have been evaluated in numerous studies published over the last two decades. Here, these performance evaluations are reviewed and summarized, with a focus on information that facilitates practical application to real populations in nature. Potential sources of bias that are discussed include calculation of r2 (a measure of LD), adjustments for sampling error, physical linkage, age structure, migration and spatial structure, mutation and selection, mating systems, changes in abundance, rare alleles, missing data, genotyping errors, data filtering choices and methods for combining multiple Ne estimates. Factors that affect precision are reviewed, including pseudoreplication that limits the information gained from large genomics datasets, constraints imposed by small samples of individuals, and the challenges in obtaining robust estimates for large populations. Topics that merit further research include the potential to weight r2 values by allele frequency, lump samples of individuals, use genotypic likelihoods rather than called genotypes, prune large LD values and apply the method to species practising partial monogamy.
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Affiliation(s)
- Robin S Waples
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, USA
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3
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Weise EM, Scribner KT, Boeberitz O, Bravener G, Johnson NS, Robinson JD. Evaluating the utility of effective breeding size estimates for monitoring sea lamprey spawning abundance. Ecol Evol 2023; 13:e10519. [PMID: 37745785 PMCID: PMC10511834 DOI: 10.1002/ece3.10519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 08/25/2023] [Accepted: 08/29/2023] [Indexed: 09/26/2023] Open
Abstract
Sea lamprey (Petromyzon marinus) is an invasive species that is a significant source of mortality for populations of valued fish species across the North American Great Lakes. Large annual control programs are needed to reduce the species' impacts; however, the number of successfully spawning adults cannot currently be accurately assessed. In this study, effective breeding size (N b) and the minimum number of spawning adults (N s) were estimated for larval cohorts from 17 tributaries across all five Great Lakes using single nucleotide polymorphisms (SNP) genotyped via RAD-capture sequencing. Reconstructed larval pedigrees showed substantial variability in the size and number of full- and half-sibling groups, N b (<1-367), and N s (5-545) among streams. Generalized linear models examining the effects of stream environmental characteristics and aspects of sampling regimes on N b and N s estimates identified sample size, the number of sampling sites, and drainage area as important factors predicting N b and N s. Correlations between N b, N s, and capture-mark-recapture estimates of adult census size (N c) increased when streams with small sample sizes (n < 50) were removed. Results collectively indicate that parameters estimated from genetic data can provide valuable information on spawning adults in a river system, especially if sampling regimes are standardized and physical stream covariates are included.
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Affiliation(s)
- Ellen M. Weise
- Department of Fisheries and WildlifeMichigan State UniversityEast LansingMichiganUSA
- Present address:
Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | - Kim T. Scribner
- Department of Fisheries and WildlifeMichigan State UniversityEast LansingMichiganUSA
- Department of Integrative BiologyMichigan State UniversityEast LansingMichiganUSA
| | - Olivia Boeberitz
- Department of Fisheries and WildlifeMichigan State UniversityEast LansingMichiganUSA
- Present address:
Pacific States Marine Fisheries CommissionPortlandOregonUSA
| | - Gale Bravener
- Fisheries and Oceans CanadaSea Lamprey Control CentreSault Ste. MarieOntarioCanada
| | - Nicholas S. Johnson
- U.S. Geological SurveyGreat Lakes Science Center, Hammond Bay Biological StationMillersburgMichiganUSA
| | - John D. Robinson
- Department of Fisheries and WildlifeMichigan State UniversityEast LansingMichiganUSA
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4
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Ryman N, Laikre L, Hössjer O. Variance effective population size is affected by census size in sub-structured populations. Mol Ecol Resour 2023. [PMID: 37122118 DOI: 10.1111/1755-0998.13804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 05/02/2023]
Abstract
Measurement of allele frequency shifts between temporally spaced samples has long been used for assessment of effective population size (Ne ), and this 'temporal method' provides estimates of Ne referred to as variance effective size (NeV ). We show that NeV 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 (Nc ). The realized NeV of a local population can either increase or decrease with increasing m, depending on the relationship between Ne and Nc in isolation. This is shown by explicit mathematical expressions for the factors affecting NeV 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 Nc on the realized NeV of a local subpopulation is most pronounced at high migration rates. We show that Nc only affects local NeV , whereas NeV for the metapopulation as a whole, inbreeding (NeI ), and linkage disequilibrium (NeLD ) effective size are all independent of Nc . Our results provide a possible explanation to the large variation of Ne /Nc ratios reported in the literature, where Ne is frequently estimated by NeV . They are also important for the interpretation of empirical Ne estimates in genetic management where local NeV is often used as a substitute for inbreeding effective size, and we suggest an increased focus on metapopulation NeV as a proxy for NeI .
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Affiliation(s)
- Nils Ryman
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Linda Laikre
- Division of Population Genetics, Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Ola Hössjer
- Department of Mathematics, Stockholm University, Stockholm, Sweden
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5
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Brooks GC, Wendt A, Haas CA, Roberts JH. Comparing estimates of census and effective population size in an endangered amphibian. Anim Conserv 2023. [DOI: 10.1111/acv.12871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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6
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Kitanishi S, Kondou T, Takahashi H, Takeshita N, Nagata S, Edo K. Recent reduction of genetic diversity in markless form of the red-spotted masu salmon Oncorhynchus masou ishikawae in the Ono River, Kyushu, Japan. CONSERV GENET 2023. [DOI: 10.1007/s10592-023-01515-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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7
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Liu SYV, Chen YY, Cheng C. Genetic structure and relatedness of juvenile sicklefin lemon shark (Negaprion acutidens) at Dongsha Island. Sci Rep 2023; 13:988. [PMID: 36653472 PMCID: PMC9849347 DOI: 10.1038/s41598-023-28186-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 01/13/2023] [Indexed: 01/19/2023] Open
Abstract
Negaprion acutidens (sicklefin lemon shark) is distributed in the Indo-Pacific and in close association with coral reefs. Under the protection of the Dongsha Atoll National Park, a small but well-established juvenile population of N. acutidens inhabiting coastal areas of Dongsha Island was recently observed to display site fidelity by using acoustic telemetry. This study was designed to reveal the fine scale genetic structure and relatedness within and among 5 juvenile shark cohorts inhabiting 3 sampling sites at Dongsha Island. A total 188 juveniles were caught and sampled between 2016 and 2017, and genotyped with twelve loci. They were assigned to 5 year cohorts (2013-2017) based on the body length and date they were caught, also assigned to 3 sites based on where they were caught. Among five cohorts, the percentage of unrelated pairs within a cohort is more than 62% in average, suggesting a potential high mortality during their early life stage. The results of Fst and assignment testing showed that there was no significant genetic structure between sites and cohorts indicating that there was no fine scale genetic structure, even though the juveniles possessed strong site fidelity. A small effective population size (Ne) was detected (Ne = 86.7) which indicates the presence of a potentially isolated and vulnerable population at Dongsha. These results provide the genetic diversity as a baseline for future management and conservation of N. acutidens in the South China Sea.
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Affiliation(s)
- Shang Yin Vanson Liu
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan. .,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan. .,Graduate Institute of Natural Products College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan.
| | - Yu-Yun Chen
- Division of Natural Science, General Education Center, Aletheia University, New Taipei City, Taiwan
| | - Chi Cheng
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
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8
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Pool Age and Local Habitat Are Associated with Effective Number of Breeders in Spotted Salamander Populations Colonizing Created Vernal Pools. DIVERSITY 2023. [DOI: 10.3390/d15020124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Population genetics can reveal whether colonization of created habitats has been successful and inform future strategies for habitat creation. We used genetic analysis to investigate spotted salamander (Ambystoma maculatum) colonization of created vernal pools and explored the impact of habitat characteristics on the genetic diversity and connectivity of the pools. Our first objective was to examine genetic structure, differentiation, diversity, and potential for a founder effect. Our second objective was to determine if habitat characteristics were associated with effective number of breeders, relatedness, or genetic diversity. We sampled spotted salamander larvae in 31 created vernal pools (1–5 years old) in Monongahela National Forest (WV) in May and June 2015 and 2016. The youngest pools exhibited genetic differentiation, a founder effect, and low effective number of breeders. Effective number of breeders was positively associated with pool age, vegetation cover, pool diameter, and sample size. Vegetation cover was also negatively associated with relatedness. Genetic diversity did not have strong environmental predictors. Our results indicated the effective number of breeders increased and genetic differentiation decreased within 4–5 years of pool creation, a sign of rapid colonization and potential population establishment. Our research also showed that higher vegetative cover within the pool and larger pool diameters could impact habitat quality and should be incorporated into future pool creation.
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9
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Clarke SH, McCracken GR, Humphries S, Ruzzante D, Grant JWA, Fraser DJ. Demographic resilience of brook trout populations subjected to experimental size‐selective. Evol Appl 2022; 15:1792-1805. [DOI: 10.1111/eva.13478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
| | | | - Shelley Humphries
- Lake Louise, Yoho, and Kootenay Field Unit, Parks Canada Radium Hot Springs British Columbia Canada
| | | | | | - Dylan J. Fraser
- Department of Biology Concordia University Montreal Quebec Canada
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10
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Hemstrom W, Dauwalter D, Peacock M, Leasure D, Wenger S, Miller M, Neville. Population genomic monitoring provides insight into conservation status but no correlation with demographic estimates of extinction risk in a threatened trout. Evol Appl 2022; 15:1449-1468. [PMID: 36187186 PMCID: PMC9488680 DOI: 10.1111/eva.13473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 08/12/2022] [Indexed: 12/03/2022] Open
Abstract
The current extinction crisis requires effective assessment and monitoring tools. Genetic approaches are appealing given the relative ease of field sampling required to estimate genetic diversity characteristics assumed related to population size, evolutionary potential, and extinction risk, and to evaluate hybridization with non‐native species simultaneously. However, linkages between population genetic metrics of diversity from survey‐style field collections and demographic estimates of population size and extinction risk are still in need of empirical examples, especially for remotely distributed species of conservation concern where the approach might be most beneficial. We capitalized on an exceptional opportunity to evaluate congruence between genetic diversity metrics and demographic‐based estimates of abundance and extinction risk from a comprehensive Multiple Population Viability Analysis (MPVA) in a threatened fish, the Lahontan cutthroat trout (LCT). We sequenced non‐native trout reference samples and recently collected and archived tissue samples of most remaining populations of LCT (N = 60) and estimated common genetic assessment metrics, predicting minimal hybridization with non‐native trout, low diversity, and declining diversity over time. We further hypothesized genetic metrics would correlate positively with MPVA‐estimated abundance and negatively with extinction probability. We uncovered several instances of hybridization that pointed to immediate management needs. After removing hybridized individuals, cautious interpretation of low effective population sizes (2–63) suggested reduced evolutionary potential for many LCT populations. Other genetic metrics did not decline over time nor correlate with MPVA‐based estimates of harmonic mean abundance or 30‐year extinction probability. Our results demonstrate benefits of genetic monitoring for efficiently detecting hybridization and, though genetic results were disconnected from demographic assessment of conservation status, they suggest reduced evolutionary potential and likely a higher conservation risk than currently recognized for this threatened fish. We emphasize that genetic information provides essential complementary insight, in addition to demographic information, for evaluating species status.
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Affiliation(s)
- W. Hemstrom
- Department of Animal Science University of California Davis California U.S.A
| | | | - M. Peacock
- Department of Biology University of Nevada Reno Nevada U.S.A
| | - D. Leasure
- WorldPop, Geography and Environmental Science University of Southampton Southampton United Kingdom
| | - S. Wenger
- Odum School of Ecology University of Georgia Athens GA U.S.A
| | - M. Miller
- Department of Animal Science University of California Davis California U.S.A
| | - Neville
- Science Program, Trout Unlimited Boise ID U.S.A
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11
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Waples RS.
TheWeight
: A simple and flexible algorithm for simulating non‐ideal, age‐structured populations. Methods Ecol Evol 2022. [DOI: 10.1111/2041-210x.13926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robin S. Waples
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Seattle, WA, 98112 USA
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12
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Nadachowska‐Brzyska K, Konczal M, Babik W. Navigating the temporal continuum of effective population size. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13740] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | | | - Wieslaw Babik
- Jagiellonian University in Kraków Faculty of Biology Institute of Environmental Sciences Kraków Poland
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13
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Wright PGR, Schofield H, Mathews F. Can effective population size estimates be used to monitor population trends of woodland bats? A case study of Myotis bechsteinii. Ecol Evol 2021; 11:2015-2023. [PMID: 33717438 PMCID: PMC7920762 DOI: 10.1002/ece3.7143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 11/26/2020] [Accepted: 12/04/2020] [Indexed: 12/01/2022] Open
Abstract
Molecular approaches to calculate effective population size estimates (Ne) are increasingly used as an alternative to long-term demographic monitoring of wildlife populations. However, the complex ecology of most long-lived species and the consequent uncertainties in model assumptions means that effective population size estimates are often imprecise. Although methods exist to incorporate age structure into Ne estimations for long-lived species with overlapping generations, they are rarely used owing to the lack of relevant information for most wild populations. Here, we performed a case study on an elusive woodland bat, Myotis bechsteinii, to compare the use of the parentage assignment Ne estimator (EPA) with the more commonly used linkage disequilibrium (LD) Ne estimator in detecting long-term population trends, and assessed the impacts of deploying different overall sample sizes. We used genotypic data from a previously published study, and simulated 48 contrasting demographic scenarios over 150 years using the life history characteristics of this species The LD method strongly outperformed the EPA method. As expected, smaller sample sizes resulted in a reduced ability to detect population trends. Nevertheless, even the smallest sample size tested (n = 30) could detect important changes (60%-80% decline) with the LD method. These results demonstrate that genetic approaches can be an effective way to monitor long-lived species, such as bats, provided that they are undertaken over multiple decades.
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Affiliation(s)
- Patrick G. R. Wright
- Department of Life SciencesUniversity of SussexFalmerUK
- Vincent Wildlife TrustLedburyUK
| | | | - Fiona Mathews
- Department of Life SciencesUniversity of SussexFalmerUK
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14
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Antao T, Cosart T, Trethewey B, Waples RS, Ackerman MW, Luikart G, Hand BK. AgeStrucNb: Software for Simulating and Detecting Changes in the Effective Number of Breeders (Nb). J Hered 2020. [DOI: 10.1093/jhered/esaa028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Estimation of the effective number of breeders per reproductive event (Nb) using single sample DNA-marker-based methods has rapidly grown in recent years. However, estimating Nb is difficult in age-structured populations because the performance of estimators is influenced by the Nb / Ne ratio, which varies among species with different life histories. We provide a computer program, AgeStrucNb, to simulate age-structured populations (including life history) and also estimate Nb. The AgeStrucNb program is composed of 4 major components to simulate, subsample, estimate, and then visualize Nb time series data. AgeStrucNb allows users to also quantify the precision and accuracy of any set of loci or sample size to estimate Nb for many species and populations. AgeStrucNb allows users to conduct power analysis to evaluate sensitivity to detect changes in Nb or the power to detect a correlation between trends in Nb and environmental variables (e.g., temperature, habitat quality, predator or pathogen abundance) that could be driving changes in Nb. The software provides Nb estimates for empirical data sets using the LDNe (linkage disequilibrium) method, includes publication-quality output graphs, and outputs genotype files in Genepop format for use in other programs. AgeStrucNb will help advance the application of genetic markers for monitoring Nb, which will help biologists to detect population declines and growth, which is crucial for research and conservation of natural and managed populations.
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Affiliation(s)
- Tiago Antao
- Division of Biological Sciences, The University of Montana, Missoula, MT
| | - Ted Cosart
- Flathead Lake Biological Station, University of Montana, Polson, MT
| | | | - Robin S Waples
- NOAA Fisheries, Northwest Fisheries Science Center, Seattle, WA
| | | | - Gordon Luikart
- Division of Biological Sciences, The University of Montana, Missoula, MT
- Flathead Lake Biological Station, University of Montana, Polson, MT
| | - Brian K Hand
- Division of Biological Sciences, The University of Montana, Missoula, MT
- Flathead Lake Biological Station, University of Montana, Polson, MT
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15
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Genotyping-by-sequencing reveals the effects of riverscape, climate and interspecific introgression on the genetic diversity and local adaptation of the endangered Mexican golden trout (Oncorhynchus chrysogaster). CONSERV GENET 2020. [DOI: 10.1007/s10592-020-01297-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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16
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Glasgow J, De Groot JD, Small MP. Genetic composition and conservation status of coastal cutthroat trout (Oncorhynchus clarki clarki) in the San Juan Islands, Washington. CONSERV GENET 2019. [DOI: 10.1007/s10592-019-01238-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractUnderstanding the conservation status of native fish populations is increasingly important because they are put at risk by mounting anthropogenic pressures, including climate change. Conventional approaches to assess fish populations can be logistically challenging and cost-prohibitive. As a result, resource managers often make assumptions about the status of fish populations based on limited information. The watersheds of Washington’s San Juan Islands were considered too small to support wild salmonid populations. Many streams flow only seasonally, and all have been subjected to varying degrees of anthropogenic impacts affecting their ecological integrity. Nonetheless, we found that at least five watersheds in the archipelago support populations of coastal cutthroat trout (Oncorhynchus clarki clarki). To better understand the conservation status of coastal cutthroat trout populations there, we genotyped approximately fifty trout in each of three watersheds: Cascade and Doe Bay creeks on Orcas Island and Garrison Creek on San Juan Island. Results suggest that two watersheds support native populations and one supports naturalized hatchery fish. The likely native coastal cutthroat trout diversity documented in the two watersheds contributes to the overall diversity of the species, demonstrates that species’ resiliency, and provides justification for conservation measures. Effective management and conservation planning in data-limited situations requires the use of a precautionary approach. Population genetics provide a useful tool for identifying vulnerable fish populations and understanding their relationships with other conspecific populations. This information can inform restoration goals and help identify and prioritize restoration and protection measures.
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17
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Ruzzante DE, McCracken GR, Førland B, MacMillan J, Notte D, Buhariwalla C, Mills Flemming J, Skaug H. Validation of close‐kin mark–recapture (CKMR) methods for estimating population abundance. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13243] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | | | - Brage Førland
- Department of Mathematics University of Bergen Bergen Norway
| | - John MacMillan
- Inland Fisheries Division, Nova Scotia Department of Fisheries and Aquaculture Halifax Nova Scotia Canada
| | - Daniela Notte
- Department of Biology Dalhousie University Halifax Nova Scotia Canada
| | - Colin Buhariwalla
- Inland Fisheries Division, Nova Scotia Department of Fisheries and Aquaculture Halifax Nova Scotia Canada
| | - Joanna Mills Flemming
- Department of Mathematics and Statistics Dalhousie University Halifax Nova Scotia Canada
| | - Hans Skaug
- Department of Mathematics University of Bergen Bergen Norway
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18
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Gossieaux P, Bernatchez L, Sirois P, Garant D. Impacts of stocking and its intensity on effective population size in Brook Charr (Salvelinus fontinalis) populations. CONSERV GENET 2019. [DOI: 10.1007/s10592-019-01168-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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19
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Pregler KC, Kanno Y, Rankin D, Coombs JA, Whiteley AR. Characterizing genetic integrity of rear-edge trout populations in the southern Appalachians. CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1116-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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White SL, Miller WL, Dowell SA, Bartron ML, Wagner T. Limited hatchery introgression into wild brook trout ( Salvelinus fontinalis) populations despite reoccurring stocking. Evol Appl 2018; 11:1567-1581. [PMID: 30344628 PMCID: PMC6183464 DOI: 10.1111/eva.12646] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 05/04/2018] [Accepted: 05/07/2018] [Indexed: 01/17/2023] Open
Abstract
Due to increased anthropogenic pressures on many fish populations, supplementing wild populations with captive-raised individuals has become an increasingly common management practice. Stocking programs can be controversial due to uncertainty about the long-term fitness effects of genetic introgression on wild populations. In particular, introgression between hatchery and wild individuals can cause declines in wild population fitness, resiliency, and adaptive potential and contribute to local population extirpation. However, low survival and fitness of captive-raised individuals can minimize the long-term genetic consequences of stocking in wild populations, and to date the prevalence of introgression in actively stocked ecosystems has not been rigorously evaluated. We quantified the extent of introgression in 30 populations of wild brook trout (Salvelinus fontinalis) in a Pennsylvania watershed and examined the correlation between introgression and 11 environmental covariates. Genetic assignment tests were used to determine the origin (wild vs. captive-raised) for 1,742 wild-caught and 300 hatchery brook trout. To avoid assignment biases, individuals were assigned to two simulated populations that represented the average allele frequencies in wild and hatchery groups. Fish with intermediate probabilities of wild ancestry were classified as introgressed, with threshold values determined through simulation. Even with reoccurring stocking at most sites, over 93% of wild-caught individuals probabilistically assigned to wild origin, and only 5.6% of wild-caught fish assigned to introgressed. Models examining environmental drivers of introgression explained <3% of the among-population variability, and all estimated effects were highly uncertain. This was not surprising given overall low introgression observed in this study. Our results suggest that introgression of hatchery-derived genotypes can occur at low rates, even in actively stocked ecosystems and across a range of habitats. However, a cautious approach to stocking may still be warranted, as the potential effects of stocking on wild population fitness and the mechanisms limiting introgression are not known.
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Affiliation(s)
- Shannon L. White
- Pennsylvania Cooperative Fish and Wildlife Research UnitPennsylvania State UniversityUniversity ParkPennsylvania
- Department of Ecosystem Science and ManagementPennsylvania State UniversityUniversity ParkPennsylvania
| | - William L. Miller
- Pennsylvania Cooperative Fish and Wildlife Research UnitPennsylvania State UniversityUniversity ParkPennsylvania
- Department of Ecosystem Science and ManagementPennsylvania State UniversityUniversity ParkPennsylvania
| | | | | | - Tyler Wagner
- U.S. Geological SurveyPennsylvania Cooperative Fish and Wildlife Research UnitPennsylvania State UniversityUniversity ParkPennsylvania
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21
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Resh CA, Galaska MP, Mahon AR. Genomic analyses of Northern snakehead ( Channa argus) populations in North America. PeerJ 2018; 6:e4581. [PMID: 29637024 PMCID: PMC5889702 DOI: 10.7717/peerj.4581] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/15/2018] [Indexed: 12/20/2022] Open
Abstract
Background The introduction of northern snakehead (Channa argus; Anabantiformes: Channidae) and their subsequent expansion is one of many problematic biological invasions in the United States. This harmful aquatic invasive species has become established in various parts of the eastern United States, including the Potomac River basin, and has recently become established in the Mississippi River basin in Arkansas. Effective management of C. argus and prevention of its further spread depends upon knowledge of current population structure in the United States. Methods Novel methods for invasive species using whole genomic scans provide unprecedented levels of data, which are able to investigate fine scale differences between and within populations of organisms. In this study, we utilize 2b-RAD genomic sequencing to recover 1,007 single-nucleotide polymorphism (SNP) loci from genomic DNA extracted from 165 C. argus individuals: 147 individuals sampled along the East Coast of the United States and 18 individuals sampled throughout Arkansas. Results Analysis of those SNP loci help to resolve existing population structure and recover five genetically distinct populations of C. argus in the United States. Additionally, information from the SNP loci enable us to begin to calculate the long-term effective population size ranges of this harmful aquatic invasive species. We estimate long-term Ne to be 1,840,000–18,400,000 for the Upper Hudson River basin, 4,537,500–45,375,000 for the Lower Hudson River basin, 3,422,500–34,225,000 for the Potomac River basin, 2,715,000–7,150,000 for Philadelphia, and 2,580,000–25,800,000 for Arkansas populations. Discussion and Conclusions This work provides evidence for the presence of more genetic populations than previously estimated and estimates population size, showing the invasive potential of C. argus in the United States. The valuable information gained from this study will allow effective management of the existing populations to avoid expansion and possibly enable future eradication efforts.
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Affiliation(s)
- Carlee A Resh
- Department of Biology, Central Michigan University, Mount Pleasant, MI, United States of America
| | - Matthew P Galaska
- Department of Biological Sciences, Lehigh Univervsity, Bethlehem, PA, United States of America
| | - Andrew R Mahon
- Department of Biology, Institute for Great Lakes Research, Central Michigan University, Mount Pleasant, MI, United States of America
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22
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Genetic diversity through time and space: diversity and demographic history from natural history specimens and serially sampled contemporary populations of the threatened Gouldian finch (Erythrura gouldiae). CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1051-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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23
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Kopatz A, Eiken HG, Schregel J, Aspi J, Kojola I, Hagen SB. Genetic substructure and admixture as important factors in linkage disequilibrium-based estimation of effective number of breeders in recovering wildlife populations. Ecol Evol 2017; 7:10721-10732. [PMID: 29299252 PMCID: PMC5743533 DOI: 10.1002/ece3.3577] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/03/2017] [Accepted: 10/04/2017] [Indexed: 01/18/2023] Open
Abstract
The number of effective breeders (Nb ) and effective population size (Ne ) are population parameters reflective of evolutionary potential, susceptibility to stochasticity, and viability. We have estimated these parameters using the linkage disequilibrium-based approach with LDNE through the latest phase of population recovery of the brown bears (Ursus arctos) in Finland (1993-2010; N = 621). This phase of the recovery was recently documented to be associated with major changes in genetic composition. In particular, differentiation between the northern and the southern genetic cluster declined rapidly within 1.5 generations. Based on this, we have studied effects of the changing genetic structure on Nb and Ne , by comparing estimates for whole Finland with the estimates for the two genetic clusters. We expected a potentially strong relationship between estimate sizes and genetic differentiation, which should disappear as the population recovers and clusters merge. Consistent with this, our estimates for whole Finland were lower than the sum of the estimates of the two genetic clusters and both approaches produced similar estimates in the end. Notably, we also found that admixed genotypes strongly increased the estimates. In all analyses, our estimates for Ne were larger than Nb and likely reflective for brown bears of the larger region of Finland and northwestern Russia. Conclusively, we find that neglecting genetic substructure may lead to a massive underestimation of Nb and Ne . Our results also suggest the need for further empirical analysis focusing on individuals with admixed genotypes and their potential high influence on Nb and Ne .
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Affiliation(s)
| | - Hans Geir Eiken
- NIBIO—Norwegian Institute of Bioeconomy ResearchSvanvikNorway
| | - Julia Schregel
- NIBIO—Norwegian Institute of Bioeconomy ResearchSvanvikNorway
| | - Jouni Aspi
- Department of BiologyUniversity of OuluOuluFinland
| | - Ilpo Kojola
- Natural Resources Institute Finland (Luke)RovaniemiFinland
| | - Snorre B. Hagen
- NIBIO—Norwegian Institute of Bioeconomy ResearchSvanvikNorway
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Sánchez‐Montes G, Wang J, Ariño AH, Vizmanos JL, Martínez‐Solano I. Reliable effective number of breeders/adult census size ratios in seasonal-breeding species: Opportunity for integrative demographic inferences based on capture-mark-recapture data and multilocus genotypes. Ecol Evol 2017; 7:10301-10314. [PMID: 29238556 PMCID: PMC5723585 DOI: 10.1002/ece3.3387] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/20/2017] [Accepted: 08/03/2017] [Indexed: 01/18/2023] Open
Abstract
The ratio of the effective number of breeders (Nb) to the adult census size (Na), Nb/Na, approximates the departure from the standard capacity of a population to maintain genetic diversity in one reproductive season. This information is relevant for assessing population status, understanding evolutionary processes operating at local scales, and unraveling how life-history traits affect these processes. However, our knowledge on Nb/Na ratios in nature is limited because estimation of both parameters is challenging. The sibship frequency (SF) method is adequate for reliable Nb estimation because it is based on sibship and parentage reconstruction from genetic marker data, thereby providing demographic inferences that can be compared with field-based information. In addition, capture-mark-recapture (CMR) robust design methods are well suited for Na estimation in seasonal-breeding species. We used tadpole genotypes of three pond-breeding amphibian species (Epidalea calamita, Hyla molleri, and Pelophylax perezi, n = 73-96 single-cohort tadpoles/species genotyped at 15-17 microsatellite loci) and candidate parental genotypes (n = 94-300 adults/species) to estimate Nb by the SF method. To assess the reliability of Nb estimates, we compared sibship and parentage inferences with field-based information and checked for the convergence of results in replicated subsampled analyses. Finally, we used CMR data from a 6-year monitoring program to estimate annual Na in the three species and calculate the Nb/Na ratio. Reliable ratios were obtained for E. calamita (Nb/Na = 0.18-0.28) and P. perezi (0.5), but in H. molleri, Na could not be estimated and genetic information proved insufficient for reliable Nb estimation. Integrative demographic studies taking full advantage of SF and CMR methods can provide accurate estimates of the Nb/Na ratio in seasonal-breeding species. Importantly, the SF method provides results that can be readily evaluated for reliability. This represents a good opportunity for obtaining robust demographic inferences with wide applications for evolutionary and conservation research.
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Affiliation(s)
- Gregorio Sánchez‐Montes
- Department of Environmental BiologyUniversidad de NavarraPamplonaSpain
- Museo Nacional de Ciencias Naturales, CSICMadridSpain
- Institute of ZoologyZoological Society of LondonLondonUK
- Ecology, Evolution, and Development GroupDepartment of Wetland EcologyDoñana Biological Station, CSICSevilleSpain
| | - Jinliang Wang
- Institute of ZoologyZoological Society of LondonLondonUK
| | - Arturo H. Ariño
- Department of Environmental BiologyUniversidad de NavarraPamplonaSpain
| | - José Luis Vizmanos
- Department of Biochemistry and GeneticsUniversidad de NavarraPamplonaSpain
| | - Iñigo Martínez‐Solano
- Museo Nacional de Ciencias Naturales, CSICMadridSpain
- Ecology, Evolution, and Development GroupDepartment of Wetland EcologyDoñana Biological Station, CSICSevilleSpain
- Instituto de Investigación en Recursos Cinegéticos (IREC‐CSIC‐UCLM‐JCCM)Ciudad RealSpain
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Yates MC, Bernos TA, Fraser DJ. A critical assessment of estimating census population size from genetic population size (or vice versa) in three fishes. Evol Appl 2017; 10:935-945. [PMID: 29151884 PMCID: PMC5680432 DOI: 10.1111/eva.12496] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 05/22/2017] [Indexed: 12/25/2022] Open
Abstract
Technological and methodological advances have facilitated the use of genetic data to infer census population size (Nc) in natural populations, particularly where traditional mark-and-recapture is challenging. The effective number of breeders (Nb) describes how many adults effectively contribute to a cohort and is often correlated with Nc. Predicting Nc from Nb or vice versa in species with overlapping generations has important implications for conservation by permitting (i) estimation of the more difficult to quantify variable and (ii) inferences of Nb/Nc relationships in related species lacking data. We quantitatively synthesized Nb/Nc relationships in three salmonid fishes where sufficient data have recently accumulated. Mixed-effects models were analysed in which each variable was included as a dependent variable or predictor term (Nb from Nc and vice versa). Species-dependent Nb/Nc slope estimates were significantly positive in two of three species. Variation in species slopes was likely due to varying life histories and reinforce caution when inferring Nb/Nc from taxonomically related species. Models provided maximum probable estimates for Nb and Nc for two species. However, study, population and year effects explained substantial amounts of variation (39%-57%). Consequently, prediction intervals were wide and included or were close to zero for all population sizes and species; model predictive utility was limited. Cost-benefit trade-offs when estimating Nb and/or Nc were also discussed using a real-world system example. Our findings based on salmonids suggest that no short cuts currently exist when estimating population size and researchers should focus on quantifying the variable of interest or be aware of caveats when inferring the desired variable because of cost or logistics. We caution that the salmonid species examined share life-history traits that may obscure relationships between Nb and Nc. Sufficient data on other taxa were unavailable; additional research examining Nb/Nc relationships in species with potentially relevant life-history trait differences (e.g., differing survival curves) is needed.
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Affiliation(s)
- Matthew Carl Yates
- Department of BiologyConcordia UniversityMontrealQCCanada
- Group for Interuniversity Research in Limnology and Aquatic Environments (GRIL)Universite du QuebecTrois‐RivieresQCCanada
| | | | - Dylan J. Fraser
- Department of BiologyConcordia UniversityMontrealQCCanada
- Group for Interuniversity Research in Limnology and Aquatic Environments (GRIL)Universite du QuebecTrois‐RivieresQCCanada
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Schou MF, Loeschcke V, Bechsgaard J, Schlötterer C, Kristensen TN. Unexpected high genetic diversity in small populations suggests maintenance by associative overdominance. Mol Ecol 2017; 26:6510-6523. [PMID: 28746770 DOI: 10.1111/mec.14262] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/23/2017] [Accepted: 06/28/2017] [Indexed: 12/17/2022]
Abstract
The effective population size (Ne ) is a central factor in determining maintenance of genetic variation. The neutral theory predicts that loss of variation depends on Ne , with less genetic drift in larger populations. We monitored genetic drift in 42 Drosophila melanogaster populations of different adult census population sizes (10, 50 or 500) using pooled RAD sequencing. In small populations, variation was lost at a substantially lower rate than expected. This observation was consistent across two ecological relevant thermal regimes, one stable and one with a stressful increase in temperature across generations. Estimated ratios between Ne and adult census size were consistently higher in small than in larger populations. The finding provides evidence for a slower than expected loss of genetic diversity and consequently a higher than expected long-term evolutionary potential in small fragmented populations. More genetic diversity was retained in areas of low recombination, suggesting that associative overdominance, driven by disfavoured homozygosity of recessive deleterious alleles, is responsible for the maintenance of genetic diversity in smaller populations. Consistent with this hypothesis, the X-chromosome, which is largely free of recessive deleterious alleles due to hemizygosity in males, fits neutral expectations even in small populations. Our experiments provide experimental answers to a range of unexpected patterns in natural populations, ranging from variable diversity on X-chromosomes and autosomes to surprisingly high levels of nucleotide diversity in small populations.
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Affiliation(s)
- Mads F Schou
- Department of Bioscience, Aarhus University, Aarhus C, Denmark
| | | | | | | | - Torsten N Kristensen
- Department of Bioscience, Aarhus University, Aarhus C, Denmark.,Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
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27
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Trask AE, Bignal EM, McCracken DI, Piertney SB, Reid JM. Estimating demographic contributions to effective population size in an age-structured wild population experiencing environmental and demographic stochasticity. J Anim Ecol 2017; 86:1082-1093. [PMID: 28543048 DOI: 10.1111/1365-2656.12703] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 05/05/2017] [Indexed: 01/25/2023]
Abstract
A population's effective size (Ne ) is a key parameter that shapes rates of inbreeding and loss of genetic diversity, thereby influencing evolutionary processes and population viability. However, estimating Ne , and identifying key demographic mechanisms that underlie the Ne to census population size (N) ratio, remains challenging, especially for small populations with overlapping generations and substantial environmental and demographic stochasticity and hence dynamic age-structure. A sophisticated demographic method of estimating Ne /N, which uses Fisher's reproductive value to account for dynamic age-structure, has been formulated. However, this method requires detailed individual- and population-level data on sex- and age-specific reproduction and survival, and has rarely been implemented. Here, we use the reproductive value method and detailed demographic data to estimate Ne /N for a small and apparently isolated red-billed chough (Pyrrhocorax pyrrhocorax) population of high conservation concern. We additionally calculated two single-sample molecular genetic estimates of Ne to corroborate the demographic estimate and examine evidence for unobserved immigration and gene flow. The demographic estimate of Ne /N was 0.21, reflecting a high total demographic variance (σ2dg) of 0.71. Females and males made similar overall contributions to σ2dg. However, contributions varied among sex-age classes, with greater contributions from 3 year-old females than males, but greater contributions from ≥5 year-old males than females. The demographic estimate of Ne was ~30, suggesting that rates of increase of inbreeding and loss of genetic variation per generation will be relatively high. Molecular genetic estimates of Ne computed from linkage disequilibrium and approximate Bayesian computation were approximately 50 and 30, respectively, providing no evidence of substantial unobserved immigration which could bias demographic estimates of Ne . Our analyses identify key sex-age classes contributing to demographic variance and thus decreasing Ne /N in a small age-structured population inhabiting a variable environment. They thereby demonstrate how assessments of Ne can incorporate stochastic sex- and age-specific demography and elucidate key demographic processes affecting a population's evolutionary trajectory and viability. Furthermore, our analyses show that Ne for the focal chough population is critically small, implying that management to re-establish genetic connectivity may be required to ensure population viability.
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Affiliation(s)
- Amanda E Trask
- Institute of Biological & Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Eric M Bignal
- Scottish Chough Study Group, Isle of Islay, Argyll, UK
| | | | - Stuart B Piertney
- Institute of Biological & Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Jane M Reid
- Institute of Biological & Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen, UK
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Gutiérrez-Rodríguez J, Sánchez-Montes G, Martínez-Solano I. Effective to census population size ratios in two Near Threatened Mediterranean amphibians: Pleurodeles waltl and Pelobates cultripes. CONSERV GENET 2017. [DOI: 10.1007/s10592-017-0971-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Garg KM, Ramakrishnan U. Variance in Female Reproductive Success Differentially Impacts Effective Population Size in the Short-Nosed Fruit Bat, Cynopterus sphinx. Evol Biol 2017. [DOI: 10.1007/s11692-017-9414-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Whiteley AR, Coombs JA, O'Donnell MJ, Nislow KH, Letcher BH. Keeping things local: Subpopulation Nb and Ne in a stream network with partial barriers to fish migration. Evol Appl 2017; 10:348-365. [PMID: 28352295 PMCID: PMC5367083 DOI: 10.1111/eva.12454] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 12/11/2016] [Indexed: 01/17/2023] Open
Abstract
For organisms with overlapping generations that occur in metapopulations, uncertainty remains regarding the spatiotemporal scale of inference of estimates of the effective number of breeders (N^b) and whether these estimates can be used to predict generational Ne. We conducted a series of tests of the spatiotemporal scale of inference of estimates of Nb in nine consecutive cohorts within a long‐term study of brook trout (Salvelinus fontinalis). We also tested a recently developed approach to estimate generational Ne from N^b and compared this to an alternative approach for estimating N^e that also accounts for age structure. Multiple lines of evidence were consistent with N^b corresponding to the local (subpopulation) spatial scale and the cohort‐specific temporal scale. We found that at least four consecutive cohort‐specific estimates of N^b were necessary to obtain reliable estimates of harmonic mean N^b for a subpopulation. Generational N^e derived from cohort‐specific N^b was within 7%–50% of an alternative approach to obtain N^e, suggesting some population specificity for concordance between approaches. Our results regarding the spatiotemporal scale of inference for Nb should apply broadly to many taxa that exhibit overlapping generations and metapopulation structure and point to promising avenues for using cohort‐specific N^b for local‐scale genetic monitoring.
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Affiliation(s)
- Andrew R Whiteley
- Wildlife Biology Program Department of Ecosystem and Conservation Sciences College of Forestry and Conservation University of Montana Missoula MT USA
| | - Jason A Coombs
- Department of Environmental Conservation University of Massachusetts Amherst Amherst MA USA; U.S. Forest Service Northern Research Station University of Massachusetts Amherst MA USA
| | - Matthew J O'Donnell
- U.S. Geological Survey Leetown Science Center S.O. Conte Anadromous Fish Research Center Turners Falls MA USA
| | - Keith H Nislow
- U.S. Forest Service Northern Research Station University of Massachusetts Amherst MA USA
| | - Benjamin H Letcher
- U.S. Geological Survey Leetown Science Center S.O. Conte Anadromous Fish Research Center Turners Falls MA USA
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Two decades of genetic consistency in a reproductive population in the face of exploitation: patterns of adult and larval walleye (Sander vitreus) from Lake Erie’s Maumee River. CONSERV GENET 2016. [DOI: 10.1007/s10592-016-0866-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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