scholarly journals The Last Two Remaining Populations of the Critically Endangered Estuarine Pipefish Are Inbred and Not Genetically Distinct

2022 ◽  
Vol 8 ◽  
Author(s):  
Sven-Erick Weiss ◽  
Arsalan Emami-Khoyi ◽  
Horst Kaiser ◽  
Paul D. Cowley ◽  
Nicola C. James ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Extinction Risk ◽  
Significant Risk ◽  
Small Population ◽  
Environmental Stochasticity ◽  
Critically Endangered ◽  
Conservation Strategy ◽  
Genome Wide Data ◽  
Significant Genetic Structure ◽  
Population Sizes

The critically endangered estuarine pipefish, Syngnathus watermeyeri, is one of Africa’s rarest fish species and currently faces a significant risk of extinction. A combination of anthropogenic and natural factors threaten submerged macrophyte beds in the two South African estuaries (Bushmans and Kariega) in which the species’ only two known remaining populations reside. Here, we genotyped 34 pipefish from both populations using genome-wide data to determine whether the two estuaries harbour distinct genetic diversity, such that translocating individuals between them might improve the genetic health of both. Our results show that both populations are highly inbred, and no statistically significant genetic structure was found between them. Moreover, individuals both within and between estuaries were very closely related to each other. These results indicate that the remaining populations of the estuarine pipefish suffer from the adverse genetic effects of small population sizes. Even though recent surveys have estimated population sizes in the order of thousands of individuals, these may fluctuate considerably. Although the translocation of genetically similar individuals between habitats will not increase local genetic diversity, the creation of additional populations across the species’ historical range may be a suitable conservation strategy to prevent further loss of genetic diversity, and to minimise the overall extinction risk posed by environmental stochasticity.

scholarly journals Extinction risk and conservation of critically endangered angel sharks in the Eastern Atlantic and Mediterranean Sea

2019 ◽  
Vol 77 (1) ◽  
pp. 12-29 ◽  
Author(s):  
Julia M Lawson ◽  
Riley A Pollom ◽  
Cat A Gordon ◽  
Joanna Barker ◽  
Eva K M Meyers ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Extinction Risk ◽  
International Management ◽  
Conservation Strategy ◽  
Conservation Action ◽  
Geographic Ranges ◽  
Distribution Maps ◽  
Management Measures ◽  
Global Status ◽  
Population Sizes

Abstract Understanding the details of local and regional extinctions allows for more efficient allocation of conservation activities and resources. This involves identifying where populations persist, where populations may still be present, and where populations may be locally extinct. Three threatened angel sharks occur in the Eastern Atlantic and Mediterranean Sea: Sawback Angelshark (Squatina aculeata), Smoothback Angelshark (Squatina oculata), and Angelshark (Squatina squatina). Population sizes and geographic ranges of these species have been reduced due to overfishing and habitat loss, placing them among the world s most threatened chondrichthyans. We revise distribution maps, review global status, and present a Conservation Strategy to protect and restore these angel shark populations by minimizing fishing mortality, protecting critical habitat, and mitigating human disturbance. Updated distributions reveal that a halving of the geographic extent may have occurred for all three species, with potential declines of 51% for Sawback Angelshark, 48% for Smoothback Angelshark, and 58% for Angelshark. While 20 national and international management measures are now in place for Angelshark, only half of these include the other two species. We encourage further conservation action to adopt and develop this Conservation Strategy to restore angel shark populations to robust levels and safeguard them throughout their range.

Population viability analysis on a native Danish cattle breed

2016 ◽  
Vol 59 ◽  
pp. 105-112 ◽  
Author(s):  
Morten Hertz ◽  
Iben Ravnborg Jensen ◽  
Laura Østergaard Jensen ◽  
Iben Vejrum Nielsen ◽  
Jacob Winde ◽  
...  
Keyword(s):  
Bos Taurus ◽  
Extinction Risk ◽  
Population Viability Analysis ◽  
Cattle Breed ◽  
Population Viability ◽  
Small Population ◽  
Viability Analysis ◽  
Probability Of Survival ◽  
Population Sizes ◽  
Breeding Pool

SummaryMany domestic breeds face challenges concerning genetic variability, because of their small population sizes along with a high risk of inbreeding. Therefore, it is important to obtain knowledge on their extinction risk, along with the possible benefits of certain breeding strategies. Since many domestic breeds face the same problems, results from such studies can be applied across breeds and species. Here a Population Viability Analysis (PVA) was implemented to simulate the future probability of extinction for a population of the endangered Danish Jutland cattle (Bos taurus), based on the software Vortex. A PVA evaluates the extinction risk of a population by including threats and demographic values. According to the results from the PVA the population will go extinct after 122 years with the current management. Four scenarios were created to investigate which changes in the breeding scheme would have the largest effect on the survival probabilities, including Scenario 1: More females in the breeding pool, scenario 2: More males in the breeding pool, scenario 3: Increased carrying capacity, and scenario 4: Supplementing males to the population through artificial insemination using semen from bulls used in the populations in past generations. All scenarios showed a positive effect on the population's probability of survival, and with a combination of the different scenarios, the population size seems to be stabilized.

scholarly journals Evidence for r - and K -selection in a wild bird population: a reciprocal link between ecology and evolution

2016 ◽  
Vol 283 (1829) ◽  
pp. 20152411 ◽  
Author(s):  
Bernt-Erik Sæther ◽  
Marcel E. Visser ◽  
Vidar Grøtan ◽  
Steinar Engen
Keyword(s):  
Density Dependence ◽  
Population Size ◽  
Clutch Size ◽  
Balancing Selection ◽  
Empirical Support ◽  
Small Population ◽  
Environmental Stochasticity ◽  
Fluctuating Environments ◽  
Population Sizes ◽  
Large Clutch

Understanding the variation in selection pressure on key life-history traits is crucial in our rapidly changing world. Density is rarely considered as a selective agent. To study its importance, we partition phenotypic selection in fluctuating environments into components representing the population growth rate at low densities and the strength of density dependence, using a new stochastic modelling framework. We analysed the number of eggs laid per season in a small song-bird, the great tit, and found balancing selection favouring large clutch sizes at small population densities and smaller clutches in years with large populations. A significant interaction between clutch size and population size in the regression for the Malthusian fitness reveals that those females producing large clutch sizes at small population sizes also are those that show the strongest reduction in fitness when population size is increased. This provides empirical support for ongoing r - and K -selection in this population, favouring phenotypes with large growth rates r at small population sizes and phenotypes with high competitive skills when populations are close to the carrying capacity K . This selection causes long-term fluctuations around a stable mean clutch size caused by variation in population size, implying that r - and K -selection is an important mechanism influencing phenotypic evolution in fluctuating environments. This provides a general link between ecological dynamics and evolutionary processes, operating through a joint influence of density dependence and environmental stochasticity on fluctuations in population size.

scholarly journals How well does SARS-CoV-2 spread in hospitals?

2021 ◽  
Author(s):  
George Shirreff ◽  
Jean-Ralph Zahar ◽  
Simon Cauchemez ◽  
Laura Temime ◽  
Lulla Opatowski ◽  
...  
Keyword(s):  
Particle Filtering ◽  
Transmission Rate ◽  
Significant Risk ◽  
Small Population ◽  
Control Measures ◽  
Hospital Outbreak ◽  
Contact Patterns ◽  
Population Sizes ◽  
Asymptomatic Infections ◽  
Using Data

AbstractCovid-19 poses significant risk of nosocomial transmission, and preventing this requires good estimates of the basic reproduction number R0 in hospitals and care facilities, but these are currently lacking. Such estimates are challenging due to small population sizes in these facilities and inconsistent testing practices.We estimate the patient-to-patient R0 and daily transmission rate of SARS-CoV-2 using data from a closely monitored hospital outbreak in Paris 2020 during the first wave. We use a realistic epidemic model which accounts for progressive stages of infection, stochastic effects and a large proportion of asymptomatic infections. Innovatively, we explicitly include changes in testing capacity over time, as well as the evolving sensitivity of PCR testing at different stages of infection. We conduct rigorous statistical inference using iterative particle filtering to fit the model to the observed patient data and validate this methodology using simulation.We provide estimates for R0 across the entire hospital (2.6) and in individual wards (from 3 to 15), possibly reflecting heterogeneity in contact patterns or control measures. An obligatory mask-wearing policy introduced during the outbreak is likely to have changed the R0, and we estimate values before (8.7) and after (1.3) its introduction, corresponding to a policy efficacy of 85%.

scholarly journals Genetic diversity of seeds from four German Douglas fir (Pseudotsuga menziesii) seed orchards

2021 ◽  
Author(s):  
Birte Pakull ◽  
Pascal Eusemann ◽  
Janine Wojacki ◽  
Diana Ahnert ◽  
Heike Liesebach
Keyword(s):  
Genetic Diversity ◽  
Pseudotsuga Menziesii ◽  
Seed Orchard ◽  
Small Population ◽  
Douglas Fir ◽  
Next Generation ◽  
Seed Orchards ◽  
Population Sizes ◽  
Spatial Isolation ◽  
Offspring Generation

AbstractIn Germany, Douglas fir (Pseudotsuga menziesii Franco) is seen as a valuable species for future cultivation in times of climate change. Local seed production in seed stands and seed orchards may secure that local adaptation is transferred to the next generation, but small population sizes could lower genetic diversity and thus future adaptability. Here we analyse the transfer of genetic diversity from parent to offspring generation in four older German seed orchards. We detected low pollen contamination rates due to high levels of spatial isolation. Even with a relatively low number of 40 clones, seed orchard design with randomized and repeated planting of clones led to low selfing rates, and despite uneven parental contributions, the number of successful parents and the level of genetic intermixture were high enough to allow the transfer of an adequate part of the genetic diversity to the next generation. Larger numbers, however, might be needed to reliably conserve the entire genetic diversity over succeeding generations. Conclusions on the establishment of future seed orchards and regarding areas requiring further research are drawn at the end of the paper.

scholarly journals Classification of Genus Acanthopanax in Korea and Genetic Diversity Using Allozymes

2005 ◽  
Vol 54 (1-6) ◽  
pp. 206-210 ◽  
Author(s):  
M. K. Huh ◽  
H. W. Huh
Keyword(s):  
Genetic Diversity ◽  
Representative Sample ◽  
Genetic Relationships ◽  
Woody Species ◽  
Small Population ◽  
Geographic Ranges ◽  
Low Level ◽  
Low Genetic Diversity ◽  
Population Sizes

Abstract Genus Acanthopanax is a long-lived woody species that is primarily distributed throughout Asia. Many species of this genus are regarded as medically and ecologically important. We evaluated a representative sample of the nine taxa with allozymes to estimate genetic relationships within the genus. As some Korean populations were isolated and patchily distributed, they exhibited a low level of genetic diversity. The narrow geographic ranges, artificial distribution of habitats, and small population sizes are proposed as factors contributing to low genetic diversity. Acanthopanax seoulense was similar to A. sessiliflorus, while a cluster of the A. rufinerve population is distant from any other species. A. senticosus is closely related to A. seoulense and A. sessiliflorus, whereas other species (A. koreanum) are more distinct from the Korean populations. Korean species are clustered together and clearly differentiated from the Chinese and Russian Acanthopanax taxa, genus Acanthopanax

Genetics of reintroduced populations of the narrowly endemic thistle, Cirsium pitcheri (Asteraceae)

Botany ◽  
2013 ◽  
Vol 91 (5) ◽  
pp. 301-308 ◽  
Author(s):  
Jeremie B. Fant ◽  
Andrea Kramer ◽  
Eileen Sirkin ◽  
Kayri Havens
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Empirical Studies ◽  
Small Population ◽  
Native Plant ◽  
Effective Population ◽  
Term Survival ◽  
Inbreeding Coefficients ◽  
Native Populations ◽  
Population Sizes

The aim of any reintroduction is to provide sufficient genetic variability to buffer against changing selection pressures and ensure long-term survival. To date, few empirical studies have compared levels of genetic diversity in reintroduced and native plant populations. Using microsatellite markers, we measured the genetic diversity within reintroduced and native populations of the threatened Cirsium pitcher (Eaton) Torrey and Gray. We found that the use of local mixed source was successful in establishing populations with significantly higher genetic diversity (P < 0.005) than the native populations (allelic richness is 3.39 in reintroduced and 1.84 in native populations). However, the reintroduced populations had significantly higher inbreeding coefficients (P < 0.002) (FIS is 0.405 and 0.213 in reintroduced and in native populations, respectively), despite having multiple genetic founders, population sizes equivalent to native populations and a positive growth rate. These results may be due to inbreeding or the Wahlund effect, driven by genetic substructuring. This suggests that the small population size of these reintroduced populations may lead to genetic issues in the future, given the low number of flowering individuals each year. This highlights the importance of considering not only the number of source individuals but the effective population size of the reintroduction.

scholarly journals Range-wide neutral and adaptive genetic structure of an endemic herb from Amazonian Savannas

AoB Plants ◽  
2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Amanda R Silva ◽  
Luciana C Resende-Moreira ◽  
Carolina S Carvalho ◽  
Eder C M Lanes ◽  
Mabel P Ortiz-Vera ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Extinction Risk ◽  
Clustering Methods ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Management Actions ◽  
Temperature And Precipitation ◽  
Population Sizes ◽  
Genetic Clustering

Abstract Conserving genetic diversity in rare and narrowly distributed endemic species is essential to maintain their evolutionary potential and minimize extinction risk under future environmental change. In this study we assess neutral and adaptive genetic structure and genetic diversity in Brasilianthus carajensis (Melastomataceae), an endemic herb from Amazonian Savannas. Using RAD sequencing we identified a total of 9365 SNPs in 150 individuals collected across the species’ entire distribution range. Relying on assumption-free genetic clustering methods and environmental association tests we then compared neutral with adaptive genetic structure. We found three neutral and six adaptive genetic clusters, which could be considered management units (MU) and adaptive units (AU), respectively. Pairwise genetic differentiation (FST) ranged between 0.024 and 0.048, and even though effective population sizes were below 100, no significant inbreeding was found in any inferred cluster. Nearly 10 % of all analysed sequences contained loci associated with temperature and precipitation, from which only 25 sequences contained annotated proteins, with some of them being very relevant for physiological processes in plants. Our findings provide a detailed insight into genetic diversity, neutral and adaptive genetic structure in a rare endemic herb, which can help guide conservation and management actions to avoid the loss of unique genetic variation.

scholarly journals Global distribution and drivers of language extinction risk

2014 ◽  
Vol 281 (1793) ◽  
pp. 20141574 ◽  
Author(s):  
Tatsuya Amano ◽  
Brody Sandel ◽  
Heidi Eager ◽  
Edouard Bulteau ◽  
Jens-Christian Svenning ◽  
...  
Keyword(s):  
Economic Growth ◽  
Extinction Risk ◽  
Small Population ◽  
Global Distribution ◽  
Human Populations ◽  
Small Range ◽  
Geographical Patterns ◽  
Socioeconomic Drivers ◽  
Population Sizes ◽  
The Tropics

Many of the world's languages face serious risk of extinction. Efforts to prevent this cultural loss are severely constrained by a poor understanding of the geographical patterns and drivers of extinction risk. We quantify the global distribution of language extinction risk—represented by small range and speaker population sizes and rapid declines in the number of speakers—and identify the underlying environmental and socioeconomic drivers. We show that both small range and speaker population sizes are associated with rapid declines in speaker numbers, causing 25% of existing languages to be threatened based on criteria used for species. Language range and population sizes are small in tropical and arctic regions, particularly in areas with high rainfall, high topographic heterogeneity and/or rapidly growing human populations. By contrast, recent speaker declines have mainly occurred at high latitudes and are strongly linked to high economic growth. Threatened languages are numerous in the tropics, the Himalayas and northwestern North America. These results indicate that small-population languages remaining in economically developed regions are seriously threatened by continued speaker declines. However, risks of future language losses are especially high in the tropics and in the Himalayas, as these regions harbour many small-population languages and are undergoing rapid economic growth.

scholarly journals Interactions between demography, genetics, and landscape connectivity increase extinction probability for a small population of large carnivores in a major metropolitan area

2016 ◽  
Vol 283 (1837) ◽  
pp. 20160957 ◽  
Author(s):  
John F. Benson ◽  
Peter J. Mahoney ◽  
Jeff A. Sikich ◽  
Laurel E. K. Serieys ◽  
John P. Pollinger ◽  
...  
Keyword(s):  
Los Angeles ◽  
Inbreeding Depression ◽  
Landscape Connectivity ◽  
Extinction Risk ◽  
Empirical Support ◽  
Small Population ◽  
Environmental Stochasticity ◽  
Extinction Probability ◽  
Isolated Populations ◽  
Extinction Vortex

The extinction vortex is a theoretical model describing the process by which extinction risk is elevated in small, isolated populations owing to interactions between environmental, demographic, and genetic factors. However, empirical demonstrations of these interactions have been elusive. We modelled the dynamics of a small mountain lion population isolated by anthropogenic barriers in greater Los Angeles, California, to evaluate the influence of demographic, genetic, and landscape factors on extinction probability. The population exhibited strong survival and reproduction, and the model predicted stable median population growth and a 15% probability of extinction over 50 years in the absence of inbreeding depression. However, our model also predicted the population will lose 40–57% of its heterozygosity in 50 years. When we reduced demographic parameters proportional to reductions documented in another wild population of mountain lions that experienced inbreeding depression, extinction probability rose to 99.7%. Simulating greater landscape connectivity by increasing immigration to greater than or equal to one migrant per generation appears sufficient to largely maintain genetic diversity and reduce extinction probability. We provide empirical support for the central tenet of the extinction vortex as interactions between genetics and demography greatly increased extinction probability relative to the risk from demographic and environmental stochasticity alone. Our modelling approach realistically integrates demographic and genetic data to provide a comprehensive assessment of factors threatening small populations.

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