Estimates Of Population Size Research Articles

Estimating the Inbreeding Rate in Natural Populations of The Black-Naped Fruit Dove (Ptilinopus melanasphila)

This research aimed to determine the population of the Black-Naped Fruit Dove (Ptilinopus melanasphila) by estimating population size, sex ratio, effective population, and inbreeding rate, providing a basis for ex-situ design considerations. Data collection employed survey techniques such as the line transect and concentration count point methods. Data analysis focused on determining population size, sex ratio, effective population, and inbreeding rate. The research was conducted in the Sula Islands, North Maluku. Observations and discussions were conducted separately for each location to obtain empirical and comprehensive data serving as a reference for further research. Results revealed the inbreeding rates at the research locations were observed as follows: Soamole village (1.42%), Wai Ipa village (1.56%), and Bega village (1.60%). Sex ratios were observed as follows: Soamole village (male : female ratio of 22.17 : 85.38), Wai Ipa village (male : female ratio of 19.48 : 73.78), and Bega village (male : female ratio of 19.61:80.39). Effective populations were observed as follows: Soamole village (22.39 heads), Wai Ipa village (16.48 heads), and Bega village (16.08 heads). The inbreeding rate is in the good category, while the population number, sex ratio and effective population are in the medium category, however habitat destruction and continuous excessive hunting can result in decline and extinction.

Efficacy of Daily Walking as a Potential Predictor of Improved Health-Related Quality of Life in Patients with Type 2 Diabetes in Korea.

This study examines whether health-related quality of life (HRQoL) scores differ due to the frequency of walking or physical activity (PA) throughout a week in diabetic patients in Korea. This population-based cross-sectional study used data from the 2018-2021 Korea National Health and Nutrition Examination Survey. The dependent variable was HRQoL scores as measured with EuroQol-5D (EQ-5D). The independent variables were defined as three types of PA: (1) walking; (2) moderate; and (3) vigorous. An estimated population size of 2,376,066 was included in this study. The mean (95% confidence interval (CI)) age of patients was 60.12 years (59.23, 60.81), and 53.0% were female. The mean (95% CI) of EQ-5D was 0.867 (0.857, 0.877). The majority of diabetic patients reported walking daily (39.05%, 95% CI; 36.28-41.81%), while a significant proportion did not engage in moderate (65.45%, 95% CI; 62.79-68.11%) or vigorous (78.38%, 95% CI; 73.02-77.73%) PA at all. After controlling for covariates, EQ-5D scores significantly increased when patients had walked once per week for at least 10 min in the Tobit regression model. The frequency of walking was the most significant predicting factor for better HRQoL in patients with type 2 diabetes.

A semi-parametric maximum-likelihood analysis of measurement error in population size estimation

Abstract This work addresses the challenge of measurement errors in capture–recapture (CR) studies with covariates. These errors can introduce bias and undermine inference quality. To address this issue, we introduce a nonparametric measurement error model tailored to the ‘repeated counts’ setting, employing EM-type algorithms for parameter estimation. We use the Horvitz–Thompson estimator for population size estimates. Rigorous simulations, covering varying degrees of measurement error reliability, confirm our approach’s effectiveness. Applied to benchmark datasets, it consistently provides more accurate point estimates and robust uncertainty quantification, enhancing the reliability of CR analyses.

Assessing population status and influencing factors of alpine musk deer in patchy habitats: Implications for conservation strategies

Musk deer (Moschus spp.) are widely known for its musk and are globally endangered as a result of poaching, habitat loss, and fragmentation. To facilitate restoration of the alpine musk deer (M. chrysogaster) in existing areas, reliable estimates of population size and influencing factors are essential to assess effectiveness of conservation interventions, particularly for isolated musk deer populations in patches. In this paper, we used line transect and camera trap data collected from 2020 to 2022 in the Helan mountains to assess the population status and characterized the influencing factors of alpine musk deer. Our findings indicate that musk deer are patchily distributed in three areas of high elevation, with the population limited to less than 200 individuals, remaining below historic levels (compared to 1995). There was a significant positive correlation between the role of sympatric species on musk deer, with red fox (Vulpes vulpes), badger (Meles meles) and blue eared-pheasant (Crossoptilon auritum) having a significant effect on the out-modeled pathway. Variable but insignificant effects of anthropogenic activities were observed across all species categories, which could be due to mutual adaptation over time. Our results imply that the recovery of sensitive population in island-like habitats remains challenging and may be exacerbated by limited environment and resources. Our study underscores the necessity of establishing ecological corridors to enhance habitat connectivity for alpine musk deer, undertaking conservation genetics research on isolated populations, controlling stray dogs to maintain interspecific balance, and implementing electronic fencing to mitigate human disturbance and resource competition. This study provides basic information for understanding the population status of alpine musk deer and offers insights for conservation efforts.

Assessing Consistency of Respondent-driven Sampling Estimators by Using Repeated Surveys among People Who Inject Drugs (PWID) in New Jersey.

Respondent-driven sampling (RDS) is widely used to sample populations with higher risk of HIV infection for whom no sampling frames exist. However, few studies have been done to assess the consistency of RDS estimators in real world settings. We conducted an assessment study on the consistency of RDS estimators using data from the National HIV Behavioral Surveillance - People Who Inject Drugs surveys in Newark, New Jersey from 2005 to 2018. Population parameter estimates based on RDS-I, RDS-II, Gile's SS, and HCG were compared longitudinally and cross-sectionally. Population homophily statistics and differential recruitment statistics were estimated and compared. Convergence plots were used for RDS diagnosis. Sensitivity analyses were conducted on population size estimates and seeds biases. By comparing time-insensitive population parameters and population homophily statistics estimated by four RDS estimators, the study found that RDS-II and Gile's SS could provide longitudinally and cross-sectionally consistent estimates and population homophily statistics on gender and sexual orientation. Cross-sectional comparison of time-sensitive population parameter estimates also supported the consistency of RDS-II and Gile's SS. However, RDS-I and HCG did not perform well in those comparisons. In conclusion, RDS estimators may not address all inconsistencies, but RDS-II and Gile's SS are recommended to weight RDS samples given enough consistency was observed in them.

Evidence for transient deleterious thermal acclimation in field recapture rates of an invasive tropical species, Bactrocera dorsalis (Diptera: Tephritidae).

Knowing how environmental conditions affect performance traits in pest insects is important to improve pest management strategies. It can be informative for monitoring, but also for control programs where insects are mass-reared, and field-released. Here, we investigated how adult thermal acclimation in sterile Bactrocera dorsalis affects dispersal and recapture rates in the field using a mark-release-recapture method. We also considered how current abiotic factors may affect recapture rates and interact with thermal history. We found that acclimation at 20 or 30 °C for 4 d prior to release reduced the number of recaptures in comparison with the 25 °C control group, but with no differences between groups in the willingness to disperse upon release. However, the deleterious effects of acclimation were only detectable in the first week following release, whereafter only the recent abiotic conditions explained recapture rates. In addition, we found that recent field conditions contributed more than thermal history to explain patterns of recaptures. The two most important variables affecting the number of recaptures were the maximum temperature and the average relative humidity experienced in the 24 h preceding trapping. Our results add to the handful of studies that have considered the effect of thermal acclimation on insect field performance, but notably lend support to the deleterious acclimation hypothesis among the various hypotheses that have been proposed. Finally, this study shows that there are specific abiotic conditions (cold/hot and dry) in which recaptures will be reduced, which may therefore bias estimates of wild population size.

When enough is enough: Optimising monitoring effort for large-scale wolf population size estimation in the Italian Alps.

The ongoing expansion of wolf (Canis lupus) populations in Europe has led to a growing demand for up-to-date abundance estimates. Non-invasive genetic sampling (NGS) is now widely used to monitor wolves, as it allows individual identification and abundance estimation without physically capturing individuals. However, NGS is resource-intensive, partly due to the elusive behaviour and wide distribution of wolves, as well as the cost of DNA analyses. Optimisation of sampling strategies is therefore a requirement for the long-term sustainability of wolf monitoring programs. Using data from the 2020-2021 Italian Alpine wolf monitoring, we investigate how (i) reducing the number of samples genotyped, (ii) reducing the number of transects, and (iii) reducing the number of repetitions of each search transect impacted spatial capture-recapture population size estimates. Our study revealed that a 25% reduction in the number of transects or, alternatively, a 50% reduction in the maximum number of repetitions yielded abundance estimates comparable to those obtained using the entire dataset. These modifications would result in a 2046 km reduction in total transect length and 19,628 km reduction in total distance searched. Further reducing the number of transects resulted in up to 15% lower and up to 17% less precise abundance estimates. Reducing only the number of genotyped samples led to higher (5%) and less precise (20%) abundance estimates. Randomly subsampling genotyped samples reduced the number of detections per individual, whereas subsampling search transects resulted in a less pronounced decrease in both the total number of detections and individuals detected. Our work shows how it is possible to optimise wolf monitoring by reducing search effort while maintaining the quality of abundance estimates, by adopting a modelling framework that uses a first survey dataset. We further provide general guidelines on how to optimise sampling effort when using spatial capture-recapture in large-scale monitoring programmes.

Assessing the information-content of messy data to reconstruct population recovery dynamics for the world's rarest primate.

Understanding the dynamics of population recovery in threatened species requires robust longitudinal monitoring datasets. However, evidence-based decision-making is often impeded by variable data collection approaches, necessitating critical evaluation of restricted available baselines. The Hainan gibbon, the world's rarest primate, had possibly declined to only seven or eight individuals in 1978 at Bawangling National Nature Reserve but has experienced subsequent population growth. Past population estimates lack detailed reporting of survey effort, and multiple conflicting estimates are available, hindering assessment of gibbon recovery. We investigated all reported estimates of Bawangling gibbon population size from 1978 to 2022, to evaluate the biological signal of population trends and the extent to which noise associated with varying survey effort, reporting and estimation may mask or misrepresent any underlying signal. This longitudinal dataset demonstrates that the Bawangling population experienced a series of bottlenecks and recoveries, with three successive periods of growth interspersed by population crashes (1978-1989, 1989-2000 and 2000-2022). The rate of gibbon population recovery was progressively slower over time in each successive period of growth, and this potential decline in recovery rate following serial bottlenecks suggests that additional management strategies may be required alongside "nature-based solutions" for this species. However, population viability analysis suggests the 1978 founder population is unlikely to have been as low as seven individuals, raising concerns for interpreting reported historical population counts and understanding the dynamics of the species' recovery. We caution against overinterpreting potential signals within "messy" conservation datasets, and we emphasise the crucial importance of standardised replicable survey methods and transparent reporting of data and effort in all future surveys of Hainan gibbons and other highly threatened species.

Trends and status of harbor seals in Washington State, USA (1977–2023)

AbstractHarbor seal (Phoca vitulina) numbers in the United States rebounded after the implementation of conservation measures associated with the Marine Mammal Protection Act of 1972 (MMPA). Stock estimates are a critical tool for assessing species status and management options under the MMPA and for modeling efforts designed to evaluate the role of pinnipeds in marine ecosystems. We conducted aerial surveys of harbor seal haul‐out sites between 1977 and 2023 to estimate population size and trends in four Washington State, USA, stocks: (1) Hood Canal, (2) Southern Puget Sound, (3) Washington Northern Inland Waters, and (4) the Washington portion of the Oregon‐Washington Coastal Stock. We fit a Bayesian state‐space model to estimate population trends for all stocks, as well as the Washington Coast region, and present carrying capacities and maximum net productivity levels for all stocks. The most recent population estimates for the three inland water stocks are within their optimal sustainable population range, with some evidence that the Southern Puget Sound Stock is continuing to grow.

A community case detection tool to promote help-seeking for mental health care among children and adolescents in Ugandan refugee settlements: a stepped wedge cluster randomised trial

Strategies to promote mental health care help-seeking among children are needed, especially in low-income and middle-income countries and in complex settings. The aim of this trial was to compare a vignette-based, community-level, proactive case detection tool (CCDT) against standard awareness raising for promoting mental health help-seeking among children and adolescents. This stepped wedge cluster randomised trial was conducted in the Bidi Bidi, Kyaka II, Kyangwali, Omugo, and Rhino refugee settlements in Uganda. Community gatekeepers received a 2-day training session on using the CCDT to proactively detect children with mental health concerns and encourage children (or their caregivers) to use the mental health-care service run by Transcultural Psychosocial Organization Uganda. At baseline, organisations implemented routine detection or mental health awareness-raising activities. At cross-over to CCDT implementation, gatekeepers used the tool in their daily activities. The primary outcome was mental health-care service use by children and adolescents. Child population size estimates at the zone level were not available. Therefore, service use was calculated using total population size. We report the effect of CCDT implementation as an incidence rate ratio (IRR), which we produced from a model that accounts for calendar time, exposure time, and person-time. IRRs were estimated for the analysis of effect over time in the per-protocol and intention-to-treat populations. The trial is registered with the ISRCTN registry, number ISRCTN19056780. 28 administrative zones were selected for trial participation by October, 2021. Between Jan 1, and Nov 8, 2022, seven clusters of four zones sequentially crossed over from routine care to CCDT implementation in 1-month intervals. The CCDT was implemented by 177 trained community gatekeepers. In 9 months, 2385 children visited a mental health-care service; of these, 1118 (47%) were girls and 1267 (53%) were boys (mean age 12·18 years [SD 4.03]). 1998 children made a first or re-entry visit to a service; of these, 937 (47%) were girls and 1061 (53%) were boys (mean age 12·08 years [SD 4·06]). Compared to standard awareness-raising activities, CCDT implementation was associated with an increase in mental health-care service use in the first month after implementation (20·91-fold change [95% CI 12·87-33·99]). Despite a slight decline in service use over time in both the CCDT and pre-CCDT zones, CCDT zones maintained a time-average 16·89-fold increase (95% CI 8·15-34·99) in mental health service use. The CCDT enabled community gatekeepers to increase mental health-care service use by children and adolescents. Vignette-based strategies rooted in the community could become a valuable contribution towards reducing the mental health-care gap among children, especially when accompanied by accessible mental health-care services. Sint Antonius Stichting Projects. For the Arabic, French and Spanish translations of the abstract see Supplementary Materials section.

Environmental DNA concentrations vary greatly across productive and degradative conditions, with implications for the precision of population estimates

Population size is an important metric to inform the conservation and management of species. For aquatic species, environmental DNA (eDNA) concentration has been suggested for non-invasively estimating population size. However, many biotic and abiotic factors simultaneously influence the production and degradation of eDNA which can alter the relationship between population size and eDNA concentration. We investigated the influence of temperature, salinity, and ranavirus infection on eDNA concentrations using tadpole mesocosms. Using linear regression models, we tested the influence of each experimental treatment on eDNA concentrations at three time points before and during epidemics. Prior to infection, elevated temperatures lowered eDNA concentrations, indicating that degradation was the driving force influencing eDNA concentrations. During early epidemics, no treatments strongly influenced eDNA concentrations and in late epidemics, productive forces dominated as ranavirus intensity and dead organisms increased eDNA concentrations. Finally, population size was only an important predictor of eDNA concentration in late epidemics and we observed high levels of variation between samples of replicate mesocosms. We demonstrate the complexities of several interacting factors influencing productive and degradative forces, variation in influences on eDNA concentration over short time spans, and examine the limitations of estimating population sizes from eDNA with precision in semi-natural conditions.

Demography and natural history of the damselfly Mesamphiagrion gaudiimontanum (Coenagrionidae), a Páramo endemic species in the Colombian Andes

The páramos are high mountain ecosystems in the tropical regions of the New World, and they are particularly threatened by climate change. The Belmira páramo complex in Colombia is home to Mesamphiagrion gaudiimontanum, an endemic and endangered damselfly species. This study presents the first demographic assessment of M. gaudii­montanum using the capture-recapture method to estimate population size, survival, and detection probabilities, focusing on differences in age, sex, female color morphs, and parasite infestation. The population size was estimated to be 730 ± 186.59 individuals, with an average survival probability of 0.89 ± 0.04 and a life expectancy of 8.34 days, these data are like the reported for other populations in the same genus in harsh environmental conditions. Ectoparasitic mites were more common on juveniles than adults. After several hours of observing the species few copula events have been recorded, all of them involving juvenile adult females, which points to a monandrous reproduction syndrome for the species. Another phenomenon observed in the species was a change in coloration due to body temperature in individuals, in which bright coloration becomes grayish in cold weather. This study provides fundamental data for future monitoring and conservation efforts, highlighting the species’ vulnerability to environmental changes and the need for specific conservation strategies.

Population genomics and demographic modeling enhance our understanding of trophic level interactions in biological control

In this paper, we focus on the application of population genomics, including next-generation sequencing and demographic modeling, to enhance the understanding of historical and contemporary trophic level interactions that are a fundamental basis of biological control. We outline how the integration of ecological approaches with population genomics and demographic modeling can provide additional insights into existing trophic interactions and how natural enemies, their parasitoids, and pest species evolve through these interactions, potentially affecting future levels of biological control. We briefly review and summarize our recent population genomic studies of predatory ladybird beetles and discuss how our results provide guidelines for the use of population genomics techniques and population demographic modeling to enhance our understanding of trophic level interactions. Our intent is to demonstrate as a proof of concept, how these methods can supplement currently used techniques and add a complementary genomic aspect to ecological understandings of trophic level interactions, including estimates of effective population sizes of natural enemies and pest species, examination of correlations between these effective population sizes, and evolutionary changes in natural enemies and pest species which may influence levels of biological control. This in combination with experiments and simulations provide a well-rounded framework for using population genomics to inform multi-tier trophic level interactions.

ONeSAMP 3.0: estimation of effective population size via single nucleotide polymorphism data from one population.

The genetic effective size (Ne) is arguably one of the most important characteristics of a population as it impacts the rate of loss of genetic diversity. Methods that estimate Ne are important in population and conservation genetic studies as they quantify the risk of a population being inbred or lacking genetic diversity. Yet there are very few methods that can estimate the Ne from data from a single population and without extensive information about the genetics of the population, such as a linkage map, or a reference genome of the species of interest. We present ONeSAMP 3.0, an algorithm for estimating Ne from single nucleotide polymorphism data collected from a single population sample using approximate Bayesian computation and local linear regression. We demonstrate the utility of this approach using simulated Wright-Fisher populations, and empirical data from five endangered Channel Island fox (Urocyon littoralis) populations to evaluate the performance of ONeSAMP 3.0 compared to a commonly used Ne estimator. Our results show that ONeSAMP 3.0 is broadly applicable to natural populations and is flexible enough that future versions could easily include summary statistics appropriate for a suite of biological and sampling conditions. ONeSAMP 3.0 is publicly available under the GNU General Public License at https://github.com/AaronHong1024/ONeSAMP_3.

Detecting diversifying selection for a trait from within and between-species genotypes and phenotypes.

To quantify selection acting on a trait, methods have been developed using either within or between-species variation. However, methods using within-species variation do not integrate the changes at the macroevolutionary scale. Conversely, current methods using between-species variation usually discard within-species variation, thus not accounting for processes at the micro-evolutionary scale. The main goal of this study is to define a neutrality index for a quantitative trait, by combining withinand between-species variation. This neutrality index integrates nucleotide polymorphism and divergence for normalizing trait variation. As such, it does not require estimation of population size nor of time of speciation for normalization. Our index can be used to seek deviation from the null model of neutral evolution, and test for diversifying selection. Applied to brain mass and body mass at the mammalian scale, we show that brain mass is under diversifying selection. Finally, we show that our test is not sensitive to the assumption that population sizes, mutation rates and generation time are constant across the phylogeny, and automatically adjust for it.

Cross-sectional analysis for lymphedema epidemiology in South Korea by HIRA data: An observational study.

Lymphedema is known to affect as many as 140 to 250 million people worldwide. Approximately 99% of lymphedemas are secondary cases after lymphadenectomy, radiation, or parasite infection. There has been no accurate estimate of the lymphedema population size in South Korea. This study aimed to quantify the epidemiology of lymphedema in South Korea and analyze the clinical characteristics of patients with lymphedema using a nationwide database. This large-scale cross-sectional study included patients who received one of the following three diagnostic codes - Q82.0 (hereditary lymphedema), I97.2 (breast cancer-related lymphedema), and I89.0 (unclassified lymphedema) from the Korean Health Insurance Review and Assessment service between January 2019 and July 2022 at tertiary hospitals, general hospitals, or other hospitals. The demographics of the lymphedema population, medication use, and medical characteristics were identified. Over the last 4 years, the annual incidence of lymphedema has steadily increased and peaked in 2021 with the number 1.85 out of 1000. Of all patients, 81% were located in the upper extremity, and 10.6% had previous cancer. Most patients were diagnosed in general hospitals (53.2%), at orthopedic surgery department (41.9%). On average, lymphedema patients spent 70.17 US dollar for medication and hospitalized for 16.9 days annually after diagnosis. Commonly prescribed medications were Entelon® (Vitis vinifera seed extract) (66.9%), steroids (40.5%), non-steroidal anti-inflammatory drugs (26.5%) and diuretics (21.8%). Only 5.7% of patients received surgery and 19.2% received herbal medicine. This is the first study in South Korea to quantify demographic and medical characteristics of lymphedema patients. These results will contribute to a comprehensive understanding of lymphedema diagnosis and treatment in our nation.

Survival and population size of the Indo‐Pacific humpback dolphins off the eastern Leizhou Peninsula

AbstractIndo‐Pacific humpback dolphins form a resident population off the east coast of Leizhou Peninsula (LZP) in South China. The most recent study suggested ~1,500 individuals in this area, making this population one of only two populations of this species exceeding 1,000 individuals. However, demographic information regarding this population has been lacking since 2012. Using a 5‐year (2019–2023) photo‐identification data set, we examined two key demographic parameters of the LZP population, namely the apparent survival and population size, using multistate capture‐recapture analyses. Annual survival probabilities (φ) changed over time, fluctuating between 0.942 and 0.961 for adults, and between 0.787 and 0.837 for juveniles. Jolly‐Seber multistate model analyses resulted in highly comparable noncalf population size estimates from 2020 to 2023 (2020 = 479, SE = 28; 2021 = 458, SE = 29; 2022 = 481, SE = 27; 2023 = 446, SE = 31). By reviewing the available demographic information, we conclude that the population size of LZP humpback dolphins has been previously overestimated. The time‐dependent survivals seemingly reflect a dynamic development of anthropogenic disturbance during the pandemic period. We propose that the population status should be re‐evaluated, especially in the postpandemic era when the human activities came back to “normal” levels.

Nesting ecology of chimpanzee (Pan troglodytes) in the Yoko Council Forest, Centre Cameroon: assessing nest characteristics and decay rate

ABSTRACT Lack of data on the population size of chimpanzees (Pan troglodytes) in the Yoko Council Forest (YCF), located in the Centre region of Cameroon has hindered the ability to develop conservation measures. The sustainable management of this species requires reliable knowledge of their ecology, habits and resource needs. This study was conducted from February–July 2022 to assess nesting ecology and to use nest decay rates to estimate population size. The retrospective method for studying the degradation of animal indices was used. The mean nest decay rate was 77.5 days and density was estimated at 69.3 [54.9 86.7] nests/ km2 to 113 chimpanzees per km2. We also found a high preference for nests in specific forest types, with 92% of nests in marantaceous forests, and a preference for nests to be on Khaya grandifolia (Meliaceae) (28.24%) or Uapaca guinensis (Euphorbiaceae) (27.06%) trees. The preferential position for construction of chimpanzee nests was on a branch (58.82%) as opposed to in a branch fork (40.39%), which is interesting since one would assume a fork would offer more nest stability. Our study offers crucial insights that can guide policymakers in formulating targeted conservation strategies for the substantial chimpanzee population in the YCF.

Hierarchical Bayesian Integrated Modeling of Age- and Sex-Structured Wildlife Population Dynamics

AbstractBiodiversity of large wild mammals is declining at alarming rates worldwide. It is therefore imperative to develop effective population conservation and recovery strategies. Population dynamics models can provide insights into processes driving declines of particular populations of a species and their relative importance. But there are insufficient tools, namely population dynamics models for wild herbivores, for characterizing their decline and for guiding conservation and management actions. Therefore, we have developed a model which can serve as a tool to fill that void. Specifically, we develop an integrated Bayesian state-space population dynamics model for wildlife populations and illustrate it using a topi population inhabiting the Greater Mara-Serengeti Ecosystem in Kenya and Tanzania. The model integrates ground demographic survey with aerial survey monitoring data. It incorporates population age and sex structure and life history traits and strategies and relates birth rates, age-specific survival rates and sex ratios with meteorological covariates, prior population density, environmental seasonality and predation risk. It runs on a monthly time step, enabling accurate characterization of reproductive seasonality, phenology, synchrony and prolificacy of births, juvenile and adult recruitments. Model performance is evaluated using balanced bootstrap sampling and by comparing model predictions with empirical aerial population size estimates. The hierarchical Bayesian model is implemented using MCMC methods for parameter estimation, prediction and inference and reproduces several well-known features of the Mara topi population, including striking and persistent population decline, seasonality of births, juvenile and adult recruitments. It is general and can be readily adapted for other wildlife species and extended to incorporate several additional useful features. Supplementary materials accompanying this paper appear on-line.

Environmental effects on faecal genotyping success in mesocarnivores

AbstractNon-invasive genetic sampling can be used in research, monitoring, and conservation of wild animals to, for example, provide insights into diets, identify individuals and estimate population sizes. Non-invasive genetic sampling may be especially useful to monitor elusive species because DNA can be derived from materials such as hairs and faeces without handling individuals. However, the reliability of the results derived from this technique is dependent on the quality of DNA obtained from samples, which can deteriorate from exposure to environmental conditions and sample age. While freshness of the sample is an important factor, the combined effect of different field conditions on the genotyping success is not fully understood. To address this gap, we systematically investigated the effects of sample age and environmental conditions on genotyping success of faeces, in an experimental setting of four treatments that combined rain and temperature conditions typical of central European climates. We compared the performance of a microsatellite marker set and a SNP panel for red fox (Vulpes vulpes), as well as a microsatellite marker set for pine marten (Martes martes) from faeces resampled over 21 days. We found that genotyping success decreased significantly with sample age, however environmental treatments did not impact the success. Furthermore, the SNPs we used amplified more successfully over time than the respective microsatellites. Therefore, the use of SNPs instead of conventional microsatellites, when using faecal samples for analysis relying on correct amplifications, could be advantageous. We recommend to prioritise the collection of fresh faeces regardless of environmental conditions.