Evidence of a genetic bottleneck in an El Nino affected population of South American fur seals, Arctocephalus australis

The South American fur seal, Arctocephalus australis, was one of the earliest otariid seals to be exploited by humans: at least 6000 years ago on the Atlantic coast and 4000 on the Pacific coast of South America. More than 750,000 fur seals were killed in Uruguay until 1991. However, a climatological phenomenon-the severe 1997-1998 El Nino Southern Oscillation (ENSO)-was responsible for the decline of 72% Of the Peruvian fur seal population due to starvation as a consequence of warming of sea-surface temperatures and primary productivity reduction. Currently, there is no precise information on global population size or on the species` conservation status. The present study includes the first bottleneck test for the Pacific and Atlantic populations of A. australis based on the analysis of seven microsatellite loci. Genetic bottleneck compromises the evolutionary potential of a population to respond to environmental changes. The perspective becomes even more alarming due to current global warming models that predict stronger and more frequent ENSO events in the future. Our analysis found moderate support for deviation from neutrality-equilibrium for the Pacific population of fur seals and none for the Atlantic population. This difference among population reflects different demographic histories, and is consistent with a greater reduction in population size in the Pacific. Such an event could be a result of the synergic effects of recurrent ENSO events and the anthropogenic impact (sealing and prey overfishing) on this population.

Methods and background characteristics of the TOHNN study : a population-based study of oral health conditions in northern Norway

OBJECTIVES: The aim of the Tromstannen - Oral Health in Northern Norway (TOHNN) study was to investigate oral health and dental-related diseases in an adult population. This article provides an overview of the background of the study and a description of the sample characteristics and methods employed in data collection. STUDY DESIGN: Cross-sectional population-based study including a questionnaire and clinical dental examination. METHODS: A randomly selected sample of 2,909 individuals (20-79 years old) drawn from the population register was invited to participate in the study. The data were collected between October 2013 and November 2014 in Troms County in northern Norway. The questionnaire focused on oral health-related behaviours and attitudes, oral health-related quality of life, sense of coherence, dental anxiety and symptoms from the temporomandibular joint. The dental examinations, including radiographs, were conducted by 11 dental teams in 5 dental offices. The examination comprised of registration of dental caries, full mouth periodontal status, temporomandibular disorders, mucosal lesions and height and weight. The participants were grouped by age (20-34, 35-49, 50-64 and 65-79) and ethnicity (Norwegian, Sámi, other European and other world). RESULTS: From the original sample of 2,909 individuals, 1,986 (68.3%) people participated, of whom 1,019 (51.3%) were women. The highest attendance rate was among women 20-34 years old (80.3%) and the lowest in the oldest age group of women (55.4%). There was no difference in response rate between rural and urban areas. There was a positive correlation between population size and household gross income (p < 0.001) and education level (p < 0.001). The majority of Sámi resided in smaller municipalities. In larger cities, most participants used private dental health care services, whereas, in rural areas, most participants used the public dental health care service. CONCLUSION: The TOHNN study has the potential to generate new knowledge on a wide range of oral health conditions beneficial to the population in Troms County. Due to the high participation rate, generalization both nationally and to the circumpolar area ought to be possible.

Effect of density on population development in the Amazon River prawn Macrobrachium amazonicum

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison of selective genotyping strategies for prediction of breeding values in a population undergoing selection

Genomewide marker information can improve the reliability of breeding value predictions for young selection candidates in genomic selection. However, the cost of genotyping limits its use to elite animals, and how such selective genotyping affects predictive ability of genomic selection models is an open question. We performed a simulation study to evaluate the quality of breeding value predictions for selection candidates based on different selective genotyping strategies in a population undergoing selection. The genome consisted of 10 chromosomes of 100 cM each. After 5,000 generations of random mating with a population size of 100 (50 males and 50 females), generation G(0) (reference population) was produced via a full factorial mating between the 50 males and 50 females from generation 5,000. Different levels of selection intensities (animals with the largest yield deviation value) in G(0) or random sampling (no selection) were used to produce offspring of G(0) generation (G(1)). Five genotyping strategies were used to choose 500 animals in G(0) to be genotyped: 1) Random: randomly selected animals, 2) Top: animals with largest yield deviation values, 3) Bottom: animals with lowest yield deviations values, 4) Extreme: animals with the 250 largest and the 250 lowest yield deviations values, and 5) Less Related: less genetically related animals. The number of individuals in G(0) and G(1) was fixed at 2,500 each, and different levels of heritability were considered (0.10, 0.25, and 0.50). Additionally, all 5 selective genotyping strategies (Random, Top, Bottom, Extreme, and Less Related) were applied to an indicator trait in generation G(0), and the results were evaluated for the target trait in generation G(1), with the genetic correlation between the 2 traits set to 0.50. The 5 genotyping strategies applied to individuals in G(0) (reference population) were compared in terms of their ability to predict the genetic values of the animals in G(1) (selection candidates). Lower correlations between genomic-based estimates of breeding values (GEBV) and true breeding values (TBV) were obtained when using the Bottom strategy. For Random, Extreme, and Less Related strategies, the correlation between GEBV and TBV became slightly larger as selection intensity decreased and was largest when no selection occurred. These 3 strategies were better than the Top approach. In addition, the Extreme, Random, and Less Related strategies had smaller predictive mean squared errors (PMSE) followed by the Top and Bottom methods. Overall, the Extreme genotyping strategy led to the best predictive ability of breeding values, indicating that animals with extreme yield deviations values in a reference population are the most informative when training genomic selection models.

Geographic Distribution and Population Estimate of Leaf-cutting Ants of the Genus Acromyrmex (Hymenoptera: Formicidae) in Southwestern Bahia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimation of population profiles of two strains of the fly Megaselia scalaris (Diptera: Phoridae) by bootstrap simulation

A partir de perfis populacionais experimentais de linhagens do díptero forídeo Megaselia scalaris, foi determinado o número mínimo de perfis amostrais que devem ser repetidos, via processo de simulação bootstrap, para se ter uma estimativa confiável do perfil médio populacional e apresentar estimativas do erro-padrão como medida da precisão das simulações realizadas. Os dados originais são provenientes de populações experimentais fundadas com as linhagens SR e R4, com três réplicas cada, e que foram mantidas por 33 semanas pela técnica da transferência seriada em câmara de temperatura constante (25 ± 1,0ºC). A variável usada foi tamanho populacional e o modelo adotado para cada perfíl foi o de um processo estocástico estacionário. Por meio das simulações, os perfis de três populações experimentais foram amplificados, determinando-se, dessa forma, o tamanho mínimo de amostra. Fixado o tamanho de amostra, simulações bootstrap foram realizadas para construção de intervalos de confiança e comparação dos perfis médios populacionais das duas linhagens. Os resultados mostram que com o tamanho de amostra igual a 50 inicia-se o processo de estabilização dos valores médios.

Genetic variation along time in a brazilian population of Aedes aegypti (Diptera : Culicidae), detected by changes in the esterase patterns

Aedes aegypti from the Brazilian cities of Sao Jose do Rio Preto (SJ) and Goiania (GO) were analyzed as to their esterase patterns and the results were compared with data obtained about 5 years before for SJ population. Esterase bands not detected in the previous study were now observed in mosquitoes from both SJ and GO populations, being the last considered a population resistant to insecticides. Other similarities between SJ and GO populations in this study, and some differences in comparison with the previous data on SJ were observed, involving, in addition to changes in band type, changes in frequency of mosquitoes expressing them and differential gene activation during development. As it is generally true for genetic features, changes in the esterase patterns are expected to be the result of factors such as selection by environmental conditions and genetic drift. In the present case, continuous use of insecticides aiming mosquito population size control in SJ by sanitary authorities could be involved in the observed changes. Changed esterases were classified as carboxylesterases and cholinesterases, which are enzymes already shown to take part in the development of resistance in several organisms. In addition, data obtained in the elapsed time by authorities responsible for the mosquito control has shown increasing insecticide resistance of SJ population mosquitoes parallel to increase in the total amount of esterases, reinforcing the mentioned possibility.

Solving the Levins' paradox in the logistic model to the population growth

We introduce a new method to improve Markov maps by means of a Bayesian approach. The method starts from an initial map model, wherefrom a likelihood function is defined which is regulated by a temperature-like parameter. Then, the new constraints are added by the use of Bayes rule in the prior distribution. We applied the method to the logistic map of population growth of a single species. We show that the population size is limited for all ranges of parameters, allowing thus to overcome difficulties in interpretation of the concept of carrying capacity known as the Levins paradox. © Published under licence by IOP Publishing Ltd.

Distribution of Brazilian dermatologists according to geographic location, population and HDI of municipalities: an ecological study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise temporal da dinâmica populacional de Aedes aegypti

Dengue virus is a major public health problem worldwide. Aedes (Stegomyia) aegypti is the main dengue vector. Since there is no specific treatment or effective vaccine, control measure is focused on vector control. It is believed that population density is higher in the warmer/rainy season than in cold/dry. The study aimed to genetically characterize population dynamics of Ae. aegypti during climatic variations. Collections were performed at least once in both periods over five years by oviposition traps at Botucatu city. The technique of TaqMan allelic discrimination was used for genetic analysis, in which SNPs from nine genes distributed on three chromosomes of the mosquito were genotyped. Bayesian analysis did not show variance on population structure over the five year period. The percentage of variation among samples in statistical analysis was low (Fst = 0.0028, p = 0.7634), furthermore the allele frequencies were constant. The results show that despite wide variation in the density of adults, population size does not vary. Therefore, there is variation in the prevalence of the species life stages: adults in warmer/rainy, and possibly eggs in cold/dry, resulting in different control strategies for each period. Moreover, estimation of population size should not consider only winged adults, but all other found life stages forms

The Economics of Threatened Species Conservation: A Review and Analysis

Stabilizing human population size and reducing human-caused impacts on the environment are keys to conserving threatened species (TS). Earth's human population is ~ 7 billion and increasing by ~ 76 million per year. This equates to a human birth-death ratio of 2.35 annually. The 2007 Red List prepared by the International Union for Conservation of Nature and Natural Resources (IUCN) categorized 16,306 species of vertebrates, invertebrates, plants, and other organisms (e.g., lichens, algae) as TS. This is ~ 1 percent of the 1,589,161 species described by IUCN or ~ 0.0033 percent of the believed 5,000,000 total species. Of the IUCN’s described species, vertebrates comprised relatively the most TS listings within respective taxonomic categories (5,742 of 59,811), while invertebrates (2,108 of 1,203,175), plants (8,447 of 297,326), and other species (9 of 28,849) accounted for minor class percentages. Conservation economics comprises microeconomic and macroeconomic principles involving interactions among ecological, environmental, and natural resource economics. A sustainable-growth (steady-state) economy has been posited as instrumental to preserving biological diversity and slowing extinctions in the wild, but few nations endorse this approach. Expanding growth principles characterize most nations' economic policies. To date, statutory fine, captive breeding cost, contingent valuation analysis, hedonic pricing, and travel cost methods are used to value TS in economic research and models. Improved valuation methods of TS are needed for benefit-cost analysis (BCA) of conservation plans. This Chapter provides a review and analysis of: (1) the IUCN status of species, (2) economic principles inherent to sustainable versus growth economies, and (3) methodological issues which hinder effective BCAs of TS conservation.

Model complexity affects transient population dynamics following a dispersal event: A case study with pea aphids

Stage-structured population models predict transient population dynamics if the population deviates from the stable stage distribution. Ecologists’ interest in transient dynamics is growing because populations regularly deviate from the stable stage distribution, which can lead to transient dynamics that differ significantly from the stable stage dynamics. Because the structure of a population matrix (i.e., the number of life-history stages) can influence the predicted scale of the deviation, we explored the effect of matrix size on predicted transient dynamics and the resulting amplification of population size. First, we experimentally measured the transition rates between the different life-history stages and the adult fecundity and survival of the aphid, Acythosiphon pisum. Second, we used these data to parameterize models with different numbers of stages. Third, we compared model predictions with empirically measured transient population growth following the introduction of a single adult aphid. We find that the models with the largest number of life-history stages predicted the largest transient population growth rates, but in all models there was a considerable discrepancy between predicted and empirically measured transient peaks and a dramatic underestimation of final population sizes. For instance, the mean population size after 20 days was 2394 aphids compared to the highest predicted population size of 531 aphids; the predicted asymptotic growth rate (λmax) was consistent with the experiments. Possible explanations for this discrepancy are discussed. Includes 4 supplemental files.

First assessment on genetic structure and phylogeography of Mediterranean blue shark (prionace glauca, L. 1758) population using mitochondrial gene variation: a comparison with the Atlantic.

The blue shark, Prionace glauca, is one of the most vagile shark species worldwide distributed. The particular body shape allows blue sharks make transoceanic movements, leading to a circumglobal distribution. Due to its reproductive cycle, an extraordinarily high number of specimens is globally registered but, even if it is still a major bycatch of longline fishery rather than a commercial target, it is characterized by a high vulnerability. In this perspective it is important to increase the amount of informations regarding its population extent in the different worldwide areas, evaluating the possible phylogeographic patterns between different locations. This study, included in the "MedBlueSGen" European project, aims exactly at filling a gap in knowledges regarding the genetic population structure of the Mediterranean blue sharks, which has never been investigated before, with a comparison with the North-Eastern Atlantic blue shark population. To reach this objective, we used a dataset of samples from different Mediterranean areas implementing it with some samples from North-Eastern Atlantic. Analyzing the variability of the two mitochondrial markers control region and cytochrome b, with the design of new species-specific primer pairs, we assessed the mitochondrial genetic structure of Mediterranean and North-Eastern Atlantic samples, focusing on the analysis of their possible connectivity, and we tried to reconstruct their demographic history and population size. Data analyses highlighted the absence of a genetic structuring within the Mediterranean and among it and North-Eastern Atlantic, suggesting that the Strait of Gibraltar doesn't represent a phylogeographic barrier. These results are coherent to what has been found in similar investigations on other worldwide blue shark populations. Analysis of the historical demographic trend revealed a general stable pattern for the cytochrome-b and a slightly population expansion for the control region marker.

Learning Spike-Based Population Codes by Reward and Population Feedback

We investigate a recently proposed model for decision learning in a population of spiking neurons where synaptic plasticity is modulated by a population signal in addition to reward feedback. For the basic model, binary population decision making based on spike/no-spike coding, a detailed computational analysis is given about how learning performance depends on population size and task complexity. Next, we extend the basic model to n-ary decision making and show that it can also be used in conjunction with other population codes such as rate or even latency coding.

Habitat-specific demography and source-sink dynamics in a population of Siberian jays

P>1. There are a number of models describing population structure, many of which have the capacity to incorporate spatial habitat effects. One such model is the source-sink model, that describes a system where some habitats have a natality that is higher than mortality (source) and others have a mortality that exceeds natality (sink). A source can be maintained in the absence of migration, whereas a sink will go extinct. 2. However, the interaction between population dynamics and habitat quality is complex, and concerns have been raised about the validity of published empirical studies addressing source-sink dynamics. In particular, some of these studies fail to provide data on survival, a significant component in disentangling a sink from a low quality source. Moreover, failing to account for a density-dependent increase in mortality, or decrease in fecundity, can result in a territory being falsely assigned as a sink, when in fact, this density-dependent suppression only decreases the population size to a lower level, hence indicating a 'pseudo-sink'. 3. In this study, we investigate a long-term data set for key components of territory-specific demography (mortality and reproduction) and their relationship to habitat characteristics in the territorial, group-living Siberian jay (Perisoreus infaustus). We also assess territory-specific population growth rates (r), to test whether spatial population dynamics are consistent with the ideas of source-sink dynamics. 4. Although average mortality did not differ between sexes, habitat-specific mortality did. Female mortality was higher in older forests, a pattern not observed in males. Male mortality only increased with an increasing amount of open areas. Moreover, reproductive success was higher further away from human settlement, indicating a strong effect of human-associated nest predators. 5. Averaged over all years, 76% of the territories were sources. These territories generally consisted of less open areas, and were located further away from human settlement. 6. The source-sink model provides a tool for modelling demography in distinct habitat patches of different quality, which can aid in identifying key habitats within the landscape, and thus, reduce the risk of implementing unsound management decisions.