scholarly journals Population structure and reproductive biology of the smalltail shark (Carcharhinus porosus) off Maranhão (Brazil)

1999 ◽  
Vol 50 (5) ◽  
pp. 383 ◽  
Author(s):  
Rosangela Lessa ◽  
Francisco Santana ◽  
Roberto Menni ◽  
Zafira Almeida
Keyword(s):  
Population Structure ◽  
Coastal Waters ◽  
Age Distribution ◽  
Shallow Waters ◽  
Female Size ◽  
Male And Female ◽  
Pregnant Females ◽  
Nidamental Gland ◽  
Elasmobranch Species ◽  
Northern Brazil

C. porosus is common throughout the year in shallow waters off the Maranhão coast, northern Brazil, where it is the most abundant elasmobranch species. Of 1128 smalltail sharks collected from June 1984 to November 1987 in gill-nets from coastal waters, ~80% were juveniles. Male and female numbers did not differ from a 1:1 ratio. Modal classes were 50.0–60.0 cm (TL) for both sexes. A 120.5 cm female was the largest specimen caught and a 29.4 cm male was the smallest. Age distribution for the whole sample ranged from 0 to >12 years. The length–weight relationship did not differ significantly between the sexes. Diameter of ovarian follicles, presence of eggs/embryos and nidamental gland traits in females point to a major physiological change toward maturity at about 70.0 cm. Vitellogenesis was first observed at 63.0 cm, and the smallest of the six pregnant females was 70.0 cm. There was a significant relationship between the number of embryos and female size. From September to November, ovulation and newborns were observed in catches. Resumo. Carcharhinus porosus é comum ao longo do ano em águas rasas do norte do Brasil onde é a espécie mais abundante entre os elasmobrânquios. De 1128 exemplares coletados em águas costeiras de junho 1984 a novembro 1987 em redes de emalhar ~80% eram jovens. O número de machos e fêmeas não diferiu da razão 1:1. A classe modal foi a de 50.0–60.0 cm para ambos os sexos. Uma fêmea de 120.5 e um macho de 29.4 cm corresponderam ao maior e ao menor exemplar capturado, respectivamente. A distribuição de idades na amostra total variou de 0 a >12 anos. Arelação peso–comprimento não mostrou diferenças significativas entre os sexos. O diâmetro dos ovócitos, presença de embriões/ovos e largura da glândula nidamentária nas fêmeas indica aquisição da maturidade em 70.0 cm. Foi estabelecida uma relação significativa entre o número de embriões e o tamanho das femeas. Entre setembro e novembro ocorre a ovulação e recém nascidos foram observados nas capturas.

scholarly journals Dynamics of population structure of two species of Echinogammarus genus (Gammaridae, Amphipoda) from Laspi Bay (Crimea, Black Sea)

2016 ◽  
Vol 1 (3) ◽  
pp. 22-26 ◽  
Author(s):  
V. A. Grintsov
Keyword(s):  
Population Structure ◽  
Black Sea ◽  
Adult Male ◽  
Coastal Waters ◽  
Abundant Species ◽  
Coastal Ecosystems ◽  
Male And Female ◽  
Estimation And Prediction ◽  
Dynamics Of Population ◽  
Gravel Beach

The investigation of population structure of abundant species of invertebrata in coastal waters is important for estimation and prediction of life of coastal ecosystems. Population structure of two abundant species of Amphipoda (Echinogammarus karadagiensis Grintsov, 2009 and Echinogammarus foxi (Schellenberg, 1928)) from coastal waters of sand-gravel beach was investigated. Specimens were collected from sand-gravel samples. 50 specimens were collected and analyzed in each sample. Some important elements of population structure (length of specimens, proportion of adult male and female, proportion of adult and juvenile specimens, number of eggs in females) were investigated.

scholarly journals Abundance and population structure of Plesionika narval (Fabricius, 1787) in the Northeastern Atlantic

2019 ◽  
Vol 79 (1) ◽  
pp. 111-119 ◽  
Author(s):  
R. Sousa ◽  
M. R. Pinho ◽  
J. Delgado ◽  
A. R. Pinto ◽  
M. Biscoito ◽  
...  
Keyword(s):  
Population Structure ◽  
Sex Ratio ◽  
Carapace Length ◽  
Late Summer ◽  
Shallow Waters ◽  
Female Size ◽  
Depth Range ◽  
Madeira Archipelago ◽  
Seasonal Migrations ◽  
Northeastern Atlantic

Abstract Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic) between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant differences were found between seasons, probably as a result of an increment of population in the spring during the recruitment season. The analysis of size distribution revealed that the carapace length (CL) ranged from 2.45 to 28.61 mm and that mean female size consistently exceeded that of males. Differences in mean CL were statistically significant between depth strata and seasons. Of the specimens sampled, 57.00% were males, 41.88% females and 1.42% undetermined. Sex ratio also differed significantly between seasons according to depth strata, consolidating the hypothesis of the existence of seasonal migrations related with the reproductive cycle of this species. Ovigerous females showed larger sizes and occurred all year around and remain in shallow waters in winter, summer and autumn and move to deeper waters in spring. The highest frequency of ovigerous females was recorded in summer, between 151 and 200 m deep supporting the hypothesis that spawning of this species occurs in shallow waters, especially in late summer.

scholarly journals Hyperostosis frontalis interna in Arctic groups according to craniology

2021 ◽  
pp. 102-120
Author(s):  
Alexandra P. Buzhilova ◽  
◽  
Anna S. Kolyasnikova ◽  
Keyword(s):  
Metabolic Disorders ◽  
Elderly Women ◽  
Age Distribution ◽  
The Other ◽  
The Arctic ◽  
Extreme Conditions ◽  
Hormonal Changes ◽  
Male And Female ◽  
Males And Females ◽  
Age Category

We have examined 942 skulls from the collections of the Anuchin Research Institute and Museum of Anthropology (13 craniological collections of the Arctic groups). We have analyzed the total frequency of HFI, used a comparative intergroup analysis, and evaluated the degree of HFI expression and the distribution of the trait according to sex and age. Univariate nonparametric statistics was applied. Results. It was found that the rate of HFI in the Arctic groups is much lower than in other groups of modern Eurasian and American populations. In the combined series, HFI was equally represented in both males and females. However, according to the age distribution, the male and female groups are different. HFI was more frequent in males in the Adultus and Maturus groups and in the Senilis group in females. Discussion. The significantly lower frequency of HFI in the Arctic series relative to the other modern groups show us a low level of metabolic disorders in the Arctic population and a good adaptation to the type of nutrition and living in extreme conditions. The obtained data show the predominance of the trait in the groups of mature and elderly women, and the appearance of HFI of different severity in men regardless of the age category. Probably, in the Arctic samples in women, HFI identifies metabolic disorders due to normal hormonal changes in women aging. HFI should be considered as an indicator of the presence of metabolic disorders in young and mature age in Arctic men group.

scholarly journals Effects of logging on Virola surinamensis in an Amazonian floodplain forest

2014 ◽  
Vol 15 (3) ◽  
pp. 1-8
Author(s):  
Leandro V. Ferreira ◽  
Denise A. Cunha ◽  
Pia Parolin
Keyword(s):  
Population Structure ◽  
Genetic Resources ◽  
Economic Value ◽  
Timber Species ◽  
Floodplain Forests ◽  
Male And Female ◽  
Conservation Program ◽  
Priority Species ◽  
New Policies ◽  
The Impact

Virola surinamensis is a dioecious timber species of Amazonian floodplain forests. It is threatened by extinction and a priority species in the conservation program of genetic resources with high economic value for Brazil. The present study was aimed to assess the population structure of Virola surinamensis and the impact of logging in the estuary region of Brazilian Amazonia. Our data suggest that altering the dioecious population structure by logging likely creates the imbalance of male and female individuals in the population. New policies are needed to protect Virola trees with a special regard on reproductive matriarch trees.

The age distribution in the Taimyr population wild northern deer (Rangifer Tarandus) in the first decades of 21 centuries

2021 ◽  
pp. 15-21
Author(s):  
A. Shapkin ◽  
R. Ivanova ◽  
N. Arsentseva ◽  
N. Sukhanova
Keyword(s):  
Age Structure ◽  
Rangifer Tarandus ◽  
Age Distribution ◽  
Age Groups ◽  
Base Material ◽  
Middle Level ◽  
Reproduction Rate ◽  
Male And Female ◽  
Field Samples ◽  
Wild Deer

Objective: mathematical demography means to identify and evaluate the age distribution of male and female of Taimyr tundra reindeer in the first decade of the XXI century and future trends in demographic situation Taimyr population.Materials and methods. The base material for evaluating the current state of the population age structure Taimyr steel fishing representative sample of male and female wild deer (n = 10845 individuals) collected in the West, Central and Taimyr Putorana in 2001-2008., And the deer samples (n = 1569 individuals), the floor of which is unknown. Determination of individual animals from age and older (n = 9773 individuals) performed on histological sections of cutters according to the corresponding procedure. To repay the random deviations of sample data because of a lack of presence of immature animals (calves, yearlings, young 1-2 years) (selectivity of fishing is directed primarily at the production of individuals older than 3 years, why animals in different age groups in the samples is greater than there are in the population) applies a smoothing procedure. Then, positive deviation of the number of individuals in the same age group were leveled due to negative deviations in adjacent groups.Results. By smoothed age ranges of the field samples from 2001-2008 the current age distribution of Taimyr wild reindeer calculated and analyzed. The study showed that the theoretical current age distribution of males with realized breeding is 77.03, females - 80.56, in the combined groups of animals - 82.35%. The real population has 18-19 age generations of males and females. The reproductive core of males from 3 to 10 years old is 48.43%, individuals of age limit 11 years and older occupy 1.96% of this sex and age structure, calves and young animals for 1-2 years - 24.64%. For the reproductive part of females aged 3–15 years, the overall age distribution is 55.34%, and the proportion of juveniles and young animals, according to calculations, is determined in this part of the population at 25.16%. In the combined current age distribution, males, females: calves and young animals accounted for 27.72%, the sexually mature part with animals of older and age-specific ages - 54.63%.Conclusion. Demographic Taimir population modeling operation in the first decade of the XXI century long materials commercial samples collected at commercial points shown at current age distribution of the realized and reproduction conditions for existing commercial load males - 77.03 for females - 80.56 and for unified groups (males, females) - 82.4%. Meanwhile, the steady state and stable age distribution Taimyr tundra wild deer can reach a middle-level only when the fecundity of female reproductive generations with clean reproduction rate (R0) equal in population groupings 1.0

On the Estimated Age-Distribution of the Indian Population, as Recorded at the Census of 1911, and the Estimated Rates of Mortality, Deduced from a Comparison of the Census Returns for 1901 and 1911

1913 ◽  
Vol 47 (3) ◽  
pp. 315-414
Author(s):  
Thomas G. Ackland
Keyword(s):  
Indian Population ◽  
Age Distribution ◽  
Indian Government ◽  
Female Population ◽  
Male And Female

The age-distribution, and the rates of mortality, of the male and female population, recorded by the General Census for India, have been investigated by Mr. G. F. Hardy, in connection with the separate Censuses of 1881,1891 and 1901. The methods adopted in his investigations, and the resulting tabular figures. are set out in Mr. Hardy's Reports to the Indian Government on these several Censuses, and these are summarized, as regards the 1881 Census, in a Paper submitted by him to the Institute, and published in Vol. XXV of the Journal, p. 217 et seq.

scholarly journals Genetic improvement and population structure of the Nelore breed in Northern Brazil

2010 ◽  
Vol 45 (10) ◽  
pp. 1109-1116 ◽  
Author(s):  
Carlos Henrique Mendes Malhado ◽  
Paulo Luiz Souza Carneiro ◽  
Ana Claudia Mendes Malhado ◽  
Raimundo Martins Filho ◽  
Riccardo Bozzi ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Variability ◽  
Genetic Improvement ◽  
Selective Breeding ◽  
Growth Traits ◽  
Management Strategies ◽  
Pedigree Information ◽  
Effective Number ◽  
Northern Brazil ◽  
Nelore Cattle

The objective of this work was to evaluate the population structure and the genetic and phenotypic progress of Nelore cattle in Northern Brazil. Pedigree information concerning animals born between 1942 and 2006 were analyzed. Population structure was performed using the Endog program. Out of the 140,628 animals studied, 67.7, 14.52 and 3.18% had complete pedigree record of the first, second and third parental generation, respectively. Inbreeding and average relatedness coefficients were low: 0.2 and 0.13%, respectively. However, these parameters may have been underestimated, since information on pedigree was incomplete. The effective number of founders was 370 and the genetic contribution of 10, 50 and 448 most influent ancestors explained 13.2, 28 and 50% of the genetic variability in the population, respectively. The genetic variability for growth traits and population structure demonstrates high probability of increasing productivity through selective breeding. Moreover, management strategies to reduce the currently observed age at first calving and generation intervals are important for Nelore cattle genetic improvement.

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