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| Registros recuperados: 84 | |
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| Vandeputte, Marc; Dupont Nivet, M; Chavanne, H; Chatain, Beatrice. |
| Polygenic sex determination, although suspected in several species, is thought to be evolutionarily unstable and has been proven in very few cases. In the European sea bass, temperature is known to influence the sex ratio. We set up a factorial mating, producing 5.893 individuals from 253 full-sib families, all reared in a single batch to avoid any between-families environmental effects. The proportion of females in the offspring was 18.3%, with a large variation between families. Interpreting sex as a threshold trait, the heritability estimate was 0.62 +/- 0.12. The observed distribution of family sex ratios was in accordance with a polygenic model or with a four-sex-factors system with environmental variance and could not be explained by any genetic... |
| Tipo: Text |
Palavras-chave: Dicentrarchus labrax; Fish; Growth; Heritability; Sex ratio. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3526.pdf |
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| Peres,Pedro Henrique F.; Polverini,Maxihilian S.; Oliveira,Márcio L.; Duarte,José Maurício B.. |
| ABSTRACT Demographic information is the basis for evaluating and planning conservation strategies for an endangered species. However, in numerous situations there are methodological or financial limitations to obtain such information for some species. The marsh deer, an endangered Neotropical cervid, is a challenging species to obtain biological information. To help achieve such aims, the study evaluated the applicability of camera traps to obtain demographic information on the marsh deer compared to the traditional aerial census method. Fourteen camera traps were installed for three months on the Capão da Cruz floodplain, in state of São Paulo, and ten helicopter flyovers were made along a 13-kilometer trajectory to detect resident marsh deer. In addition... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aerial survey; Capture-recapture; Distance sampling; Population estimate; Sex ratio. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212017000100241 |
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| SARNO,RONALD J.; FRANKLIN,WILLIAM L.; PREXL,WALTER S.. |
| Data were collected on general activity patterns and population characteristics of free-ranging Andean Condors Vultur gryphus in Torres del Paine National Park, Chile from July 1992 to June 1994 during 3,680 h of observation. Seasonal differences were evident in relative abundance and activity patterns. The mean number of condors sighted/ observation significantly higher in fall-winter than in spring-summer. There was a significant decrease from spring-summer to fall-winter in the percentage of observations during which we sighted solitary condors and a significant increase in the number of groups of condors. In addition, mean monthly maximum group size was significantly larger in fall-winter than spring-summer. The sex ratio (males:females ) of juveniles... |
| Tipo: Journal article |
Palavras-chave: Andean Condor; Activity; Patagonia; Sex ratio. |
| Ano: 2000 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2000000100001 |
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| Vandeputte, Marc; Quillet, Edwige; Chatain, Beatrice. |
| Sex ratios in farmed European sea bass are highly biased towards males (75 to 95%), which is problematic for aquaculture. In this mini-review, we re-analyse fisheries literature data about sex ratios in wild sea bass from 13 population samples, representing altogether 4889 individuals covering the major part of the distribution range of the species. We find that as a whole, the sex ratio of wild populations is biased towards females (59.4% females, p < 0.001), but that the sex ratio of the younger fish (< 30 cm total length) is balanced (52.0% females, p = 0.15), while the sex ratio of the older fish is heavily biased towards females (69.5% females, p < 0.01). Possible causes of these differences (differential longevity, biased sampling) are... |
| Tipo: Text |
Palavras-chave: Sex ratio; Genetics; Sex determination; Fish aquaculture; Dicentrarchus labrax. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00078/18882/16450.pdf |
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| Драпун, И. Е.. |
| Анализировали соотношение полов ( ♀/♂) и возрастную структуру в популяциях 16 видов планктонных остракод (сем. Halocyprididae) из разных районов Южной Атлантики на основе зоопланктонных материалов, собранных в 1976 - 1979 гг. в трех рейсах научных судов. В популяциях планктонных остракод, как правило, преобладали самки, превышая количество самцов в среднем в два - три раза. Величины соотношения полов, заметно отклоняющиеся от 1. а также неравномерное в большинстве случаев распределение в популяциях одновозрастных групп, вероятно, свидетельствуют о периодичности размножения, характерной для большинства видов остракод. Наблюдаемое разнообразие форм возрастных пирамид у массовых видов остракод указывает на возможные различия в их биологии, в частности, на... |
| Tipo: Journal Contribution |
Palavras-chave: Планктонные остракоды; Возрастная структура; Соотношение полов; Южная Атлантика; Planktonic ostracods; Halocyprididae; Age structure; Sex ratio; South Atlantic Sex ratio Sex ratio http://aims.fao.org/aos/agrovoc/c_7014. |
| Ano: 2005 |
URL: http://repository.ibss.org.ua/dspace/handle/99011/218 |
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| Brook, Barry W; Northern Territory University; barry.brook@ntu.edu.au; Burgman, Mark A; University of Melbourne; m.burgman@botany.unimelb.edu.au; Frankham, Richard; Macquarie University; rfrankha@rna.bio.mq.edu.au. |
| Population viability analysis (PVA) is used in conservation biology to predict extinction probabilities for threatened species. Previous studies have revealed large differences between the predictions of PVA modeling packages, but these comparisons included a range of nonstandard factors. A standardized comparison of five PVA packages (GAPPS, INMAT, RAMAS Metapop, RAMAS Stage, and VORTEX) was conducted on six examples (two mammals, two birds, one reptile, and a hypothetical bird/mammal-like life history). The individual-based packages (GAPPS and VORTEX) predicted a consistently higher risk of extinction than their matrix-based counterparts (INMAT and the RAMAS programs). This arose as only the former considered the effect of demographic stochasticity in... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Demographic stochasticity; Extinction risk; Individual-based models; Matrix-based models; Model comparison; Parameter estimation; Population viability analysis; Sex ratio. |
| Ano: 2000 |
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| COLLA,MARÍA FLORENCIA; CÉSAR,INÉS I.. |
| Abstract: Freshwater amphipods of the genus Hyalella have a great importance in aquatic ecosystems due to their role in matter and energy cycling and its utilization as bioindicators of environmental health. The aim of this work was to analyze relevant population parameters of Hyalellapampeana, such as population density and structure, individual body size, sex ratio, fecundity and recruitment, and to study the possible relation of these parameters to variations in environmental variables. Samples were taken monthly during a one-year period (2006) at three small ponds in the Natural Reserve Island of Martín García, Argentina. The inland aquatic environments showed distinctive physicochemical characteristics, mainly related to pH and conductivity values.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Freshwater amphipoda; Body size; Fecundity; Sex ratio. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000100620 |
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| 林, 佐季; 仲島, 義貴. |
| We investigated effects of sugar solution on adult longevity, progeny production and progeny sex ratio of Aphidius ervi in the presence and absence of host aphids. When female parasitoids were provided with 50% glucose–fructose solution in 1 : 1 ratio, they lived approximately twice longer than those provided with distilled water, irrespective of host aphid provision. The same effect of sugar solution was also observed on progeny production. When the parasitoid was fed sugar solution, its lifetime progeny production approximately doubled in comparison to that provided with water, whereas daily progeny production did not differ. Total number of female progeny did not differ between adult female provided with water and sugar solution, but significantly... |
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Palavras-chave: Biological control; Sex ratio; Sugar; Longevity; Fecundity. |
| Ano: 2014 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4035 |
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| Registros recuperados: 84 | |
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