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1.
Proceedings. Biological sciences / The Royal Society ; 271(Suppl. 6): S427-S429, Dec. 2004. graf
Artigo em Inglês | MedCarib | ID: med-17657

RESUMO

Because not all females are equally attractive, and because mating reduces the chances of getting further copulations, males should prefer better-quality mates. In this paper, we use the Trinidadian guppy (Poecilia reticulata) to explore the effects of two non-correlated measures of female quality--size and reproductive status--on male mating decisions. All male guppies employ two alternative mating tactics. We found that large females, particularly those from a high predation site, were the target of most sneaky mating attempts. The response persisted in fish raised under standard conditions over several generations in the laboratory. In addition, non-pregnant females received more courtship displays. We conclude that males can discriminate among females and that they uncouple their mating tactics to track different axes of quality.


Assuntos
Animais , Masculino , Feminino , Estudo Comparativo , Research Support, Non-U.S. Gov't , Análise de Variância , Tamanho Corporal , Observação , Poecilia/fisiologia , Reprodução/fisiologia , Rios , Fatores Sexuais , Trinidad e Tobago
2.
Proceedings. Biological sciences / The Royal Society ; 271(1543): 1009-1014, May 2004. tab, graf
Artigo em Inglês | MedCarib | ID: med-17607

RESUMO

Male offspring production in promiscuously mating species is typically more skewed than female offspring production. It is therefore advantageous for males to seek as many mating partners as possible. However, given the documented benefits of polyandry we expect females, as well as males, to mate multiply. We tested these ideas using Trinidadian guppies, Poecilia reticulata. Fishes were collected from the wild, housed in groups of 10 males and 10 females and allowed to reproduce freely over a period of three months. We used hypervariable microsatellite loci to identify the parents of 840 offspring and to quantify the variance in mating success. As anticipated, and in line with the Bateman gradient, there was greater skew in the number of progeny produced by males. By contrast, we found no sex difference in mating partner number over the duration of the experiment. A median of two males fathered each brood and there was marked turnover in the identities of the sires of successive broods. Female partner turnover was, however, less than expected under random mating. We suggest that partner switching over time, as well as polyandry within broods, could contribute to the maintenance of genetic diversity in guppy populations.


Assuntos
Animais , Masculino , Feminino , Estudo Comparativo , Research Support, Non-U.S. Gov't , Análise de Variância , Primers do DNA , Variação Genética , Genótipo , Poecilia/genética , Poecilia/fisiologia , Repetições de Microssatélites/genética , Modelos Biológicos , Reprodução/fisiologia , Rios , Trinidad e Tobago
3.
Proceedings of the Royal Society B: biological sciences ; 268(1468): 719-724, Apr. 2001. tab, graf
Artigo em Inglês | MedCarib | ID: med-17770

RESUMO

Despite its widespread occurrence in animals, sperm competition has been studied in a limited range of taxa. Among the most neglected groups in this respect are internally fertilizing fish in which virtually nothing is known about the dynamics of sperm competition. In this study, we examined the outcome of sperm competition when virgin female guppies mated with two males. Behavioural cues were used to ensure that each male mated once (with female cooperation) and that sperm were successfully inseminated at copulation. Two polymorphic microsatellite loci were used to estimate the proportion of offspring sired by the second male (P2) and the results revealed a bimodal distribution with either first or (more often) second male priority The observed P2 distribution differed from that expected under the 'fair raffle' model of sperm competition. Random sperm mixing is therefore unlikely to account for the observed variance in P2 in this study. A further aim of our study was to identify predictors of male reproductive success. Using logistic linear modelling, we found that the best predictors of paternity were time to remating and the difference in courtship display rate between first and second males. Males that mated quickly and performed relatively high numbers of sigmoid displays obtained greater parentage than their slower and less vigorous counterparts. Since females are attracted to high-displaying males, our results suggest that female choice may facilitate sperm competition and/or sperm choice in guppies.


Assuntos
Animais , Masculino , Feminino , Research Support, Non-U.S. Gov't , Repetições de Microssatélites , Paternidade , Poecilia/fisiologia , Distribuição Aleatória , Reprodução/fisiologia , Espermatozoides , Trinidad e Tobago
4.
In. Howe, Glenford D; Cobley, Alan G. The Caribbean AIDS epidemic. Kingston, University of the West Indies Press, 2000. p.122-38, tab.
Monografia em Inglês | MedCarib | ID: med-625
7.
J Pineal Res ; 20(2): 90-7, Mar. 1996.
Artigo em Inglês | MedCarib | ID: med-2998

RESUMO

It has been hypothesized that pineal structure and function might differ between temperature zone and tropical species of mammals because of lower amplitudes of seasonal change in photoperiod and, in some areas, less seasonal climatic variation. Anoura geoffroyi produce a single offspring in November or December of each year on the Caribbean island of Trinidad, at 10 degrees N latitude in the deep tropics. Previous work has shown that this population lacks reproductive responses to photoperiod, and must be enforcing seasonal breeding using a non-photoperiodic cue. Anoura geoffroyi have a minute, thin, and rod-like pineal gland. Throughout much of its length, the pineal courses irregularly within the ventrolateral wall of the great cerebral vein. This intimate relationship may have functional implications. Despite having a very small pineal gland, this species produced a nocturnal rise in serum melatonin. Serum melatonin levels in most individuals were below or near undetectable levels during the light period and rose to a peak averaging 100 pg/ml in the last third of the dark period. Our results indicate that, although the pineal gland of A. geoffroyi is extremely small, serum melatonin levels are comparable to those of other mammals.(AU)


Assuntos
21003 , Masculino , Quirópteros/anatomia & histologia , Quirópteros/fisiologia , Melatonina/sangue , Glândula Pineal/anatomia & histologia , Glândula Pineal/fisiologia , Ritmo Circadiano , Fotoperíodo , Radioimunoensaio , Reprodução
8.
London; Macmillan in co-operation with the Technical Centre for Agricultural and Rural Co-operation (CTA); 1 ed; 1994. viii,208 p. ilus, tab.
Monografia em Inglês | MedCarib | ID: med-16569

RESUMO

Animal Breeding examines in detail the various techniques that can be used in breeding animals, such as selection, cross-breeding and inbreeding. Examples of the various techniques are given, including their advantages and disadvantages in tropical and sub-tropical environments, and how they can be used to improve the core traits of animals. The book also deals with basic genetics and examines factors such as the effect of climate on animals and the importance of preserving the gene pool in native tropical breeds. This book will be an invaluable guide for anyone involved with animal breeding and livestock improvement in the tropics


Assuntos
Animais , Bovinos , Animais Domésticos/genética , Cruzamento/estatística & dados numéricos , Países em Desenvolvimento , Agricultura/estatística & dados numéricos , Ecossistema Tropical , Reprodução , Região do Caribe
9.
Washington; Pan American Health Organization; 1992. xii,593 p. ilus, maps, tab.
Monografia em Inglês | MedCarib | ID: med-16746

RESUMO

The region of the Americas provides a unique assortment or even a microcosm of the prevailing reproductive patterns in the world. The specific objectives of this book, therefore, are: (a) to describe for the Americas the various reproductive patterns; (b) to evaluate the impact on health of family formation patterns and changing attitudes toward reproduction; (c) to provide the most up-to-date accounts of methods of fertility regulation; (d) to display the existing experiences in reproductive health; and (e) to identify unmet needs in service and research in these areas, and suggest strategies for filling the gaps (AU)


Assuntos
Humanos , Fertilidade , América , Infertilidade/complicações , Serviços de Planejamento Familiar/estatística & dados numéricos , Serviços de Planejamento Familiar/métodos , Serviços de Planejamento Familiar/educação , Serviços de Planejamento Familiar/tendências , Região do Caribe , Atenção Primária à Saúde/estatística & dados numéricos , Países em Desenvolvimento , Reprodução
10.
Ann Arbor; University Microfilms International; May 1991. 149 p. ills.
Tese em Inglês | MedCarib | ID: med-7640

RESUMO

Fertility has decreased gradually on the island of Dominica since 1978. In 1986 the government initiated a policy to decrease fertility and population growth. Factors controlling fertility on Dominica are the focus of this dissertation. The introduction of Western methods of birth control explains declining fertility in other parts of the world. Analysis of data collected on Dominica, however, indicates that there is no significant difference between women who use and others who do not use Western forms of birth control. Birth control appears to space births rather than to limit completed family size. Analysis is based on standard demographic methods performed on a sample of 10,929 women aged 15-44, including interviews with 243 of these women. Family size is the same for those who do and those who do not use birth control (approx.4.2). A modification of Bongaart's (1983) and Wood's (1990) fertility models is utilized to determine which factors affect fertility on Dominica. Data indicate other factors affecting fertility include sexual activity, age at menarche and menopause, pregnancy rate, lactational amenorrhea, location of villages relative to health centers and urban areas, type of subsistence, economic status, religion and education. The importance of these factors for explaining Dominican fertility trends is addressed. (AU)


Assuntos
Humanos , Feminino , Reprodução , Fertilidade , Fatores Socioeconômicos , Dominica , Serviços de Planejamento Familiar/métodos , Gravidez
11.
Kingston; s.n; Oct. 1984. 224 p. ills, tab.
Tese em Inglês | MedCarib | ID: med-13632

RESUMO

In recent years interest has mounted concerning the role of marihuana on reproductive physiology. Various reports in the literature suggest that marihuana influences female reproduction, and pose significant risks for the offspring. It has also been blamed for its embryotoxic/foetotoxic and teratogenic manifestations in animals. These reports are conflicting, confusing and sometimes contradictory. However, it could be conceived that marihuana use induces reproductive hazard. Moreover, marihuana has been used for facilitating childbirth and was tried in the management of menstrual disorders, but there is no evidence to establish the scientific basis for such claims. Despite the widespread use of marihuana, there are only a few studies available describing the effects of this drug in the female. This study was designed to investigate the potential effects of marihuana smoking on female reproductive process and foetal development. Albino rats were utilized for this experiment due to various practical advantages like availability, low cost, large number of animals per litter and brief gestational periods. Marihuana smoking has been employed to mimic human use and to restrict the use of heavy doses. Uterine smooth muscle contractility was studied to determine the influence of marihuana extract and the consequences of smoke exposure on uterine contractility. A chronic study, i.e. follow-up through two generations, was carried out since acute effects of marihuana may be insignificant and since continous maternal exposure could damage the foetus and chronic use could further deleterious effects. During this study a close watch was kept on the body weight to rule out the possible influence of undernutrition which may affect the reproductive function. Marihuana smoking has resulted in the reduction of body weight within the first week, but these animals later demonstrated a positive gain in weight and did not exhibit any obvious signs of undernutrition which may affect the reproductive function. Marihuana smoking has resulted in the reduction of body weight within the first week, but these animals later demonstrated a positive gain in weight and did not exhibit any obvious signs of undernutrition. A positive gain in body weight suggests development of tolerance following the smoking exposure. All the marihuana smoke-exposed rats exhibited delayed onset of oestrous activity but frequent oestrous cycles with a reduction in the duration of oestrous period. Such a change could interfere with fertility rate. Smoking also has resulted in suppression of ovalution. The fertility index (number of pregnant females/number of mated females) was significantly lowered. Other observations were shortened gestation period, low birth weight and diminished litter size. Reduction in fertility index and the gestation period may be the consequence of uterine stimulatory action of marihuana or suppressed ovarian activity. Low birth weight and reduction in the litter size could be due to probable embryotoxic effects of interference with transport mechanisms. Uterine contractile responses produced by crude aqueous marihuana extract (CAME) were significantly higher in smoke-exposed rats. CAME seems to depolarize the uterine smooth muscle, by activiting the muscarinic receptors. Chronic exposure to marihuana smoke seems to alter this response at receptor level. CAME is shown to possess both contractile and relaxing properties with dominant activity of the former. Chronic exposure to marihuana smoke resulted in appearance of tumours, like serous cystomata, follicular cysts, telengiectatic cysts, adenofibroma and adenocarcinoma in 50 percent of the experimental animals. The significance of this uterine stimulatory and tumorigenic potential of marihuana may have far-reaching consequences due to interference with foetal blood flow. Such a situation couls lead to deficient transport of O2, nutrients and toxic metabolities and precipitate not only foetal underdevelopment, but also reduction in litter size. Use of marihuana seems to influence the reproductive activity in females as evidences by delayed onset of oestrous activity, frequent oestrous cycles with reduced fertility index, shortened gestation periods, increased litter mortality, low birth weight, etc. This study clearly indicates that the marihuana smoke not only affects the maternal well-being but also jeopardizes the conditions under which the foetuses grow and develop (AU)


Assuntos
Gravidez , Ratos , Feminino , Fumar Maconha/efeitos adversos , Reprodução/efeitos dos fármacos , Desenvolvimento Embrionário e Fetal/efeitos dos fármacos , Contração Uterina/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Alterações do Peso Corporal , Ovulação/efeitos dos fármacos , Fertilidade/efeitos dos fármacos , Seguimentos
13.
Ann Trop Med Parasitol ; 66(3): 385-90, Sept. 1972.
Artigo em Inglês | MedCarib | ID: med-13056

RESUMO

Life tables were obtained over 16 fortnights for three cohorts of Biomphalaria glabrata at 20§C, 25§C and 30§C respectively. At 35§C no eggs hatched. The intrinsic rate of natural increase r was greater at 25§C(0.8834) but the mean generation time T was similar to that at 30§C(8-9 fortnights). Egg production and survival were reduced at 30§C but r(0.6866) was higher than at 20§C(0.4725). T was greatest at 20§C(12 fortnights) due to the delay in the onset of egg laying. The growth rate at 30§C was only a little faster than that at 25§C, but both were greater than that at 20§C. Comparison of these results with those of similar studies elsewhere suggests that the St. Lucians strain of B. glabrata is adapted to living in unstable, temporary habitats. B. glabrata, unlike its African relatives, is capable of surviving prolonged exposure to temperatures of 30§C so that, despite reduced fecundity, it can colonize the hot, low lying coastal plains of northeastern South America. (AU)


Assuntos
21003 , Biomphalaria/crescimento & desenvolvimento , Vetores de Doenças , Schistosoma mansoni , Esquistossomose/epidemiologia , Adaptação Biológica , Fertilidade , Reprodução , Temperatura , Santa Lúcia
15.
Ann Trop Med Parasitol ; 63(1): 39-45, Mar. 1969.
Artigo em Inglês | MedCarib | ID: med-12379

RESUMO

The morphology is described of the tissue stages of Trypanosoma cruzi observed in strains isolated in British Honduras. The persistent presence of crithidia forms of the parasite in infected vertebrate tissues suggests that T. cruzi strains found in British Honduras differ from strains described from other geographical areas. It is suggested that such strains may be suitable for studies on trypanocidal drugs in vivo and for comparative studies on the morphology of reproduction in tissues. (AU)


Assuntos
Camundongos , Ratos , 21003 , Trypanosoma , Doença de Chagas/epidemiologia , Doença de Chagas/microbiologia , Belize , Cérebro/microbiologia , Diafragma/microbiologia , Coração/microbiologia , Reprodução , Trypanosoma/citologia , Doença de Chagas/diagnóstico
17.
Artigo em Inglês | MedCarib | ID: med-16870

RESUMO

A retrospective study was conducted on a large farrow-to-finish pig farm in southern Trinidad. The study examined the influence of season (wet vs dry) on litter size, litter birth weight, number of piglets weaned, litter 21-day weight, and weaning-to-remating interval (WTRI). Season of birth, season of mating, and month of mating had no effect on any of the traits examined (P>0.05). There was a higher level of preweaning mortality among piglets that were born in the month of January (P=0.02). The average temperatures for the wet season and dry season for the three year study period were 26.1 (C) and 27.2 (C), respectively. The average temperature-humidity indicies for the two seasons were 75.4 for the wet season and 77.6 for the dry season (AU)


Assuntos
Animais , Gravidez , Suínos , Reprodução , Trinidad e Tobago , Estações do Ano
18.
Artigo em Inglês | MedCarib | ID: med-16872

RESUMO

A retrospective study was conducted on two farms in Trinidad to determine the impact of retained foetal membranes (RFM) on reproductive efficiency in dairy cattle. The measures of reproductive efficiency examined were days open, services per conception, calving interval, and first-service conception rate.(AU)


Assuntos
Bovinos , Gravidez , Doenças dos Bovinos/embriologia , Membranas Extraembrionárias/anormalidades , Trinidad e Tobago , Medicina Reprodutiva/estatística & dados numéricos , Reprodução , Paridade , Indústria de Laticínios/estatística & dados numéricos
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