RESUMO
In polygynous primates, a greater reproductive variance in males have been linked to their reduced life expectancy relative to females. The mortality patterns of monogamous pair-bonded primates, however, are less clear. We analyzed the sex differences in mortality within wild (NMales = 70, NFemales = 73) and captive (NMales = 25, NFemales = 29) populations of Azara's owl monkeys (Aotus azarae), a socially and genetically monogamous primate exhibiting biparental care. We used Bayesian Survival Trajectory Analysis (BaSTA) to test age-dependent models of mortality. The wild and captive populations were best fit by the logistic and Gompertz models, respectively, implying greater heterogeneity in the wild environment likely due to harsher conditions. We found that age patterns of mortality were similar between the sexes in both populations. We calculated life expectancy and disparity, the latter a measure of the steepness of senescence, for both sexes in each population. Males and females had similar life expectancies in both populations; the wild population overall having a shorter life expectancy than the captive one. Furthermore, captive females had a reduced life disparity relative to captive males and to both sexes in the wild. We interpret this pattern in light of the hazards associated with reproduction. In captivity, where reproduction is intensely managed, the risks associated with gestation and birth are tempered so that there is a reduction in the likelihood of captive females dying prematurely, decreasing their overall life disparity.
Assuntos
Animais de Zoológico/fisiologia , Aotidae/fisiologia , Longevidade , Animais , Argentina , Teorema de Bayes , Feminino , Expectativa de Vida , Masculino , Ligação do Par , Reprodução , Caracteres Sexuais , TexasRESUMO
Understanding the mechanisms that drive population dynamics is fundamental for management of wild populations. The guanaco (Lama guanicoe) is one of two wild camelid species in South America. We evaluated the effects of density dependence and weather variables on population regulation based on a time series of 36 years of population sampling of guanacos in Tierra del Fuego, Chile. The population density varied between 2.7 and 30.7 guanaco/km2, with an apparent monotonic growth during the first 25 years; however, in the last 10 years the population has shown large fluctuations, suggesting that it might have reached its carrying capacity. We used a Bayesian state-space framework and model selection to determine the effect of density and environmental variables on guanaco population dynamics. Our results show that the population is under density dependent regulation and that it is currently fluctuating around an average carrying capacity of 45,000 guanacos. We also found a significant positive effect of previous winter temperature while sheep density has a strong negative effect on the guanaco population growth. We conclude that there are significant density dependent processes and that climate as well as competition with domestic species have important effects determining the population size of guanacos, with important implications for management and conservation.
Assuntos
Camelídeos Americanos/fisiologia , Conservação dos Recursos Naturais/métodos , Ecossistema , Modelos Biológicos , Animais , Teorema de Bayes , Chile , Conservação dos Recursos Naturais/estatística & dados numéricos , Densidade Demográfica , Dinâmica Populacional , Ovinos/fisiologia , Tempo (Meteorologia)RESUMO
1. Our understanding of the interplay between density dependence, climatic perturbations, and conservation practices on the dynamics of small populations is still limited. This can result in uninformed strategies that put endangered populations at risk. Moreover, the data available for a large number of populations in such circumstances are sparse and mined with missing data. Under the current climate change scenarios, it is essential to develop appropriate inferential methods that can make use of such data sets. 2. We studied a population of desert bighorn sheep introduced to Tiburon Island, Mexico in 1975 and subjected to irregular extractions for the last 10 years. The unique attributes of this population are absence of predation and disease, thereby permitting us to explore the combined effect of density dependence, environmental variability and extraction in a 'controlled setting.' Using a combination of nonlinear discrete models with long-term field data, we constructed three basic Bayesian state space models with increasing density dependence (DD), and the same three models with the addition of summer drought effects. 3. We subsequently used Monte Carlo simulations to evaluate the combined effect of drought, DD, and increasing extractions on the probability of population survival under two climate change scenarios (based on the Intergovernmental Panel on Climate Change predictions): (i) increase in drought variability; and (ii) increase in mean drought severity. 4. The population grew from 16 individuals introduced in 1975 to close to 700 by 1993. Our results show that the population's growth was dominated by DD, with drought having a secondary but still relevant effect on its dynamics. 5. Our predictions suggest that under climate change scenario (i), extraction dominates the fate of the population, while for scenario (ii), an increase in mean drought affects the population's probability of survival in an equivalent magnitude as extractions. Thus, for the long-term survival of the population, our results stress that a more variable environment is less threatening than one in which the mean conditions become harsher. Current climate change scenarios and their underlying uncertainty make studies such as this one crucial for understanding the dynamics of ungulate populations and their conservation.
Assuntos
Secas , Efeito Estufa , Carneiro da Montanha/fisiologia , Adaptação Biológica , Animais , Extinção Biológica , Geografia , México , Método de Monte Carlo , Dinâmica Populacional , Fatores de TempoRESUMO
Se presentan 722 casos de no unión ósea (en tibia 344, en fémur 292 y en húmero 86) tratados por medio del clavo Colchero intramedular con pernos. En 382 pacientes el padecimiento fue aséptico y en 340 infectados por lo cual hubo que retirar la sepsis por el método de escarificación, para convertir la falta de unión en aséptica y dejarla preparada para la osteosíntesis. En las no uniones atróficas se utilizó hueso esponjoso autólogo y en las hipertróficas no hubo que recurrir a este procedimiento. La unión se logró con una cirugía en 720 casos, existiendo 2 no uniones que se volvieron a operar por el mismo método y se resolvieron. La marcha con apoyo total se inició a los tres días de la cirugía; con ello, la consolidación fue rápida, el enfermo pudo volver al trabajo pronto y a una vida social activa
Assuntos
Adolescente , Adulto , Pessoa de Meia-Idade , Humanos , Masculino , Fixação Interna de Fraturas/efeitos adversos , Fixação Interna de Fraturas/reabilitação , Fraturas do Fêmur/cirurgia , Fraturas do Fêmur/complicações , Fraturas não Consolidadas/complicações , Fraturas não Consolidadas/reabilitação , Infecção da Ferida Cirúrgica/reabilitação , Fixadores Internos/efeitos adversos , Fraturas da Tíbia/complicações , Fraturas da Tíbia/cirurgiaRESUMO
A pesar de todos los esfuerzos que se han hecho para resolver el problema de las fracturas de tobillo, todavía es frecuente la reducción inadecuada de la mortaja tibio-peroneo-astragalina, sobre todo por el acortamiento del peroné que se produce en las fracturas "C" y algunas "B" de Weber. Por medio de mediciones, se pudo observar en tobillos fracturados y ya operados, que el 58 por ciento de ellos presentaban acortamiento de peroné, con apertura de la mortaja, lo que explica la frecuencia de la artrosis. No existe un método que nos indique cuando el peroné, se encuentra nuevamente en la incisura tibial, que es su lugar correcto, lo que resulta imprescindible para la reducción de la articulación. Para resolver este problema, el autor comprobó en quince radiografías de tobillos sanos, que ambos maléolos son de la misma dimensión, trazando una línea recta perpendicular de la tibia y otra a la punta del maléolo externo que parten del punto más distal de la apófisis anterior de la incisura tibial. Por lo tanto, al hacer la cirugía esta medida se puede extrapolar al peroné fracturado y traccionarlo hasta que tenga los milímetros que tiene el peroné sano, con lo que se puede lograr una correcta reducción de la fractura o fractura-luxación de tobillo