Search

The ectothermic nature of reptiles makes them especially sensitive to global warming. Although climate change and its implications are a frequent topic of detailed studies, most of these studies are carried out without making a distinction between populations. Here we present the first study of an Aspidoscelis species that evaluates the effects of global warming on its distribution using ecological niche modeling. The aims of our study were (1) to understand whether predicted warmer climatic conditions affect the geographic potential distribution of different climatic groups of Aspidoscelis costata costata and (2) to identify potential altitudinal changes of these groups under global warming. We used the maximum entropy species distribution model (MaxEnt) to project the potential distributions expected for the years 2020, 2050, and 2080 under a single simulated climatic scenario. Our analysis suggests that some climatic groups of Aspidoscelis costata costata will exhibit reductions and in others expansions in their distribution, with potential upward shifts toward higher elevation in response to climate warming. Different climatic groups were revealed in our analysis that subsequently showed heterogeneous responses to climatic change illustrating the complex nature of species geographic responses to environmental change and the importance of modeling climatic or geographic groups and/or populations instead of the entire species' range treated as a homogeneous entity.

Optimal offspring size theory states that natural selection should balance reproductive output by optimizing between offspring size and offspring number. If a species has evolved an optimal offspring size, the fitness of larger females should be increased by simply producing more offspring of an optimum size. In contrast, when offspring size is not optimized, the morphological constraint hypothesis may apply, and in this case, maternal fitness is increased by producing the greatest number of the largest offspring that mothers are physically capable of producing. We used a log-log allometric regression approach on clutch size, egg size, and body size data to test the application of optimal offspring size theory and the morphological constraint hypothesis in the Mexican mud turtle (Kinosternon integrum) in southern Mexico. Our results indicate that this turtle seems to follow the morphological constraint hypothesis when all data are analyzed together, but when data are divided between small (< 140 mm plastron length) and large females (> 140 mm plastron length), optimal offspring (egg) size theory was supported only in large females, while the morphological constraint hypothesis was supported in small females. Our results thus indicate that K. integrum females may increase their fitness in two different, size-dependent ways as they grow from size at sexual maturity to maximum body size.

Objective: To identify specific fractures risks of the following bones: distal femur, patella and tibia plateau, according to sex and age, with special interest in women >or= 50 y.o., Material and Methods: An epidemiologic case-control study was done between January 2002 and December 2005. The incidence rate for fractures were got by year, sex and age. The group exposed to the risk factors, was represented by female patients >or=50 y.o. The cases with fracture's worst prognosis were: distal femur (supracondylar, supraintercondylar or condylar), tibial plateau (Schatzker IV-VI); the control group was made with patients which fractures were in: proximal femur (Subtrocantheric, diaphysis), tibial plateau (Schatzker I-III). Descriptive and inferential analysis were done separately and together., Results: 1578 Patients were studied. Incidence of fractures in the studied regions was of 5.9 per 10 000 persons/year (py), being of 5.7 and 4.9 per 10,000 py for men and women, respectively (p < 0.001). In subjects with age >or=50 y.o. the incidence rate was of 10.5 and 6.6 per 10 000 py for men and women, respectively. In the study patients less than 50 y.o. the incidence rate was of 1.6 per 10 000 py for both sexes (p < 0.001). The women >or=50 y.o. presented an OR of 5.1 (95% CI: 2.7-9.8, p < 0.001)., Conclusions: In this study sample, the risk of fracture of the femur and the knee was greater in men than in women. In the >or= 50 y.o. age group, the ratio was inverted, with special interest in distal femur fractures. According to sex and age, no differences were identified in tibia plateau fractures.