It is predicted that climate change will cause species extinctions and distributional shifts in coming decades, but data to validate these predictions are relatively scarce. Here, we compare recent and historical surveys for 48 Mexican lizard species at 200 sites. Since 1975, 12% of local populations have gone extinct. We verified physiological models of extinction risk with observed local extinctions and extended projections worldwide. Since 1975, we estimate that 4% of local populations have gone extinct worldwide, but by 2080 local extinctions are projected to reach 39% worldwide, and species extinctions may reach 20%. Global extinction projections were validated with local extinctions observed from 1975 to 2009 for regional biotas on four other continents, suggesting that lizards have already crossed a threshold for extinctions caused by climate change.

Both matrotrophy, the maternal provisioning of nutrients to developing embryos after fertilization, and superfetation, the simultaneous presence of two or more groups of embryos at different stages of development, occur at varying degrees among species of the fish family Poeciliidae. However, it is still unclear if these two reproductive modes depend on the presence of relatively complex placentas. We describe the ultrastructure of the maternal follicular placenta of 11 poeciliid fishes using electron microscopy. In addition, we quantified six ultrastructure characteristics that reflect the degree of complexity (number of vesicles, area of vesicles, number of microvilli, microvilli length, thickness of the maternal follicle and follicular area). Using phylogenetic comparative methods, we evaluated the relationship between degree of matrotrophy and placental characteristics. We also analysed the potential effect of the presence of superfetation on placental complexity. We found a positive relationship between the degree of matrotrophy and follicular area, number of microvilli and number and area of vesicles. Similarly, follicular area and number of microvilli were larger in species with superfetation than in those without superfetation. We conclude that high degrees of matrotrophy and superfetation are associated with placental characteristics that increase the efficiency of nutrient transfer between mother and embryos. K E Y W O R D Sfollicular placenta, matrotrophy, placentation, Poeciliidae, superfetation

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Se estudió el ciclo de reproducción de Sceloporus ochoterenae en una población que vive en un relicto de selva baja caducifolia en el centro de Morelos. Los machos con longitud hocico-cloaca (LHC) promedio de 49.53 ± 2.40 mm, son más grandes y más pesados (x = 3.66 ± 0.68 g) que las hembras (LHC 46.37 ± 2.08 mm, peso 3.34 ± 1.23 g), lo que revela dimorfismo sexual como ocurre en otras especies de lagartijas sceloporinas. Existen diferencias en los ciclos de reproducción entre los sexos, los machos inician la actividad reproductora en marzo con la máxima actividad en mayo, y las hembras al inicio de la temporada de lluvias (mayo), con el periodo de mayor actividad durante la temporada de lluvias (julio). La temperatura y precipitación están correlacionadas positivamente con los ciclos de reproducción de machos y hembras. El tamaño promedio de la nidada, fue de 5 huevos y se relaciona positivamente con el tamaño de las hembras. En contraste, el tamaño y peso de las hembras no tuvieron efecto significativo sobre la masa relativa de la nidada (promedio = 0.245). En general, las características reproductoras de la población de Morelos son diferentes a las observadas en Guerrero.

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