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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. [ABSTRACT FROM AUTHOR]

Toe-clipping is an extensively used technique for individual identification of amphibians and reptiles. However, this method might result in negative effects including reduced survival. In this study, we used capture-mark-recapture data obtained from ten different lizard species, including more than one population for two species, to examine whether survival rates varied as a function of the number of toes that were clipped. We used likelihood methods and multi-state models to estimate survival probabilities. Specifically, we tested if the number of clipped toes had an effect on annual survival, comparing survival among groups of individuals that shared the same number of toes that were clipped. We found clear reductions in survival associated with the removal of several toes in seven study sites that correspond to five different species. These represent 37% of all the species and populations that we examined. Therefore, we conclude that this marking method potentially causes severe damage and may lead to biased parameter estimates in ecological studies of lizard species. Whenever possible, toe-clipping should be avoided and replaced by less invasive methods for individual identification. [ABSTRACT FROM AUTHOR]