The magnitude and direction of sexual size dimorphism (SSD) varies greatly across the animal kingdom, reflecting differential selection pressures on the reproductive and/or ecological roles of males and females. If the selection pressures and constraints imposed on body size change along environmental gradients, then SSD will vary geographically in a predictable way. Here, we uncover a biogeographical reversal in SSD of lizards from Central and North America: in warm, low latitude environments, males are larger than females, but at colder, high latitudes, females are larger than males. Comparisons to expectations under a Brownian motion model of SSD evolution indicate that this pattern reflects differences in the evolutionary rates and/or trajectories of sex-specific body sizes. The SSD gradient we found is strongly related to mean annual temperature, but is independent of species richness and body size differences among species within grid cells, suggesting that the biogeography of SSD reflects gradients in sexual and/or fecundity selection, rather than intersexual niche divergence to minimize intraspecific competition. We demonstrate that the SSD gradient is driven by stronger variation in male size than in female size and is independent of clutch mass. This suggests that gradients in sexual selection and male-male competition, rather than fecundity selection to maximize reproductive output by females in seasonal environments, are predominantly responsible for the gradient.

A vascular plant species list and description is provided for the San Pastor Savanna, an isolated area of savanna within the Chiquibul Forest Reserve, Belize. Of the 126 species recorded, 28 are new records for the Chiquibul Forest Reserve with one previously unrecorded for the country. The maintenance of the current vegetation classification under the Belize Ecosystems Map for the San Pastor Savanna is supported. The coarse-textured soils are typical for extremely seasonal climates with some evidence of prolonged inundation during wet periods and dry seasons affected by burning. Although clear floristic affinities exist with other local and regional savanna areas, the San Pastor Savanna has some unique features and its flora includes national endemics. Although it is currently protected as part of the Chiquibul Forest Reserve and this status should be maintained, its inaccessible location makes frequent monitoring by the Forest Department problematic. Through providing a source of water and a source of forage for horses, the San Pastor Savanna plays a pivotal role in supporting the illegal Chamaedorea (xaté) palm leaf harvesting industry. This activity has also adversely impacted local wildlife. Like the nearby Mountain Pine Ridge, the San Pastor Savanna has suffered intense pine beetle (Dendroctonus spp.) attack.

This study compared the resource use of juvenile zoo-living Chinese crocodile lizards, Shinisaurus crocodilurus crocodilurus across three observation windows, spanning nine months, accounting for time of day and lizard age, and under consistent environmental conditions. Lizards showed a significant difference in proportionate resource use, quantified using a modified spread of participation indices between the second and final sampling period, such that with increasing age, resources were more equally utilised. The time of day did not have a significant effect on resource use. Lizards in this study significantly increased their use of water bodies and branches outside the bask zone and decreased their use of the land areas within the bask zones over time. Resource use data suggests the importance of providing enclosures which cater to ontogenetic shifts in captive individuals or within mixed age groupings.