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Within delphinoid cetaceans, snout shape is significantly correlated to diet, with long-snouted raptorial-feeding predators preying on smaller and more agile prey than shorter-snouted species. Although there have been several studies into longirostry from a functional perspective there have been no quantitative analyses of spatial variation in skull shape or how the pattern in skull shape morphospace occupation varies between assemblages. Here we analyse the cranial morphological variation of Delphinoidea assemblages. Firstly, we calculate mean and Gi* hotspot statistics of skull shape across the world's oceans. We find that tropical and subtropical assemblages exhibit higher average measures of longirostry. This pattern is likely caused by differences in the availability of certain prey types in warmer and cooler environments. Secondly, we calculate mean pairwise distance as well as mean nearest taxon distance in functional traits between the members of 119 unique delphinoid assemblages. There was a trend for low latitude assemblages to exhibit greater overdispersion in PC1 (snout length) compared those from high latitudes. Our results suggest that ocean temperature is influential in determining the diversity, range limits and assemblage structure of delphinoid cetaceans. [ABSTRACT FROM AUTHOR]

Aims We aimed to test the hypothesis that plants that grow at lower latitudes will be better structurally defended than plants from higher latitudes. Methods We collated binary spinescence data for 5145 species across Australia and New Zealand. Our dataset spanned 35° of latitude, and included over 1 million observations, making it the largest empirical study ever conducted for a single physical defence trait. A weighted logistic regression was applied first within Australia and New Zealand separately, and then across the combined dataset. Important Findings There was no significant latitudinal gradient in the proportion of species with spinescence in Australia or New Zealand, or in the overall dataset. That is, plant species are no more likely to be defended by spines at low latitudes than at high latitudes. This finding is counter to the idea that plant defences increase with latitude due to increased selective pressure from higher levels of herbivory. We suggest that future studies should investigate the relationship between herbivory and defence directly, without using latitude as a proxy. [ABSTRACT FROM AUTHOR]