Meeting Abstract
More than a century ago, Allen and Bergmann observed that temperate mammals are often larger and have lower surface area to volume ratios than their tropical counterparts. Since then, many studies have documented morphological gradients associated with latitude, but few have linked these gradients to any one mechanism. Here we investigate how morphological diversity (disparity), phenotypic integration, and the rate of morphological evolution differ between temperate and tropical mammals. We gathered landmark data from the jaws of three large families of carnivorans, Canidae, Felidae, and Mustelidae, which contain both temperate and tropical species. We compared the disparity, the level of integration between the anterior (corpus) and posterior (ramus) portions of the jaw, and the rate of jaw evolution between temperate and tropical species within each clade. Temperate and tropical species occupied similar regions of morphospace and exhibit similar levels of disparity across all clades. All clades exhibit significantly higher levels of integration in the tropics. Temperate canids also exhibit high levels of integration, but temperate felids and mustelids exhibit low levels of integration. Those groups with high integration (canids, tropical felids and tropical mustelids) also exhibit slow rates of morphological evolution, highlighting a potential relationship between morphological rates and phenotypic integration. We hypothesize that the difference in rates and integration between temperate and tropical members of a clade is influenced by the wider climatic fluctuations experienced by temperate taxa. Those taxa living in more hostile conditions may evolve less integrated phenotypes to more quickly respond to changing environmental conditions and as a result, are more evolvable.
