Competing Selective Pressures Drive Habitat-Specific Functional Trade-Offs Between Hurricane Survival and Sprint Speed in the Anolis cristatellus

Abstract

Humans have been major drivers of evolutionary change. Anthropogenic influences like industrialization and urbanization have resulted in significant, negative impacts to the environment and ecosystem. These influences have exacerbated climate change and increased the severity and frequency of extreme weather events like hurricanes. As hurricanes are becoming more frequent in tropical regions, research on their effects for the species living in these areas is much needed. Our study aims to address a gap in the literature and understand how different modes of anthropogenic change act together in exerting selective pressures in a species of tropical lizards, the Anolis cristatellus or the Crested Anole. For anoles to survive hurricanes, they have to display good clinging ability. In order to carry out necessary life functions, anoles also have to sprint well. As such, we conducted sprinting and hurricane clinging trials to understand the relationship between these two performance metrics. We found that since anoles have had to experience hurricanes throughout their evolutionary history, they have evolved a balance between sprinting ability and hurricane survival. They have developed morphological combinations such as larger forelimbs, pelvises, and fourth toes but smaller metacarpals and pectorals to perform well in clinging and sprinting. However, their urban counterparts have additionally experienced the selective pressures posed by urbanization. Due to this, they have shifted in their morphology to evolve sprinting specialization. This has disrupted the balance between sprinting and clinging performance that anoles have ancestrally maintained. While larger forelimbs but smaller pelvises, fourth toes, metacarpals, and pectorals confer good sprinting ability, their clinging performance is insensitive to morphological variation. They display a trade-off as sprinting specialization has made them poor performers when it comes to hurricane clinging ability.