Meeting Abstract
Predator-based selection is considered a major driver of phenotypic diversity, from the dynamics of mimicry systems to the extraordinary patterns of crypsis and background matching. Research focused on aposematism and mimicry has revealed that antipredator coloration has multiple independent origins and is characterized by substantial rate heterogeneity. Both mimetic and aposematic coloration are warning signals (sometimes dishonest) for antipredator defenses, but simple contrasting coloration can also effectively startle or confuse a predator. Importantly, differences in costs to the predator and prey between warning signals (mimicry and aposematism) and defensive coloration (startle and decoy coloration) have the potential for alternative macroevolutionary consequences. We studied the evolution of startle coloration in snakes, which often have brightly colored ventral surfaces (red to yellowish-orange) that are displayed to predators during an attack. Using a combination of phylogenetic comparative methods, large phylogenies, and a dataset of ventral color for over 800 species, we found that there have been multiple independent origins of the brightly colored venter, with most extant occurrences of this trait reflecting independent origins. Contrastingly, there have been very few losses, and most of the origins were relatively recent (last 10 million years). Our results suggest differing dynamics for the evolution of startle coloration compared to aposematism and mimicry, implying that the evolution of traits driven by the same predator-based selection pressure may have alternate macroevolutionary outcomes.
