Phylogeny of Courtship and Male-male Combat Behavior in Snakes: An Updated Analysis

Abstract: To elucidate phylogenetic patterns in courtship and male-male combat (MMC) behaviors in snakes, I plotted behavioral characters (BCs) onto phylogenetic trees of snakes. For courtship, I plotted 33 BCs onto a phylogenetic tree of 155 snake species in 12 families. For MMC, I plotted 21 BCs onto a phylogenetic tree of 128 snake species in 11 families. For courtship, results suggest the following. Spur Contact and Spur Movement are ancestral for the clade Pythonidae+Boidae and were present as early as the Paleocene Epoch. The Jerk, Chin-Rub, and Dorsal Advance are ancestral for the clade Endoglyptodonta and were present by the late Oligocene. A coital Bite was added in the colubrid clade Zamenis+Lampropeltini by the early Miocene. For MMC, results suggest the following. The Coil, Hook, Type 2 Head Raise, and Downward Push are ancestral for the clade Afrophidia and were present by the early Paleocene. The Type 1 Head Raise replaced the Type 2 Head Raise in Micrurus by the mid-Miocene and in the Lampropeltini by the early Miocene. In the Lampropeltini, Body Bowing was added and Pinning the Head replaced the Type 2 Head Raise by the early Miocene. In addition to written literature, this study utilized a large amount of documentation in the form of video footage on YouTube. For many species, the footage documents behaviors that were unrecorded in the written literature. The results demonstrate that social media can be a highly useful data source in the scientific study of animal behavior.