AOS 2018 Annual Conference

Animal weaponry has long been of interest to biologists. While most birds lack structures that likely evolved specifically as weapons, birds in the order Galliformes (guineafowl, pheasants, partridges, etc.) are unique in possessing tarsal spurs. These horn-like structure located on the back of the tarsus vary vastly in size, shape and number between species; and although spurs are known worldwide for their role in male-male competition (see: cockfighting) spurs are also present in the females of many species - for unknown reasons. Although several papers have proposed hypotheses about tarsal spurs, this study is the first to examine spurs in a phylogenetic context. Using data collected from museum skins and literary sources, our results thus far support the hypothesis that tarsal spurs originate from a common ancestor in both males and females, and that there has been a rapid loss of tarsal spurs in females whereas males have largely retained them. Further, we have begun to analyze the correlation of spur presence and other characteristics, such as mating system, parental care mode, nesting habitat, and dimorphism in a phylogenetic framework in order to explore “why” tarsal spurs may have evolved. Initial analyses have suggested some correlated traits for male spur presence; however, thus far there are no clear correlates with the presence of spurs on females of a species. How this, and other findings, contradict previous hypotheses about spur origin and function will be discussed further, along with future directions for research on this subject.