Over evolutionary timescales, organisms must reckon with their abiotic and biotic environments. Oftentimes, we see adaptations, both morphological and behavioral, to deal with external pressures. The challenge for evolutionary biologists is to tease apart the highly intricate, and sometimes convoluted, relationship between behavior and morphology. Here I present 3 manuscripts on the integration of behavior and morphological diversity across ant lineages. In Chapter 1, I investigated the variation of aggressive behaviors across ant lineages. I used phylogenetic comparative methods to test for correlations among aggressive behavior and other key functional traits. I developed an interaction framework for contextualizing the variation of behaviors and suggested a new scale for quantifying those behaviors. Finally, I found that there is a negative correlation between eye length and aggressive behavior. I also found that there is a positive correlation between body size, worker polymorphism, and potentially participation in mutualisms with other organisms and aggressive behavior. In Chapter 2, I conducted an in-situ study examining the variation of nest defense behavior in Australian dolichoderine species. This study was focused on 4 species: Anonychomyrma sp., Iridomyrmex bicknelli, I. purpureus, and I. turbineus. I examined the latency to recognize a foreign dead conspecific at the nest entrance. I found that the species of the genus Anonychomyrma differ from species of the genus Iridomyrmex in latency to contact and latency to aggression, suggesting distinct nest-patrolling and threat-response strategies between the genera. Furthermore, I found that body size was a key predictor for all latency measures across all species measured. In Chapter 3, I used Ultraconserved elements to infer the ancestral relationships among species of the genus Iridomyrmex. I was able to determine monophyly for the genus and estimate the age of the genus to be about 10.8 million years. The aridification of Australia matches up with the age of the group, showing that the expansion of this habitat could have been key to the evolutionary and ecological success of the genus.