We humans rarely have punch ups with each other to decide who will mate. However, an anole lizards life is frequently interrupted by brawls. Neil Losin is an evolutionary biologist from UCLA who studies aggressive behavior among anole lizards. Anole lizards not only have punch ups among each other (intraspecific aggression) but they also have such interactions with other species (interspecific aggression). This is when things get even more interesting. In less than 10 minutes this documentary outlines the research questions (hypothesis) and shows how to test these hypotheses on aggression. A cordial well done goes to Day’s Edge Productions.
Anoles of the Carribean have been an interesting species complex for studying how new species evolve. In 2011 the complete genome of green Carolina anole lizard has been sequenced and published in the scientific journal Nature. One research example is an on going manipulative experiment with the brown anole lizards in Bahamas. One of the principal investigators of the study Jonathan Losos describes what have happened during the past two decades since the experiment began.
Losin’s study takes place on the mainland Florida where three anole species overlap because two of them have been introduced unintentionally by humans. This natural experiment provides an excellent setting for comparative evolution of aggressive behavior.
The following video shows a territorial dispute between two male Carolina anoles. Color difference between the two shouldn’t confuse you since these lizards can change color between green and brown quite effectively. The destructiveness of the behavior may explain the selective pressure towards evolution of ritualized aggression. As we can see from the video the ordeal of loosing a fight doesn’t end there. During the recovery period individuals become rather exposed to predators.
Females of the green anole lizards are quite peaceful. If approached properly it is possible to capture details of their behavior. Green Carolina anole is a branch/leaf top specialist. Using a binocular or a high powered zoom camera one can appreciate the level of attentiveness of this species while hunting for insects especially in hot days. High temperatures elevate metabolic rates of reptiles much faster than warm-blooded animals. They burn calories faster and get hungry more often. For that reason, climate change due to global warming brings a special risk to this group. The following female individual is rather emaciated and is therefore a bit more active in pursuing insects.