Most of the phylogenies you'll find in textbooks represent evolutionary events that happened millions (or even billions) of years ago the splitting of the human lineage from that of other primates, the diversification of mammals after the dinosaur extinction, or the first branching events after the origin of life. But phylogenetics is much more than ancient history. All around us, and even inside of us, lineages are splitting and going extinct in real time, forming their own twigs on the tree of life.
Satish Pillai, a researcher at UCSF medical center, studies one such lineage. HIV reproduces and accumulates mutations so quickly that it evolves not just as it moves from one human to another, but within a single infected individual. A new infection may begin with a single virus particle, but within weeks that particle will have multiplied, diversified into new strains, and wriggled its way into the nooks and crannies of the human body. An HIV infection is caused not by a single entity, but by a diverse population of related viruses that is constantly evolving. Here we will see how Satish uses the tools of phylogenetics to investigate the possibilities of developing an effective vaccine and of curing the disease.