In the Reed Lab we study the shared evolutionary history of assemblages of symbionts. Specifically, we study mammals, their ectoparasitic lice, and bacteria that live within the lice.


Because these assemblages can answer some very interesting evolutionary questions. Lice are insects that live on birds and mammals. Often times they can only live on a single species of host. Take human head lice for example, they can only live on us. This specificity leaves them stranded on a host species over long periods of time, millions of years, in some cases. The closest living relative of the human louse is found on chimpanzees. Human and chimpanzee lice last shared a common ancestor 5-7 million years ago, just like their human and chimpanzee hosts. When the lineages leading to chimps and humans split, so did the lineages of their lice. When parasites speciate in tandem with their hosts, its called cospeciation. In lice, we see this pattern over and over again. We also see it in the bacteria that live within the lice

Mammals, Lice, & Bacteria

Some lice are blood feeders, which often have bacteria that help them survive. These bacteria are symbionts that live within the lice. Like the lice they are very specific about the hosts they associate with. They also cospeciate with their hosts. In all, we have three very different organisms (mammals, lice, and bacteria) that have evolved together for millions of years.

We use these organisms to answer questions about host ecological interactions, which provide opportunities for the parasites to switch hosts.

We also use this assemblage to study how genomes evolve.