External Seminar: Stuart Barber (Leeds)

[Statistics & Probability Seminar]

Analysing cospeciation using an electrical circuit analogy

Imagine an evolutionary "arms race", where a host tries to develop defences against a parasite and the parasite tries to catch up. This is an example of cospeciation with two "trophic layers" -- host and parasite. Meanwhile, there can be more layers in the system if the host species' food source is also evolving, or the parasite is in turn prey to another species. Each layer has its own phylogeny, or evolutionary family tree, and there is a set of links between trees showing which species interacts with which other species.  One question of interest is which trees appear to be involved in the cospeciation? More subtly, which trees show more cospeciation than can be explained by their interactions with the other trees?  It turns out that we can use the analogy of an electrical circuit, where the tree branches and interactions are equivalent to wires in a circuit, to create a statistic which we can use to address this problem.

Joint work with Colleen Nooney, Arief Gusnanto, & Walter R. Gilks.