A new tool to better understand coevolution between associated organisms

What is it about?

It is a well known fact that hosts and parasites, or other similarly associated organisms, such as pollinators and flowering plants, evolve in concert. Scientists have struggled to better understand the patterns and processes behind this concerted evolution. PACo (Procrustes Approach to Cophylogeny) renders a new tool to study the congruence between phylogenetic trees of hosts and their associated parasites. We analyze the statistical properties of PACo and show that it is a sound method to determine whether the phylogenies are congruent or not, which indirectly indicate the degree of cospeciation between parasites and their hosts.

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Why is it important?

PACo is unique in that it produces an informative graphical output for both global evaluation of the fit and assessing the contribution of the individual host-parasite links. PACo is also a more specific test than other previous methods since it is especially suited for systems where dependence of one phylogeny upon another is assumed. Thus it is ideal to test for the common coevolutionary model that assumes that parasites that spend part of all their life in or on their hosts track the phylogeny of their hosts or in studies of historical area relationships that are expected to determine taxa diversification. In addition, PACo stands out by its overall higher statistical power. For greater usability, PACo can be implemented in the public-domain statistical software R.