Cophylogenetic analyses reveal extensive host-shift speciation in a highly specialized and host-specific symbiont system

Host-shift speciation and cospeciation are the two major processes driving symbiont macroevolutionary diversification. Cospeciation is expected to be frequent in vertically transmitted and host-specific symbionts, and leads to congruent host-symbiont phylogenies. However, the cophylogenetic dynamics of many groups of highly specialized host-specific symbionts is largely unstudied. Thus, the relevance of cospeciation vs. host-shift speciation...