The prevalent view about genetic structuring in parasitic plants is that host-race formation is due to varying degrees of host specificity. However, the relative importance of ecological niche divergence and host specificity remains poorly understood.
In our most recent publication (New Phytologist, in press) we analyzed the genetic structure of the widely-distributed, ecologically diverse Psittacanthus schiedeanus mistletoe complex (Loranthaceae). These analyses suggested that the population genetic structure of the parasite is largely determined by its own climatic niche and to a lesser degree by host specificity. This indicates that the processes associated with the genetic differentiation of populations appears to be more complex than previously thought.
The characteristic bright orange flowers of Psittacanthus schiedeanus in Santiago Comaltepec, Oaxaca. (photo by S Ramírez B)