Plants growing in similar climates with extensively overlapping distributions may exhibit similar phylogeographic patterns, due to similarities in range shifts during past climatic oscillations. We tested and exploited this expectation in a comparison of the evolutionary and demographic histories of two related and co-distributed species endemic to Japan – Rhododendron pentaphyllum and R. quinquefolium. Genetic variation in sequences of noncoding chloroplast DNA regions and hundreds of nuclear single nucleotide polymorphisms were used to investigate 191...