Figure 1 from Hudson & Price 2014, with illustrations by Emiko Paul. It depicts a couple exemplary groups of where sexual selection appears to have led to the evolution of multiple species. On the left, we have bellbirds: clockwise from top left, we have 3-wattled, White, Bare-throated, and Bearded Bellbirds; males look different, but females have remained similar. On the left, we have a similar system in the subspecies of Golden Whistler. Note that ALL of these species/subspecies are essentially allopatric.