On the Origin of Species
When two groups of an organism no longer mate with each other, we recognize them as separate species. Reproductive isolation can arise when groups of plants accrue adaptations to different pollinators. Columbine (genus Aquilegia) flower petals have a unique shape, forming a tube (spur) that produces nectar desirable to pollinators. Hummingbirds are attracted to the red and yellow color of A. formosa and most efficiently transfer pollen between short spurred flowers (right, center). Hawkmoths are attracted to the white color of A. pubescens and most efficiently transfer pollen between long spurred flowers (left, center). We can use natural hybrids of these species in which color and spur length vary (petals imaged using an Epson Perfection V370 scanner) in order to identify the genes that cause variation in these traits, adding to our knowledge of the genetic basis of the process of speciation.