"It is hard not to be curious about the origin of the curious rat's tail of Babiana ringens, which is unique in the flowering plants," commented Anderson.
"We noticed that in populations of the sister species, B. hirsuta, many plants had suffered damage from herbivores, with the upper portions of the stems completely eaten off," De Waal noted. "We then started to wonder: what if herbivory could contribute to selection for the floral display in B. ringens?"
Given the close phylogenetic relatedness of these species and their similar floral morphologies and pollinators, De Waal and colleagues hypothesized that the specialized bird perch in B. ringens may have originated from a B. hirsuta-like ancestor through reduction in the production of the side branches. This could happen if mammalian herbivores preferentially eat apical flowers and left the basal flowers alone.
Indeed, when De Waal and co-authors compared herbivory rates in three B. hirsuta and three B. ringens populations, they found much higher levels of herbivore damage to B. hirsuta---as much as 53% of the inflorescences were eaten. Moreover, they found that Cape grysbok (the primary herbivore) mostly grazed the top parts of inflorescences, leaving the basal parts to continu
|Contact: Richard Hund|
American Journal of Botany