Another important discovery was the finding that in "Babiana ringens perch size and flower size were of different sizes depending on the geographical location of populations. We found that the bigger the perch, the more birds visited the plant. If that's the case, then why do some Babiana ringens plants have small perches?"
To find out what happened if no birds visited, the team experimented with self-pollination. "If you're a plant that's adapted for cross-pollination we might not expect self-pollination to be very successful: it's better for a species if genes are spread around, whereas self-pollination can lead to severe inbreeding. Indeed one of the Babiana species that were investigated B. hirusta was largely self-sterile but the remaining species that were investigated could set seed from self-pollination.
"What we also found with Babiana ringens is that the perch length was smaller in the east of our survey area. This is the region where we saw fewest sunbird visits to plants. So with fewer pollinators around there's less natural selection to maintain large perches, and it also makes sense to have self-pollination as a back-up when the alternative may be no pollination at all".
Barrett is pleased that the work provides insight into the most specialized bird perch in the plant kingdom, but warns that there is still much that we do not know about how the perch evolved in the first place: "Our research shows a clear functional basis between perches and bird pollination, but that's not all it shows. At the same time we're also seeing self-pollination and it's clear Babiana can adopt different mating strategies in diffe
|Contact: David Frost|
Oxford University Press