SANTA CRUZ, CA--Of the two bat species known to visit the flowers of the cardon cactus in Baja California, one depends entirely on nectar and is highly specialized to feed from the flowers, which are adapted for pollination by bats. The other is an insect-eating bat best known for its ability to hear the footsteps of large insects and scorpions and capture them on the ground.
In a surprising result, scientists at the University of California, Santa Cruz, have found that the insect-eating pallid bat is a more effective pollinator of the cactus flowers than the nectar-feeding specialist, the lesser long-nosed bat.
"The lesser long-nosed bat is highly specialized for nectar-feeding and was thought to be the primary pollinator of the cardon cactus. But when we measured their effectiveness, we found that the pallid bat actually delivers about 13 times as much pollen per visit," said Winifred Frick, a research scientist at UC Santa Cruz. Frick is first author of a paper on the new findings published online in American Naturalist.
The study highlights the complex nature of the mutually beneficial relationships between plants and their pollinators, which in most cases have evolved together over long periods of time. There are often conflicts of interest between the partners, according to coauthor Kathleen Kay, assistant professor of ecology and evolutionary biology at UC Santa Cruz.
"What is actually happening in terms of how species are mutually interacting can be more complicated than what meets the eye," Kay said. "You would think the coevolved species would be a better pollinator than a naive interloper. But the adaptations for nectar-feeding of the lesser long-nosed bat are to enable it to get more nectar, not for it to do a better job pollinating."
Frick said several factors may explain the difference between the two bat species in pollination effectiveness. The lesser long-nosed bat is able to hover at the
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University of California - Santa Cruz