Leong, Joan M. , Jones, Marry .
Reproductive output and pollinator interactions of an endangered, montane Sidalcea species.
BIRD-FOOT checkerbloom, Sidalcea pedata, is an endangered species restricted to montane meadow habitats of the Big Bear Valley in the San Bernardino Mountains of Southern California. Little is known of the biology or ecology of this species, despite several surveys that have been done. This research investigated two key aspects of checkerbloom biology that are important to understand for conservation prioritization of S. pedata populations: reproductive output and pollination requirements. Patterns of fruit set, seed set, floral visitation and insect foraging were examined in five populations. All S. pedata populations examined were comprised of female and hermaphrodite individuals: prior surveys did not recognize the sex morphs even though many Sidalcea species are gynodioecious. In all populations, females had significantly greater fruit set then hermaphrodites. Hermaphrodites at all sites exhibited an interesting pattern of increasing fruit set with apical position on the stem. For females, this trend was much weaker. Female flowers had significantly more ovules than hermaphrodite flowers, though they are smaller in size. The number of viable seeds per fruit did not consistently differ between the two morphs at the three sites sampled. Floral visitation by insects differed markedly between the two S. pedata populations that were intensively observed. In one population, honey bees and bumble bees were the dominant floral visitors; at a second population, a diversity of small and medium sized bees in the families Halictidae and Megachilidae were the most abundant floral visitors. Observations of bees foraging on checkerbloom revealed significant variation in the number of flowers visited per stem among bumble bees, honey bees, and small-medium sized bees. Such differences in foraging suggest that there is functional diversity in the pollinator interactions observed and that some bee species may supply more geitonogamous pollination services than others.
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1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 West Temple Avenue, Pomona, California, 91768, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM