Abstract Detail

Pollination Biology

Weller, Stephen G [1], Sakai, Ann K. [1], Campbell, Diane R. [1], Weisenberger, Lauren [2].

An enigmatic Hawaiian moth is a missing link in the adaptive radiation of Schiedea.

Island settings have provided insights into traits involved in adaptive radiations, including the evolution of breeding systems and pollination biology. The monophyletic genus Schiedea is one of the largest lineages in the Hawaiian Islands, with spectacular diversity in habitats and reproductive systems distributed among the 32 extant species. The ancestral condition for the group is hypothesized to be hermaphroditic with biotic pollination. The occurrence of species with separate sexes and wind pollination in dry, windy habitats is presumably a derived condition. In very wet habitats, facultative or obligate self-fertilization has evolved in a number of species. Despite the prediction of biotic pollination as the basal condition, this key element of the pollination biology has remained undocumented. In a study of a large experimental field population of Schiedea kaalae, we document that Pseudoschrankia brevipalpis (Erebidae), a recently-described moth species known only from O`ahu, removes nectar from the unique tubular nectary extensions of Schiedea flowers, suggesting that these very small flowers with their minute nectaries are highly specialized to attract and reward microlepidoptera. Pseudoschrankia brevipalpis is an effective pollinator of S. kaalae; single visits to emasculated flowers resulted in transfer of pollen, and flowers exposed to pollinators in the evening when moths were active accumulated pollen on stigmas as flowers aged. The numbers of pollen grains and moth scales deposited onto stigmas were strongly correlated, suggesting that the presence of moth scales is an indication that moths are active pollinators, even in the absence of direct observations. Discovery of biotic pollination of a hermaphroditic species of Schiedea is consistent with the hypothesis that the evolutionary shift from hermaphroditic, biotically pollinated species to species with separate sexes and wind pollination resulted from loss of pollinators in the dry, windy habitats where gynodioecious, subdioecious, and dioecious species are always found. The occurrence of abundant pollination by a previously unknown native moth in an experimental population of S. kaalae also suggests the potential for restoration of rare plant species to re-establish plant-pollinator interactions critical for production of outcrossed offspring with high fitness.

1 - University Of California Irvine, Department Of Ecology And Evolutionary Biology, 321 Steinhaus Hall, Irvine, CA, 92697, USA
2 - Oahu Army Natural Resources Program, University of Hawaii, Pacific Cooperative Studies Unit, Honolulu, HI, 96857, USA

Keywords:
moth pollination
pollinator effectiveness
microlepidoptera
Schiedea kaalae
Pseudoschrankia brevipalpis.

Presentation Type: Oral Paper
Session: 36, Pollination Biology
Location: 203/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 8:30 AM
Number: 36003
Abstract ID:138
Candidate for Awards:None