Abstract Detail

Conservation Biology

Paris, Nathan J. [1], Boyd, Robert Steven [1].

Floral biology of the federally threatened Apios priceana (Fabaceae) at Redstone Arsenal, Alabama.

Apios priceana (Price’s Potato Bean) is a federally threatened plant found in (usually) small, scattered populations in several U.S. states. Climbing stems emerge in late spring from underground tubers and make inflorescences of large, pink flowers that can produce many-seeded legumes. Stems die back to the tuber in fall. Seed production can be sporadic, and little is known about the pollination biology of the species. At a population at Redstone Arsenal, Alabama, we studied the breeding system, determined the major floral visitors and compared their pollination effectiveness, and explored the role of pollen limitation to fruit set and seed production. We also monitored fruit production over several seasons to document yearly variation and explore the relationship between rainfall patterns and flower/fruit production. For the breeding system study, fruit initiation was low for cross-pollinated flowers (3.9%) but still was significantly greater than for self-pollinated or non-pollinated flowers, none of which initiated a fruit. The vast majority of floral visits (97% of 564 visits) were by bees with 43% of visits by large bees(>1.5 cm in length) and 51% by medium bees (1-1.5 cm in length). In flowers of this legume species, the keel petals enclose the style and stamens and flowers must be “tripped” to expose the stigma for pollination. Large and medium bees were equally effective in tripping flowers, whereas small bees (< 1 cm in length) did not trip flowers. The success of several large bee species (Bombus and Megachile) in initiating legumes after a single floral visit ranged from 17-35% but did not differ significantly among bee species. A pollen supplementation study showed that initiation of legumes was pollen-limited, as 24% of supplemented flowers produced fruits compared to only 6% of non-supplemented (control) flowers. Comparison of seed counts in legumes from the two treatments revealed a trend for more seeds to be produced in legumes from pollen-supplemented flowers (but this was only marginally significant: P=0.067). Over a four-year period, there was a strong linear relationship between flowering season (April-June) rainfall and fruit production, suggesting that rainfall was a primary controller of reproductive output. We conclude that this rare plant species is dependent on large-bodied bees for successful pollination and fruit initiation, and that seed output is partially pollen-limited. A more important controlling factor, however, is flowering season rainfall, as Apios priceana produces few seeds in low-rainfall years due to abortion of inflorescences, flowers and legumes.

1 - Auburn University, Department Of Biological Sciences, 101 ROUSE LIFE SCIENCES BLDG, AUBURN UNIVERSITY, AL, 36849-5407, USA

Keywords:
conservation
Reproductive Biology
pollination biology
Fabaceae.

Presentation Type: Poster
Session: P, Conservation Biology Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PCB004
Abstract ID:339
Candidate for Awards:None