Abstract Detail

Pollination Biology

Zweck, Justin [1], Arduser, Michael [2], Baum, Taylor [1], Meier, Retha [3].

Pollination ecology and interspecific isolation in two sympatric Dalea species.

Dalea candida and Dalea purpurea (Fabaceae) are sister taxa co-occuring in prairies and glades across the central U.S.A. Aside from their differently colored flowers these species strongly resemble each other and have overlapping flowering periods. Both possess spike inflorescences of many small flowers. Furthermore, their sexual organs are not enclosed within keel petals, unlike those Dalea species which have retained zygomorhpy. We compared the breeding systems and pollination ecology of sympatric, co-blooming populations of these two species in order to investigate the consequences of keel-less flowers and reproductive boundaries to interspecific hybridization. D. candida and D. purpurea shared 48% of flower-visiting insects representing 4 orders (Hymenoptera, Coleoptera, Diptera, Lepidoptera). The majority of visitors belonged to the bee families Apidae and Halictidae. A broad size range (length 4.34mm-19.45mm) of insects carried pollen, and there was no significant relationship between insect length and pollen presence for either Dalea species. Hand pollinations showed that pollen tubes reached the ovary in self, cross, and interspecies treatments. As previous studies showed limited seed set following self-pollination, we conclude that both species possess late acting (ovarian-type) self-incompatibility systems, as in other legumes. A form of late-acting incompatibility may also explain the lack of known hybridization between D. candida and D. purpurea, as so many pollinators are shared when these species bloom together. Evolution of the open, keel-free form of D. candida and D. purpurea flowers has permitted pollination by a wide range of generalist foragers. We hypothesize that pollination in Dalea species maintaining zygomorphy requires pollinators specialized in size and behavior.

Broader Impacts:

1 - Saint Louis University, Biology, 3507 Laclede Ave, Macelwane Hall, St. Louis, MO, 63103, USA
2 - 2360 HWY D, St. Charles, MO, 63304, USA
3 - Saint Louis University, Educational Studeis, 205 Summit Ridge Place, Weldon Spring, MO, 63304, USA

Keywords:
pollination
floral evolution
Fabaceae
sympatry.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PPL009
Abstract ID:579
Candidate for Awards:None