| Abstract Detail
Recent Topics Posters Stanton-Geddes, John [1], Miller, Jill S. [2]. Gynodioecy in Lobelia siphilitica and L. spicata (Lobeliaceae) from western Massachusetts. Gynodioecy is a polymorphic sexual system in which male-sterile plants (i.e., females) coexist with hermaphroditic individuals in populations. Previous studies of two species of Lobelia in North America have documented gynodioecy in parts of their ranges, but to date no study has examined these species in the Northeast. Here, we document gynodioecy for a single population of L. siphilitica and in two populations of L. spicata from western Massachusetts. The frequency of female plants was only 3% in L. siphilitica, whereas both populations of L. spicata contained 12% females, a result similar to the overall ratio recorded for herbarium specimens of this species. Consistent with previous studies, hermaphrodites in both species were self-compatible and estimates of mating system parameters confirmed mixed-mating in L. spicata. Females (compared to hermaphrodites) of L. spicata had higher fruit and seed production and showed significant floral size dimorphism. In contrast, there was no sexual dimorphism and no differences in fruit and seed set between females and hermaphrodites in L. siphilitica. Herbarium records indicate that these two congeners are well separated temporally in the Northeast and that northeastern collections of L. spicata, but not L. siphilitica, flower significantly later in the season compared to herbarium specimens collected from outside this region. Further, we confirm Bowden's (1959) re-classification of L. spicata var. campanulata, given that this variety is a pollen-sterile form (i.e., female) of L. spicata.
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1 - University of Minnesota, Ecology, Evolution and Behavior, 100 Ecology Bldg, 1987 Buford Cir., St. Paul, MN, 55108, USA
2 - Amherst College, Department of Biology, Mcguire Life Sciences Building, Amherst, Massachusetts, 01002, USA
Keywords:
Lobelia spicata
Lobelia siphilitica
sex ratios
gynodioecy
herbarium records
self-fertilization
sexual dimorphism
mating system.
Presentation Type: Recent Topics Poster
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P79028
Abstract ID:2718 |
