Bryological and Lichenological Section - ABLS 226
CHMIELEWSKI, MATTHEW* 1 and EPPLEY, SARAH 2
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FERNANDO, THILINA* 1, HERLIHY, CHRIS 2 and WALCK, JEFFREY 3
Bryophytes on the Wing: First Evidence of Widespread Bryophyte Spore Vectoring on Bird Surfaces
Role of local adaptation to abiotic factors during seed germination stage in the maintenance of flower color polymorphism in Leavenworthia stylosa
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ittle attention has been given to animals as potential vectors for bryophyte dispersal, despite experimental evidence that spore dispersal via air is often highly leptokurtic. The few studies addressing this phenomenon have focused on mammals or invertebrates mainly dispersing fragments of gametophytic tissue at the local level. Long distance dispersal by birds has been speculated, but the incidence of moss spore epizoochory has not been explicitly addressed. Given the close association of birds with mosses as nesting material as well as a reservoir of invertebrate food items, birds frequently come into contact with sporophytes that are actively releasing spores, many of which may adhere to the surface of bird feet and feathers. Avian behavior has the potential to vastly impact the ecological community composition of bryoflora at local and regional scales. Animal, and particularly avian dispersers are considered important vectors of seed plants due to their high vagility and preference for particular habitat locales. I hypothesized that bird surfaces would regularly harbor bryophyte spores, that these spores would belong to a variety of bryophyte taxa, be viable, and would be present across a variety of bird species. In addition, I hypothesized that prevalence of bryophyte spores would depend on avian behavioral group, with vector likelihood being dependent on ecological role rather than taxonomic similarity. Passerine birds were captured via mist nets in the Wind River Experimental Forest in Gifford Pinchot National Forest, WA. I topically sampled the legs, feet, and rectrices of each bird using cotton swabs. The number of spores from each sample were determined via microscopy before being germinated on nutrient agar plates. Bryophyte species were identified by PCR amplification and Sanger sequencing of the trnL region of the chloroplast genome. Abundance and species composition of spores were determined for each bird species, and comparisons made between birds with different ecological roles. These data provide the first evidence of the potential widespread avian-mediated dispersal of bryophytes. Given the influential role of birds on the dispersal of tracheophytes, this newly described relationship has the potential to fundamentally improve our understanding of how bryophyte communities are formed and maintained. This also provides an independent system in which the theories regarding the importance of vectors and modes of dispersal that have been developed in seed plants can be tested. Finally, understanding this relationship may enhance our ability to better project the development of epiphytic community recolonization in managed forested landscapes.
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nderstanding the mechanisms that maintain variation among populations is a main focus of evolutionary biology. Flower color which varies across the geographic range is a striking feature in many plant species. In addition to pollinator mediated selection, a growing body of knowledge suggests that this type of geographic variation can be maintained by local adaptation to abiotic conditions. Early life history stages of a plant such as seed germination may be especially sensitive to abiotic conditions such as soil type or water availability. Our study species Leavenworthia stylosa is a cedar glade endemic winter annual herbaceous species which is restricted to the inner central basin of Tennessee. It has two main flower color morphs: yellow and white, with most populations containing only one flower color morph. The goal of this study was to determine if local adaptation to abiotic factors and differential responses to abiotic stresses during the seed germination stage can play a role in maintenance of this geographic pattern of flower color distribution. We conducted two reciprocal transplant experiments, one with dormant seeds and one with non-dormant seeds. Seeds were collected from two yellow-flowered and two white-flowered source populations. Seeds from all source populations were transplanted into each of these four populations. To assess the effect of edaphic factors on seed germination in these L. stylosa sites, seed germination success of yellow and white morphs was determined in soil from each of the four transplant sites in the laboratory. In addition, seed dormancy break of the two color morphs was studied under a relative humidity gradient. Seed dormancy loss and seed germination of both color morphs was highest in white transplant sites. However, in the laboratory, there was no significant difference between white and yellow seed germination in each other’s soils. Under low relative humidity conditions white morphs showed a higher dormancy break compared to yellow morphs. Overall, our results suggest that the geographic pattern of the flower color variation cannot be explained by local adaptation to edaphic conditions at the seed germination stage.
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Portland State University, Biology, 1719 SW 10th Avenue, SRTC rm 246, Portland, OR, 97201, USA2Portland State University, Biology, 1719 SW 10th Avenue, SRTC rm 246, Portland, OR, 97201, United States
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Middle Tennessee State University, Biology, P.O. Box 60, Murfreesboro, TN, 37132, United States2Middle Tennessee State University, P.O. Box 60, Murfreesboro, TN, 37132, United States3Middle Tennessee State University, 1301 East Main St, PO Box 60, Murfreesboro, TN, 37132, USA
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