Abstract Detail

Pteridology

Furlong, Tristan [1], Kerstein, Chase [1], McKenna, Sarah [1], Holmlund, Helen [1], Nofziger, Donna E. [1].

Early Fern Gametophyte Growth Patterns Are Consistent with Sporophyte Niche Segregation in Four Chaparral Fern Species.

The fern life cycle alternates between two distinct phases: a diploid sporophyte phase and a haploid gametophyte phase. Early events and changes in gametophyte development can have considerable consequences in the morphologies of these different fern species and may facilitate the various adaptive strategies employed by the gametophytes in their different habitats. This study investigates early developmental events in the gametophytes of four different fern species found in the Santa Monica Mountains: Woodwardia fimbriata (riparian, evergreen sporophyte), Dryopteris arguta (chaparral understory, evergreen sporophyte), Adiantum jordanii (chaparral understory, summer deciduous sporophyte), and Pentagramma triangularis (chaparral understory, resurrection sporophyte). Previous studies have found differences among the sporophytes of these four species, revealing niche segregation with respect to water use. Consequently, we hypothesized that we would find differences in the growth rate and morphology of these gametophytes that may correspond to the sporophyte niche. Every 2-3 days between germination and 20 days post germination, images of developing gametophytes were captured using a Nikon Eclipse Ti2 inverted microscope. Gametophyte two-dimensional surface area, rhizoid number, and rhizoid length were recorded and analyzed using computational and image analysis software (Nikon NIS-Elements platform) in order to quantitatively examine the timing and patterns of key developmental events. Using morphological landmarks, a developmental staging system was created for early gametophyte development for all four species of ferns. Data analysis showed that W. fimbriata and A. jordanii had significantly greater area than D. arguta and P. triangularis (one-way ANOVA followed by Tukey’s HSD post-hoc test, p < 0.05). All four species had significantly different rhizoid lengths. A. jordanii also had a significantly greater number of rhizoids than P. triangularis. The results show that gametophyte growth patterns are consistent with observed sporophyte growth. W. fimbriata is riparian with a large sporophyte, and the gametophyte stage appears to have consistent patterns: large with long rhizoids that may provide a competitive advantage. A. jordanii also grows large with long rhizoids, which may indicate evolutionary constraint, because many other Adiantum species are riparian, clinging to rocks in streams and waterfalls. Despite the morphological disparity between the sporophyte and gametophyte stages, our data suggest that chaparral fern gametophytes follow the same growth patterns and strategies as their respective sporophyte.

1 - Pepperdine University, Department of Natural Science, 24255 Pacific Coast Hwy, Malibu, CA, 90263, USA

Keywords:
fern
gametophyte
chaparral
Development
Growth Patterns
Niche Partitioning
Staging.

Presentation Type: Poster
Number: PPT001
Abstract ID:397
Candidate for Awards:None