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Distribution of two co-occuring bracken species Pteridium arachnoideum and Pteridium caudatum along an altitudinal gradient in the San Francisco valley, South Ecuador

DFG Mittel für Gleichstellungsmaßnahmen „Distribution of two co-occuring bracken species…“ Mittel aus dem Frauenförderfond der DFG-Forschergruppe 816“

Distribution of two co-occuring bracken species Pteridium arachnoideum and Pteridium caudatum along an altitudinal gradient in the San Francisco valley, South Ecuador

In Ecuador two representatives of bracken, Pteridium arachnoideum (diploid) and Pteridium caudatum (allotetraploid) co-occur in overlapping areas. Using morphological leaf characters for differentiation, P. arachnoideum is considered an upland species (1300 - 3200 m), while P. caudatum prefers the lowlands (600 - 2100 m) (Alonso-Amelot et al., 1995). In a similar investigation of the species composition around the Estación Científica San Francisco (1800 - 2000 m), the mixed stands were identified as P. arachnoideum as the dominant species with 84%, P. caudatum (15%), and putative intermediates (1%). Because of a high phenotypic plasticity and a high potential for hybridization and apomixis, morphological characters are not sufficient for a clear differentiation of bracken species. Thus, molecular markers as microsatellites represent a promising additional tool for the identification of specimens. Based on own studies, six microsatellites could be proven as useful to distinguish between the two occurring species (Roos, 2010).

In our project the natural habitat ranges of the two bracken species in Ecuador will be analysed using morphological characters and microsatellite markers. Therefore, an altitudinal transect starting at 1000 m (Kutzunza) until 2900 m (Argentina) was installed in April 2011. At each of the 6 sampling sites within the transect 40 bracken samples will be collected and analysed. The investigation is carried out in cooperation with the Centro de Biología Cellular y Molecular of the Universidad Técnica Particular de Loja by Ing. Marianne Montero with help of Ximena Cevallos (in the scope of her diploma thesis). After finalisation of sample collection and presorting by morphological characters in Ecuador, the microsatellite analysis will be carried out in the laboratory of DNA Analytics and Ecoinformatics of the University of Bayreuth.

References

Alonso-Amelot, ME & Rodulfo-Baechler, S (1996) Comparative spatial distribution, size, biomass, and growth rate of two varities of bracken fern (Pteridium aquilinum L. Kuhn) in an neotropical montane habitat. Vegetatio (Plant Ecology) 125: 137-147.

Roos, K (2010) Tropical bracken, a powerful invader of pastures in South Ecuador: Species composition, ecology, control measures, and pasture restoration. PhD thesis, University of Bayreuth.