Integrating Plant Systematics
Bogonovich, Marc , Watson, Maxine .
Broad-Scale Patterns of Richness of North American ferns at three different taxonomic levels.
Continental patterns of species richness are examined for the Pteridophytes of North America, north of Mexico. In a comparison of the strength of correlations of family, genera and species richness with environmental variables, we test the hypothesis that biological diversity is governed (or best understood) at the species level rather than higher taxonomic levels of organization. In selecting the ferns, a separate phylogenetic branch from most other plant species studied, we are able to assess the generality of patterns among plant groups and, by comparison with studies of tropical ferns in Africa and Australia, geographic generality.
In contrast to expectations, we find stronger correlations between environmental variables and family richness than species richness (AET and family richness R2 = 0.61, AET and species richness R2 = 0.38). In addition, a multiple regression including AET and annual temperature explained 70.2% of the variation in pteridophyte family richness while only explaining 44.5% of the variation in species richness. These results suggest that for the pteridophytes in North America, mechanisms that control biological diversity on a continental scale do not operate or are obscured at the species level. Finally, North American ferns exhibit multiple species richness peaks two of which are at mid-latitudes and are spatially concordant with the glacial maximum; suggesting a possible role of glaciations in the generation of fern species richness.
This study represents one kind of biogeographical application of GIS mapping and herbarium data integration. This study assesses richness from GIS range maps ultimately based on herbarium records; therefore, studies like this would profit from integrated herbarium databases. Such databases would both allow comprehensive studies of richness distribution and species distribution, with conservation and management implications in the context of a changing climate.
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1 - Indiana University, Bloomington, Biology Department, 1001 E Third St, Jordan Hall rm 142, Bloomington, IN, 47405, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Boulevard C/Hilton
Date: Wednesday, July 11th, 2007
Time: 3:30 PM