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32nd Annual Arctic Workshop Abstracts
March 14-16, 2002
INSTAAR, University of Colorado at Boulder

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EVOLUTION AND ENDEMISM OF FRESHWATER DIATOMS IN EAST ANTARCTICA

AUTHORS

SPAULDING, SARAH A . California Academy of Sciences.
McKnight, Diane M. INSTAAR.

Although it is often accepted that freshwater diatoms are widely distributed, recent evidence points increasingly to the regional distribution of species (Kociolek & Spaulding 2000). In Antarctica, a number of diatom species are endemic to the east, and the lakes of East and West Antarctica share very few species in common (Prescott 1979, Jones 1999). Diatoms endemic to lakes of East Antarctica may be considered along two separate gradients: one gradient lies in terms of evolutionary position, and the other lies in terms of distribution. The range of evolutionary position extends from relatively primitive or relatively advanced within a given diatom lineage. Similarly, historical distribution may range from existence as a relict of a warmer Antarctic continent to invasive species with a relatively recent history on the continent. We are examining the phylogenetic relationships of species endemic to East Antarctica in order to resolve the position of endemic taxa on each of these gradients. Evidence from records of Muelleria (Spaulding & Stoermer 1997, Spaulding et al. 1999) show that this genus has a long Antarctic history, and its distribution is more related to continental position than environmental conditions. While this appears to be the pattern for Muelleria, there may be alternate explanations for other taxa. We suggest that biogeographic distribution of individual species may lie on a spectrum ranging from historical contingency to ecological tolerance. Resolving the position of each taxon on this spectrum will aid in determining the evolutionary history of species and increase the utility of diatoms in making interpretations of paleoenvironments.

REFERENCES
Jones, V. 1999. The diversity, distribution and ecology of diatoms from Antarctic inland waters. Biodiversity and Conservation



Kociolek, J.P. & S.A. Spaulding. 1999. Freshwater diatom biogeography. Nova Hedwigia 71: 223-241.



Prescott, G.W. 1979. A contribution to a bibliography of Antarctic and Subantarctic algae. Bibliotheca Phycologica 45: 1-312.



Spaulding, S.A., J.P. Kociolek & D. Wong. 1999. A taxonomic and systematic revision of the genus Muelleria (Bacillariophyta). Phycologia 38: 314-341.



Spaulding, S.A. & E.F. Stoermer. 1997. Taxonomy and distribution of the genus Muelleria Frenguelli. Diatom Research 12: 95-113.

 

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