FAWLEY, MARVIN W.1, KAREN P. FAWLEY1, and MICHELLE L. DEAN2.* 1Department of Biological Sciences, North Dakota State University, Fargo, ND 58105; 28715 W. Mallard Ct., Franklin, WI 53132. - Assessing the biodiversity of Monoraphidium using 18S rDNA sequences.
The taxonomy of the genus Monoraphidium is unclear due in part
to the absence of morphological features to clearly distinguish one
species from another. Phytoplankton samples collected from lakes in
the Arrowwood National Refuge in eastern North Dakota were found to
contain several morphological species of Monoraphidium.
Eighteen Monoraphidium isolates were examined with light
microscopy and 6 morphological species were identified. PCR-RFLP of
the 18S rDNA was used to type the isolates. Following digestion by
Hae III and Taq I, the 18S rDNA PCR-RFLP patterns
indicated 10 different types. Presently, the 18S rDNA product is being
sequenced for each of the ten types. By examining morphological
characters and 18S rDNA sequences, congruence between morphology and
sequence data may be compared. Also, because there is a lack of
morphological characters defining Monoraphidium species,
diversity within the 18S rDNA sequences may aid in the taxonomy of the
genus and its place within the Chlorococcales. Supported by National
Science Foundation grants MCB-0084188 and DBI-0070387.
Key words: 18S rDNA, Monoraphidium, PCR-RFLP