N. Bowers et al., Diversity and geographic distribution of riboprints from three cosmopolitan species of Colpoda Muller (Ciliophora : Colpodea), EUR J PROT, 34(4), 1998, pp. 341-347
Ribosomal RNA gene restriction site polymorphisms were determined for 114 i
solates of three cosmopolitanly distributed species of Colpoda, a common so
il ciliate genus. Isolates were obtained from soil samples and identificati
ons confirmed using silver staining techniques. Based on restriction site a
nalysis of a 1095 bp region of the large subunit (LSU) rRNA gene, thirty-on
e distinct riboprints were observed; 11 unique to Colpoda steinii, 8 unique
to Colpoda inflata, 10 unique to Colpoda cucullus, and two riboprints shar
ed by several isolates of C. inflata and C. cucullus. The average intraspec
ific genetic distance estimated from riboprint data was greatest among C. s
teinii isolates (0.0790, n = 37), intermediate among C. cucullus isolates (
0.0519, n = 37), and the least among C. inflata isolates (0.0383, n = 40).
Phylogenetic analysis of riboprint data using distance methods revealed no
geographic pattern in the distribution of riboprints in any of the species
examined. Furthermore, many of the riboprints were globally distributed, su
ggesting no equatorial barrier to species dispersal in the species examined
. Several riboprints, however, appeared to be restricted on the basis of te
mperature, suggesting the possibility of fitness differences among riboprin
ts with respect to environmental variables. Shared riboprints between two s
pecies of Colpoda indicates the limitations of riboprints in species discri
mination within in this group, possibly due to the retention of ancestral p
olymorphisms or the inadequate resolution of the region of LSU rRNA gene th
at we examined. Additional molecular markers will be needed in order to res
olve this issue.