VARIATION IN MORPHOLOGY, ECOLOGY, AND TOXICOLOGICAL RESPONSES OF COLPODA-INFLATA (STOKES) COLLECTED FROM 5 BIOGEOGRAPHIC REALMS

Recent studies have revealed low genetic variation within soil isolate s of Colpoda inflata from several biogeographic realms, prompting us t o question whether such isolates mere equally similar with respect to morphological and ecological variables. We also compared the sensitivi ty of these isolates to acute exposure to three heavy metals (copper, zinc and cadmium), since toxicological response may reflect difference s in morphological or ecological parameters. Multivariate analysis of twelve morphological parameters revealed substantial overlap among the six isolates. Isolates from USA and Canada and isolates from China an d Kenya tended to cluster together, respectively. Isolates from Mexico and Russia appeared to be intermediate between these two groups, Isol ates from China exhibited the greatest growth rate in contrast to the lowest shown by isolates from USA and Canada. Growth rates following e xposure to per, did not differ among the six isolates, however, Kenya isolate appeared to be the most sensitive to zinc and cadmium. Aside f rom the Kenya isolate, variation among the other five isolates was rel atively small although they were isolated from soils from four biogeog raphic realms. Our results indicate that morphological, ecological and toxicological variation within C. inflata isolates is sufficiently lo w especially among those from the Northern hemisphere, to allow the us e of native populations of this species in screening tests for toxicit y assessment.