The Effect of Light on Rates of Cloning of the Symbiont-Bearing
Acoel Convolutriloba longifissura The acoel turbellarian
Convolutriloba longifissura reproduces primarily by asexual
fission and engages in an obligate symbiotic relationship with
unicellular algae belonging to the genus Tetraselrnis. The
obligate nature of the symbiosis between these species suggests
that algal photosynthesis may influence rates of flatworm
asexual reproduction. To test this hypothesis we explored the
effect of light on C. longifissura 's ability to clone. Worms
(n= 18/treatment) were incubated at light regimes of total
darkness, 8L:16D, and 12L:12D for 30 days at 26 ± 10C. Worms
held in complete darkness experienced 100% mortality after 14
days; mortality in all other light treatments was <4% . Cloning
increased with a greater exposure to light (p=0.03). The average
rate of cloning for worms exposed to 8L:16D light cycle was
0.022/day; rates of cloning by individuals held at 12D:12L was
nearly 3X greater (0.061/day). Flatworm l