F. Dufresne et Pdn. Hebert, Temperature-related differences in life-history characteristics between diploid and polyploid clones of the Daphnia pulex complex, ECOSCIENCE, 5(4), 1998, pp. 433-437
This study compares life-history characteristics of diploid and polyploid c
lones of the Daphnia pulex complex at different temperatures to better comp
rehend their co-existence in the low Canadian arctic. Life-history experime
nts revealed that polyploid clones had larger eggs and neonates, as well as
larger body sizes than diploid clones under 10 degrees C, 17 degrees C, an
d 24 degrees C. In contrast to high temperature results, polyploid clones m
atured earlier than diploid clones at 10 degrees C. Our results indicate th
at polyploid Daphnia may have a headstart over diploid clones at the beginn
ing of the reproductive season when temperature are low. The similarity bet
ween cold tolerance in polyploids and organisms with large genomes suggests
that it may be large cell size rather than large genomes or hybrid origin
that is of selective value in cold environments.