Temperature-related differences in life-history characteristics between diploid and polyploid clones of the Daphnia pulex complex

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.