QUANTITATIVE GENETICS OF JUVENILE GROWTH AND SHAPE IN THE MUD CRAB EURYPANOPEUS DEPRESSUS 1.

Rates of growth and development were measured for the first six molts following the crab 1 stage in the mud crab Eurypanopeus depressus. The genetic contribution to variation in growth rate, development rate, and shape was determined for each molt interval. Genetic variation in growth rate, measured as increases in both width and length, was evident at most molt intervals. There were also significant genetic effects upon the intermolt interval. Growth rates for each molt interval, calculated on a daily basis to remove the interaction between growth rate and development rate also showed genetic variation. There was no evidence that genetic variation in these parameters changed during early juvenile development; there were substantial levels of genetic variation in growth rate at most ontological stages. Despite high levels of genetic variation for growth rate in dimensions of the carapace, there was no evidence of genetic variation in shape. This analysis does not provide a quantitative estimate of the levels of genetic variance for these traits but does indicate that the magnitude of this source of variance must be very significant.