INHERITANCE OF DEMOGRAPHIC AND PRODUCTION PARAMETERS IN THE MARINE COPEPODEURYTEMORA HERDMANI

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Abstract
Heritabilities (h2, the ratio of additive genetic variance to total phenotypic variance) were estimated for a number of traits of Eurytemora herdmani from families of known parents reared with excess food at 10°, 12.5°, and 15° C. Age of maturity was strongly heritable only among female offspring at 15° C and size only among male offspring at 15° C. This temperature is extreme for waters near Halifax, Nova Scotia. Low and sometimes nonsignificant heritabilities at 10° and 12.5° C are as expected at these natural temperatures for fitness traits that have had their genetic variance trimmed by natural selection. There were strong maternal (nongenetic) effects on age of maturity of males (which benefit from accelerated maturation) and on size, especially of females (which would benefit from enhanced fecundity). Adult size and age of maturity are negatively correlated, so that growth rate should be even more strongly heritable. There is a suggestion that survivorship (not significantly heritable) is maternally influenced (probably along with development rate) early in life. Unbalanced sex ratios appear to be controlled by a major gene, with polygenic overlay of variance. The genetic variations reported here may be important in the design of experiments with copepods, indicate capacity for quite rapid change of some traits in nature, but should not at this stage be taken as "typical" of marine copepods.