Partitioning Genetic and Environmental Components of Reproduction and Lifespan In Artemia

Abstract

Reproductive and lifespan characteristics were determined for 12 populations of the brine shrimp, Artemia. Based upon geographical distribution and reproductive mode these could be separated into three distinct groups: obligate parthenogenetic populations, Old World sexual populations, and New World sexual populations. The three groups were found to be distinctly different in regard to reproductive and lifespan characteristics. Variance levels were compared between uniparental and biparental populations, allowing estimates to be made of the relative contribution of the genetic and environmental components for 11 life history traits. The environmental portion was estimated to be 100% for encystment traits and for the length of the prereproductive period, while the number of offspring produced (both as a lifetime total and a production rate) and the recovery period between broods had genetic components for variance °50%. To test for the interrelatedness of life history traits, a correlation coefficient matrix was constructed. In contradiction to most theoretical assumptions, extremely now correlation coefficients were found between the length of the female prereproductive period and the remaining lifespan and reproductive traits. However, recovery time between broods showed a significant positive correlation with number of broods produced, total offspring produced, and female lifespan.