Growth and Heterozygosity in a 12‐Month‐Old Cohort of Ostrea chilensis Obtained by Mass Spawning in the Laboratory

Abstract

Abstract. Oysters Ostrea chilensis Philippi 1845. from a 40‐month‐old cohort which came from the natural population of the Quempillen River Estuary Southern Chile, were used as parental stock n = 600 for a hatchery‐produced cohort. At 12 months of age this cohort was analysed physiologically filtration rate, organic ingestion rate, absorption rate, assimilation efficiency, excretion rate, respiration rate and electrophoretically multilocus heterozygosity MLH using four loci: LAP, GPI, PGM, CA. Most physiological variables were positively correlated with dry weight P < 0.05. with the exception of assimilation efficiency, excretion size and net growth efficiency P > 0.05. Also. there was a positive correlation between body size, ingestion rate, absorption rate and net growth efficiency with MLH. Respiration rate and consequently energy losses were negatively correlated with MLH. The energetic efficiency product of a lower metabolic cost in the heterozygous individuals in this cohort is reflected in a higher net growth efficiency and a positive correlation between growth and MLH. The genetic basis for the relationship between metabolic parameters and heterozygosity can be due to an overdominance in this 12‐month‐old cohort.