OBSERVATIONS ON MERISTIC VARIATION IN NINESPINE STICKLEBACKS, PUNGITIUS PUNGITIUS, REARED AT DIFFERENT TEMPERATURES

Abstract

Eggs of 10 pairs of wild ninespine sticklebacks from Hobson's Brook near Cambridge, England, were reared under various controlled temperatures. Temperature for optimum survival to hatching differed between genotypes. Ninety young were examined for counts of vertebrae, spines, and dorsal, anal, and pectoral fin rays. Survivors at high temperature had markedly more vertebrae than survivors at low. Curves of temperature against vertebral count may be V-shaped for each genotype, and optimum survival temperature may produce lowest vertebral count. More basal supports to the dorsal and anal fins and spines were produced at high temperature. Disruptions in one-to-one serial conformity between ray or spine, basal, and vertebral series became progressively commoner at higher rearing temperatures. Parents showed positive correlation between dorsal and anal fin ray counts and number of caudal scutes. Comparisons are made with Gasterosteus aculeatus.