Seasonal Fluctuations in Liver and Fat Body Weights of the Japanese Lacertid Takydromus tachydromoides Schlegel

Abstract

Seasonal fluctuations in liver and fat body weights were studied in a population of Takydromus tachydromoides (Lacertidae) during two annual cycles. Liver and fat body weights are at minimum levels in late summer and rise rapidly in September and early October prior to hibernation. Livers of adult females and juveniles of both sexes show no apparent weight loss, but livers of adult males decrease in weight during hibernation, and continue to decline throughout spring and early summer. Livers of juvenile males and all females increase in weight during spring; those of adult females decrease during formation of clutches two and three in June and early July. Fat bodies of each age group of both sexes decrease in weight by approximately 50% during hibernation. Fat bodies of males continue to decline until July, although those of juvenile males increase immediately following hibernation. Adult and juvenile females increase fat reserves until vitellinogenesis for the first clutch increases sharply in the last half of April by adults and in late May by juveniles. Later clutches then exhaust remaining fat reserves. Fat bodies of adult females decreased in weight by 83 and 74% during formation of clutch one in 1966 and 1967. Age differences exist in proportionate organ weights of each sex during much of the season. During formation of clutch one, second year females had available approximately three times as much fat as did first year females.