Relationship between Clutch Development and Variation in Fatbody Mass and Liver Mass of Female Keeled Earless Lizards, Holbrookia propinqua (Sauria: Iguanidae)

Abstract

A study was conducted on changes in fatbody mass and liver mass during reproduction of female Holbrookia propinqua. Fatbody mass was inversely correlated with clutch mass, indicating that fatbodies were depleted as clutches developed. The major depletion of fatbodies occurred in the early stages of clutch development. Fatbodies were essentially depleted during production of the first clutch and remained small until the post-reproductive period. Liver mass of reproductive females was significantly greater than that of non-reproductive females. Apparently, fatbody lipid was mobilized to the liver at the onset of reproduction. Liver mass was high during formation of the first and second clutches, but was significantly lower during formation of the third clutch. The decrease in liver mass was possibly due to use of stored lipid for egg production at a time when ingestion supplied insufficient energy. It is suggested that fatbodies may serve to insure a reserve of lipid in the liver to supplement clutches which are produced during periods of low energy intake.