Reproductive Strategies: Food Availability as a Source of Proximal Variation in a Lizard

Abstract

Reduced food availability in 1974 significantly altered the reproductive characteristics of a population of Urosaurus near Animas, Hidalgo County, New Mexico compared to 1973. Relative food availability, which was monitored using sticky traps, was attributed to reduced precipitation levels. Fat storage prior to reproduction was greatly reduced in 1974. As a result, size of the first clutch was reduced from 10.9 (1973) to 6.8 eggs, and clutch frequency was reduced from two clutches by most females (90%) in 1973 to only one clutch in 1974 (8.7% produced two). The reproductive strategy in this population of Urosaurus compared to that previously presented for a Texas population differs primarily by a restriction of the reproductive season and reduced clutch frequency but an increase in clutch size. The limited reproduction in a low resource year may represent an adaptation to reduce risk and effort when current reproduction is less profitable than survivorship and future reproduction