Sons are made from old stores: sperm storage effects on sex ratio in a lizard

Authors

Tonia S. Schwartz, University of WollongongFollow
Mats M. Olsson, The University Of SydneyFollow
Tobias O. Uller, University of WollongongFollow
Mo Healey, University of WollongongFollow

RIS ID

22723

Publication Details

Olsson, M. M., Schwartz, T. S., Uller, T. O. & Healey, M. (2007). Sons are made from old stores: sperm storage effects on sex ratio in a lizard. Biology Letters, 3 491-493.

Abstract

Sperm storage is a widespread phenomenon across taxa and mating systems but its consequences for central fitness parameters, such as sex ratios, has rarely been investigated. In Australian painted dragon lizards (Ctenophorus pictus), we describe elsewhere that male reproductive success via sperm competition is largely an effect of sperm storage. That is, sperm being stored in the female reproductive tract out-compete more recently inseminated sperm in subsequent ovarian cycles. Here we look at the consequences of such sperm storage for sex allocation in the same species, which has genetic sex determination. We show that stored sperm have a 23% higher probability of producing sons than daughters. Thus, shifts in sex ratio, for example over the reproductive season, can partly be explained by different survival of son-producing sperm or some unidentified female mechanism taking effect during prolonged storage.