Adult sex ratios in captive reptiles, birds and mammals vary with the sex determination system

Authors:
Open Access
Publisher website
Google Scholar
Abstract
The adult sex ratio (ASR; the proportion of males in the adult population) is a key demographic trait that varies widely across species and is linked to mating systems and sexually selected traits. Previous research on wild tetrapods showed that ASR is associated with genotypic sex determination system: species with male-heterogamety (XY sex chromosome system) tend to have more female-biased ASRs than species with female-heterogamety (ZW system). If genotypic mechanisms of sex determination are involved, these may also shape ASRs in controlled environments. Here, we test the latter proposition using demographic data from 1,192 zoo-housed reptile, bird, and mammal species. Across amniotes, ASRs in captive populations follow patterns similar to those observed in the wild: XY species tend to have more female-biased ASRs than ZW species. Captive mammals and birds showed similar ASR biases as found in wild populations, although in reptiles, the clade with diverse sex determination systems, the ASR did not differ significantly between XY and ZW species. Instead, reptiles with temperature-dependent sex determination (TSD) differed from reptiles of both genotypic sex determination groups. Together these results support that non-ecological processes linked to sex determination systems contribute to ASR patterns both in captive and wild animals.
Funding Information
  • University of Pannonia

This publication has 69 references indexed in Scilit: