Segregating variation for temperature-dependent sex determination in a lizard

T. Rhen, A. Schroeder, J. T. Sakata, V. Huang, D. Crews

    Research output: Contribution to journalArticlepeer-review

    28 Scopus citations

    Abstract

    Temperature-dependent sex determination (TSD) was first reported in 1966 in an African lizard. It has since been shown that TSD occurs in some fish, several lizards, tuataras, numerous turtles and all crocodilians. Extreme temperatures can also cause sex reversal in several amphibians and lizards with genotypic sex determination. Research in TSD species indicates that estrogen signaling is important for ovary development and that orthologs of mammalian genes have a function in gonad differentiation. Nevertheless, the mechanism that actually transduces temperature into a biological signal for ovary versus testis development is not known in any species. Classical genetics could be used to identify the loci underlying TSD, but only if there is segregating variation for TSD. Here, we use the animal model to analyze inheritance of sexual phenotype in a 13-generation pedigree of captive leopard geckos, Eublepharis macularius, a TSD reptile. We directly show genetic variance and genotype-by-temperature interactions for sex determination. Additive genetic variation was significant at a temperature that produces a female-biased sex ratio (30 °C), but not at a temperature that produces a male-biased sex ratio (32.5 °C). Conversely, dominance variance was significant at the male-biased temperature (32.5 °C), but not at the female-biased temperature (30 °C). Non-genetic maternal effects on sex determination were negligible in comparison with additive genetic variance, dominance variance and the primary effect of temperature. These data show for the first time that there is segregating variation for TSD in a reptile and consequently that a quantitative trait locus analysis would be practicable for identifying the genes underlying TSD.

    Original languageEnglish (US)
    Pages (from-to)649-660
    Number of pages12
    JournalHeredity
    Volume106
    Issue number4
    DOIs
    StatePublished - Apr 2011

    Bibliographical note

    Funding Information:
    We thank the continuing support of NIH (MH57874) and NSF (IOS 0750938). The breeding of leopard geckos from 1992 to 2001 followed IACUC protocol A1469. We thank P Coomber and S Simmonds for their assistance with data collection. We also thank Lukas Kratochvíl and two anonymous reviewers for helpful comments on the paper.

    Keywords

    • maternal effects
    • quantitative genetics
    • reptile
    • sex ratio
    • temperature-dependent sex determination

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