Evolutionary transitions between mechanisms of sex determination in vertebrates - PubMed (original) (raw)

Evolutionary transitions between mechanisms of sex determination in vertebrates

Alexander E Quinn et al. Biol Lett. 2011.

Abstract

Sex in many organisms is a dichotomous phenotype--individuals are either male or female. The molecular pathways underlying sex determination are governed by the genetic contribution of parents to the zygote, the environment in which the zygote develops or interaction of the two, depending on the species. Systems in which multiple interacting influences or a continuously varying influence (such as temperature) determines a dichotomous outcome have at least one threshold. We show that when sex is viewed as a threshold trait, evolution in that threshold can permit novel transitions between genotypic and temperature-dependent sex determination (TSD) and remarkably, between male (XX/XY) and female (ZZ/ZW) heterogamety. Transitions are possible without substantive genotypic innovation of novel sex-determining mutations or transpositions, so that the master sex gene and sex chromosome pair can be retained in ZW-XY transitions. We also show that evolution in the threshold can explain all observed patterns in vertebrate TSD, when coupled with evolution in embryonic survivorship limits.

PubMed Disclaimer

Figures

Figure 1.

Figure 1.

Transitions between sex-determining mechanisms caused by shifts in the sex-determining threshold. Black curves, magnitude of the regulatory signal for male development (arbitrarily scaled); dashed blue line, threshold value for male development; dashed red line, nest site distribution; vertical red lines, upper _T_H and lower _T_L thermal limits for embryo viability; solid blue line, population thermal reaction norm for sex ratio. (a_–_c) Effect of increasing the threshold for male development; (d_–_f) the effect of decreasing the threshold.

Figure 2.

Figure 2.

Evolutionary continua of sex-determining systems for populations with thermosensitivity in (a) male or (b) female differentiation. Red lines, threshold values at transition points between sex-determining systems; coloured bars, relative genotypic frequencies at equilibrium. Viability limits = −1.0, 1.0; nest survival = 95%; initial genotypic frequencies ZZ : ZW : WW = 1 : 1 : 1.

Similar articles

Cited by

References

    1. Sinclair A. H., Berta P., Palmer M. S., Hawkins J. R., Griffiths B. L., Smith M. J. 1990. A gene from the human sex-determining region encodes a protein with homology to a conserved DNA-binding motif. Nature 346, 240–24410.1038/346240a0 (doi:10.1038/346240a0) - DOI - DOI - PubMed
    1. Koopman P., Gubbay J., Vivian N., Goodfellow P., Lovellbadge R. 1991. Male development of chromosomally female mice transgenic for Sry. Nature 351, 117–12110.1038/351117a0 (doi:10.1038/351117a0) - DOI - DOI - PubMed
    1. Smith C. A., Roeszler K. N., Ohnesorg T., Cummins D. M., Farlie P. G., Doran T. J., Sinclair A. H. 2009. The avian Z-linked gene DMRT1 is required for male sex determination in the chicken. Nature 461, 267–27110.1038/nature08298 (doi:10.1038/nature08298) - DOI - DOI - PubMed
    1. Bull J. J. 1983. Evolution of sex determining mechanisms. San Francisco, CA: Benjamin/Cummings Publishing Company
    1. Bull J. J. 1985. Sex determining mechanisms: an evolutionary perspective. Experientia 41, 1285–129610.1007/BF01952071 (doi:10.1007/BF01952071) - DOI - DOI - PubMed

Publication types

MeSH terms

LinkOut - more resources