Sex determination, longevity, and the birth and death of reptilian species

Niv Sabath, Yuval Itescu, Anat Feldman, Shai Meiri, Itay Mayrose*, Nicole Valenzuela

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Vertebrate sex-determining mechanisms (SDMs) are triggered by the genotype (GSD), by temperature (TSD), or occasionally, by both. The causes and consequences of SDM diversity remain enigmatic. Theory predicts SDM effects on species diversification, and life-span effects on SDM evolutionary turnover. Yet, evidence is conflicting in clades with labile SDMs, such as reptiles. Here, we investigate whether SDM is associated with diversification in turtles and lizards, and whether alterative factors, such as lifespan's effect on transition rates, could explain the relative prevalence of SDMs in turtles and lizards (including and excluding snakes). We assembled a comprehensive dataset of SDM states for squamates and turtles and leveraged large phylogenies for these two groups. We found no evidence that SDMs affect turtle, squamate, or lizard diversification. However, SDM transition rates differ between groups. In lizards TSD-to-GSD surpass GSD-to-TSD transitions, explaining the predominance of GSD lizards in nature. SDM transitions are fewer in turtles and the rates are similar to each other (TSD-to-GSD equals GSD-to-TSD), which, coupled with TSD ancestry, could explain TSD's predominance in turtles. These contrasting patterns can be explained by differences in life history. Namely, our data support the notion that in general, shorter lizard lifespan renders TSD detrimental favoring GSD evolution in squamates, whereas turtle longevity permits TSD retention. Thus, based on the macro-evolutionary evidence we uncovered, we hypothesize that turtles and lizards followed different evolutionary trajectories with respect to SDM, likely mediated by differences in lifespan. Combined, our findings revealed a complex evolutionary interplay between SDMs and life histories that warrants further research that should make use of expanded datasets on unexamined taxa to enable more conclusive analyses.

Original languageEnglish
Pages (from-to)5207-5220
Number of pages14
JournalEcology and Evolution
Issue number15
StatePublished - 1 Aug 2016


FundersFunder number
Sex Working Group
USA National Science Foundation
National Science Foundation2011-293878, 1244355, MCB 1244355
National Science Foundation
Edmond J. Safra Center for Ethics, Harvard University
National Evolutionary Synthesis Center
Iowa State University
Seventh Framework Programme293878
Seventh Framework Programme


    • Evolution and natural selection
    • life span and longevity, life history
    • phenotypic plasticity
    • sex chromosomes
    • sexual development
    • speciation, extinction, and net diversification
    • temperature-dependent (TSD) and genotypic (GSD) sex determination
    • turtles, lizards, snakes, and squamate reptiles
    • vertebrate speciation and extinction


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