Temperature-Dependent Sex Determination in Podocnemis expansa (Testudinata: Pelomedusidae)

Biotropica ◽  
1985 ◽  
Vol 17 (1) ◽  
pp. 75 ◽  
Author(s):  
Cleber J. R. Alho ◽  
Tania M. S. Danni ◽  
Luiz F. M. Padua
Keyword(s):  
Sex Determination ◽  
Temperature Dependent ◽  
Podocnemis Expansa

scholarly journals Podocnemis expansa Turtles Hint to a Unifying Explanation for the Evolution of Temperature-Dependent Sex Determination in Long-Lived and Short-Lived Vertebrates

2021 ◽  
pp. 1-15
Author(s):  
Nicole Valenzuela
Keyword(s):  
Sex Determination ◽  
Resource Availability ◽  
Incubation Temperature ◽  
Genetic Data ◽  
Adaptive Significance ◽  
Temperature Dependent ◽  
Flood Plains ◽  
Optimal Resource ◽  
Technical Advances ◽  
Podocnemis Expansa

The adaptive significance of temperature-dependent sex determination (TSD) remains elusive for many long-lived reptiles. Various hypotheses proposed potential ecological drivers of TSD. The Charnov-Bull’77 model remains the most robust and explains the maintenance of TSD in short-lived vertebrates, where sex ratios correlate with seasonal temperatures within years that confer sex-specific fitness (colder springs produce females who grow larger and gain in fecundity, whereas warmer summers produce males who mature at smaller size). Yet, evidence of fitness differentials correlated with incubation temperature is scarce for long-lived taxa. Here, it is proposed that the Charnov-Bull’77 model applies similarly to long-lived taxa, but at a longer temporal scale, by revisiting ecological and genetic data from the long-lived turtle <i>Podocnemis expansa</i>. After ruling out multiple alternatives, it is hypothesized that warmer-drier years overproduce females and correlate with optimal resource availability in the flood plains, benefitting daughters more than sons, whereas resources are scarcer (due to reduced flowering/fruiting) during colder-rainier years that overproduce males, whose fitness is less impacted by slower growth rates. New technical advances and collaborative interdisciplinary efforts are delineated that should facilitate testing this hypothesis directly, illuminating the understanding of TSD evolution in <i>P. expansa</i> and other long-lived TSD reptiles.

scholarly journals Molecular and Cellular Mechanisms Underlying Temperature-Dependent Sex Determination in Turtles

2021 ◽  
pp. 1-9
Author(s):  
Horacio Merchant-Larios ◽  
Verónica Díaz-Hernández ◽  
Diego Cortez
Keyword(s):  
Animal Models ◽  
Sex Determination ◽  
Incubation Temperature ◽  
State Of The Art ◽  
Current Understanding ◽  
Temperature Dependent ◽  
Cellular Mechanisms ◽  
Male Phenotype ◽  
History Of ◽  
Reptilian Species

The discovery in mammals that fetal testes are required in order to develop the male phenotype inspired research efforts to elucidate the mechanisms underlying gonadal sex determination and differentiation in vertebrates. A pioneer work in 1966 that demonstrated the influence of incubation temperature on sexual phenotype in some reptilian species triggered great interest in the environment’s role as a modulator of plasticity in sex determination. Several chelonian species have been used as animal models to test hypotheses concerning the mechanisms involved in temperature-dependent sex determination (TSD). This brief review intends to outline the history of scientific efforts that corroborate our current understanding of the state-of-the-art in TSD using chelonian species as a reference.

scholarly journals Evolutionary transitions between mechanisms of sex determination in vertebrates

2011 ◽  
Vol 7 (3) ◽  
pp. 443-448 ◽  
Author(s):  
Alexander E. Quinn ◽  
Stephen D. Sarre ◽  
Tariq Ezaz ◽  
Jennifer A. Marshall Graves ◽  
Arthur Georges
Keyword(s):  
Sex Determination ◽  
Chromosome Pair ◽  
Sex Chromosome ◽  
Molecular Pathways ◽  
Genetic Contribution ◽  
Temperature Dependent ◽  
Trait Evolution ◽  
Evolutionary Transitions ◽  
Dichotomous Outcome ◽  
Threshold Trait

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.

scholarly journals Measurement and modelling of primary sex ratios for species with temperature-dependent sex determination

2018 ◽  
Vol 222 (1) ◽  
pp. jeb190215 ◽  
Author(s):  
Melanie D. Massey ◽  
Sarah M. Holt ◽  
Ronald J. Brooks ◽  
Njal Rollinson
Keyword(s):  
Sex Determination ◽  
Sex Ratios ◽  
Temperature Dependent
Sign in / Sign up

Export Citation Format

Share Document