Variation in nesting patterns affecting nest temperatures in two populations of painted turtles (Chrysemys picta) with temperature-dependent sex determination

2003 ◽  
Vol 53 (4) ◽  
pp. 254-261 ◽  
Author(s):  
Carrie L. Morjan
Keyword(s):  
Sex Determination ◽  
Chrysemys Picta ◽  
Temperature Dependent ◽  
Painted Turtles ◽  
Nesting Patterns ◽  
Two Populations

Sex determination in northern painted turtles: effect of incubation at constant and fluctuating temperatures

1985 ◽  
Vol 63 (11) ◽  
pp. 2543-2547 ◽  
Author(s):  
Lin Schwarzkopf ◽  
Ronald J. Brooks
Keyword(s):  
Sex Determination ◽  
Sex Ratios ◽  
Chrysemys Picta ◽  
Temperature Dependent ◽  
Northern Population ◽  
Painted Turtles ◽  
Threshold Temperatures ◽  
Warm Summer ◽  
Summer Temperatures ◽  
Fluctuating Temperatures

Temperature-dependent sex determination was studied in a northern population of painted turtles (Chrysemys picta) in both laboratory and field. Eggs incubated at constant temperatures of 30 and 32 °C produced females only, whereas those kept at 22, 24, and 26 °C produced males only. Both sexes occurred at 20 and 28 °C. The threshold temperatures (temperatures producing 50% males) were estimated to be 27.5 and 20.0 °C, and were similar to those reported for more southerly populations of C. picta. In both 1983 (a relatively warm summer) and 1984 (an average summer), temperatures in natural nests regularly fluctuated above and below both threshold temperatures. Mean nest temperatures were warmer in 1983 than in 1984, but were not useful to predict nest sex ratios. Mean nest temperatures were not similar to constant temperatures in their effect on sex ratio. Sex ratios in nests could be described best by the total number of hours for which the temperature at each nest was intermediate to the two threshold temperatures. Sex ratios (proportion male) of hatchlings in 1983 and 1984 were similar and female biased (0.12 and 0.13, respectively).

scholarly journals Inheritance of nesting behaviour across natural environmental variation in a turtle with temperature-dependent sex determination

2009 ◽  
Vol 277 (1685) ◽  
pp. 1219-1226 ◽  
Author(s):  
Suzanne E. McGaugh ◽  
Lisa E. Schwanz ◽  
Rachel M. Bowden ◽  
Julie E. Gonzalez ◽  
Fredric J. Janzen
Keyword(s):  
Sex Determination ◽  
Vegetation Cover ◽  
Incubation Temperature ◽  
Additive Genetic Variance ◽  
Thermal Conditions ◽  
Evolutionary Change ◽  
Temperature Dependent ◽  
Painted Turtles ◽  
Julian Date ◽  
Nesting Behaviour

Nesting behaviour is critical for reproductive success in oviparous organisms with no parental care. In organisms where sex is determined by incubation temperature, nesting behaviour may be a prime target of selection in response to unbalanced sex ratios. To produce an evolutionary change in response to sex-ratio selection, components of nesting behaviour must be heritable. We estimated the field heritability of two key components of nesting behaviour in a population of painted turtles ( Chrysemys picta ) with temperature-dependent sex determination by applying the ‘animal model’ to a pedigree reconstructed from genotype data. We obtained estimates of low to non-detectable heritability using repeated records across all environments. We then determined environment-specific heritability by grouping records with similar temperatures for the winter preceding the nesting season, a variable known to be highly associated with our two traits of interest, nest vegetation cover and Julian date of nesting. The heritability estimates of nest vegetation cover and Julian date of nesting were qualitatively highest and significant, or nearly so, after hot winters. Additive genetic variance for these traits was not detectable after cold winters. Our analysis suggests that the potential for evolutionary change of nesting behaviour may be dependent on the thermal conditions of the preceding winter, a season that is predicted to be especially subject to climate change.

Do low incubation temperatures yield females in painted turtles?

1992 ◽  
Vol 70 (2) ◽  
pp. 391-394 ◽  
Author(s):  
Cory R. Etchberger ◽  
Michael A. Ewert ◽  
Beth A. Raper ◽  
Craig E. Nelson
Keyword(s):  
Sex Determination ◽  
Histological Examination ◽  
High Temperatures ◽  
Low Temperatures ◽  
Incubation Temperature ◽  
Chrysemys Picta ◽  
Painted Turtles ◽  
Incubation Temperatures

The sex of painted turtles (Chrysemys picta) is determined by the incubation temperature of the egg. At high temperatures (> 30 °C), all females are produced, with a transition to all males at most lower temperatures (24–27 °C). However, two of three previous studies have reported that some females also result when incubation temperatures are low (20–22 °C). In this study C. picta eggs were incubated at low temperatures (21.5 and 22.5 °C); however, macroscopic and histological examination of both embryos and hatchlings did not confirm these reports. Thus, C. picta has, at least typically, the pattern of sex determination that is most common among the genera to which it is most closely allied.

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.

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