Literaturdatenbank
Literaturdatenbank |
|
 |
|
Georges, A., Doody, S. J., Beggs, K., & Young, J. E. (2004). Thermal models of tsd under laboratory and field conditions. In N. Valenzuela & V. Lance (Eds.), Temperature-Dependent Sex Determination in Vertebrates (pp. 79–89). Washington, DC: Smithsonian Institution Press.
Added by: Sarina Wunderlich (18 Nov 2012 17:43:27 UTC) |
| Resource type: Book Article BibTeX citation key: Georges2004 View all bibliographic details  |
Categories: General Keywords: Schildkröten = turtles + tortoises, Zeitigung = incubation Creators: Beggs, Doody, Georges, Lance, Valenzuela, Young Publisher: Smithsonian Institution Press (Washington, DC) Collection: Temperature-Dependent Sex Determination in Vertebrates |
Views: 2/582
Views index: 13% Popularity index: 3.25% |
| Abstract |
|
Recent studies have demonstrated a remarkable range of interactions between environmental conditions and developmental attributes and outcomes in reptilian eggs_ Rate of embryonie development and length of incubation period (Ewert 1985), yolk reserves remaining at hatching (Allsteadt and Lang 1995a), hatchling size and morphology (Osgood 1978), coloration (Murray et al. 1990; Etchberger et al. 1993), posthatching behavior (Lang 1987; Burger 1991; Janzen 1993; Shine and Harlow 1996), posthatching growth rates (Joanen et al. 1987; Rhen and Lang 1995), and offspring sex (Bull 1980; Ewert and Nelson 1991; Janzen and Paukstis 1991a) may all be direct1y influenced by the incubation environment. These results have been established primarily in laboratory experiments using constant temperatures. Much less focus has been placed on reproducing, in the laboratory; the thermal regimes that prevail in reptile nests (butsee Paukstis et al. 1984; Packard et al. 1991; Georges et al. 1994). Yet daily temperature fluctuations, variable weather conditions, seasonal trends, thermal gradients within nests, and stochastic events such as rainfall, which temporarily depress nest temperatures, can all be expected to complicate the relationship between nest temperature and developmental outcomes. Developmental times of insect eggs and larvae may be affected by daily fluctuations in temperature, quite independent of the effects of average temperature (Hagstrum and Hagstrum 1970), and there is at least one instance where this is so for a reptile species (Shine and Harlow 1996). Daily fluctuations in temperature also have an impact on phenotypic attributes, inc1uding sex (Georges et al. 1994). In this chapter, the evidence in sup- -'port of an independent influence of variability in temperature on developmental times and offspring sex ratios in reptil~ 5 is reviewed. The consequences for translating the results of laboratory experiments into a field context, the context in which sex-determination traits evolved, are explored. In particular, the potential of degree-hour approaches for predicting off spring sex ratios is explored, and these approaches are extended to cover cases where there is a nonlinear response of developmental rate to changes in incubation temperature. An improved algorithm for calculating the daily constant-temperature equivalent (CTE) for a natural nest is presented.
Added by: Sarina Wunderlich |