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271.
Huang V Sakata JT Rhen T Coomber P Simmonds S Crews D 《Die Naturwissenschaften》2008,95(12):1137-1142
Kratochvil et al. (Naturwissenschaften 95:209–215, 2008) reported recently that in the leopard gecko (Eublepharis macularius) of the family Eublepharidae with temperature-dependent sex determination (TSD), clutches in which eggs were incubated at
the same temperature produce only same-sex siblings. Interpreting this result in light of studies of sex steroid hormone involvement
in sex determination, they suggested that maternally derived yolk steroid hormones could constrain sex-determining mechanisms
in TSD reptiles. We have worked extensively with this species and have routinely incubated clutches at constant temperatures.
To test the consistency of high frequency same-sex clutches across different incubation temperatures, we examined our records
of clutches at the University of Texas at Austin from 1992 to 2001. We observed that clutches in which eggs were incubated
at the same incubation temperature produced mixed-sex clutches as well as same-sex clutches. Furthermore, cases in which eggs
within a clutch were separated and incubated at different temperatures produced the expected number of mixed-sex clutches.
These results suggest that maternal influences on sex determination are secondary relative to incubation temperature effects. 相似文献
272.
Harvey F. Ludwig 《The Environmentalist》1990,10(4):257-280
Summary Environmental degradation in the Asian Pacific area developing countries continues and has probably increased since the Stockholm Conference of 1972. The causes for this continued environmental degradation in Asia are analyzed. The paper assesses the actions of the International Assistance Agencies in providing support for the Asian developing countries since Stockholm. The Asian Development Bank project on Economic Policies for Sustained Development is described, and advocated as an important first step in a strategy moving towards economic-cum-environmental sustainability. Drastic changes and bold initiatives are suggested and required to establish true sustainable development for the developing countries.Dr Harvey F. Ludwig is Chairman of SEATEC International Consulting Engineers. He is a regular contributor to this journal. 相似文献
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Ludwig Gräper 《Die Naturwissenschaften》1922,10(49):1056-1057
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