Literaturdatenbank
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St. Clair, R. C. (1995). How developmental environment affects life history in box turtles. Unpublished thesis PhD, University of Oklahoma, Norman.
Added by: Sarina Wunderlich (12 Dec 2010 20:43:14 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: StClair1995 View all bibliographic details  |
Categories: General Keywords: Emydidae, Schildkröten = turtles + tortoises, Terrapene, Terrapene carolina, Terrapene ornata, Zeitigung = incubation Creators: St. Clair Publisher: University of Oklahoma (Norman) |
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| Abstract |
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In box turtles (Terrapene), sex is determined by ineubation temperature. An adaptive explanation is that, if(l) developmental environment influenees growth and (2) larger size benefits one sex more then the other, then it is beneficial for developmental environment to determine sex because this a1lows a match of faster growth with the sex that benefits more trom larger size. I tested so me assumptions of tbis model in nature and in the laboratory, namely: (1) does larger size inerease feeundity in females, the sex that is determined by higher ineubation temperatures? (2) do females grow faster? (3) under eontrolled eonditions, what are the effeets of ineubation temperature on growth and metabolie rate before hatehing? and (4) what are the effeets after hatehing? I examined two species ofbox turtles (Terrapene carolina triunguis and Terrapene ornata) in Oklahoma. There was no effeet of maternal body size on egg size and number in either species. In addition, there was no differenee in growth rates between the sexes in T. ornata and a signifieant differenee in T. carolina. However, growth was fastest in T. carolina males, the sex that resuIts from lower ineubation temperatures. In both species, females are larger than males beeause they delay maturity rather than grow faster. In the laboratory, I eontrolled developmental temperature and measured size at hatehing and metabolie rate of eggs. Eggs were ineubated at 25 C and 30 C to produee males and females, respeetively. Hatehlings from lower ineubation temperature (males) were slightly larger and eonsumed more oxygen throughout development. The hatehlings were then raised under eommon eonditions. After two years, growth differed between speeies but not sexes. Metabolie rate at 20 C, 25 C, and 30 C differed signifieantly between the sexes. In eonc1usion, a simple relationship between ineubation temperature and body size does not exist in nature or in the laboratory. Reproduetive output is little affeeted by body size and adult body size is determined by timing of maturation rather than growth rate. Under controlled conditions, incubation temperature does not affeet subsequent hatehling growth, nevertheless, it does affeet size at hatehing, energetie costs, and metabolie rate.
Added by: Sarina Wunderlich |