Can natural phenotypic variances be estimated reliably under homogeneous laboratory conditions?

Authors

  • J. R. ST JULIANA,

    1. Department of Animal Ecology, Iowa State University, Ames, IA, USA
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      Present address: J. R. St Juliana, Department of Ecology and Organismal Biology, Indiana State University, Terre Haute, IN 47809, USA.

  • F. J. JANZEN

    1. Department of Ecology, Evolution, & Organismal Biology, Iowa State University, Ames, IA, USA
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Fredric J. Janzen, Department of Ecology, Evolution, & Organismal Biology, 253 Bessey Hall, Iowa State University, Ames, IA 50011-1020, USA.
Tel.: +1-5152944230; fax: +1-5152941337; e-mail: fjanzen@iastate.edu

Abstract

Abstract The phenotypic variance is assumed to be greater in a more heterogeneous environment. The validity of this assumption is important for microevolutionists to extrapolate results from the laboratory to field environments. We subjected clutches of eggs from common snapping turtles (Chelydra serpentina) to a split-family design to evaluate the variability in incubation time and four size traits of neonates from eggs incubated in the laboratory and those left in situ. Mean size measurements were similar between the laboratory and the field, but incubation time was systematically longer in the field. We found no tendency among clutches for hatchlings resulting from eggs incubated in laboratory or field environments to demonstrate greater variability. Also contrary to expectation, clutches that experienced greater thermal variation in the field did not exhibit greater variation in phenotypic traits. Consequently, extrapolating results from the laboratory to the field may not always be problematic for microevolutionary analyses.

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