Sex and incubation temperature independently affect embryonic development and offspring size in a turtle with temperature-dependent sex determination

Daniel A. Warner, Timothy S. Mitchell, Brooke L. Bodensteiner, Fredric J. Janzen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Developmental environments can have lasting effects on an in-dividual’s phenotype. Inmany reptiles, for example, egg incubation temperature permanently determines offspring sex (temperature-dependent sex determination, TSD) and also influences a suite of morphological, physiological, and behavioral traits. Thus, the contributions of sex and incubation temperature to phenotypic variation are difficult to identify because these factors are confounded under TSD. We used chemical manipulations to experimentally decouple gonadal sex and incubation temperature in a turtle with TSD (Chrysemys picta) to examine their relative and interactive effects on variation in incubation duration and offspring size. We show that warm incubation temperature accelerates development as expected and that exogenous estradiol treatment to eggs further shortens incubation duration across all incubation temperatures. Moreover, estradiol unexpectedly induced male development, resulting in male offspring hatching sooner than female offspring. Variation in offspring size was also influenced by incubation temperature and gonadal sex, but interactions between these two variables were relatively small or nonsignificant. The fitness consequences of these effects are unknown, but we provide preliminary results from our attempts at examining the long-term and sex-specific effects of incubation temperature. Manipulative experimental approaches, combined with longer-term experiments that track individuals through reproduction, will provide novel insights into the adaptive significance of developmental plasticity in long-lived organisms.

Original languageEnglish (US)
Pages (from-to)62-74
Number of pages13
JournalPhysiological and Biochemical Zoology
Volume93
Issue number1
DOIs
StatePublished - Jan 1 2020

Bibliographical note

Funding Information:
We are grateful to Nick Howell and the staff at the Iowa State University (ISU) Horticulture Research Station for their generous support during this work. Thanks to R. Alverio, K. Chris-tiansen, M. Columba, K. Fetterman, A. Sethuraman, and J. Ward for assistance during many aspects of this research. Thanks to A. Bronikowski for statistical advice and to members of the Warner Lab and Janzen Lab for comments on earlier versions of the manuscript. This research was supported by the National Science Foundation (DEB-1242510) and was approved by the

Funding Information:
We are grateful to Nick Howell and the staff at the Iowa State University (ISU) Horticulture Research Station for their generous support during this work. Thanks to R. Alverio, K. Chris-tiansen, M. Columba, K. Fetterman, A. Sethuraman, and J. Ward for assistance during many aspects of this research. Thanks to A. Bronikowski for statistical advice and to members of the Warner Lab and Janzen Lab for comments on earlier versions of the manuscript. This research was supported by the National Science Foundation (DEB-1242510) and was approved by the Illinois Department of Natural Resources and the ISU Institutional Animal Care and Use Committee (protocol 5-08-6566-J).

Publisher Copyright:
© 2019 by The University of Chicago.

Keywords

  • Aromatase
  • Charnov-Bull model
  • Chrysemys picta
  • Developmental plasticity
  • Developmental rate hypothesis
  • Estradiol
  • Exogenous steroids
  • Painted turtle
  • Survival

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.

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