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First published online May 2, 2008
Journal of Experimental Biology 211, 1535-1540 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.016071
Alternating egg-brooding behaviors create and modulate a hypoxic developmental micro-environment in Children's pythons (Antaresia childreni)
School of Life Sciences, Arizona State University, Tempe, AZ 85287-460, USA
* Author for correspondence (e-mail: zs{at}asu.edu)
Accepted 11 March 2008
Parental care is a widespread and ecologically relevant adaptation known to
enhance the developmental environment of offspring. Parental behaviors,
however, may entail both costs and benefits for developing offspring. In
Children's pythons (Antaresia childreni), we monitored both maternal
egg-brooding behavior and intra-clutch oxygen partial pressure
(PO2) in real-time to assess the effects of
various brooding behaviors on PO2 in the clutch
micro-environment at three stages of development. Furthermore, at the same
developmental stages, we measured O2 consumption rates
(
O2) of eggs at
varying PO2 to determine their critical oxygen
tension (i.e. the minimal PO2 that supports
normal respiratory gas exchange) and to predict the impact that naturally
brooded intra-clutch PO2 has on embryonic
metabolism. At all three stages of development, a tightly coiled brooding
posture created an intra-clutch PO2 that was
significantly lower than the surrounding nest environment. Maternal postural
adjustments alleviated this hypoxia, and the magnitude of such corrections
increased with developmental stage. Mean intra-clutch
PO2 decreased with stage of development,
probably because of increasing egg
O2.
Additionally, embryo critical oxygen tension increased with developmental
stage. Together, these results suggest that python embryos are unable to
maintain normal metabolism under brooded conditions during the final 10% of
incubation. These results demonstrate that specific parental behaviors can
impose obligatory costs to developing offspring and that balancing these
behaviors can mediate deleterious consequences.
Key words: adjustable diffusive barrier, critical oxygen tension, hypoxia, metabolism, parental care, snake, trade-off
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K. Phillips PYTHON MUMS SUFFOCATE EGGS J. Exp. Biol., May 15, 2008; 211(10): i - i. [Full Text] [PDF] |
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