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The adaptive significance of reptilian viviparity in the tropics: Testing the maternal manipulation hypothesis

Webb, Jonathan K., Shine, Richard and Christian, Keith A. (2006). The adaptive significance of reptilian viviparity in the tropics: Testing the maternal manipulation hypothesis. Evolution,60(1):115-122.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 54 times in Scopus Article | Citations

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IRMA ID 80801501xPUB2
Title The adaptive significance of reptilian viviparity in the tropics: Testing the maternal manipulation hypothesis
Author Webb, Jonathan K.
Shine, Richard
Christian, Keith A.
Journal Name Evolution
Publication Date 2006
Volume Number 60
Issue Number 1
ISSN 0014-3820   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-33646699117
Start Page 115
End Page 122
Total Pages 8
Place of Publication USA
Publisher Social Study Evolution
Field of Research 1603 - Demography
1608 - Sociology
HERDC Category C1 - Journal Article (DEST)
Abstract Phylogenetic transitions from oviparity to viviparity in reptiles generally have occurred in cold climates, apparently driven by selective advantages accruing from maternal regulation of incubation temperature. But why, then, are viviparous reptiles so successful in tropical climates? Viviparity might enhance fitness in the tropics via the same pathway as in the temperate zone, if pregnant female reptiles in the tropics maintain more stable temperatures than are available in nests (Shine's maternal manipulation hypothesis). Alternatively, viviparity might succeed in the tropics for entirely different reasons than apply in the temperate zone. Our data support the maternal manipulation hypothesis. In a laboratory thermal gradient, pregnant death adders (Acanthophis praelongus) from tropical Australia maintained less variable body temperatures (but similar mean temperatures) than did nonpregnant females. Females kept at a diel range of 25-31 degrees C (as selected by pregnant females) gave birth earlier and produced larger offspring (greater body length and head size) than did females kept at 23-33 degrees C (as selected by nonpregnant snakes). Larger body size enhanced offspring recapture rates (presumably reflecting survival rates) in the field. Thus, even in the tropics, reproducing female reptiles manipulate the thermal regimes experienced by their developing embryos in ways that enhance the fitness of their offspring. This similarity across climatic zones suggests that a single general hypothesis-maternal manipulation of thermal conditions for embryogenesis-may explain the selective advantage of viviparity in tropical as well as cold-climate reptiles.
Keywords adaptation
egg-laying
incubation
live-bearing
reproduction
snake
garter snakes thamnophis
reproductive influences
acanthophis-praelongus
phenotypic plasticity
reaction norms
death adder
lizard
evolution
thermoregulation
temperature
DOI http://dx.doi.org/10.1554/05-460.1   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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