plasticity in reproductive traits: geographical variation in plasticity
in a viviparous snake
A. Seigel1 and N. B. Ford2
Louisiana University, Department of Biological Sciences, Hammond, LA 70402-0736,
2University of Texas-Tyler, Department of Biology, Tyler, TX
Previous experiments showed that Checkered Garter Snakes (Thamnophis
marcianus) from south Texas, USA (an environment subject to high seasonal
and annual variation in environmental conditions), demonstrated marked
phenotypic plasticity in clutch size and clutch mass in response to experimental
changes in prey availability.
In this study, the extent of phenotypic plasticity in life-history traits
in Checkered Garter Snakes from south Texas was experimentally compared
with a population of the same species from south-eastern Arizona, where
the environment may be more constant.
Unlike results from south Texas, Checkered Garter Snakes from Arizona
showed no significant phenotypic plasticity in clutch size, clutch mass
or any other life-history trait in response to changes in food availability,
at least within the boundaries of our experimental conditions.
The data indicate that the degree of phenotypic plasticity in life-history
traits differs among populations within the same species. However, these
differences are subject to both adaptive and non-adaptive explanations.
Fecundity, geographic variation, phenotypic plasticity
A., and N. B. Ford. 2001. Phenotypic plasticity in reproductive traits:
geographical variation in plasticity in a viviparous snake. Functional
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