Patterns
of Reproductive Allocation: Clutch and Egg Size Variation in Three Freshwater
Turtles
Lucas Rand Wilkinson and J. Whitfield Gibbons
Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken,
South Carolina 29802
Abstract
Understanding the mechanisms and patterns of how energy is allocated into
the reproductive components of offspring size and number is central to
life-history theory. We used X-ray photographs from a long-term mark recapture
study of Kinosternon subrubrum, Sternotherus odoratus, and Pseudemys floridana
to investigate hypotheses concerning variation in reproductive allocation
due to constraint on egg size, within-female variability (within and among
clutches), interannual environmental variation, multiple annual clutches,
allocation of continuous resources into small integer numbers of offspring
(fractional offspring-size problem), and age. Patterns of reproductive
allocation varied markedly within and among species. Overall, egg size
varied as a function of maternal body size and age, intra-annual clutch
frequency, the fractional offspring-size problem, and environmental variation.
Clutch size varied with maternal body size, clutch frequency, and environmental
variation. We examine how effectively the data support optimal-egg-size
and phenotypic-plasticity models of reproductive allocation, and identify
limitations of fundamental biological findings necessary to address the
issues.
(LRW) E-mail: lwilkinson@srel.edu. Send reprint requests to LRW.
SREL Reprint #2907
Wilkinson,
L. R. and J. W. Gibbons. 2005. Patterns of Reproductive Allocation: Clutch
and Egg Size Variation in Three Freshwater Turtles. Copeia 4:868-879.
