|
Vol. 48 No. 3, 2009
Sexual Size and Shape Dimorphism in an Agamid Lizard, Japalura swinhonis (Squamata: Lacertilia: Agamidae)
Chi-Yun Kuo1,3,*, Yu-Teh Lin1,2, and Yao-Sung Lin1,2
1Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei 106, Taiwan
2Department of Life Science, National Taiwan University, Taipei 106, Taiwan
3Biodiversity Research Center, Academia Sinica, Nankang, Taipei 115, Taiwan
Chi-Yun Kuo, Yu-Teh Lin, and Yao-Sung Lin (2009)
Sexual dimorphism in size and shape is a widespread phenomenon in the
animal kingdom. Sexual dimorphism in morphology can be explained
in proximate (growth pattern/sampling effects) and ultimate
(evolutionary payoffs) contexts. There are 3 mutually
non-exclusive hypotheses for the evolution of sexual dimorphism:
fecundity advantage, intersexual resource partitioning, and sexual
selection, each of which can make specific predictions regarding a
lizard’s morphology. In this study, we describe sexual dimorphism
in size and shape in an agamid lizard, Japalura swinhonis,
with discussions from both proximate and ultimate perspectives.
The results showed that all body parts of males were larger than those
of females. After the effect of body size was accounted for,
males had proportionately longer and wider heads, and shorter limbs and
body length. Sexual shape dimorphism can be proximately explained
by different growth patterns between the 2 sexes. We found a
correlation between morphology and perch habitat, but not between
morphology and diet since the 2 sexes exhibited extensive dietary
overlap. Our results rejected the resource partitioning
hypothesis and provided support for the fecundity advantage hypothesis
as the underlying mechanisms of sexual dimorphism in J. swinhonis.
Key words: Allometry, Intersexual resource partitioning, Life history adaptation, Morphometrics, Sexual selection.
*Correspondence: Tel: 886-2-27899525. E-mail:chiyunkuo@ntu.edu.tw
|
