Sexual Size and Shape Dimorphism in an Agamid Lizard, Japalura swinhonis (Squamata: Lacertilia: Agamidae)

摘要

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. http://zoolstud.sinica.edu.tw/Journals/48.3/351 .pdf