Morphology and resource partitioning between Japalura swinhonis and Japalura polygonata xanthostoma
Date Issued
2006
Date
2006
Author(s)
Kuo, Chi-Yun
DOI
en-US
Abstract
The first part of this thesis describes sexual dimorphism in size and shape in two Japalura lizards, J. swinhonis and J. polygonata xanthostoma. Univariate and multivariate statistics were applied to test interesexual differences in size and shape of the following body parts: body length, tail length, head width, head length, forelimb length, hindlimb length, length of the longest finger, and length of the longest toe. The results showed that male J. swinhonis were larger in size of all body parts. After the effect of body size was accounted for, males had proportionately longer and wider heads, shorter body lengths and limbs. Male and female J. polygonata xanthostoma, on the other hand, differed only in the size of the longest finger and toe, with males larger in finger length and females larger in toe length. After the effect of body size was accounted for, males still had longer fingers, and females had longer toes and body lengths. Via the examination of allometric patterns of both species, shape dimorphism was found to result either from different growths trajectories or an initial difference in proportion maintained by identical growth patterns between the two sexes. Sexual dimorphism in J. swinhonis could be explained in the context of sexual and natural selection. Prominent heads of male lizards were likely to be the consequence of sexual selection to enhance fighting ability, and longer bodies of females might evolve for accommodation of eggs. Sexual dimorphism in limb shape suggests that the two sexes might have different behavioral response to predators.
The second part of this thesis investigates resource partitioning between the two species and two ecomorphological relationships: relative limb lengths vs. perch habitat and head size vs. diet. The correspondence between relative limb lengths and perch habitat was only found intraspecifically in J. polygonata xanthostoma: males and females did not differ in perch habitat and relative limb lengths. The matching between relative limb lengths and perch habitat disappeared interspecifcally, which may be explained by biomechanics. The correspondence between head size and diet was not found both intra- and interspecifically. Feeding niche overlap was high between male and female J. swinhonis and J. polygonata xanthostoma despite significant differences in head sizes. The similarity of perch habitat, diet, and daily activity patterns between male J. swinhonis and J. polygonata xanthostoma, with the fact that antagonistic behaviors were observed more often between heterospecific males, suggested that males of the two species might compete over territories. To clarify their ecological relationships, comparisons of morphology and resource use between different populations, and experimental manipulations involving addition and removal in either allopatric or sympatric populations are required as the next steps.
Subjects
攀蜥
雌雄二形性
體型
體態
異質生長
生態形態學
資源分配
棲地利用
食性
Japalura
sexual dimorphism
size
shape
allometry
ecomorphology
resource partitioning
habitat use
diet
Type
other
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