Vol. 53, 2014
Altitudinal variation in body size and age structure of the
Sauter’s frog Rana sauteri in Taiwan
Hsu1*, Yi-Shan Hsieh1, Sheng-Hai Wu2
and Yeong-Choy Kam3
of Biological Resources, National Chiayi University, 300 University
Road, Chiayi 600, Taiwan
2Department of Life Sciences, National Chung Hsiung
University, Taichung 402, Taiwan
3Department of Life Sciences, Tunghai University,
Taichung 407, Taiwan
Background: The tendency for
organisms to be larger in cooler climates, the so-called Bergmann’s
rule, has been widely observed in endotherms, but it is debatable in
ectothermic anurans. Altitudinal variations in body size, age, and
growth rate of the Sauter’s frog Rana sauteri were investigated with
skeletochronology at six sites along the altitudinal gradients from 330
to 2,320 m in subtropical Taiwan. The aims of this study were to
determine whether these life history traits vary with altitude and
differ between males and females.
Results: The body size of male R. sauteri followed
a converse Bergmann’s cline; the size decreased with increase in
altitude, while no significant altitudinal change was found for
females. The size dimorphism was female-biased and became greater at
higher altitudes because of the altitudinal decrease in male size. Ages
ranged between 1 and 5 years for males and 1 and 6 years for females.
There was no significant difference in the age structures between the
two sexes, but both sexes had higher average ages at higher-altitude
sites. According to von Bertalanffy’s model, the growth coefficients
decreased with increase in altitude for males but not for females. The
rates were greater for all age classes of females than males,
suggesting that growth rate was a major factor underlying body size
patterns of both sexes.
Conclusions: Growth rate was a
major factor underlying body size patterns in both sexes of R. sauteri.
It could be affected by not only altitudinal temperature gradient but
also sex-biased life history traits and environmental factors.
Key words: Rana sauteri; Skeletochronology;
Body size; Altitudinal gradient; Growth rate; Bergmann’s rule.