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Vol. 49 No. 3, 2010
Thermal Effects on Embryogenesis and Hatchlings of the Grass
Lizard Takydromus stejnegeri (Squamata: Lacertidae) and Implications of
Their Potential for Limiting Its Altitudinal Distribution in Taiwan
Yi-Huei
Chen, Shu-Ping Huang, Mu-Hsuan Chang, and Ming-Chung Tu*
Department
of Life Science, National Taiwan Normal University, 88 Ting-Chow Rd.,
Sec. 4, Taipei 116, Taiwan
Yi-Huei
Chen, Shu-Ping Huang, Mu-Hsuan Chang, and Ming-Chung Tu(2010)
Among the life stages of oviparous reptiles, embryo and h atchling are
particularly susceptible to temperatures. Since temperature
decreases with altitude, the upper altitudinal limit of some lowland
species could be related to the temperature requirement for
embryogenesis. The endemic grass lizard Takydromus stejnegeri is
widely distributed at altitudes below 1000 m in Taiwan. In this
study, we examined the thermal effects on embryogenesis of this species
and evaluated its potential influence on current altitudinal
distribution of T. stejnegeri. We measured some indices of
embryogenesis and hatchling after incubation at 5 constant temperatures
(15, 20, 25, 30, and 33°C). The results revealed that (1)
hatching success increased with temperatures from 15°C to 20°C, reached
100% at 25°C and 30°C, and then declined at 33°C; and (2) the
incubation duration increased with decreasing temperatures. Based
on polynomial regression analysis, we predicted the development of
embryos would cease at 16°C. Comparing the monthly average
temperature at 3 different altitudes, we found that the T. stejnegeri
would have an incubation success <100 % at areas higher than 1000 m
(monthly average soil temperature < 25°C), and its eggs would not
have enough time to hatch in the areas above 1600 m. We assumed
that the temperature requirement for embryogenesis could be a limiting
factor for the current altitudinal distribution of T. stejnegeri.
Key words: Thermal effect, Altitudinal
distribution, Takydromus stejnegeri, Incubation temperature.
*Correspondence: Tel: 886-2-77346320. Fax:
886-2-29312904. E-mail:biofv026@ntnu.edu.tw
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