Vol. 51 No. 7, 2012
Cutaneous Resistance to Evaporative Water Loss in Taiwanese Arboreal Rhacophorid Frog
Jian-Nan Liu1,2,* and Ping-Chun Lucy Hou1
1Department of Life Sciences, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan
2Department
of Forest and Wildlife Ecology, University of Wisconsin-Madison, A227
Russell Labs, 1630 Linden Dr., Madison, WI 53706, USA
Jian-Nan Liu and Ping-Chun Lucy Hou (2012) In
this study, we investigated whether arboreal rhacophorid amphibians in
humid subtropical Taiwan exhibit significant cutaneous resistance (Rc)
to evaporative water loss (CWL). Animals from 7 arboreal
rhacophorid and 3 non-arboreal amphibian species were injected with a
neuromuscular blocking agent to eliminate pulmonary water loss, and
their rates of CWL were measured gravimetrically in a wind tunnel at a
wind speed of approximately 1.0 m/s. For each individual, we used
a same-sized 3% agar replica to determine its boundary layer
resistance, which allowed us to calculate Rc. Our results showed that all 7 arboreal species exhibited a detectable Rc
that ranged 1.2-3.3 s/cm, and rates of CWL of arboreal species were
1/2-1/5 those of non-arboreal species. We further tested whether
arboreal species actively adjusted their Rc in response to an increase
in CWL associated with a high wind speed. Rates of total
evaporative water loss (EWL) and Rc of physically restricted animals
were measured at wind speeds of 0.6 cm/s and 1.0 m/s. Results
showed that the Rc
of arboreal rhacophorid species did not significantly differ between
the 2 wind speeds despite substantially increased rates of EWL at the
high wind speed. A comparison between the CWL of paralyzed frogs
and the EWL of restricted frogs showed that the ratio of pulmonary
water loss to total EWL in Taiwanese amphibians is very low and can be
neglected.
Key words: Cutaneous resistance, Rhacophoridae, Subtropical, Tree frog, Wind speed.
*Correspondence: Tel: 886-2-27871594. Fax: 886-2-27858059. E-mail:jnliu@gate.sinica.edu.tw
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