The Interaction of High Temperature and UV-B Radiation on Tadpole Development, Morphology and Predator Avoidance Behaviour
Date Issued
2016
Date
2016
Author(s)
Pai, Jen-Hui
Abstract
Amphibians are ectotherms that reside in both aquatic and terrestrial systems which make them extremely sensitive to changes in their environment, and past research has shown that global climate change has contributed substantially to the recent global amphibian decline. Although there are plentiful research on the effects of temperature or UV-B radiation on amphibian development, morphology, and behaviour, respectively, there has been very little research on the interaction of high temperature and UV-B on amphibians. The aim of this study is to determine the interaction effects of high temperature and UV-B, under a global warming scenario, on tadpole development and morphology, as well as to determine how these effects would impact the predator avoidance behaviour of tadpoles. I examined the independent and interaction effects of temperature and UV-B on various developmental and morphological traits of the LaTouche''s frog (Hylarana latouchii) by randomly distributing the egg masses into 4 different treatment groups in a 2 x 2 factorial combination of high and low temperature and UV-B. The developmental and morphological traits of the embryos/tadpoles were recorded and analyzed from Gosner stage 9 (G9) to Gosner stage 32 (G32). I also examined the predator avoidance response of tadpoles that have successfully reached G32 by measuring burst swimming speed. The results indicated that high UV-B had negatively affected the majority of tadpole traits including increased mortality and abnormalities, decreased longevity, and decreased tadpole overall size and width (including total length, body length, body width, and tail muscle width). This may be due to the DNA damage accumulated due to prolonged UV-B exposure. High temperature, on the other hand, had only decrease longevity and increased tail muscle width of tadpoles. The decrease in longevity revealed that slight increase in temperature may have a direct negative effect on tadpole development. Moreover, there was an interaction effect of temperature and UV-B. In this study, high temperature was ameliorating the negative effects that UV-B was exerting on tadpole. Also, morphological abnormality and damage did seem to carry over and significantly decreased burst swimming performance of tadpoles which may lead to increase in predation and decrease foraging capabilities. This study shows that under a global warming scenario, UV-B radiation is a much higher stressor to amphibian species than temperature and an incremental increase in temperature, within the species’ thermal range, may help ameliorate the morphological damages caused by UV-B.
Subjects
Hylarana latouchii
tadpole development
predator avoidance behavior
interaction effect of temperature and UV-B radiation
tadpole burst swimming speed
Type
thesis
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