Date of Completion


Embargo Period



Mark Urban, Elizabeth Jockusch

Field of Study

Ecology and Evolutionary Biology


Master of Science

Open Access

Open Access


The fact that tadpoles breathe air is an oft over-looked aspect of anuran biology. The air-breathing behavior of small tadpoles is particularly interesting, as they are not large enough to overcome the physical constraints imposed by surface tension. Instead of breaching the water’s surface to access air, small tadpoles perform “bubble-sucking”, a breathing mode that circumvents the need to breach the water’s surface tension. In my first chapter, I find that Hyla versicolor (Anura: Hylidae) tadpoles are bubble-sucking specialists that perform both the typical, single bubble-suck seen in other tadpole species as well as an undescribed, double bubble-suck. A combination of functional, behavioral, and morphological evidence suggests that double bubble-sucking increases the efficiency of gas exchange by separating the deoxygenated air from the lungs from freshly breathed air to decrease mixing during breathing. I also comment on the potential significance of this finding for understanding the evolutionary history of vertebrate breathing mechanisms. In my second chapter, I examine the evolutionary patterns of lungs and air-breathing across anurans, finding evidence for a phylogenetic trait correlation between a stream-adapted larval habitat and larval lunglessness. I hypothesized that due to this correlation, the true toads (Anura: Bufonidae) may have evolved from a stream-breeding ancestor, but my results do not support this conclusion.

Major Advisor

Kurt Schwenk