Date of Award


Degree Name

Master of Science


Biological Sciences


Jerry D. Johnson


Spea is a genus of toad-like, arid adapted frogs distributed throughout much of the western U.S. and northern Mexico. Two species, (S. Bombifrons and S. Multiplicata) are syntopic throughout most of the northern Chihuahuan Desert, a region that is experiencing rapid urbanization. For this study, I examined 936 male advertisement calls from urban and rural populations of S. multiplicata, and a rural population of S. bombifrons in west Texas and south-central New Mexico. Advertisement calls from urban and rural S. multiplicata were compared against light level to assess the potential influence ecological light pollution plays in sexual selection at urban breeding sites. Univariate statistical analyses and principal components analysis indicated that urban frogs call at significantly different rates and frequencies after the effects of light level and water temperature are removed. Rural spadefoots call at a wider breadth of frequencies and call more slowly than urban populations. Additionally, hybrid (S. bombifrons x multiplicata) advertisement calls were identified at one rural breeding site. One suspected hybrid and three specimens from each parent species were vouchered for hybrid verification. Analysis of the mitochondrial gene cyt b recovered the suspected hybrid female parentage as S. bombifrons. Whereas, analysis of the nuclear gene RAG1 indicated that the hybrid sequence is heterozygous at 55% of variable sites. Univariate analysis of hybrid advertisement calls indicate that call interval, calls per minute, and pulses per second are intermediate between S. bombifrons and S. multiplicata.




Received from ProQuest

File Size

70 pages

File Format


Rights Holder

Katie Anderson