Biology ETDs


Mason J. Ryan

Publication Date



During the course of the Anthropocene, humans have modified the landscape and atmosphere resulting in increased global temperatures and intensification of the hydrologic cycle over the last 100 years. Amphibians and reptiles are especially vulnerable to climate change because of their ectothermic physiology and sensitivity to changes in water availability. The role of moisture or precipitation in ectotherm responses to climate change has not been well studied, but moisture plays a vital role in all aspects of the lives of lizards and frogs. It is exceedingly difficult to study the ecological effects of changing precipitation patterns due the stochastic nature of rainfall events. Obtaining accurate and local rainfall measurements is problematic, as is having population and community data covering multiple years. During the course of my dissertation I collected five-years of data on two tropical leaf-litter frog communities Costa Rica and three-years of data on an arid lizard community data in New Mexico. Because I incorporated accurate and local rainfall and temperature measurements, I was able to address the role of changing rainfall on these disparate herpetofaunal communities. This dissertation focuses on how frogs and lizards respond to changing precipitation patterns and events at multiple spatial and temporal scales. My first chapter deals with how five species of tropical litter frogs that occur in two distinct elevationally separated environments, respond to changing environmental factors over 42-years. Significant changes in dry season rainfall were associated with species and population specific responses between the two elevations. Chapter Two deals with how a midelevation frog community responded to the extreme La Niña event of 2010-2012. Extreme rainfall during 2010-2012 resulted in over population declines and a drop in species diversity, but the community returned to pre-La Niña levels within 13-months following a return to normal rainfall conditions. Chapter Three focuses on the effect of short-term rainfall on a lizard species in New Mexico. Contrary to previous work, my work shows that rainfall, not temperature, influences lizard microhabitat use, and that shade may act as a buffer against dry conditions.




frogs, lizards, ecology, precipitation, climate change

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Advisor

Poe, Steven

First Committee Member (Chair)

Cook, Joseph

Second Committee Member

Snell, Howard

Third Committee Member

Fitzgerald, Lee

Fourth Committee Member

Scott, Norman