Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Teresa Patricia Feria Arroyo

Second Advisor

Dr. Frederic Zaidan

Third Advisor

Dr. Drew R. Davis


Climate change is inducing changes in the distributions of many species, causing range shifts and habitat loss as well as facilitating invasions. It is a broad contributor to global amphibian decline, already causing mass extinctions and extirpations of amphibian populations, a phenomenon which is expected to continue. The understudied direct-developing frog Eleutherodactylus cystignathoides is a notable outlier, having rapidly expanded its distribution in recent years. This is of particular interest given that other eleutherodactylids, such as E. coqui and E. planirostris, have already shown propensity for rapid dispersal and invasion. Originally found in the southernmost tip of Texas, USA and northeastern Mexico, E. cystignathoides has established populations far into northeastern Texas, in addition to southern Louisiana, USA, and Alabama, USA. This expansion has been assumed to be ecologically neutral due to lack of evidence of negative impact, but no confirmational investigation has occurred. The dearth of information about this species’ dispersal and ecology, coupled with the documented negative impacts of other successful eleutherodactylid invaders, warrants investigation that preempts waiting for any potential consequences of this geographical expansion to make themselves known. To conduct an investigation into the potential range limits of this species as they are defined by bioclimatic variables, we used spatially rarefied occurrences and selected future climate models to develop Maxent projections of potentially suitable habitat of E. cystignathoides. These methods were repeated with the better-studied congener E. planirostris, a Cuban frog with an introduced range from Florida to Texas, for the purposes of contextualization and comparison. Our models suggest the existence of currently non-invaded potentially suitable habitat across the southeastern USA under both current and future models for E. cystignathoides, but widespread range contractions for E. planirostris. The models additionally predict habitat loss in the native ranges of each species under future climate conditions.


Copyright 2022 Rebecca T. Chastain. All Rights Reserved.

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