Date of Award
Spring 2026
Thesis Type
Rollins Access Only
Degree Name
Honors Bachelor of Arts
Department
Biology
Sponsor
Jay Pieczynski
Committee Member
Bobby Fokidis
Committee Member
Paul Stephenson
Abstract
One effect of global climate change is loss of species diversity. While there are many systems at work, dispersal of animal ranges and the introduction of invasive species play key roles. In some cases, these factors lead to hybridization of closely related species, which, in turn, has severe impacts on carefully balanced ecosystems. The Dominican Republic is home to two endemic Antillean turtle subspecies (Trachemys stejnegeri and Trachemys decorata). A third species, the invasive red-eared slider (Trachemys scripta), threatens the native Trachemys populations as well as the island's ecological balance as a whole. To understand factors leading to the development and subsequent loss of species diversity, we undertook physical and genetic surveys of Trachemys sp. in the Dominican Republic in May of 2024 with the goals of further defining the ranges of the endemic species and identifying potential hybrid zones. In addition, as part of the genetic analysis, we aimed to develop a low cost and robust field assay for assessing hybridization of closely related species and potential hybrids. Our field test uses a lateral flow strip assay to detect the presence of T. scripta DNA in blood samples by taking advantage of the high specificity of CRISPR and its ability to distinguish between highly similar DNA sequences. We hypothesized that urbanization would be a significant factor in loss of species diversity. Thus far, our data suggest a disconnect between our field assessments and laboratory experiments. Our field assay and field assessments have put preliminary estimates of T. scripta/T. stejnegeri hybrids at 30% of the sampled individuals in our more urban field site, compared to an estimated hybridization rate of < 1% for our western, more rural field site. However, our Sanger sequencing data suggests no presence of hybrids at our first field site. Furthermore, our data suggests that variables such as introgression or maternal loading effects might be confounding factors in establishing true Trachemys hybrid zones.
Recommended Citation
Burton, Embry, "Assessment of hybridization of endemic and invasive Trachemys sp. in the Dominican Republic using CRISPR-based diagnostics" (2026). Honors Program Theses. 277.
https://scholarship.rollins.edu/honors/277