Date of Award

Fall 2021

Publication Type


Degree Name



Biological Sciences


Colour, Crogs, Incilius luetkenii, Parasite-mediated sexual selection, Parasites, Toads


C. Houser


C. Febria



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Parasitism is among the most common and successful life history strategies on Earth, leading to constant coevolution between parasites and hosts. Parasites continuously pressure hosts to evolve more effective parasite resistance, fueling interest in the relationships between expression of sexually selected host ornamentation and parasite resistance. By studying parasite-mediated sexual selection we gain unique insights into the evolution of animal traits. In this thesis, I attempt to further our understanding of a sexually dichromatic neotropical anuran by studying its parasites in the context of sexual selection. Firstly, in the General Introduction (Chapter 1), I reviewed important background information key to understanding anuran host-parasite relationships, as well as the literature studied so far on anuran parasite-mediated sexual selection. In my data chapter (Chapter 2), I used neotropical yellow toad blood samples to identify blood parasites, which have never been explored in this species. I identified four groups of parasites infecting neotropical yellow toads: Apicomplexa, Nematoda, frog erythrocytic virus, and bacteria. Furthermore, I used blood samples, colour, and morphometrics to explore parasite-mediated sexual selection in neotropical yellow toads. I found evidence that some blood parasites of neotropical yellow toads are correlated with colour and body condition, suggesting that parasite resistance and expression of sexual traits may be related in this species. In the General Discussion (Chapter 3), I reviewed the findings of Chapter 2 and their implications for parasite-mediated sexual selection in anurans. Motivating this thesis is my interest in amphibian conservation due to recent population declines and extinctions owing to climate change and disease. My aim is for this research to further our understanding of anuran host-parasite relationships and sexual selection and to contribute to amphibian conservation efforts.