Thomas Gillespie

Forest loss makes monkeys sick

Contributed by Thomas Gillespie @BiodiversHealth


Africa, Agriculture, Animals, Biodiversity, Class, Community ecology, Conservation, Disease ecology, Ecology, Field, First generation, Income, Indirect, Interactions, Lab, Medicine, Observational, Rainforest, Species richness



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Thomas R. Gillespie and Colin A. Chapman. 2006. Prediction of Parasite Infection Dynamics in Primate Metapopulations Based on Attributes of Forest Fragmentation. Conservation Biology. 20: 441–448. link



Slide 1: Researcher’s Background

Thomas is a disease ecologist at Emory University who studies how anthropogenic disturbance affects zoonotic transmission of pathogens among people, wildlife & domesticated animals.


PB: Why did you become a biologist?

TG: As a child, I was in awe of the natural diversity of the world. I was especially intrigued by primates and their relationship to us. My parents and teachers guided my passion for natural history toward the marketable field of medicine. However, as an undergraduate at the University of Illinois at Urbana-Champaign with the support of an Illinois State Senate General Assembly Merit Scholarship, I was able to explore my academic passions as a double major in Ecology, Ethology and Evolution and Anthropology.


PB: What is your favorite part about your job?

TG: Making the world a better place


PB: What obstacles have you overcome to get where you are?

TG: I was often told that what I was passionate about was either a “hobby” or didn’t exist as a career option.


PB: What advice do you have for aspiring biologists?

TG: Don’t give up!


PB: Do you feel that any dimension of your identity is invisible or under-represented/marginalized in STEM?

TG: Yes. I am a first generation college graduate. My father was a mechanic and my mother was a homemaker who grew up on a subsistence farm.


Slide 2: Research Overview

Take home message of study

Although it was known that anthropogenic disturbance of natural systems could facilitate the transmission of diseases between wildlife and humans, this study demonstrated for the first time that specific characteristics of fragmentation of forests by humans can hasten the decline of a wildlife populations by making common parasites more abundant and introducing new ones.


Study system

The endangered Ugandan red colobus (Piliocolobus tephrosceles)

Slide 3: Key Research Points

Main figure

This table demonstrates that tree stump density (highlighted in orange), an index of active human use of fragmented forest, was the strongest correlate to red colobus monkey infection with a diversity of pathogenic parasites. Areas with more tree stumps had higher prevalence of pathogenic parasites. The second most important factor in this dynamic was forest fragment size (highlighted in yellow). Larger forest fragments were associated with lower prevalence of pathogenic parasites. 

Societal Relevance

This study demonstrated that clearing of forest for agriculture can have unintended consequences to the conservation of endangered species and zoonotic transmission of infectious diseases.

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