Date of Award

Spring 5-21-2022

Document Type


Degree Name

Bachelor of Arts



First Advisor

Dr. Iris Levin


Early life in animals is often a time of rapid growth and morphological change. In a resource-limited environment, life history theory predicts that there must be trade-offs between resource sinks in a way that optimizes future survival and reproductive success. Telomeres have emerged as a possible indicator of these early life trade-offs, but there are many conflicting accounts within the literature as to how developmental traits and conditions impact telomere length and dynamics. For two years, I studied the nestlings of a breeding population of barn swallows from day six to day twelve of life, measuring various ontogenetic factors to determine to what extent they explain variation in telomere length and change. I predicted that telomeres would be shorter in both fast growing individuals and in individuals reared in large broods, as the somatic demands of growth paired with the resource limitation due to larger broods would lead to shortened telomeres. In the second year of study, I reduced a subset of four- and five-egg clutches down to three eggs to gain more even sample sizes. I unexpectedly found that telomeres lengthened over the course of the study. Nestlings in large broods did in fact have shorter telomeres, but surprisingly, individuals that grew faster had longer telomeres and more telomere lengthening. These effects were only found in the first year of study, as the second year of study had substantially less telomere variation. Telomere lengthening may be due to telomerase expression in bone marrow coupled with increases in blood volume during development, resulting in new red blood cells that have apparently longer telomeres. The lengthening of telomeres with increased growth may be due to little to no resource limitation, allowing for high growth without a cost to telomere length or dynamics.

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