ORCID ID

https://orcid.org/0000-0003-1379-3065

Date Awarded

2023

Document Type

Thesis

Degree Name

Master of Science (M.Sc.)

Department

Biology

Advisor

John P. Swaddle

Committee Member

Daniel A. Cristol

Committee Member

Jennifer E. Bestman

Abstract

Globally, the contamination of anthropogenically-disturbed environments with lead (Pb) pollution constitutes a major threat for exposed organisms. While Pb is widely known to be toxic at high levels of exposure, recent literature has shown that sublethal levels of this toxin can cause a suite of deleterious effects on individual organismal systems. However, there remain considerable holes in our understanding of how multi-systematic and sensitive responses like behavior are impacted by this form of pollution. Moreover, recent work has suggested that the high selective pressure caused by chronic Pb exposure may drive the resistance and local adaptation of terrestrial organisms. However, these blossoming lines of research lack evidence on whether behavioral responses may be subject to this pollutant-incurred adaptation. To better understand the effects of sublethal Pb on organismal behavior, Chapter 1 details an experimental dosing study conducted to examine the effect of sublethal Pb exposure on three key behaviors in an avian model-the House Sparrow (Passer domesticus). Specifically, we chose to examine escape flight performance, activity in a novel environment, and in-hand aggression; behaviors that have all been shown to be crucial for avian fitness. Compared to controls, birds exposed to environmentally-relevant levels of sublethal Pb exhibited significant decreases in metrics related to escape flight performance, as well as and movement activity. However, our in-hand aggression assessments (Number of struggles, average breathing rate, agonism score) did not capture any Pb-induced behavioral shifts. Together, these results indicate that sublethal Pb exposure selectively impacts different behavioral endpoints with those reliant on more biomechanical attributes more susceptible to this pollutants’ deleterious effects. A clearer understanding in how sublethal Pb impacts the behavior of commensal species like HOSP provides a vantage point into how this toxin may impact other organisms inhabiting anthropogenically-polluted environments. In Chapter 2 we investigate the scale of Pb-influenced selection on avian behaviors by sampling a population of House Sparrows in Broken Hill, an Australian mining town chronically-polluted with Pb. We caught 600+ birds across a well-characterized soil Pb gradient and then conducted field-modified versions of the same behavioral assays of escape flight performance, activity in a novel environment, and in-hand aggression. We found that the birds caught in sites of high Pb exposure exhibited impaired takeoff flight performance, as well as a decreased average breathing rate when compared to birds caught in low Pb-polluted sites. Conversely however, there was no differences among high and low Pb birds’ movement activity scores, as well as the other two in-hand aggression metrics of number of struggles and agonism score. Collectively, our results suggest that while local adaptation may be occurring in regards to some behaviors, this adaptation is incomplete for other vital behavioral responses.

DOI

https://dx.doi.org/10.21220/s2-z2s1-cr18

Rights

© The Author

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