Degree

Doctor of Philosophy (PhD)

Department

Biological Sciences

Document Type

Dissertation

Abstract

Human-altered altered landscapes are replacing natural environments at an alarming rate, and animals must adapt to ensure survival. Successful invasive species can help us understand the behavioral and neurobiological mechanisms that allow animals to adjust to new environments. House sparrows are prominent global invaders that show variation in ecologically relevant behaviors, including neophobia (an aversive response towards novelty). In my dissertation, I aim to better understand how potentially threatening stimuli (including novel stimuli, alarm calls, and predator calls) influence neural mechanisms and behavioral outputs. First, I explored neophobia experimental design choices to determine how neophobia research is done broadly in behavioral fields, make recommendations to improve future work, and optimize my own approach. Next, I examined neophobia across two different contexts (spatial and object) to better understand neophobia behavior as a whole. I found that responses to these two contexts were not correlated in house sparrows, which implies that they are controlled by different functional circuits. I next examined whether neophobic and non-neophobic house sparrows showed regional differences in neuronal responses to novel objects. While I did not find differences between phenotypes, I found activation in the rostral but not caudal hippocampus, which provides support for a rostro-caudal functional gradient in the songbird hippocampus. To better understand the function of the caudal dorsomedial hippocampus, and to investigate whether neophobia is lateralized in this region, I next inactivated this region with lidocaine infusion and measured neophobia behavior. I found some evidence that this region mediates some aspects of neophobia but did not find any evidence for lateralization. For my next chapter, I investigated the effects of a glucocorticoid receptor antagonist on neophobia behavior, and my results suggest that glucocorticoid receptors do not mediate neophobia. For my last two chapters I zoomed out to look at the effects of environmental factors on behavior. I found that conspecific alarm calls prevented the attenuation of neophobia, which supports the hypothesis that social learning influences neophobia. Lastly, I found that female house sparrows in breeding condition maintained high neuronal activity and vigilance towards relevant reproductive and predatory signals. Overall, the results of my dissertation contribute to our understanding of the behavioral and neural mechanisms that help animals respond to a changing world.

Date

4-16-2024

Committee Chair

Lattin, Christine R.

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