Graduate Studies

 

First Advisor

Eileen Hebets

Department

Biological Sciences

Date of this Version

Spring 2024

Document Type

Dissertation

Comments

Copyright 2024, Brandi June Pessman. Used by permission

Abstract

Animals experience their world through diverse sensory systems, leveraging information from prey, predators, and potential mates to inform behavioral decisions. Environmental noise disrupts information via spectral or amplitude masking, degradation, or distortion, potentially leading to costly errors in responses. Critically, urbanization has accelerated the proliferation of novel noise sources, triggering significant shifts in communication, foraging, and predator-prey dynamics among urban wildlife. While vertebrate studies have illuminated urban animals’ flexibility to anthropogenic acoustic noise, a comprehensive understanding requires broader investigations across diverse animal taxa and sensory modalities. To address these gaps, my dissertation explored the impacts of anthropogenic substrate-borne (vibratory) noise on the sensory ecology of the funnel-weaving spider, Agelenopsis pennsylvanica. Field observations in the first chapter revealed that A. pennsylvanica spatial patterns were associated with urban features, notably decreasing spider abundance in areas with indicators of potential traffic disturbance, suggesting the possibly disruptive effects of vibratory noise. I tested this hypothesis in chapter two by recording ambient field vibrations across A. pennsylvanica’s urban-rural span and season. I found spatial variation in urban vibratory noise linked to potential traffic disturbance and seasonal variation in rural noise related to peaks in harvest activity. Despite significant differences in rural-urban noise levels, spiders did not avoid noisy microhabitats in a two-choice noise experiment with similar differences, suggesting alternative forms of behavioral plasticity. In the third chapter, I investigated A. pennsylvanica’s capacity to modulate the transmission of vibratory information across their webs in anthropogenic vibratory noise. Webs constructed under high-noise conditions exhibited divergent transmission properties based on natal noise environments: rural spiders reduced energy loss potentially aiding prey and mate detection in temporary noise, while urban spiders attenuated noise to prevent sensory overload. In chapter four, I measured the costs of detecting and assessing prey and mates under rapidly changing vibratory conditions. Urban spiders or their webs displayed greater flexibility to environmental shifts compared to rural spiders, potentially buffered by the discovered web transmission differences or real-time behavioral responses. Altogether, funnel-weaving spiders adjust to rapidly changing urban environments using previous and current experiences with vibratory noise levels and consistency to modulate web properties and behavior.

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