Document Type

Honors Thesis

Publication Date

Spring 2019

Abstract

Across the range of a species realized niche, individuals can face a range of environmental factors that change as you move from the central range towards the edge. These changes in environmental factors can have a significant impact on the fitness of an individual. In insects, one way to determine this impact is to study the difference in adult body size across the span of the species range. In western Colorado, caddisflies are the biomass dominant detritivores in alpine pond ecosystems. Caddisflies are fundamental in providing nutrients to the ecosystem because of the nutrients that they recycle as detritivores. Understanding how elevation and other factors affect caddisfly fecundity is key to understanding how climate change will affect alpine communities globally. To have a better understanding of this concept, I studied 23 ponds ranging from 2,347 to 3,505 meters in elevation and analyzed how elevation, density, sex, pond type and year affected the adult body size of the caddisfly Asynarchus nigriculus. I collected density samples of these species in each pond throughout the summer. Pupae were placed in emergence chambers, and adults were collected and measured. Elevation had a significant positive effect while density had a significant negative effect on the adult body size of Asynarchus. The effect of pond type on Asynarchus body weight was almost significant in that adults were almost significantly larger in permanent ponds. Adults in 2004 were significantly larger than adults in other years, and females were significantly larger than males. These findings can help of have a better understanding of how alpine ecosystem processes may be changing in the future. In the past years, new species of caddisflies have begun to shift their range into higher elevations. This movement could have a significant impact on the existing caddisfly populations as well as how energy is flowing through the system. This study is important because understanding how climate change affects species that are part of foundational guilds may help us better understand its far-reaching effects on ecosystems.

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