The Influence of Spatiotemporal Climate Variation on Insect Species Richness and Traits

Abstract

Anthropogenic climate change is having major impacts on global biodiversity, with effects to habitats, traits, and communities as a whole. Studying how species have changed, and will change, in response to changing climates is a critical area of research. In this thesis, I aim to better understand the response of our largest group of animals, insects, to changes in climate through time and space. I investigate two areas of possible species' responses: species richness (Chapter 1 & 2) and trait changes (Chapter 3). In chapter 1, I used a meta-analysis to determine whether there is a global pattern of insect species richness change with elevation, and what climatic factor(s) are associated with it. I found that insect richness plateaus at low elevations and then as elevation increases richness declines, associated with mean annual temperature and temperature seasonality. In chapter 2, I used collections of one of the largest groups of insects, weevils, to determine how species richness changes with elevation in an area at high risk of climatic change: tropical montane environments. I found that in this region, spring temperature, spring humidity, and surface area are associated with an increase in species richness across elevation. In chapter 3, I used museum specimens to look at how Canadian butterfly morphology is responding to climate change. I found that, since the 1950s, butterfly species have gotten paler and larger, but not in response to warming temperature, suggesting the importance of other factors like nutrition. Together, these findings help us to understand how insects are responding to changes in climate. Future research should focus on quantitative and experimental approaches to test these patterns and hopefully help to make better policy and conservation decisions in the future.