MACROEVOLUTIONARY CONSEQUENCES OF PROFOUND CLIMATE CHANGE ON NICHE EVOLUTION: AN EXAMINATION OF MARINE MOLLUSKS OVER THE PAST 3 MILLION YEARS

Determining the impacts of environmental change on evolutionary processes is fundamental to understanding large-scale patterns of evolution, as well as to predicting how future climate change will impact Earth’s biodiversity. One question of particular interest is whether species’ environmental tolerances, or niches, evolve in response to a fluctuating environment. To address this question, we integrate paleontological and biological data with environmental reconstructions to quantitatively test for evolution within the niches of 12 mollusk species over three million years of environmental change. We employ GIS and Ecological Niche Modeling (ENM), the latter of which is often used to assess how extant species may respond to future climate change by transferring present-day environmental requirements of species onto future climate landscapes. The methodology assumes stasis within the niche attributes of species over time; however, some have argued this is biologically unrealistic and produces inaccurate predictions. Here, we take a step towards validating the approach, while also providing new data on evolutionary processes. To do so, we gathered occurrence data for each species from eight museum collections, comprising over 3000 collection records, and obtained paleoenvironmental and climatic characterizations from Hadley Climate Centre, UK, for the Pliocene, Last Interglacial, and Present. We used ENM to calculate the niches of these mollusk species for the three time slices. Models were then statistically compared using kernel-smoothing techniques in environmental space. Results are informative for elucidating how species interact with their environment even in the face of environmental change. They also have epistemological implications for assessing the efficacy of ENM in predicting the fate of species as climate changes.