Exploring the Relationships Between Mammalian Functional Trait Distributions and Regional Biomes, with Application to Miocene Paleoecology

Authors

Devra Hock-Reid, University of Nebraska-LincolnFollow

First Advisor

Ross Secord

Date of this Version

Summer 7-26-2023

Document Type

Article

Citation

Hock-Reid, D. G. (2023). Exploring the Relationships Between Mammalian Functional Trait Distributions and Regional Biomes, with Application to Miocene Paleoecology [Doctoral dissertation, University of Nebraska-Lincoln]

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Earth & Atmospheric Sciences (Geology), Under the supervision of Professor Ross Secord. Lincoln, Nebraska: November 2022

Copyright © 2022 Devra G. Hock-Reid

Abstract

Paleoecology relies on understanding relationships between modern animals and their environment. Animals are adapted to niches in their environments, and those physical adaptations, or functional traits, are utilized as proxies to interpret aspects of paleo-ecosystems. Much is known about individual functional traits in extant mammals and their relationship to the environment. Less is known about how multiple functional traits across a community can be utilized for paleoecological interpretations. I develop models utilizing traits in mammalian communities at the biome level. For Chapter 1, I build a model for North American regional biomes using mammalian trait frequencies. I quantify changes in trait frequency distributions from historical (1832-1899) to modern (2008-2020) times across twelve regional biomes. Results indicate broad species loss across all taxonomic levels and decreased trait frequencies in all biomes due to widespread range contractions. For Chapter 2, I develop models of North American and African mammalian trait distributions. Additionally, I use the models to make paleoecological interpretations of a middle Miocene (late Barstovian; Ba2) Great Plains fauna. Many established paleoecological proxies use African data, even for North American environments. I compare and evaluate these models to determine which is most appropriate for North American paleoecological interpretations. North American and African trait distributions of similar biomes are distinctly different. The African model provides a paleoecological interpretation of the Ba2 Great Plains fauna consistent with past interpretations. For Chapter 3, I apply trait distributions from three Miocene Nebraskan mammalian assemblages to the paleoecological North American and African models developed in Chapter 2. Miocene assemblages are more similar to each other than to modern communities, representing fundamental underlying differences in trait distributions. Both models appear unsuited to make interpretations of local assemblages. Species richness and geographic scale contribute to differences in trait distributions of local assemblages, as does sampling and taphonomic biases against small mammals. However, the African model is the best option for making paleoecological interpretations of Miocene assemblages, though differences still remain.

Advisor: Ross Secord