UC Merced UC Merced Electronic Theses and Dissertations Title Resilience and Sensitivity to Changing Environments in North American river otters (Lontra canadensis) Permalink https://escholarship.org/uc/item/3n35n9x1 Author DeNeve Weeks, Danaan Publication Date 2020 License https://creativecommons.org/licenses/by-sa/4.0/ 4.0 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA, MERCED Resilience and Sensitivity to Changing Environments in North American river otters (Lontra canadensis) A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Quantitative & Systems Biology by Danaan L. DeNeve Weeks Committee in charge: Professor Jason P. Sexton Professor Jessica L. Blois Professor Emily Jane McTavish 2020 Copyright © 2020 Danaan L. DeNeve Weeks All rights reserved The Dissertation of Danaan L. DeNeve Weeks is approved, and it is acceptable in quality and form for publication on microfilm and electronically: ________________________________ Jessica L. Blois, Advisor _________________________________ Jason P. Sexton, Chair _________________________________ Emily Jane McTavish Table of Contents List of Tables ..................................................................................................................... iii List of Figures .................................................................................................................... iv Acknowledgements ............................................................................................................. v Curriculum Vitae ............................................................................................................... vi Abstract of the Dissertation ............................................................................................... ix Chapter 1: Ecological consequences of habitat change: how the past informs the present in two otter lineages ............................................................................................................ 1 1.1 Introduction ............................................................................................................... 1 1.1.1 Background ......................................................................................................... 1 1.1.2 River otters as a representative case study ......................................................... 2 1.2 Biogeographic history of two major semi-aquatic New World otter clades ............. 3 1.2.1 Background ......................................................................................................... 3 1.2.2 Pteronura ............................................................................................................ 4 1.2.3 Lontra ................................................................................................................. 6 1.3 Evolution & ecology of modern species ................................................................... 8 1.3.1 Pteronura brasiliensis ........................................................................................ 8 1.3.2 Lontra canadensis............................................................................................... 9 1.3.3 Lontra longicaudis ............................................................................................ 10 1.3.4 Lontra provocax ............................................................................................... 11 1.3.5 Lontra felina ..................................................................................................... 12 1.4 Synthesis & Future Directions ................................................................................ 14 1.5 References ............................................................................................................... 19 1.6 Figures ..................................................................................................................... 30 Chapter 2: Maximum entropy species distribution modeling of the North American river otter (Lontra canadensis) .................................................................................................. 32 2.1 Introduction ............................................................................................................. 32 2.2 Methods ................................................................................................................... 33 2.2.1 Model Inputs ..................................................................................................... 33 2.2.2 Modeling ........................................................................................................... 35 2.2.3 Model evaluation .............................................................................................. 36 2.3 Results ..................................................................................................................... 37 2.3.1 Model Performance .......................................................................................... 37 2.3.2 Predictor Variables ........................................................................................... 38 i 2.3.3 Predicted Range ................................................................................................ 39 2.4 Discussion ............................................................................................................... 39 2.4.1 Challenges ........................................................................................................ 39 2.4.2 Correspondence between predicted suitability and previous range maps ........ 40 2.4.3 What factors are associated with the internal structure of otter distributions? . 41 2.4.4 Challenges for modeling otter distributions ..................................................... 43 2.4.5 Overall conclusions and prospects for future river otter models ...................... 45 2.5 References ............................................................................................................... 47 2.6 Tables ...................................................................................................................... 52 2.7 Figures ..................................................................................................................... 57 2.8 Appendix ................................................................................................................. 62 Chapter 3: Patterns of morphological variation in a broadly distributed semiaquatic carnivore, the North America river otter (Lontra canadensis) ......................................... 73 3.1 Introduction ............................................................................................................. 73 3.2 Methods ................................................................................................................... 75 3.2.1 Specimen Selection & Acquisition ................................................................... 75 3.2.2 Data Collection & Processing........................................................................... 75 3.2.3 Aim 1 Analyses ................................................................................................ 76 3.2.4 Aim 2 Analyses ................................................................................................ 76 3.3 Results ..................................................................................................................... 77 3.3.1 Aim 1 Results ................................................................................................... 77 3.3.2 Aim 2 Results ................................................................................................... 78 3.4 Discussion ............................................................................................................... 78 3.5 References ............................................................................................................... 81 3.6 Tables ...................................................................................................................... 85 3.7 Figures ..................................................................................................................... 96 ii List of Tables Table 2.1: Sources and uses of distribution data............................................................... 52 Table 2.2: WorldClim variables. These variables are used in the Climate and Combined models. ........................................................................................................................ 53 Table 2.3: Landcover variables. These variables are used in the Landcover and Combined models. ........................................................................................................................ 54 Table 2.4: Summary of all models. Final models discussed in the manuscript were based on the 80km spatial resolution thin with the default number of background points. .. 55 Table 2.5: 3-way ANOVA results comparing influence of dataset type, background points, and spatial resolution on model performance as defined by AUC values. Dataset type and spatial resolution are significant at a 95% confidence interval. DF num and DF denom are degrees of freedom of the numerator and denominator, respectively. F is the f-ratio, and p is the p-value. A post-hoc Tukey HSD test indicated that 80km spatial resolution had significantly better AUC