Seed Dispersal of the Cocoplum (Chrysobalanus icaco) by Gopher Tortoises (Gopherus polyphemus) in Southeastern Florida by Carolyn J. Hanish A Thesis Submitted to the Faculty of The Charles E. Schmidt College of Science In Partial Fulfillment of the Requirements for the Degree of Master of Science Florida Atlantic University Boca Raton, FL May 2018 Copyright 2018 by Carolyn J. Hanish ii Seed Dispersal of the Cocoplum ( Chrysobalanus icaco) by Gopher Tortoises ( Gopherus polyphemus) in Southeastern Florida by Carolyn J. Hanish This thesis was prepared under the direction of the candidate's thesis advisor, Dr. Jon A. Moore, Department of Environmental Science and Harriet L. Wilkes Honors College, and has been approved by the members of her supervisory committee. It was submitted to the faculty of the Charles E. Schmidt College of Science and was accepted in partial fulfillment of the requirements for the degree of Master of Science. Jon A. Moo , li. Thesis Advisor Brian~~~- Benscoter, Ph.D. <fr~~_;ft Dareoawiik, Ph.D. ;r--d~ Tobin Hindle, Ph.D. Dale Gawlik, Ph.D. Chair, Department of Environmental Sciences Aeaifii,Ph.D.~t-- Dlt:e2. ~ofScience ();;zU 9. df)/9 Diane E. Alperi~,~' Date Interim Dean, Graduate College 111 Acknowledgements Funding for this project was provided by the Harriet L. Wilkes Honors College. I am very grateful to Corey D. Anderson of Valdosta State University for collaborating with us on the Geospatial Components in this project. His help with the spatial analysis was crucial to our project impact. I am also thankful for the constructive ideas and field help I received from Amanda Hipps, Richard Jones, and Lauren Fremont. I am especially grateful for the help Sebastian Velez committed to this project, with a great sight for samples and reliable help with the germination trials. I’m thankful to my family for supporting my endeavors and my husband Kyle Hanish for his help as both a supporter and contributor to this project. Lastly I am grateful to Jon Moore for the support, technical assistance, laboratory space, and his guidance throughout this project. iv Abstract Author: Carolyn J. Hanish Title: Seed Dispersal of the Cocoplum (Chrysobalanus icaco) by Gopher Tortoises (Gopherus polyphemus) in Southeastern Florida Institution: Florida Atlantic University Thesis Advisor: Dr. Jon A. Moore Degree: Master of Science Year: 2018 Gopher tortoises (Gopherus polyphemus) are keystone species mainly due to their burrow construction. Gopher tortoises can also impact the plants around them, but it is rarely quantifiable due to constraints in dispersal studies including time period and seasonality of fruit. The objective of this study was to measure the effect gut-passage has on a native Florida stone-pitted shrub, the cocoplum bush (Chrysobalanus icaco), as well as to attempt to model the relationship between the gopher tortoise and the plant using our unique field site. This study shows that gut-passage has a significant effect on the germination rate of the cocoplum, allowing it to germinate faster than control groups. This study also found that a model involving covariates relating to tortoise movement as a predictor for cocoplum intensity was favored over a homogeneous null model. We believe the pattern of plants is nonrandom and relates to the gopher tortoise’s seed dispersal. v Dedication This manuscript is dedicated to my loving family, for supporting me in my endeavors to chase my dreams. I would like to dedicate this work especially to my late grandmother, Jeanne M. Smith, who was a brave and compassionate scientist throughout her life, never hesitating to challenge her obstacles. Lastly, to Gertrude, who never backed down from a fight, and was always ready to defend her home. Seed Dispersal of the Cocoplum (Chrysobalanus icaco) by Gopher Tortoises (Gopherus polyphemus) in Southeastern Florida List of Tables ..................................................................................................................... ix List of Figures ..................................................................................................................... x Chapter One: Introduction .................................................................................................. 1 Chapter Two: Materials and Methods ................................................................................. 7 Seed Collection ............................................................................................................... 7 Germination Experiment ................................................................................................. 8 Seed Tray Configuration ............................................................................................. 8 Protocol ........................................................................................................................ 9 Analysis ..................................................................................................................... 10 Geospatial Component .................................................................................................. 12 Spatial data collection ................................................................................................ 12 Protocol ...................................................................................................................... 13 Point-pattern analysis ................................................................................................ 15 Chapter Three: Results ...................................................................................................... 17 Germination Experiment ............................................................................................... 17 Germinability Testing ................................................................................................ 17 One-way Analysis of Variance on Ranks .................................................................. 17 Survival Analysis ....................................................................................................... 18 Point Pattern analyses ................................................................................................ 19 vii Chapter Four: Discussion .................................................................................................. 21 Germination Experiment ............................................................................................... 22 Geospatial Component .................................................................................................. 25 Appendix ........................................................................................................................... 31 References ......................................................................................................................... 46 viii List of Tables Table 1. Analysis of deviance table for nested inhomogeneous Poisson point process models.. .......................................................................................................... 38 Table 2. Germinability results across treatments with the event of successful germination measured against the “right-censored” unknowns.................................. 39 Table 3. Chi-square results amongst final Germinability counts in all treatments.. ......... 40 Table 4. Independent-samples Kruskal-Wallis test summary of median germination times amongst treatments. ...................................................................... 40 Table 5. Pairwise Comparison of Treatment Using Dunn’s Test and Bonferroni Correction.. ............................................................................................... 41 Table 6. Means and medians for survival time with Kaplan-Meier estimator.................. 42 Table 7. Kaplan-Meier analysis of treatment groups using Log Rank and Breslow Tests.. ............................................................................................................ 43 Table 8. Pairwise comparisons across treatments groups with Breslow post-hoc.. .......... 44 Table 9. Regression table for the inhomogeneous Poisson point process model that was best supported by the data............................................................................. 45 Table 10. Day germinations in each treatment reached 50% of total germinations. ........ 45 ix List of Figures Figure 1. Graphical results of the Kruskal-Wallis analysis relating to treatment. ............ 31 Figure 2. Abacoa Greenway site showing surveyed cocoplum bush locations, tortoise burrows, and tortoise trails (High Traffic Trails)........................................... 32 Figure 3. Abacoa Greenway Site Covariates. ................................................................... 33 Figure 4. Pairwise comparison of treatment in Kruskal-Wallis test. ................................ 34 Figure 5. The Survival Distributions of the groups by treatment ..................................... 35 Figure 6. (A) Smoothed Pearson residual field for the inhomogeneous Poisson process model that was best supported by the data. (B) Areas within the study area were the absolute value of the smoothed Pearson residual exceeded 2 standard deviations (= TRUE) are shown in orange. ............................... 36 Figure 7. Partial residual plot for (A) the x-coordinate and (B) distance from gopher tortoise trails, in meter (Trail_dist) indicating that the systematic relationship between cocoplum intensity and these two predictors appears to be log-cubic............................................................................................................