Hanish et al. (2020)_AOB Plants
Data and R code for Hanish et al. (2020) in AoB Plants: "Endozoochory of Chrysobalanus icaco (Cocoplum) by Gopherus polyphemus (Gopher Tortoise) facilitates rapid germination and colonization in a suburban nature preserve" We examined whether Gopherus polyphemus (Gopher Tortoise) facilitated the spread of Chrysobalanus icaco (Cocoplum; Chrysobalanaceae) over a 14 year period in a suburban nature preserve (in Jupiter, Florida, USA) by: 1) comparing germination patterns among gut passed, hand depulped, and whole fruit treatments, and 2) testing hypotheses about environmental predictors of the spatial distribution of C. icaco, including information about G. polyphemus movement pathways and burrow locations. For the germination trials, we did not find a significant difference in the overall proportion of seeds that germinated by the end of the observation period, but Time to Event analysis revealed that gut passed seeds tended to germinate earlier than hand depulped and whole fruit treatments, supporting a lone scarification effect. Point Process Modeling revealed that the density of C. icaco bushes was higher near G. polyphemus movement pathways and was lower inside Serenoa repens (Saw Palmetto) patches, supporting a positive effect of tortoise movement patterns on plant distributions. The density of C. icaco increased from west to east, consistent with westward dispersal from the four founder bushes on the east side of the study area. After removal of outliers, we also detected a negative association between C. icaco spatial density and G. polyphemus burrow density that was presumably explained by the fact that seeds defecated deep within burrows were unlikely to germinate and establish without secondary movement. The results suggest that G. polyphemus contributed to the rapid dispersal of C. icaco by scatter dispersal of seeds (via feces) in areas where tortoises were active and that movement pathways provided suitable conditions for colonization. Data are from the MS thesis of CJH, conducted at Florida Atlantic University under the supervision of JAM. CJH and JAM conceived of the idea for the project. CJH, SV, and JAM developed methodology and conducted field work. CJH and SV maintained germination trials; designed and analyzed by CJH. Point pattern analyses were conducted by CDA. All R code (including figure files) were written by CDA. The germination data are provided as two comma delimited (.csv) files. "Cocoplum Germination Info" contains the raw data for each seed, including the fecal sample it was found in and the date it was collected. "GerminationDataCSV" contains the data from the germination trials. The R code required to reproduce Fig. 4 and SFig. 1 can be found in the text file: "Hanish et al_R code_Seed counts and germination curve". The spatial data are provided as shapefiles. The R code required to reproduce all Point Pattern Analyses and figures can be found in the text file: "Hanish et al_R code_Point pattern analysis".
Steps to reproduce
See Materials and Methods section of the manuscript for a detailed description of the analyses. For analyses conducted in R, the provided text files contain a detailed workflow and commentary.