There are ongoing efforts to reintroduce the eastern indigo snake into Alabama, where it was extirpated nearly 60 years ago. The Orianne Center for Indigo Conservation (OCIC) is spearheading efforts to breed individuals for release at Conecuh National Forest in southern Alabama, and Appalachicola Bluffs and Ravines in the Florida panhandle. This project will use simulated data to understand the longterm impact of introducing captive bred individuals with small amounts of genetic adaptation to captivity into wild populations. Estimated model parameters include population fitness, neutral genetic diversity, and population size. In addition to estimating these parameters for the reintroduced populations, I will estimate the effects of using captive bred individuals to supplement declining wild populations.
The simulation code was developed and described in Willoughby et al. (2019) and was forked on Github from jwillou/captivebreeding-IBM
The model as created includes life history parameters:
- Maximum Life Expectancy
- Fecundity
- Age at Maturity
The ecology of the eastern indigo snake is well studies and there fortunately exists data for all these life history traits. The model focuses on supplementing populations that are bounded in size by density dependent processes (e.g. - habitat loss), and the carrying capacity is reduced. Conecuh National Forest is a protected area and habitat for the species is being expanded through forestry management. Further, the small population size at Conecuh is likely not near carrying capacity. Therefore, density dependent processes are not likely to impact the estimated parameters in the short term. I will use the density-independent mortality probability outlined in the original model,
Pr(mortality) = age/maximum age
This project seeks to accomplish the following goals:
- Modify existing code from Willoughby so that it applies to eastern indigo snake
- Model the effects of introducing captive bred individuals into the re-introduced populations
- Model the effects of introducing captive bred individuals into established wild populations
Code for modeling effects of releasing captive-born individuals into wild populations associated with the publication Willoughby JR, Christie MR. 2019. Long‐term demographic and genetic effects of releasing captive‐born individuals into the wild Conservation Biology https://onlinelibrary.wiley.com/doi/pdf/10.1111/cobi.13217
Also found at https://github.rcac.purdue.edu/MarkRChristieGroup/captivebreeding-IBM
More information availalbe at lab wiki: https://wiki.itap.purdue.edu/pages/viewpage.action?pageId=82912459.
Note: Use of the provided code requires a specific configuration of folders. Within the directory holding all of the provided scripts, there should be three folders:source, plot, and output. All .R files that execute the simulation, except for RRSmodel.R, are found in source into the 'source' directory. After defining parameter values within RRSmodel.R and running the code, all output files will be directed into the 'output' directory. All code for plotting and parsing the output are found in the plot directory.