SSARP: An R Package for Easily Creating Species- and Speciation- Area Relationships Using Web Databases

Abstract

A universal method of quantifying patterns of biodiversity on islands is the species-area relationship (SAR). SARs visualize the relationship between species richness (the number of species) and the area of the land mass on which they live. An extension of this visualization, the speciation-area relationship (SpAR), helps researchers determine trends in speciation rate over a set of land masses. Comparing these relationships across island systems globally is an extremely difficult task because gathering and processing a large amount of species occurrence data and island data often requires researchers to conduct lengthy literature searches and combine datasets from several different sources. Here we present SSARP (Species/Speciation-Area Relationship Projector), an R package that provides a simple workflow for creating SARs and SpARs. The SSARP workflow allows users to gather occurrence data from GBIF, use mapping tools to determine whether the GPS points in the occurrence data refer to valid land masses, associate those land masses with their areas using a built-in dataset of island names and areas, and create SARs using linear and segmented regression. SSARP also provides multiple functions for estimating speciation rates for use in creating a SpAR. Using SSARP allows researchers to dramatically increase the scope of their biodiversity research through the creation of SARs and SpARs with data from island systems across the globe.