ssarp: An R Package for Efficiently Inferring Species- and Speciation-Area Relationships

A universal method of examining patterns of biodiversity on islands is the species-area relationship (SAR). SARs quantify the relationship between species richness (the number of species) and the area of the land mass on which they occur. An extension of the SAR, the speciation-area relationship (SpAR), quantifies the relationship between speciation rate and area. Comparing these relationships across island systems globally is a difficult task because gathering and processing a large amount of species occurrence and island data often requires researchers to conduct lengthy literature searches and combine datasets from several different sources. We present ssarp (Species-/Speciation-Area Relationship Projector), an R package that provides a systematic workflow for curating data, estimating speciation rates, and inferring SARs and SpARs. The ssarp workflow allows users to generate SARs and SpARs using either occurrence records or presence-absence matrices. Functions in ssarp use mapping tools to associate GPS points with land masses, remove points not on land, associate land masses with their areas using a built-in dataset of island names and areas, and infer SARs using unsegmented and segmented regression. The accuracy of these records can also be assessed by the user through the creation of a presence-absence matrix from ssarp's workflow. The ssarp R package also provides functions for estimating speciation rates and generating a SpAR. The ssarp R package allows researchers to increase the scope of their biodiversity research by efficiently inferring SARs and SpARs with occurrence records and presence-absence matrices.