DOI: 10.5061/dryad.d7wm37q69
title: Data from: the two faces of secondary contact on islands: introgressive hybridization between endemics and reproductive interference between endemics and introduced species

description: Aim: Hybridization is thought to have played an important role in
 shaping the evolutionary history of diverse island taxa. Here, we propose
 an ecological and evolutionary framework for understanding the causes and
 consequences of heterospecific mating on islands – with and without
 introgressive hybridization. We use this framework to support our main
 contention that cases of secondary contact among endemic species should
 commonly result in introgressive hybridization whereas cases of contact
 between endemic and introduced species should commonly result in
 reproductive interference – resulting in two qualitatively different faces
 of secondary contact on islands. Location: Canary Islands,
 Galapagos, New Zealand, Caribbean, and Hawaii. Taxa: 705
 vertebrate, invertebrate, and plant species spanning 167 genera and 99
 families. Methods: Using a quantitative analysis of empirical
 research on secondary contact on islands, we weigh evidence for the
 drivers of secondary contact and heterospecific mating on islands. In
 particular, we compare cases of secondary contact between endemic species
 versus secondary contact between endemic and introduced species.
 Results: We find that three main drivers of secondary contact and
 heterospecific mating on islands most frequently reported in the
 literature are disturbance, long-distance (e.g. inter-island) dispersal,
 and compromised assortative mating. We find support for the hypothesis
 that introgression is a more common outcome between endemic species while
 reproductive interference is a more common outcome between endemic and
 introduced species. Main conclusions: We conclude that there are
 biological reasons to predict secondary contact and heterospecific mating
 to be common on islands for all taxa, but that the consequence of
 secondary contact is categorically different for contact between endemic
 species and contact between endemic and introduced species. We conclude
 that the former likely explains the apparent frequency of hybridization on
 islands, while the latter presents a cryptic and underappreciated
 conservation threat.
description: This dataset includes an analysis of empirical research regarding
 secondary contact on islands gathered from a literature search. The
 research articles were collected from a search on Scopus, the titles and
 abstracts of each article were screened, and then the full texts were
 screened for relevance. We then extracted data surrounding the causes and
 consequences of heterospecific mating between endemic species and endemic
 and introduced species. Divergence time estimates were collected for pairs
 of taxa when available, and each individual taxon was extracted in order
 to assess the prevalence of hybridization among endemic species. All
 statistical analyses were performed using the scripts included in the
 present dataset.
description: # The two faces of secondary contact on islands: Introgressive
 hybridization between endemics and reproductive interference between
 endemics and introduced species ### General Information This
 data_availability directory contains all of the scripts and results
 necessary to recreate the analyses and plots used in the article
 "Reatini et al. (2023)The two faces of secondary contact on islands:
 Introgressive hybridization between endemics and reproductive interference
 between endemics and introduced species Below is a description of the
 results files, the meaning of the column names within those files, and the
 corresponding analyses and plots for which they were used. A description
 of the script used to carryout the analyses follows. ### Results Files
 Below is a brief description of each of the results files and the figures
 they were used to produce: Column name descriptions for all results files
 can be found in the file "csv_descriptions.xlsx"
 lit_search_full_dataset.csv - dataset of all relevant articles collected
 from the literature search on sescondary contact on islands. Used in
 lit_search_data_analysis.R to produce panel A of Figure 1 and panel D of
 Figure 2. divergence_times_endemics.csv - all pairs of taxa with weak
 intrinsic barriers and divergence estimates used in
 lit_search_data_analysis.R to produce panel E of Figure 3. taxa.csv -
 taxonomic data and distribution data for each individual parental taxon
 extracted from lit_search_full_dataset.csv. Used in
 lit_search_data_analysis.R to produce the subplots in panel A of Figure 3
 and the results in Table 1. all_endemic_species.csv - all endemic
 angiosperm and vertebrate species recorded from species checklists for
 each archipelago. Used in lit_search_data_analysis.R to produce the
 results in Table 1. Note on NA values and empty cells: all NA values and
 empty cells in the above csv files represent data points that were
 unavailable or not applicable for the category in question. ### Scripts
 lit_search_data_analysis.R - used to carry out all analyses in the
 manuscript and to produce subplots in Figures 1,2 & 3. Package
 versions: tidyverse version 1.3.2 plotly version 4.10.1 dplyr version
 1.1.2 ggplot2 version 3.4.2 VennDiagram version 1.7.3 knitr version 1.43
 UpSetR version 1.4.0 ComplexUpset version 1.3.3