DOI: 10.5061/dryad.h70rxwdsd
title: Data from: Small but connected islands can maintain populations and genetic diversity under climate change

description: In response to the striking effects of environmental change, conservation
 strategies often include the identification of conservation areas that can
 effectively maintain vulnerable species. Consequently, identifying
 system-specific conditions that maintain the demographic and genetic
 viability of species of conservation concern is essential. Connectivity
 plays a critical role in the persistence of populations. Islands have been
 model systems to understand connectivity and metapopulation processes and
 have emerged as particularly favorable targets for conservation. While
 islands can be isolated from mainland disturbances, it is unknown what
 degree of isolation is necessary to avoid unfavorable changes but remain
 sufficiently connected to maintain population viability. To test this
 question, we explored connectivity within the Apostle Islands, an
 archipelago of 22 islands within Lake Superior, by comparing historical
 and contemporary trends in ice bridge connectivity and by simulating the
 effect of reduced connectivity within this system. We developed a
 demographically informed individual-based model to explicitly test the
 role of connectivity to influence the persistence and genetic diversity of
 American marten (Martes americana), a forest carnivore at risk across its
 southern range boundary. We found that genetic diversity was resilient to
 moderate changes in ice cover, but a complete loss of connectivity
 resulted in rapid genetic erosion. Despite genetic erosion, populations
 persisted as long as nominal connectivity occurred between islands. Our
 work suggests that connectivity will decline, but martens would be
 resilient to moderate changes, and, in the short term, the Apostle Islands
 can act as a refuge along this species’ southern range boundary.
 Identifying thresholds in connectivity that maintain populations but allow
 for isolation from disturbance will be necessary to identify suitable
 areas for species conservation across space and time.
description: # Small but connected islands can maintain populations and genetic
 diversity under climate change
 [https://doi.org/10.5061/dryad.h70rxwdsd](https://doi.org/10.5061/dryad.h70rxwdsd) Summary statistics and genetic data of American martens on the Apostle Islands collected between 2017 and 2019. This dataset was used to parameterize an individual based model to infer parameters of survival and migration. Then simulate a population forward in time to track changes in genetic diversity. ## Description of the data and file structure `Smith_and_Pauli_2024_Ecography_summary_statistics.csv` - Observed population size, allelic richness, and observed heterozygosity by island used as summary statistics in approximate Bayesian computation to infer parameter values. `Smith_and_Pauli_2024_Ecography_starting_genotypes.csv` - File contains multilocus genotypes of individuals used in the analysis with a unique ID column and island identifier. Each microsatellite marker is represented by two columns. `Smith_and_Pauli_2024_Ecography_found_allele_frequencies.csv` - File contains observed allele frequencies of the founding population of the Apostle Islands. Allele frequencies were used to simulate genotypes of simulated immigrating individuals. #### DATA-SPECIFIC INFORMATION FOR: Smith\_and\_Pauli\_2024\_Ecography\_summary\_statistics.csv 1\. Number of variables: 4 columns (island/pop size/allelic richness/heterozygosity) 2\. Number of cases/rows: 5 3\. Variable List: * Island - Island name within the Apostle Islands, WI, USA * Pop size - estimated population size of martens * Allelic richness - allelic richness estimated from 13 microsatellite markers. * Heterozygosity - observed heterozygosity estimated from 13 microsatellite markers. 4\. Missing data codes: NA 5\. Specialized formats or other abbreviations used: NA #### DATA-SPECIFIC INFORMATION FOR: Smith\_and\_Pauli\_2024\_Ecography\_starting\_genotypes.csv 1\. Number of variables: 24 columns (id/pop/11 markers) 2\. Number of cases/rows: 43 3\. Variable List: * id - individual marten identity * pop - island that individual was sampled on * 11 msat markers with 2 columns for each marker. 4\. Missing data codes:-1 5\. Specialized formats or other abbreviations used: NA #### DATA-SPECIFIC INFORMATION FOR: Smith\_and\_Pauli\_2024\_Ecography\_found\_allele\_frequencies.csv 1\. Number of variables: 3 columns (marker/allele/frequency) 2\. Number of cases/rows: 63 3\. Variable List: * Marker - name of microsatellite marker * Allele - base pair length of allele * Frequency - frequency of allele in founding population of martens to the Apostle Islands. 4\. Missing data codes: NA 5\. Specialized formats or other abbreviations used: NA ## Sharing/Access information n/a ## Code/Software n/a