DOI: 10.5061/dryad.4j0zpc8c7
title: Data for: Are immigrants outbred and unrelated? Testing standard assumptions in a wild metapopulation

description: Immigration into small recipient populations is expected to alleviate
 inbreeding and increase genetic variation, and hence facilitate population
 persistence through genetic and/or evolutionary rescue. Such expectations
 depend on three standard assumptions: that immigrants are outbred,
 unrelated to existing natives at arrival, and unrelated to each other.
 These assumptions are rarely explicitly verified, including in key field
 systems in evolutionary ecology. Yet, they could be violated due to
 non-random or repeated immigration from adjacent small populations. We
 combined molecular genetic marker data for 150-160 microsatellite loci
 with comprehensive pedigree data to test the three assumptions for a song
 sparrow (Melospiza melodia) population that is a model system for
 quantifying effects of inbreeding and immigration in the wild. Immigrants
 were less homozygous than existing natives on average, with mean
 homozygosity that closely resembled outbred natives. Immigrants can
 therefore be considered outbred on the focal population scale. Comparisons
 of homozygosity of real or hypothetical offspring of immigrant-native,
 native-native and immigrant-immigrant pairings implied that immigrants
 were typically unrelated to existing natives and to each other. Indeed,
 immigrants’ offspring would be even less homozygous than outbred
 individuals on the focal population scale. The three standard assumptions
 of population genetic and evolutionary theory were consequently largely
 validated. Yet, our analyses revealed some deviations that should be
 accounted for in future analyses of heterosis and inbreeding depression,
 implying that the three assumptions should be verified in other systems to
 probe patterns of non-random or repeated dispersal and facilitate precise
 and unbiased estimation of key evolutionary parameters.
description: Data for ‘Are immigrants outbred and unrelated? Testing standard
 assumptions in a wild metapopulation’<br> Dickel et al., Molecular
 Ecology, 2021 These data come from the long-term song
 sparrow field study on Mandarte Island, BC, Canada (latitude 48.6329°,
 longitude -123.2859°). The data provided here are sufficient to replicate
 the analyses presented in the above paper, and are therefore a restricted
 subset of the full Mandarte dataset. Full methods of
 data assembly and analyses are in the main paper. See also Nietlisbach et
 al., 2017, Proceedings of the Royal Society B.
description: Each row in the dataset relates to one individual.
 Key to variables: "id" - individual
 identifier for each individual<br> "prop_homoz" -
 proportion of loci at which the individual is homozygous<br>
 "immigrant" - binary variable indicating if the individual is an
 immigrant or not<br> "parent immigrant" - binary variable
 indicating if the individual has an immigrant parent<br>
 "immigratedness" - categorical variable indicating the
 immigration status<br> "year.appearance" - indicating when
 the individual entered in the population. Either arrival of immigrants or
 hatching for Mandarte hatched individuals<br> columns titled
 "Sosp" - ending with 'a or 'b'  -
 microsatellites<br> "fcoef" - coefficient of inbreeding
 (pedigree based)<br> "main_dataset - binary variable indicating
 if the individual was included in the main analyses (dependent on the
 number of loci genotyped)<br> "adult_dataset" - binary
 variable indicating if the individual survived to adulthood