Data from: Natal philopatry increases relatedness within groups of coral reef cardinalfish

Abstract [Related Publication]:
A central issue in evolutionary ecology is how patterns of dispersal influence patterns of relatedness in populations. In terrestrial organisms, limited dispersal of offspring leads to groups of related individuals. In contrast, for most marine organisms, larval dispersal in open waters is thought to minimise kin associations within populations. However, recent molecular evidence and theoretical approaches have shown that limited dispersal, sibling cohesion, and/or differential reproductive success can lead to kin-association and elevated relatedness. Here, we tested the hypothesis that limited dispersal explains small-scale patterns of relatedness in the pajama cardinalfish Sphaeramia nematoptera. We used 19 microsatellite markers to assess parentage of 233 juveniles and pairwise relatedness among 527 individuals from 41 groups in Kimbe Bay, Papua New Guinea. Our findings support three predictions of the limited dispersal hypothesis: 1) Elevated relatedness within groups, compared to among groups, and elevated relatedness within reefs compared to among reefs; 2) A weak negative correlation of relatedness with distance; 3) More juveniles than would be expected by chance in the same group and the same reef as their parents. We provide the first example for natal philopatry at the group level causing small-scale patterns of genetic relatedness in a marine fish. 
Methods
Study location and sample collection
The study was conducted on inshore reefs near Mahonia Na Dari Research and Conservation Centre, Kimbe Bay, Papua New Guinea (5°30’S, 150°05’E), from October 2012 to September 2014. A total of 41 social groups of pajama cardinalfish, Sphaeramia nematoptera, were comprehensively sampled from nearshore reefs and along a fringing reef. The whole population was sampled as well as possible with the means available, during two years and more than 500 hours of surveying.
A total of 527 S. nematoptera were caught using hand nets and diluted clove oil as a mild anaesthetic (Munday & Wilson 1997). Each fish was measured underwater (Standard Length SL) and a fin clip was taken from the caudal fin. Tissue samples were preserved in 99% ethanol for genetic analysis. All fish were categorized as either adult (≥38mm SL), subadult (33-37mm SL) or juvenile (