First genealogy for a wild marine fish population reveals multi-generational philopatry

Abstract

Natal philopatry — the return of individuals to their natal area for reproduction — has advantages and disadvantages for animal populations. Natal philopatry may generate local genetic adaptation but may also increase the probability of inbreeding that can compromise persistence. While natal philopatry is well documented in anadromous fishes, marine fish may also return to their birth site to spawn. How philopatry shapes wild fish populations is, however, unclear because it requires constructing multi-generational pedigrees that are currently lacking for marine fishes. Here we present the first multi-generational pedigree for a marine fish population by repeatedly genotyping all individuals in a population of the orange clownfish (Amphiprion percula) at Kimbe Island (Papua New Guinea) over a 10-year period. Based on 2927 individuals, our pedigree analysis revealed that longitudinal philopatry was recurrent over five generations. Progeny tended to settle close to their parents, with related individuals often sharing the same colony. However, successful inbreeding was rare and genetic diversity remained high, suggesting occasional inbreeding does not impair local population persistence. Local reproductive success was dependent on the habitat larvae settled into, rather than the habitat they came from. Our study suggests that longitudinal philopatry can influence both population replenishment and local adaptation of marine fishes. Resolving multi-generational pedigrees over a relatively short time period, as we present here, provides a framework for assessing the ability of marine populations to persist and adapt to accelerating climate change.