Abstract
Evidence for natal philopatry, the return of individuals to their natal location for reproduction, is scarce in marine fish populations despite being common in anadromous fishes. The proportion of individuals returning to natal sites is an important metric for estimating the effects of inbreeding and the potential for local adaptation to generate resilience to climate change. Here, we present the first multigenerational pedigree for a wild marine fish. We resolved the genealogical tree of families of orange clownfish
Amphiprion percula
spanning up to five generations, using data from a 10-year genetic survey of a population at Kimbe Island, Papua New Guinea. We found that longitudinal philopatry plays a significant role in driving population renewal of the orange clownfish.
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 it may also increase the probability of inbreeding that can compromise persistence. Although 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 multigenerational pedigrees that are currently lacking for marine fishes. Here we present the first multigenerational 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) during a 10-y 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 multigenerational pedigrees during a relatively short period, as we present here, provides a framework for assessing the ability of marine populations to persist and adapt to accelerating climate change.