Mating system and extra-pair paternity in the Fan-tailed Gerygone Gerygone flavolateralis in relation to parasitism by the Shining Bronze-cuckoo Chalcites lucidus

PLoS One. 2018 Mar 8;13(3):e0194059. doi: 10.1371/journal.pone.0194059. eCollection 2018.

Abstract

Extra-pair copulation can increase genetic diversity and offspring fitness. However, it may also increase intra-nest variability in avian hosts of brood parasites, which can decrease the discrimination ability of host parents towards the parasite. In New Caledonia, the Fan-tailed Gerygone (Gerygone flavolateralis), which is parasitized by the Shining Bronze-cuckoo (Chalcites lucidus), has two nestling morphs, dark and bright, that can occur in monomorphic and polymorphic broods. Gerygone parents recognize and eject parasite nestlings from their nest, but the presence of polymorphic broods may increase the chances of recognition errors. Using 17 microsatellite markers, we investigated the mating system of the Fan-tailed Gerygone to understand the mechanisms underlying nestling polymorphism. We hypothesised that extra-pair copulations would lead to a higher proportion of polymorphic broods caused by higher genetic variability, thus creating a trade-off between genetic benefits and host defence reliability. Extra-pair paternity occurred in 6 of 36 broods, which resulted in 6 of 69 offspring sired by extra-pair males. Broods with and without mixed paternity were comparably often parasitized. Extra-pair paternity did not influence the proportions of bright, dark and polymorphic broods. Compared to bright siblings in polymorphic broods, dark nestlings tended to have lower heterozygosity, particularly in loci associated with skin coloration. The results also suggested that there is no obstacle for genetic exchange between individuals from forest and savannah, possibly due to dispersal of offspring. We conclude that the Fan-tailed Gerygone is a socially monogamous species with a low rate of extra-pair paternity compared to closely related species. Extra-pair paternity increased offspring genetic variability without measurable associated costs by brood parasitism. The results highlight the importance of studying host mating systems to assess the trade-offs between host defence and offspring fitness in co-evolutionary arms races.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Distribution
  • Animals
  • Birds / physiology*
  • Female
  • Forests
  • Genetic Association Studies
  • Grassland
  • Male
  • Nesting Behavior*
  • New Caledonia
  • Oviposition
  • Passeriformes / genetics
  • Passeriformes / growth & development
  • Passeriformes / physiology
  • Pattern Recognition, Visual
  • Phenotype
  • Sexual Behavior, Animal*
  • Skin Pigmentation / genetics
  • Territoriality

Grants and funding

This study was financed by the Polish National Science Centre (grants NCN 2012/05/E/NZ8/02694 and NCN 2016/23/B/NZ8/03082), the Japan Society for the Promotion of Science (grant 24-4578 to N.J.S., grant 24770028 to K.D.T., grant 23255004 to K.U.), and Rikkyo University (grant SFR 11-54 to N.J.S.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.