Determination of Extra-Pair Fertilization and Inbreeding Using Microsatellite Genotyping in a Captive Population of Zebra Finches

Abstract

True monogomy is atypical among animal species. The zebra finch, Taeniopygia guttata, is an exception, renown for forming life-long monogamous relationships. We explored the extent of monogamy in a captive population of breeding zebra finches by determining the rate of extra-pair fertilizations (EPFs). Six pairs of finches were placed in a large flight cage and daily observations established pair-bond formation, nest building, and incubation behaviors. Zebra finches provide biparental care, and our observations revealed five established male-female pairs and one group of three (two males and a female). Both males and females vigorously guard and defend the nest, but males also engage in mate-guarding, protecting his female from the attentions of nearby males. If no EPFs occur, all eggs within a given nest should be those belonging to a specific, identifiable, pair of birds. EPFs are detected when the expected female is the mother but a different male is revealed as the father. Egg dumping is a less well documented phenomenon that occurs when a female deposits fertile eggs in a nest other than her own so the chicks are raised by foster parents. To determine the extent of EPFs, egg dumping, and relatedness in our captive population, we took blood samples from 13 potential parent zebra finches and 39 of their offspring, isolated genomic DNA, and amplified 5 microsatellite regions known to the zebra finch genome. Analysis of the DNA sequencing allowed us to assign maternity and paternity to individual zebra finches using single nucleotide polymorphisms (SNP’s).