DNA marker analysis detects multiple maternity and paternity in single broods of the lesser snow goose

Abstract

The determination of the degree of genetic relatedness among individuals is important for many population and behavioural studies¹. Conventional genetic markers such as allozymes are usually inadequate for such determinations, especially in avian species^2,3. Restriction fragment length polymorphisms (RFLPs) which are inherited as co-dominant mendelian alleles⁴, have recently been applied to paternity and maternity analyses in humans to address both medical diagnostic and legal⁵ issues. Field observations have led to the suggestion that lesser snow geese (Anser caerulescens caerulescens) engage in intraspecific brood parasitism (IBP)⁶ and extra-pair fertilization (EPF)⁷. Direct evidence for these suggestions has been difficult to obtain because of the lack of easily detectable genetic markers⁸. We have recently prepared a recombinant genomic library from the lesser snow goose and isolated seventeen probes that all identify RFLPs⁹. Here we use some of these polymorphic loci to examine the relatedness among members of four families. This study provides evidence for mixed maternity and paternity in broods of this socially monogamous species and demonstrates the utility of DNA markers for genetic analyses of species which traditionally exhibit few conventional genetic markers.