Estimation of individual level of inbreeding using relatedness measures in haplodiploids

Although male haploidy in haplodiploid species aids purging of deleterious alleles, haplodiploid animals may nevertheless suffer significant negative effects of inbreeding. The effects may even be stronger in social Hymenoptera because the negative fitness consequences may be expressed at two levels: the individual level (inbred queens) and colony level (inbred workers). Surprisingly, in natural populations the impact of inbreeding on fitness has been studied in very few insects, and even fewer haplodiploid ones. Hence there is currently little understanding of the potential effects of inbreeding. One reason may be the difficulties in estimating inbreeding especially at the individual level, apart from the additional problems posed by haplodiploidy. In order to study the impact of inbreeding, its individual level must be estimated as precisely as possible. When the population pedigree is unknown, relatedness-based estimates of the individual inbreeding coefficient can be used to estimate inbreeding. Here we examine the relationship between inbreeding coefficients and relatedness in diploid and haplodiploid organisms, and provide guidelines for estimating inbreeding both at the individual and the colony level. Received 7 March 2005; revised 18 April 2005, accepted 20 April 2005. An erratum to this article is available at .