A sex-linked esterase locus and translocation heterozygosity in a termite

Abstract

Slow vs. fast alleles at an esterase locus show a sex-linked pattern of inheritance in colonies of the termite Incisitermes schwarzi. As might be expected where a gene has only recently been brought into sex-linkage by means of a translocation between an autosome and a sex-chromosome, males as well as females can be heterozygous; males are therefore “holozygous”, not hemizygous, for this gene. The rate of exchange of this gene between X and Y chromosomes is 2/266 or less. In the founding reproductives (male or female), X chromosomes may have either the fast or the slow allele; in males, only Y chromosomes carrying the fast allele have been found. This linkage disequilibrium may be due to a founder effect, to “hitch-hiking” of the gene with the translocation, or to a sex difference in the fitness of gene combinations at or near this locus. © 1981 The Genetical Society of Great Britain.