UNEXPECTED PATTERNS OF PARENTAGE AND RELATEDNESS IN A PRIMITIVELY EUSOCIAL BEE

IN species with haplodiploid genetic systems, full sisters are more cl osely related to each other (r = 3/4), and less closely related to the ir brothers (r = 1/4), than to their daughters and sons (r = 1/2). The classical theory for the origin of hymenopteran eusociality predicts that in many primitively or facultatively eusocial species, workers sh ould exploit this relatedness asymmetry by laying male-destined eggs w hile allowing the queen to lay gyne-destined (reproductive female) egg s(1-3). This prediction is satisfied in many species where colonies ar e founded by solitary gynes(4-8). Here we describe a surprising revers al of the classical pattern. In colonies of the bee Halictus ligatus ( Halictidae), queens produced most of the male-destined eggs whereas wo rkers produced many of the gyne-destined eggs. We suggest that this pa ttern may result from temporal constraints on the production of reprod uctive brood, and that it may be common among primitively eusocial spe cies.