A Closer LOOK: HOW DRONES BECOME DRONES

摘要

"Sex in honey bees is determined by a one gene locus (Mackensen 1951, 1955). If in a egg this locus is hemizygous (diploid cell with only one copy of a gene instead of the usual two copies) or homozygous (having two identical alleles of a particular gene), males will develop; if it is heterozygous (having two different alleles of a particular gene), females will develop. Normally, drones develop from unfertilized (haploid, having a single set of unpaired chromosomes) eggs and workers from fertilized(diploid, containing two complete sets of chromosomes, one from each parent) eggs. But drones can develop also from fertilized eggs, if the sex locus is homozygous (Bruckner 1979). Such diploid drones have been raised experimentally (Woyke 1965a), but innormal colonies they would be eaten by the workers at an early larval stage; they are recognized as abnormal (Woyke 1965c). In one population of 65 colonies, about 12 alleles (one of two or more alternative forms of a gene) were estimated to exist at the sex locus (Laidlaw et al. 1956). Since a queen mates with several drones, it is unlikely under normal conditions that the sex locus will be homozygous in many of the fertilized eggs, so no large number of diploid drone larvae will appear (and bee eaten by worker bees), which would lead to a scattered brood pattern."