Estimation of the proportion of diploid males in populations of Hymenoptera

Abstract

Diploid males occur at low frequencies in natural populations of Hymenoptera as a consequence of the sex-determination system. Routine electrophoretic surveys will often reveal heterozygous diploid males. Maximum likelihood estimates are given for the proportion of males in the population that are diploid, when data are available from males only or from both males and females. In the simplest case, using male data only, qi = B2/2pq T2, where p and q are the gene frequencies at the marker locus, B2 is the number of heterozygous diploid males and T2 is the total number of males sampled. The variance V( 0) = Ø[1 -2pqØ -(1 -4pq)Ø2]/2pqT2. When both male and female data are available then 1, the proportion of diploids that are male, can also be estimated. This allows the approximate effective number of sex-determining alleles (assuming a single locus system) to be determined. Maximum likelihood estimates of have to be obtained numerically when data are available from multiple-allelic or multiple marker loci.

Orchid bees: a new assessment on the rarity of diploid males in populations of this group of Neotropical pollinators

“…Thus, apparently, except for Eg. annectans , the frequencies of diploid males detected for populations of euglossine species analysed in our study do not suggest any declines in populations of these species, since all of them showed frequencies of 2N males within the range expected for panmictic populations (see Owen and Packer 1994). We should also consider that, in addition to null alleles, our estimates of diploid male may be elevated slightly because of overestimates of marker variability and unknown mating structure for majority of euglossine species herein studied.…”

“…According to Owen and Packer (1994), in panmictic natural populations of bees the expected frequencies of 2N males are low, 10 % or less. In our study, populations of five of six euglossine species surveyed revealed frequencies of diploid males lower than 10 % and, thus, they would be in accordance with the expected for panmictic populations.…”

Effective population size in Hymenoptera with complementary sex determination

“…Assuming that females mate singly, the norm for hymenopterans (eg Eickwort and Ginsberg, 1980;Strassmann, 2001), the proportion of diploids that are male is (Adams et al, 1977;Owen and Packer, 1994)…”

Diploid males sire triploid daughters and sons in the parasitoid wasp Cotesia vestalis

“…Sex allele diversity has been estimated for a few species; examples are 15-86 sex alleles in the fire ant Solenopsis invicta (Ross and Fletcher, 1985;Ross et al, 1993), 19 in the honeybee Apis mellifera (Adams et al, 1977; see also Hasselmann and Beye, 2004) and 9-20 in the parasitoid wasp Habrobracon hebetor (Whiting, 1943;Heimpel et al, 1999;Antolin et al, 2003). Because sex allele diversity is high and species with CSD may avoid inbreeding (Ode et al, 1995), diploid male frequencies in the field are generally low (for example, Owen and Packer, 1994;Takahashi et al, 2001). Yet to date, diploid males have been reported in more than 60 species (van Wilgenburg et al, 2006).…”