The Diversity Of Sex Alleles In Apis Cerana And The Aid Of Polyandry For Its Invasive Population's Establishment

With the genetic constraint of their sex determination system, how just one or a few founding colonies can establish in Carins, Australia recently? This study focused on the analysis of the diversity of complementary sex determiner (csd) gene and how polyandry benefits the invasiveness of Apis cerana. Based on the systematically screening of primers for microsatellite loci and the fragment of complementary sex determiner(csd) gene, the following results have been achieved.?. analysis of the sex alleles' diversity in Apis ceranaThe sex alleles' diversity of Apis cerana was assessed across 25 populations from its native and invasive range, and compared with the genotype of 10 neutral loci. Firstly, a criterion for identifying functional alleles that could induce female development was derived, based on the minimum sequence divergence observed between sex allele pairs of sampled female bees. Then, a conservative estimate of global csd alleles' diversity in Apis cerana was made using a coupon collector model and there were 170-307 functionally distinct sex alleles globally. Finally, it was confirmed that sex allele richness was always high relative to neutral loci, even in bottlenecked invasive populations. Sex alleles were generally highly differentiated between populations.?. analysis of the source population of invasive Apis ceranaThree primer pairs that discriminate sex alleles based on length polymorphisms could be used to accelerate the process of identifying unique alleles of each worker from the invasive populations. Based on the sex alleles' distribution in Papua New Guinea, Solomon Islands and Australia,Apis cerana from Papua New Guinea was supposed to be the source population of the invasive honeybee arrived in Australia.?. analysis of the influence of polyandry on invasiveness of Apis ceranaIn honey bees and other Hymenoptera, small newly-founded invasive populations must overcome the genetic constraint of their sex determination system,which requires heterozygosity at a sex-determining locus to produce viable females. Apis cerana queens in the invasive population mated with an average of 27 males, which was similar to native-range Chinese Apis cerana queens. With this mating frequency, the founding queen/s could carry 75% of their source population's sex alleles in stored sperm. Based on the number of sex alleles and their frequencies detected in the invasive population, Monte Carlo simulations revealed that extreme polyandry reduced the risk that colonies produced a high incidence of inviable brood expecially in populations that had just experienced a founder event, i.e. when sex allele diversity was low and/or allele frequencies were unequal. Extreme polyandry aided the invasiveness of Apis cerana at least in two ways: firstly, it increased the sex locus allelic richness carried to new populations with each founder, thereby increasing sex locus heterozygosity; secondly, it reduced the population variance in diploid male production (DMP), thus improving colony fitness following a founder event.These results would be helpful for the ecological risk assessment about honeybee importing and support the mechanism research about the invasiveness of social insects.