Similar but not the same: insights into the evolutionary history of paralogous sex-determining genes of the dwarf honey bee Apis florea

Abstract

Studying the fate of duplicated genes provides informative insight into the evolutionary plasticity of biological pathways to which they belong. In the paralogous sex-determining genes complementary sex determiner (csd) and feminizer (fem) of honey bee species (genus Apis), only heterozygous csd initiates female development. Here, the full-length coding sequences of the genes csd and fem of the phylogenetically basal dwarf honey bee Apis florea are characterized. Compared with other Apis species, remarkable evolutionary changes in the formation and localization of a protein-interacting (coiled-coil) motif and in the amino acids coding for the csd characteristic hypervariable region (HVR) are observed. Furthermore, functionally different csd alleles were isolated as genomic fragments from a random population sample. In the predicted potential specifying domain (PSD), a high ratio of π N /π S = 1.6 indicated positive selection, whereas signs of balancing selection, commonly found in other Apis species, are missing. Low nucleotide diversity on synonymous and genome-wide, non-coding sites as well as site frequency analyses indicated a strong impact of genetic drift in A. florea, likely linked to its biology. Along the evolutionary trajectory of 30 million years of csd evolution, episodic diversifying selection seems to have acted differently among distinct Apis branches. Consistently low amino-acid differences within the PSD among pairs of functional heterozygous csd alleles indicate that the HVR is the most important region for determining allele specificity. We propose that in the early history of the lineage-specific fem duplication giving rise to csd in Apis, A. florea csd stands as a remarkable example for the plasticity of initial sex-determining signals.

Mapping of Multiple Complementary Sex Determination Loci in a Parasitoid Wasp

“…This might be explained by much weaker balancing selection on each individual CSD locus under ml-CSD as in L. fabarum than on the one locus in sl-CSD species such as the honey bee. Similarly low diversity at the CSD locus was recently reported in the dwarf honeybee Apis florea , where it was proposed that a recent population bottleneck may have reduced the effect of balancing selection (Biewer et al. 2016).…”

The feedback loop of thetransformergene results in proper feminization under multiple sex determination signals in the ant,Vollenhovia emeryi

“…Another tra homolog, tra-like ( Figure 4 ), showed genomic structure similar to that of csd in honeybees. tra-like contains the sex-determination protein N-terminal domain, complementary sex-determiner protein and coiled-coil motif in both sexes, as with csd in honeybees [12,50,51]. In the last exon, numbers of repeated motifs differed among samples ( Supplementary figure 1AB ).…”

“…Although it is unclear whether the region actually reflects CSD allele specificity in V. emeryi , it might correspond to the hypervariable region (HVR) in csd of honeybees [50, 51]. An established zygosity test using HRM analysis enabled us to classify two CSD allele types of females produced by inbreeding and to compare allele types of two CSD loci and expression of genes related to the sex-determination pathway.…”

Gut Bacterial Inhabitants of Open Nested Honey Bee, Apis Florea

“…This is substantiated by their colony size, open nest and behavioral pattern (Kaspi and Sha r 2013; Radloff et al 2005). The evolutionary divergence of Apis orea from the common ancestor is much earlier from the remaining Apis clades (Biewer et al 2016). Apis orea is prevalent and restricted to south and southeastern part of Asia.…”

“…Apis orea is prevalent and restricted to south and southeastern part of Asia. It is commonly known as dwarf bee or little bee and survives temperature up to 50 °C (Biewer et al 2016). The honey production by these little bees is less in quantity and often consumed by them hence, not reared for commercial purpose.…”