Human-mediated dispersal of Geniotrigona thoracica (Apidae: Meliponini) colonies promotes high genetic diversity and reduces population structuring in managed populations

Abstract

The stingless bee Geniotrigona thoracica is a key managed pollinator in Southeast Asia, valued for its honey, propolis, and colony trade. In Thailand, frequent humanmediated movement of colonies raises concerns about its effects on genetic diversity and population structure.Weanalysed variation in mitochondrial (COI and 16S rRNA) and nuclear (five microsatellite loci) markers from 70 colonies sampled across 17 meliponaries in seven southern provinces. Microsatellite data revealed high genetic diversity and low nuclear differentiation (K D1; Fst D0.0024-0.1219; all P >0.05), with extensive gene flow (Nm D 3.60-207.83) among provinces. In contrast, mitochondrial markers indicated moderate-to-high differentiation (Fst D0.619), consistent with mitonuclear discordance arising from sex-biased. Managed colonies exhibited elevated heterozygosity and allelic richness, likely reflecting admixture from colony exchange, while unique haplotypes in certain provinces suggest introductions from external sources. Significant inbreeding was detected only in Yala, possibly linked to habitat loss and reduced effective population size. Our findings indicate that current meliponicultural practices maintain high genetic diversity in G. thoracica despite mitochondrial structuring, but increasing colony movement between genetically distinct populations may risk erosion of local adaptations, underscoring the need for genetic screening prior to translocation.