Urban Habitat Mosaics Structure Gene Flow but Preserve Genetic Diversity in an Invasive Termite

Urbanization is expanding rapidly in tropical regions, yet its effects on the genetic structure and connectivity of invasive social insects remain poorly understood. Here, we investigated how urban and forest habitat contexts are associated with genetic diversity, population structure, and colony organization in the invasive termite Heterotermes tenuis (Hagen, 1858) across three paired urban-forest sites in Guadeloupe, using 18 newly developed polymorphic microsatellite loci. A total of 414 workers from 50 nests were genotyped. Across habitats, we found no differences in allelic richness, observed heterozygosity, expected heterozygosity, or inbreeding coefficients, suggesting no generalized loss of neutral genetic diversity in urban populations. In contrast, analyses of population structure revealed significant genetic differentiation between urban and forest habitats within each site pair, with habitat explaining 14%-22% of the genetic variation. Isolation by distance was detected in only one site, and a landscape-level MLPE model indicated that habitat context was a stronger predictor of genetic differentiation than geographic distance. Colony genetic structure was consistent across habitats: no mixed-family nests were detected, and extended family colonies predominated in both urban and forest environments. Together, these results indicate that urban and forest populations maintain comparable neutral genetic diversity while exhibiting moderate habitat-associated genetic structuring. However, because habitat type covaried with several environmental characteristics and historical introduction structure cannot be excluded, this differentiation cannot be attributed to urbanization alone. These findings highlight the importance of considering habitat-associated genetic structure and colony organization when assessing the spread and management of invasive termites in tropical urban landscapes.