Gene Lineages in Motion: Adaptive Divergence in South African Dwarf Chameleons

Research on South Africa's dwarf chameleons of the genus Bradypodion has revealed that their genetic architecture reflects the ecological pressures of the environments they inhabit. Two species illustrate this clearly: Bradypodion pumilum, typically associated with forested habitats, and Bradypodion ventrale, which occupies more open bush vegetation.

A team of South African scientists set out to determine whether the diversification of these species is linked to evolutionary changes in specific gene families. To do so, they analysed genomes from several Bradypodion species and compared them with four previously published reptile genomes. Their aim was to identify orthologous gene families—genes inherited from a shared ancestor that diverged as the species themselves split.

The analysis showed that Bradypodion species possess expansions in gene families associated with neural connectivity, synaptic structure, cell–cell recognition, and genome maintenance. These expansions, however, differ between the two focal species. In Bradypodion pumilum, the enlarged gene families were primarily involved in synaptic organisation, localisation of postsynaptic receptors, and membrane‑associated signalling pathways. Such patterns suggest functional differentiation linked to life in forest environments, where complex spatial navigation and sensory processing may be advantageous.

In contrast, Bradypodion ventrale exhibited expansions in gene families tied to nervous‑system patterning during embryogenesis, cell adhesion, tissue architecture, and developmental signalling pathways. These functions align with the demands of living in more open, structurally variable bush habitats, where different developmental and morphological adaptations may be favoured.

The two species therefore differ not only in which gene families have expanded but also in the biological roles encoded by those genes. Their contrasting habitats appear to have shaped distinct evolutionary trajectories at the genomic level, illustrating how environmental pressures can drive functional divergence even among closely related dwarf chameleons.

More information:

Jody M Taft, Krystal A Tolley, Graham J Alexander, Anthony J Geneva, Lineage-Specific Neural and Morphogenetic Gene Family Expansions Accompany Habitat Divergence in Southern African Dwarf Chameleons (Bradypodion), Evolutionary Journal of the Linnean Society, 2026;, kzag013, https://doi.org/10.1093/evolinnean/kzag013