Limestone karsts across southern China to south-eastern Asia support high levels of species diversity and endemism. Tao et al. studied the molecular evolution of the Ca2+-permeable channel TPC1 in the genus Primulina, a group of plants that have adapted to calcium-rich soils.

Sliding window plots of the Z-scores of radically changed amino acid properties showing regions under positive destabilizing selection
Sliding window plots of the Z-scores of radically changed amino acid properties showing regions under positive destabilizing selection (Z-score values >309) in Primulina TPC1.

Molecular evolution analyses of Primulina TPC1 identified several sites under positive selection, which suggests that TPC1 may participate in local adaptation of Primulina to karst environments: this episodic diversifying selection may play a major role in TPC1 molecular evolution.