A reconnaissance of population genetic variation in arctic and subarctic sulfur butterflies (Colias spp.; Lepidoptera, Pieridae)

Genotype-phenotype-environment interactions in temperate-zone species of Colias Fabricius, 1807 have been well studied in evolutionary terms. Arctic and alpine habitats present a different range of ecological, especially thermal, conditions under which such work could be extended across species and higher clades. To this end, we survey variation in three genes that code for phosphoglucose isomerase (PGI), phosphoglucomutase (PGM), and glucose-6-phosphate dehydrogenase (G6PD) in seven arctic and alpine Colias taxa (one only for G6PD). These genes are highly polymorphic in all taxa studied. Patterns of variation for the PGI gene in these northern taxa suggest that the balancing selection seen at this gene in temperate-zone taxa may extend throughout northern North America. Comparative study of these taxa may thus give insight into the mechanisms driving genetic differentiation among subspecies, species, and broader clades, supporting the study of both micro- and macro-evolutionary questions.