We examine the effects of isolation over both ancient and contemporary timescales on evolutionary
diversification and speciation patterns of springtail species in circum-Antarctica, with special focus on
members of the genus Cryptopygus (Collembola, Isotomidae).
We employ phylogenetic analysis of mitochondrial DNA (cox1), and ribosomal DNA (18S and 28S)
genes in the programmes MrBayes and RAxML. Our aims are twofold: (1) we evaluate existing taxonomy
in light of previous work which found dubious taxonomic classification in several taxa based on cox1
analysis; (2) we evaluate the biogeographic origin of our chosen suite of springtail species based on dispersal/
vicariance scenarios, the magnitude of genetic divergence among lineages and the age and accessibility
of potential habitat.
The dubious taxonomic characterisation of Cryptopygus species highlighted previously is confirmed by
our multi-gene phylogenetic analyses. Specifically, according to the current taxonomy, Cryptopygus antarcticus
subspecies are not completely monophyletic and neither are Cryptopygus species in general. We
show that distribution patterns among species/lineages are both dispersal- and vicariance-driven. Episodes
of colonisation appear to have occurred frequently, the routes of which may have followed currents
in the Southern Ocean. In several cases, the estimated divergence dates among species correspond well
with the timing of terrestrial habitat availability.
We conclude that these isotomid springtails have a varied and diverse evolutionary history in the circum-
Antarctic that consists of both ancient and recent elements and is reflected in a dynamic contemporary