Evolution of Lycopodiaceae (Lycopsida): Estimating divergence times from rbcL gene sequences by use of nonparametric rate smoothing

By use of nonparametric rate smoothing and nucleotide sequences of the rbcL gene, divergence times in Lycopodiaceae are estimated. The results show th at much extant species diversity in Lycopodiaceae stems from relatively rec ent cladogenic events. These results corroborate previous ideas based on pa leobotanical and biogeographical data, Previous molecular phylogenetic anal yses recognized a split into neotropical and paleotropical clades in Huperz ia, which contains 85-90% of all living species. Connecting this biogeograp hical pattern with continent movements, the diversification of this epiphyt ic group was suggested to coincide with that of angiosperms in the mid to L ate Cretaceous. Results presented here are consistent with this idea, and t he diversification of the two clades is resolved as Late Cretacous (78 and 95 Myr). In the related genera Lycopodium and Lycopodiella, the patterns ar e somewhat different. Here species diversity is scattered among different s ubgeneric groups. Most of the high-diversity subgeneric groups seem to have diversified very recently (Late Tertiary), whereas the cladogenic events l eading to these groups are much older (Early to Late Cretaceous). Our analy sis shows that, although much living species diversity stems from relativel y recent cladogenesis, the origins of the family (Early Carboniferous) and generic crown groups (Early Permian to Early Jurassic) are much more ancien t events. (C) 2001 Academic Press.