Rampant homoplasy and adaptive radiation in pennate diatoms

Abstract

Background and aims – We examine the possibility of the independent evolution of the same features multiple times across the pennate diatom tree of life. Methods and key results – Features we have studied include symmetry, raphe number and amphoroid symmetry. Phylogenetic analysis, with both morphological and molecular data suggest in each of these cases that the features evolved from 5 to 6 times independently. We also look at the possibility of certain features having evolved once and diagnosing large genera of diatoms, suggestive of an adaptive radiation in genera such as Mastogloia, Diploneis and Stauroneis. Conclusion – Formal phylogenetic analyses and recognition of monophyletic groups allow for the recognition of homoplasious or homologous features.