Ancient rapid radiations of insects: challenges for phylogenetic analysis.

Phylogenies of major groups of insects based on both morphological and molecular data have sometimes been contentious, often lacking the data to distinguish between alternative views of relationships. This paucity of data is often due to real biological and historical causes, such as shortness of time spans between divergences for evolution to occur and long time spans after divergences for subsequent evolutionary changes to obscure the earlier ones. Another reason for difficulty in resolving some of the relationships using molecular data is the limited spectrum of genes so far developed for phylogeny estimation. For this latter issue, there is cause for current optimism owing to rapid increases in our knowledge of comparative genomics. At least some historical patterns of divergence may, however, continue to defy our attempts to completely reconstruct them with confidence, at least using current strategies.