Relevant Relicts: The Impact of Fossil Distributions on Biogeographic Reconstruction

Localized extinction can play a significant role in obscuring reconstructions of historical biogeography. Insects, one of the most diverse clades in the tree of life, have complex patterns of local endemism, patterns of relictual distributions, and clades which are rather widespread and cosmopolitan. At the same time, insects have a rich fossil record that can contribute to the inference of ancestral geographical distributions, in light of present ranges. Here, we review current and ancestral insect distributions to explore the impact of fossil ranges on ancestral area reconstruction. Known examples of relictual distributions within Phasmatodea and termites are discussed, while we test the impact of fossil inclusion on biogeographic reconstruction within ants and dragonflies. The inclusion of fossil distributions increases the breadth of ancestral ranges across several nodes in ant and dragonfly phylogenies, which has implications for biogeographically based interpretations of past evolutionary ecology for these groups. More broadly, the incorporation of fossil data into estimates of ancestral distributions will not only improve the accuracy of those estimates but also provide additional temporal context.