Can the frozen plasticity theory explain the shrub-like shape of phylogenetic trees?
Phylogenetic trees are usually shrub-shaped rather than tree-shaped. Most disparate species originate at the same time and possibly from a common ancestor as a result of the process of adaptive radiation. Particular species, which have originated in a common radiation event and from a single evolutionarily plastic ancestor, coexist for a long time without splitting off new species. Most branches end without producing a successor; however, some of them could split off a new plastic species which could undergo a new burst of radiation. Interestingly, such a tree is similar in shape to the figure drawn by Charles Darwin and unlike modern trees (which are usually automatically interpreted as phylogenetic trees but in fact are inspired by the shape of the cladogram, a graphic representation of the distribution of synapomorphies within a studied taxon).