2 research outputs found
Morphological convergence in "river dolphin" skulls
Convergent evolution can provide insights into the predictability of, and constraints on,
the evolution of biodiversity. One striking example of convergence is seen in the ‘river
dolphins’. The four dolphin genera that make up the ‘river dolphins’ (Inia geoffrensis,
Pontoporia blainvillei, Platanista gangetica and Lipotes vexillifer) do not represent a
single monophyletic group, despite being very similar in morphology. This has led many
to using the ‘river dolphins’ as an example of convergent evolution. We investigate
whether the skulls of the four ‘river dolphin’ genera are convergent when compared
to other toothed dolphin taxa in addition to identifying convergent cranial and
mandibular features. We use geometric morphometrics to uncover shape variation in
the skulls of the ‘river dolphins’ and then apply a number of phylogenetic techniques
to test for convergence. We find significant convergence in the skull morphology of
the ‘river dolphins’. The four genera seem to have evolved similar skull shapes, leading
to a convergent morphotype characterised by elongation of skull features. The cause
of this morphological convergence remains unclear. However, the features we uncover
as convergent, in particular elongation of the rostrum, support hypotheses of shared
feeding mode or diet and thus provide the foundation for future work into convergence
within the Odontoceti.Open access. Distributed under Creative Commons CC-BY 4.