Flamingos in the Lake Eyre Basin: sympatry and sexual size dimorphism in Australian Pleistocene flamingos

Presented by Timothée Niederer

PhD Candidate, Flinders University

Supervisors: Dr Jacqueline Nguyen (AM, Flinders University), A/Prof Trevor Worthy (Flinders University), A/Prof Vera Weisbecker (Flinders University)

Sympatry is frequently observed in modern flamingos, where it is common for two genera to coexist in one colony. Pleistocene-aged flamingo fossils from the Lake Eyre Basin, including the endemic genus Xenorhynchopsis, have previously been referred to four sympatric species in three genera: Xenorhynchopsis tibialis, Xenorhynchopsis minor, Phoenicopterus roseus (the extant Greater Flamingo) and Phoeniconaias proeses. This is the most diverse flamingo assemblage in the fossil record, and more diverse than that of extant species. Using a combination of qualitative analysis, geometric morphometrics and phylogenetic analyses, the following hypotheses were tested: 1) Only two sympatric species are present, with marked sexual size dimorphism; 2) Xenorhynchopsis minor is a smaller morph of Xenorhynchopsis tibialis; 3) Phoeniconaias proeses is a smaller morph of Phoenicopterus roseus; and 4) the genus Xenorhynchopsis is not taxonomically distinct.

The data reveal strong morphological similarities between Xenorhynchopsis minor and Phoeniconaias proeses, which was supported by geometric morphometric analyses, and a bootstrap support of 82% in the phylogenetic analyses. The fossil Phoenicopterus roseus shared morphological similarities with Xenorhynchopsis tibialis and was dissimilar to extant Phoenicopterus roseus, while Xenorhynchopsis tibialis remained distinctly separate to other taxa. Synonymy of Xenorhynchopsis minor into Phoeniconaias proeses is suggested.