ANALYSIS OF COMPLETE MITOCHONDRIAL GENOMES FROM EXTINCT AND EXTANT RHINOCEROSES REVEALS LACK OF PHYLOGENETIC RESOLUTION – Eske Willerslev, Marcus Gilbert, Jonas Binladen, Simon Ho, Paula Campos, Aakrosh Ratan, Lynn Tomsho, Rute da Fonseca, Andrei Sher, Tatanya Kuznetsova, Malgosia Nowak-Kemp, Terri Roth, Webb Miller and Stephan Schuster
Amidst the recent outcry over phylogenetic hype, it is nice to see some truth in advertising. Sure one might quibble over whether the lack of a pattern is something that can be “revealed” but microecos never quibbles over semantics…
Semantics aside, what is tremendously cool about this paper is the recovery of mitochondrial genes from preserved soft tissues of the extinct woolly rhino, Coelodonta antiquitatis. Despite the overall lack of resolution among the clade, Willerslev and company recover strongly supported sister relationships between the two African rhinos (the white rhino, Ceratotherium simum and the black rhino, Diceros bicornis) and between the congeneric Javan and Indian rhinos (Rhinoceros sondaicus, R. unicornis).
While neither of these relationships are surprising, the authors also found support for a sister relationship between the woolly rhino and the ridiculously adorable, critically endangered Sumatran rhino (Dicerorhinus sumatrensis). This relationship has been postulated before, at least partly based on the fact that Dicerorhinus is unique among living rhinos in sporting luscious, auburn locks that put agent Scully to shame. However, this hypothesis has been controversial and this new paper certainly leaves the door open for considerable improvement in our understanding of the evolutionary history of living rhinos.
One of the problems here is that today we are left with only a tattered remnant of the great perissodactyl radiation that produced some of the most impressive, perplexing and yes (ahem) EXTREME mammals that have ever existed. Aside from the four rhino genera, a handful of tapirs (all in genus Tapirus) and a rather more respectable smattering of zebras, asses and kiangs (in the familiar, but rather lumpy genus Equus) are all that remains of this once diverse order. In the recent analysis, relationships amongst the rhino couplets changed dramatically depending on whether tapirs or horses were used as the out-group, perhaps indicating a geologically explosive radiation of rhinos from their perissodactyl ancestors at some point in the Cenzoic.
Sadly, we stand to lose even more of this evolutionary majesty if the poaching and deforestation that imperil all living rhinos isn’t checked. While the recovery of genetic material from the extinct woolly rhino is a remarkable achievement, it would be terribly tragic if scraps of keratin are all that future studies of rhino evolution have to go on.
But I hate to leave you on such a bitter note, so behold, the otherworldly wonder that is a baby Sumatran rhino: