When I were a nipper, elephants were simple. Prodigiously memorious it is true but simple in their classification. African elephants Loxodonta africana had larger ears and two "fingers" to the trunk, Indian elephants Elephas maximus had smaller ears and one finger. Paradoxically E.maximus was smaller than L.africana too. There were numerous other differences for experts but for nine-year-old me that was sufficient. It is the sort of pub-quiz knowledge that I accumulated by the trunk-load in the decade after JFK didn't come home from Dallas.
Two species was good enough for us all for a couple of hundred years although some maverick taxonomists ("splitters!") maintained that there were two distinct species - forest and savanna - in Africa. Nadin Rohland and others at Harvard have confirmed that the mavericks were correct by aligning the DNA of all the suspects. Included in their studies were woolly mammoths Mammuthus primigenius which had been frozen in Siberian bogs for thousands of years. The DNA of these chaps was in sufficiently good condition to be sequenced and compared with the living species. Rohland's most recent paper on the subject shows that, while in Asia Mammuthus and Elephas are sister groups separated by some millions of years, in Africa Loxodonta africana (savanna) and Loxodonta cyclotis (forest) are even more deeply divided. So they really are good species.
Who cares? Anyone who is concerned about the extinction of species cares. Extinction is forever. Once the last passenger pigeon Ectopistes migratorius or the last Tasmanian wolf Thylacinus cynocephalus dies in a zoo, a unique combination of genes adapted to a particular place in the world's ecology is irrecoverably lost. With finite resources we might choose to keep a small breeding colony of African elephants alive until the number of people on the planet drops below 2 billion and the rest of creation can breathe a sigh of fresh-aired relief. Rohland's work says emphatically that we'll need two colonies for the big fellows from the dark continent.
Carl von Linné (1707-1778) or Carolus Linnaeus as he was known to his erudite Latinate contemporaries or plain Linnaeus was the father of modern classification. He cemented the convention that each species (a group of inter-fertile organisms separated from other such groups) should be known by a unique binomer Homo sapiens, Canis familiaris etc. Closely related species get binned into the same genus (first name) while retaining a unique specific name: Canis aureus - golden jackal; Canis latrans - coyote. An objective taxonomist from Barnard's Star would give us at least two more cousins Homo troglodytes and Homo gorilla, but that's another story. For each and any species, it's handy to designate a single specimen as the Type against which other individuals may be compared. Linnaeus designated the Type Specimen for Elephas maximus as a unbearably cute fetal elephant in a glass bottle held by the Naturhistoriska riksmuseet in Stockholm. Maverick taxonomists, indeed anyone who looked closely at the tip of its little trunk, have long wondered at this designation. Several years ago, they decided to sequence its ancient DNA to see where he came from. But formaldehyde and alcohol are distinctly un-good for preserving DNA and that plan was a bust.
Last week's Nature carries a report that Tom Gilbert and Enrico Capellini have gone and sequenced the proteins which were derived from that degraded DNA and shown unequivocally that the Stockholm specimen's ancestors hailed from Africa. That's good news for a lot of projects including conundrums of human evolution like Homo floresiensis a vertically challenged relative (cousin? sister?) of ours discovered in Indonesia ten years ago. Her DNA has been irretrievably degraded in the tropic heat.
ah another monty python reference, these things are of interest to certain readers of the blog! collected like rare coins etc etcReplyDelete
Berluddy 'ell. A reader who reads the links. All my careful cross-refs are not in vain. Thanks for that.ReplyDelete
Er...Didn't need to...classic utterance from Life of Brian...but do often hit the links, a sponge is IReplyDelete