Where is Archy when you need him? I ask because Current Biology (note, this is a link to the pdf) has an interesting paper on the analysis of mammoth mtDNA from 160 samples – 63 from North America and 97 from Eurasia – from a broad cross-section of time. To give you an idea of what the research was about, here is the first paragraph of the article:
Conventionally, the mammoth diversity of the New World is
thought to have originated in two discrete waves. In the first,
the Eurasian species Mammuthus trogontherii entered North
America circa 1.8-1.5 mega-annum (Ma); there, according to
most paleontological interpretations, it later evolved into the
temperate-adapted Columbian mammoth, M. columbi. A second
independent wave would have introduced woolly mammoths
into northwestern North America circa 200 kiloannum
(ka), a date that remains poorly constrained [3-5]. Although
re-evaluations of Eurasian paleontological records [6, 7] have
replaced the anagenetic view of mammoth evolution with one
involving bouts of allopatric speciation, vicariance, and introgressive
hybridization over a lengthy interval, the contribution
of New World populations to this model has remained unclear.
Turns out, New World populations made a significant contribution. I haven’t read the entire article yet, so I won’t say any more…
Filed under: Paleontology | Tagged: Mammoths |
Afarensis: Anthropology, Evolution, and Science 
160 samples?! Obviously this was a mammoth study….
Oops. I saw the press release, but didn’t think the paper was going to be available till next week. I guess I know what I’m doing tonight.
To summarize, mammoths divided into 2 populations around 888 ka, with some moving into North America (Mammuthus trogontherii, altho’ that date is actually the middle of a very wide range. They subsequently developed into 2 clades, an Asian one called A which more or less continued the M. trogontherii line, and another which became M. primigenius (C+D+E) in North America. About 300 ka, the latter sent a group back across Beringia into Asia, where they apparently either out-competed or swamped their cousins. Clade A became extinct during MIS 3, when there was a contraction of many megafauna species, due to climate change during the interstadial (as bears and bison and horses all suffered population downturns also). After the Last Glacial Maximum, bison numbers took a rapid downturn, but M. primigenius rebounded for awhile. Is that how y’all read it too? (There were some competing hypotheses in there as well).
I found the allopatric versus chronospecies angle interesting, assuming its not just introgression.