Friday, July 7, 2017

Everything You Ever Wanted To Know About Elephant Evolution

Elephant mtDNA and nuclear DNA phylogeny from Meyer et al. 2017. The Neumark-Nord (NN) and Weimar-Ehringsdorf (WE) straight-tusked elephants are indicated. The mtDNA tree has a time scale (bottom) but the nuclear DNA tree has no time scale associated with it.
John Hawks has a lengthy and fact filled post about our improved understanding of the evolution of the elephant (most species and clades of which are extinct now), which has been enhanced recently by ancient DNA and new paleological finds. Some important parts of this evolution happened while modern humans existed.


DDeden said...

Updated with new papers.

DDeden said...

"My own research on this dwarf elephant, Palaeoloxodon falconeri has shown that this remarkable species had an exceptionally large brain. In fact, it’s the only animal species ever recorded with a brain size comparable to a human’s."

The palaeoloxodan antiquus has been extinct for 120 000 years. This elephant roamed Europe and western Asia during the last ice age, about 400 000 years ago. A study of its DNA shows that this supposedly European animal is actually the African forest elephants’ closest relative.

andrew said...

Thanks for the tips.

DDeden said...

Two ancient elephantids in Central Asia 17ma, Gomphotherium (short legs and long lower tusks) show different diets, G. connexum retained the ancestral forest folivory, G. steinheimense had dental indications of a grazer, based on teeth wear pattern & phytoliths.

"Gomphotherium had primitive dentition consisting of low molar crowns, and numerous conical cusps arranged in few transverse enamel ridges on the chewing surface of the teeth.
"This was adapted for feeding on leaves, the primitive diet. But later on, the lineage leading to modern elephants and the extinct mammoths evolved an increased number of enamel ridges, and these eventually became densely packed tooth plates for shearing tough vegetation."

DDeden said...
Differentiating species by head crests. Expansion occurred from East Africa between 800ka and 781ka, extinction by 50ka.

DDeden said...

1.2ma mammoth DNA from tooth read. Nice diagrams on elephantids.

Temporal genomic data hold great potential for studying evolutionary processes such as speciation. However, sampling across speciation events would, in many cases, require genomic time series that stretch well back into the Early Pleistocene subepoch. Although theoretical models suggest that DNA should survive on this timescale1, the oldest genomic data recovered so far are from a horse specimen dated to 780–560 thousand years ago2. Here we report the recovery of genome-wide data from three mammoth specimens dating to the Early and Middle Pleistocene subepochs, two of which are more than one million years old. We find that two distinct mammoth lineages were present in eastern Siberia during the Early Pleistocene. One of these lineages gave rise to the woolly mammoth and the other represents a previously unrecognized lineage that was ancestral to the first mammoths to colonize North America. Our analyses reveal that the Columbian mammoth of North America traces its ancestry to a Middle Pleistocene hybridization between these two lineages, with roughly equal admixture proportions. Finally, we show that the majority of protein-coding changes associated with cold adaptation in woolly mammoths were already present one million years ago. These findings highlight the potential of deep-time palaeogenomics to expand our understanding of speciation and long-term adaptive evolution.

DDeden said...

The cite is:

You earlier linked another DNA study
A 2015 article on 1st sequence of woolly mammoth: