jim sims

Human selection pressure on domestic pigs

Quote from the paper: "Because domestication necessarily involves the separation of animals from their natural environment, the alterations in coat color during animal domestication could have been the result of a relaxation of the selection pressure against non-camouflaged coat. The evidence presented here, however, demonstrates that relaxed selection alone cannot explain the observed MC1R diversity in domestic pigs. The complete lack of non-synonymous substitutions within European and Chinese wild boar (who diverged in the Pleistocene) is contrasted sharply by the nine separate amino acid-altering mutations present within domestic pigs. This pattern implies that naturally occurring mutations that altered camouflaged coat colors were quickly eliminated in the wild, but within a domesticated context, these mutations were prized and positively selected."

Reference: Fang M, Larson G, Soares Ribeiro H, Li N, Andersson L 2009 Contrasting Mode of Evolution at a Coat Color Locus in Wild and Domestic Pigs. PLoS Genetics 5(1): e1000341 doi:10.1371/journal.pgen.1000341

Origins of European Cattle

The authors of a 2006 paper in the Proceedings of the National Academy of Sciences examined DNA from ancient and modern cattle and used mtDNA to develop a distribution of cattle populations.  As shown on the figure at left, cattle introductions into Europe appear to be by several different routes with a major introduction from Anatolia (modern-day Turkey) into Eastern Europe and the other a North Africa coastal dispersion into Spain.  Cattle in sampled European locations north of the Pyrenees, including England, appear to be mostly derived from the Eastern European route.  Spanish cattle show a more North African route of introduction.

mtDNA of Ancient Goats of Neolithic Eurasia

The authors of a paper published in the Proceedings of the National Academy of Sciences in 2006 presents evidence of the diversity of ancient goats at a Neolithic site (Baume d’Oullen) indicated by a star on the map at left.  The dotted are indicates populations of ancient goat, and the arrows depict two routes of dispersals of humans in the Neolithic into Europe.  They found evidence for goats descended from two distinct populations already by 7,700 years ago, arguing for extensive movement of goats early in the Neolithic.

Domesticated cats have Middle Eastern Origin

In a paper published on line ahead of press in the scientific journal Science, Driscoll et al., report a world-wide phylogentic tree for domestic cats and their wild kin.  Domesticated cats are most closely related to the old cats of the Fertile Crescent and there were at least five mtDNA founders in the region.  The estimated time of domestication is about 9,000 years ago.  In the tree, the tan mtDNA clade IV contains modern day domestic cats.