Sunday, 1 March 2015

Feral pigs: a correction

A while ago in my dedomestication series, I wrote that the feral pigs in the South of the USA are a good example for a regression towards the wild type through natural selection.

"Although not identical, they bear a considerable resemblance to wild boars in looks, behaviour and movement. They have a body build for agility and strength, and that's how they move. Their tusks are well-pronounced as they have a social and defensive function. The skull is very elongated, as much as in the wild boar – perhaps this is an example of a “reversal” of paedomorphism as described above through developmental cascades [UPDATE: I was pointed out to a paper that suggests that the elongated snout of feral pigs is a result of phenotypic plasticity due to the chewing mechanism]. What is also striking is their (with a few exceptions) uniform fur colour, beautiful mud-coloured brown or very dark, almost black, brown (not as greyish as in the European wild boar) – very likely camouflage in forested environment."

However, Markus Bühler from the Bestiarium provided me with additional facts that force me to revise my statements a bit. 

The fact that those feral pigs resemble wild boar is actually less surprising when considering which kind of farm pigs they descend. Pigs of former centuries cannot simply be equalled with the typical farm pigs of modern times, because they were less productive, less paedomorph, and overall less derived. Some of these populations even descend from those of early Spanish settlers which brought their pigs from the Iberian peninsular, and as everybody who reads this blog will know that Iberia is a hotspot for primitive landraces today. 
So hypothesizing that the wild boar-like apparence of these feral pigs in the South of the USA is mainly due to dedomestication is like claiming the same for an aurochs-like population of feral cattle descending from primitive cattle landraces. Apart from that, these pigs are not as homogeneously coloured as the videos on youtube suggest. In fact, there is stil a variety of colours present in their gene pool.

Therefore, the dedomestication concept, as logical as it is, looses another empirical example.

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