Fun with skewbalds: extensive white spotting in Soay sheep

The third in a series of posts about white spotting.

Part I addressed a series of questions about the frequency of white spotting in Soay sheep, whether skewbald is “normal” in Soay, and whether breeders should try to get more or less white spotting in their flocks.

Part II presented extensive lambing data in an attempt to discern what “twinks” have to do with the genetics of white spotting.

When last we met, I promised pictures to illustrate the circumstance that two plain brown Soay sheep can produce a skewbald lamb. Let’s head toward this counter-intuitive conclusion one step at a time.

White x white mating.If you read my second post on white-spotting, the one with all the lambing data, you know we have never had a breeding between two “ss” Soay sheep, parents who both express white-spotting. As relevant here, that just means I cannot show you any offspring of a white-by-white mating. But I can show you the skewbald lambs produced by three other kinds of breeding pairs.

Author’s note: In our own defense, we have not had any such breedings because we practice formal rotational conservation breeding and none of our white-spotted flocksires have drawn any of our white-spotted ewes to breed. It will be fun as white-by-white breeding pairs come up in the rotation to begin accumulating data to fill in the line of goose-eggs in our lambing data.

White x twink mating. Two of our skewbald lambs are the product of a white-by-twink mating. Given how much white Tarleton and Ossie express, it seems logical they might produce skewbald lambs, especially since we know Soay sheep with twinks carry one copy of a white-spotting gene.

Ready for the other one, this time a white-spotted ram bred to a ewe with a twink?

White x Nothing mating. One of our skewbalds appeared unexpectedly from an unlikely pairing: a plain brown ram bred to a white-spotted ewe. Who would have guessed?

Twink x Nothing mating. Perhaps our most dramatic skewbald lamb, Parkham, has one plain brown parent and one parent with a twink. At the risk of sounding like a broken record, would you expect this pair to produce a mostly white offspring? We sure didn’t!

Nothing x Nothing mating. And now for the inevitable conclusion: skewbald lambs from brown parents, both parents brown for each lamb. These two lambs’ parentage is what prompted Steve to resort to “spirits” when we sat down to analyze the data.

Last but not least, our freckle-faced ewe Wheatley:

So much for the myth that Soay sheep, sweet and lithe as they are, all look alike.

For now …

Tags: skewbald sheep