Tuesday, 21 April 2009

Steer Deer on Kodiak Island

I was all ready to write about some silly post about a story in the BBC claiming that the moon effects the flavour of wine (short version - it only effects the people who believe the moon has power), when someone passed me this story titled `malformations seen in Kodiak deer.` Hey!, I thought to my self. This looks familiar. Perhaps it's that stuff from CSU.

I should have been ready for horrible disappointment. The story is awful. The story is from AP, where they had a single writer stumble through the science, and proceed to mutilate it. Because it's from AP, and it's Alaska related, both the DNM and the ADN instantly picked it up, without even a whit of review. I don't know what's worse, the people who wrote the story, or the people who passed this on. There's a little hope for journalism, though, because the Kodiak Daily Mirror did a better job with the story. Unsurprisingly, they wrote their own version.

Here's my own version.

A little background is in order. First, Sitka Black Tailed Deer (SBTD) are small ungulates endemic to the Alexander Archipelago, mainland SE Alaska, and parts of British Columbia. In 1924, 14 animals were translocated from Baranof island to Long Island east of Kodiak Island. 2 more came from POW in 1930, and 9 more came Kupreanof Island, and were released to north of Kodiak Island. For those of you who need to whip out the calculator, that's 25 animals total. All SBTD in the Kodiak Archipelago come from these founders.

Fastforward to the early-mid 90s, when reports began to emerge about deer with abnormal antlers - antlers with extreme points on the end, frequently with poor symmetry. The body profile of these animals also seemed altered, and most interestingly (to a wildlife biologist!), they seemed to suffer from cryptorchidism, or the failure of one or both testes to develop or descend. The scientists called them `cryptorchid deer.` Locals call them `Steer Deer.` I like the latter.

To compound the issue, there appears to be a locational trend in the Steer deer. A survey of the area found that there was even higher rates of incidence on the Aliulik Peninsula animals (76%) when compared to the rest of the Archipelago (12%). When you look at the rest of the SBTD's range <<5% are steer deer. Clearly, there's something going on here.

Well, if you remembered my post on muskox, you're probably thinking `gosh, 25 animals? That's a small group!` And I would give you a cookie for remembering. 25 Animals is a really small group. It's even smaller when you consider the estimates for heterozygosity - a measure of diversity - are tiny numbers. The Tasmanian Devil, which is critically endangered, actually has the SBTD beat. Now that's just sad.

Well, some people from Colorado State University decided to take a swing at idea that the deer are really inbred, suffer from low diversity, and this is causing their problems. They came up here, did sampling across the Kodiak Archipelago, some in the Alexander, and managed to leave quite a few furious Alaskan scientists in their wake. I hadn't dealt with them directly, but rumour around the coffee pot is that they earned the animosity of a few people.

After their data collection, they looked for a few things -
  • Was there population structure between island?
  • Was there population structure between Kodiak proper, and the Aliulik peninsula?
  • Was there different levels of inbreeding between areas?

These were easy questions to answer, "Yes, No, No." The first, is almost expected, because the deer don't disperse over water, or don't frequently. So they're isolated from eachother. There were no DNA differences between SBTD on the Kodiak Archipelago between areas harder effected and areas less effected. Finally, inbreeding doesn't seem likely an effect, because measures that get at inbreeding and diversity seemed pretty comparable between SE and Kodiak, and within Kodiak.

So where does that leave us? It leaves us without any new answers, just a list of things that aren't causing it. There are still a few remaining hypotheses that need tested, but are much harder to tackle -
  • It could be environmental toxicity.
  • It could be a disease.
  • It could be an epigenetic trait.
There's currently almost no evidence for any of these. Not because they aren't necessarily true - one of them probably is - but because evidence is really, really hard to get. However, people have jumped all over environmental toxicity with vengeance. This seems the hypothesis du jour today (I say, hoping I used du jour right). The AP service story basically said the evidence points to this, when the evidence does no such thing.


flying fish said...

I'm glad I caught this post, I read the ADN article and was confused by the lack of real information. Thanks.

KC said...

I'm glad I could clear things up. That ADN article was just plain awful. I wrote a letter to the editor expressing how unhappy I was with their fact-checking...