Monday, 24 July 2017

Snow White inside

I'd like to think that one of the running themes in The Blob is that there is no such thing as little utility in black and white thinking. Der Reichskanzler was kind to children; there is some value to a belief in god; not everything the other side says is utter nonsense. On Sean Moncrieff's Newstalk FM radio program, he noted that the twitter-storm went on for 36 hours after they had a piece on the unborn (both sides going at it hammer and tongs) while a feature on homelessness among Irish 'born children' elicited only 5 comments.  But those issues are metaphorical black and white, although quite edgy. When it comes to actual black and white animals, the firm ground on allocation and definition is hard to find.

An old logic puzzle hinges on the fact that all swans are large white long-necked ducks [family Anatidae] which allows us to assert that any a) large b) white c) long-necked d) duck is a swan and failure at any of the enumerated criteria makes the thing you're considering a non-swan . . . until you go to Australia and encounter Cygnus atratus [R]. Naseem Taleb wrote The Black Swan as an investigation of certainty and our failure to correctly process information from outlier events - "unknown unknowns" like 9/11 and the inexplicable Harry Potterism of Google - to help us deal with the future. Taleb's book has plums in it but there is also a lot of duff to chew through [critical Guardian Review] and Taleb himself can sound simultaneously know-it-all and woolly, which doesn't help illuminate the plums. Black and White animals? Should make Blobbistas think pandas [no not those pandas] or rhinos or ice-floes and polar bears.

Bears, you say? Well I was reading about the unfortunate irony that the bear on the California State Flag [L] is extinct; less than 75 years after the Gold rush of 1848, the last grizzly bear Ursus arctos californicus in California was shot and killed in Tulare County in 1922.  Note that the California Grizzly is a subspecies of the Brown Bear Ursus arctos which, as a species,

 is a long way from being extinct but the key conservation-biology question remains: whom should we save if we are to retain the greatest possible genetic and ecological variation. Because variation is the stuff of evolution and we know not when a Black Swan event will put the survival of the species at risk. But when that event occurs, genetic variability is the best hedge against an uncertain future. We now have molecular tools to gather the genetic data to help conservationists make these hard decisions - El Blobbo has covered such studies for: fairy penguinsrhinos - giraffes - elephants - wildebeest - Tasmanian devils - whales.

We need that molecular data because brown bears are bigger than a bread-box and quite variable as to size and colour and so there has been a tendency to pronounce that specimens deserve their own sub-species because of a trivial difference in size, or habitat or feeding or colour.  This is partly due to ambition - getting to name a [sub-]species ensures your immortal fame while acknowledging your specimen as essentially-the-same-as is much less exciting. WWF has to hope that taxonomic lumpers eventually win over splitters: it's cheaper that way, because then they don't need to save two morphs.  You want to be a bit careful on defining things by skin/fur colour: a rat, black as my hat, ran across our yard the other day but I knew it couldn't be Rattus rattus, the black or ship [plague] rat, but rather a melanic form of Rattus norvegicus which has been so successfully invasive on the Shiants, the Scillies and Ile Bouvet.

Mais revenons nous a nos ours. There is the Black Bear Ursus americanus, for example, which is a good, reproductively isolated from Ursus arctos, species. The last common ancestor lived 5 mya, about the same separation as between us Homo sapiens and chimps Pan troglodytes according to molecular clocks. And there are melanic forms of the 'brown' bear just like there are blondies, red-heads [prev], dark-brown and sandy-coats. Grizzly refers to the grey de-pigmented tips to the hair shaft which give a distinguished pepper-and-salt look. At the other end of the spectrum is the polar bear Ursus maritimus which are definitely white but not so definitely a good species! It turns out that one of the 90 named subspecies of brown bears Ursus arctos sitkensis is endemic to the ABC islands in the Alaskan panhandle. ABC for  Admiralty, Baranof and Chichagof Islands, the largest northerly lumps of the Alexander Archipelago from which the city of Sitka faces out across the broad Pacific Ocean.  When they looked at the DNA of these beasts it turns out that they have distinctly polar-bear chunks of their genome.  It is now suggested that a population of polar bears was stranded by retreating ice on the ABC islands at the end of the last ice age. In absence of available male polar bears, some females acceded to the attentions of roving brown bears from the mainland and delivered healthy offspring. We know it was that way round because the ABC brown bear (a single individual, as far as I can make out) is most polar-like (6.5%) on the X chromosome than in the rest of the genome (1%).  Those healthy offspring grew up and started to look for potential mates in their turn and found only brown bears and so the polar-bear contribution has been stochastically diluted over the last 10,000 years. It's a bit like, if you send your saliva off to 23andme, they will analyse the DNA and tell you that  at least one of your ancestors had a romantic interlude with a Neanderthal. There will be no detectable difference on the heaviness of your brow-ridge but the DNA will bear a distinctive other-species signature. The algorithm can quantify the amount of miscegenation.

So there's hope for polar bears as the ice caps shrink and their habitat gets destroyed and they have to swim further than the cubs feel comfortable about. They have been there before and survived for some time in a brown-field site. Good news for seals?

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