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rfmcdonaldFellow felinophile Razib Khan at GNXP has recently made a post, provocatively titled "Animal Apartheid", that is not at all impressed by the interest of some conservationists in keeping some species genetically pristine. Razib's article stemmed from a Globe and Mail piece on the hydridization of animals in Canada, with wild animal populations interbreeding either with other species--either imported directly by human beings, or introduced to the other's habitat as a result of human environmental changes. Remember the famous grizzlar, the ursine creature of mixed polar and grizzly bear descent shot by a hunter in the Canadian Arctic? He was product of this sort of thing.
Me, I thought of cats, particularly of the Scottish wildcat.
The beautiful domestic cat descends from a few animals of a Middle Eastern subpopulation--Felis silvestris lybica--of Felis silvestis. Just a few wildcats chose to strike up a partnership with emergent agricultural human society, in so doing scoring a huge success, their descendants spreading worldwide and growing to number in the hundreds of millions. The domestic cat is the only feline species that is quite safe from extinction. Unfortunately, the relatives of the housecat that did not strike up a partnership with human beings, like the Scottish wildcat, have not thrived, asdetailed in Robin McKee's Guardian article.
Felis silvestris are not disappearing from the Highlands, however. Felis silvestris of wildcat lineage are not disappearinig. As one of McKee's interviewees says, they just are not reproducing exclusively with cats of wildcat lineage: "The trouble arises when household animals go wild, mate and create colonies of feral cats. These form at the edges of villages and in farms. Some of these feral animals meet up with wildcats and they mate. Female wildcats become pregnant and give birth to kittens that are not purebred wildcats. Slowly, the species loses its unique status and vigour and animals become hybridised. That is the real problem today."
Below is a picture of a European wildcat, taken from Wikipedia by Aconcagua, this is a picture of a European wildcat snapped in Germany's Bayerischer Wald national park. Contrast and compare with the domestic cats of your acquaintance.
When I blogged about the Siberian tigers, I suggested that they were overspecialized--too large carnivores, living in too restricted and endangered an environment--and that barring extensive successful aid the species will not have much of a future. Yes, in the future I suppose that descendants of the domestic cat might repopulate that niche, but that the product of millions of years of evolution specific to the Siberian tiger risks being lost. That is not the case with the Scottish wildcat; a very strong case can be made to the effect that one subpopulation of a species is simply melding with another as a consequence of environmental pressures, genes flowing in both direction, in ways no different from previous migrations and assimilations within the greater felis silvestris population. Trying to reverse irreversible trends of intermixture between two clearly infertile populations is a waste. I think these activists--in Scotland, in Canada, around the world--would do better to protect the habitats of the animals concerned.
Habitat destruction could also be pushing cross-breeding among spotted owls. Extensive logging cut down 80 per cent of the old-growth forest they live in and allowed for the invasion of barred owls. This has resulted in cases of hybridization between the two species - and today the David Suzuki Foundation calls the spotted owl the most endangered bird in Canada.
Climate change is another factor in the rise of interspecies mating. Because of changing temperatures, the blue-winged warbler has been moving north - both competing and mating with its closely related golden-winged cousins.
This also could explain the "grizzlar." Wildlife geneticist David Paetkau, whose company tested the hybrid's DNA, thinks that warming temperatures may have caused the grizzly father to spend less time hibernating, giving him more time to wander farther afield. And once he found himself so far out of his usual range, he may have chosen to mate with a polar bear because he could find no females of his own kind.
In fact, grizzlies and polar bears separated into two distinct species less than one million years ago. In evolutionary terms, this is a blink of an eye, and the bears' genes are so similar that Mr. Paetkau suspects that the offspring, like other hybrid species, was probably fertile.
Me, I thought of cats, particularly of the Scottish wildcat.
The beautiful domestic cat descends from a few animals of a Middle Eastern subpopulation--Felis silvestris lybica--of Felis silvestis. Just a few wildcats chose to strike up a partnership with emergent agricultural human society, in so doing scoring a huge success, their descendants spreading worldwide and growing to number in the hundreds of millions. The domestic cat is the only feline species that is quite safe from extinction. Unfortunately, the relatives of the housecat that did not strike up a partnership with human beings, like the Scottish wildcat, have not thrived, asdetailed in Robin McKee's Guardian article.
For several years, conservationists have warned that loss of habitat, road accidents and – worst of all – the spread of domestic cat populations are having a devastating impact on the Scottish wildcat. Populations of a species which has earned itself a reputation for its aloof ferocity and independence are plunging to catastrophic levels. There are now fewer pure-bred Scottish wildcats than there are tigers in the wild. It is estimated only 400 or so survive in the wild, mostly in the Cairngorms area.
"Until recently, we thought there were about 3,500 wildcats in Scotland," says Dr David Hetherington, manager of the Cairngorms Wildcat Project which was set up to help save the species.
"But then a detailed study was done on animals that had been killed in accidents. It was found that only about 12% of them were actually pure wildcats. The rest were either feral cats or hybrids of wildcats and feral cats. As a result, we had to drop our estimate of wildcat numbers from several thousand to only a few hundred. That was the wake-up call to the seriousness of the situation."
[. . .]
"Wildcats disappeared in lowland England around 1800," says Hetherington. "Then they vanished from Wales and northern England around 1860. Finally, they went from southern Scotland. All we have left is a few hundred around the Cairngorms and places like the Black Isle. The trick now is to find a way to stop them from disappearing completely."
Felis silvestris are not disappearing from the Highlands, however. Felis silvestris of wildcat lineage are not disappearinig. As one of McKee's interviewees says, they just are not reproducing exclusively with cats of wildcat lineage: "The trouble arises when household animals go wild, mate and create colonies of feral cats. These form at the edges of villages and in farms. Some of these feral animals meet up with wildcats and they mate. Female wildcats become pregnant and give birth to kittens that are not purebred wildcats. Slowly, the species loses its unique status and vigour and animals become hybridised. That is the real problem today."
Below is a picture of a European wildcat, taken from Wikipedia by Aconcagua, this is a picture of a European wildcat snapped in Germany's Bayerischer Wald national park. Contrast and compare with the domestic cats of your acquaintance.
When I blogged about the Siberian tigers, I suggested that they were overspecialized--too large carnivores, living in too restricted and endangered an environment--and that barring extensive successful aid the species will not have much of a future. Yes, in the future I suppose that descendants of the domestic cat might repopulate that niche, but that the product of millions of years of evolution specific to the Siberian tiger risks being lost. That is not the case with the Scottish wildcat; a very strong case can be made to the effect that one subpopulation of a species is simply melding with another as a consequence of environmental pressures, genes flowing in both direction, in ways no different from previous migrations and assimilations within the greater felis silvestris population. Trying to reverse irreversible trends of intermixture between two clearly infertile populations is a waste. I think these activists--in Scotland, in Canada, around the world--would do better to protect the habitats of the animals concerned.
