Wednesday, October 24, 2007

Felis catus, from Pantherae out of Mesopotamia


Enjoyed a piece in a recent SciAm this morning, tracing the family tree and the migrations of the Felidae family [that's cats]. These most resourceful and adaptable and efficient predators would've made short work of Australia's marsupial population if only they'd managed somehow to get here over the past few million years. Of course their great skills haven't helped them much against the great human onslaught - the domestic cat is about the only species of the 37 living ones not currently endangered or threatened.
Before the advent of DNA analysis they had difficulty with the Felidae fossil record - the skulls of lions and tigers, for example, being almost identical. The new approach has been to take blood or tissue samples from each of the 37 species, looking particularly at the x and y chromosomes and at mitochondria, to check for variation and therefore relatedness, and age - the oldest showing the most variation within any given gene. Genomic data was mathematically calibrated to a molecular clock [based on an assumption of regular evolutionary change] to yield estimates of the times of the various branchings of the tree.
Anyway I was intrigued to learn of the migratory lives of lions [there are still a handful left in India], tigers [almost wiped out in East Asia by volcanic eruptions 70,000 years ago] and cheetahs [once plentiful in North America, along with lions and Jaguars, but wiped out there by the Pleistocene extinctions]. Their roaming behaviour in the past has allowed them to survive, sometimes by the skin of their teeth, all sorts of climatic cataclysms, so it's a shame to see so many of them struggling now, largely through the wrecking of habitats.


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