I was actually going to ask this same question about kinds after reading someone else's answer to another question.
I've often wondered how exactly they define the 'kind' for the purposes of what evolution is apparently allowed within.
For example, in the dogs, there are several closely related species - including wolves, coyotes, and domestic dogs. Presumably, these would all be one 'kind', and allowed to have a common ancestor in this 'evolution within kinds' model.
How about jackals? They're pretty close, but not quite as close. Are they the same kind? They sometimes can and do interbreed with domestic dogs.
What about dholes? They're definitely dog-like, but not quite as dog-like as the wolf/coyote/dog group. Are they the same kind?
What about maned wolves, bush dogs or raccoon dogs? Also canines, but not as definitively doggie.
Where do foxes fit? Even within the foxes there are some distinct 'kinds'. Fennec foxes look less dog-like than say an arctic fox or red fox. The bat-eared fox has some very distinctive physiology, with unique auditory bullae. Are they still in the dog 'kind'?
Maybe their 'kind' is on the level of zoological families - so there are the 'dog' kinds, the 'weasel' kinds, the 'raccoon' kinds, and the 'bear kinds'.
This brings its own problems. Where do the pandas fit? They have features which are an admixture (one might even say 'transitional') between the raccoon kinds and the bear kinds (the red panda showing more of the raccoon kind features and the giant panda more the bear kind) - does the giant panda fit with the bear kind, and the red panda the raccoon? In which case, how do you define the difference between those kinds?
Perhaps the bears, raccoons, and pandas all represent one kind? In that case, you have kinkajous and ringtails as the same kind (with the same common ancestor) as polar bears and grizzlies. Which brings in even more complications when you look at the similarities between the skeletons and skulls of the grizzlies and polar bears and compare them to the sea lions.
I think the reason you don't see an operational definition of 'kind' from these people, is that such a definition ends up looking exactly like an evolutionary phylogenetic tree of the organism.
· 1 decade ago