Grolar Bears and Narlugas: Rise of the Arctic Hybrids

[Anomalocaris]

I found it of interest as I was not aware that adaptation to environment would occur so quickly. I do have a tremendous interest in science without the background so I also wonder what has "triggered" this adaptive reproduction in the animals?

Lack of suitable mates often trigger the adaptive behavior of looking further afield and/or accepting less suitable mates. This could extend to mating outside the traditional mate pool. This results in testing of the definition of species. Traditionally a species of sexual organisms like humans, dogs and bears is defined to be any population sufficiently similar genetically and behaviorally so that when individuals of different sex of breeding age are brough together, they can mate and produce offspring that are both viable and fertile.

Clearly polar bears and brown bears can mate. The important remaining question remaining is are the hybrids of polar and brown bears viable and fertile? If they are, then in fact polar bear and brown bear represent merely major variations within same species, in principle similar to, but of a greater degree then, the variation between different population of human beings. In this case the mating is merely the continuation of the species and is no threat to any species. It may alter some traits of the resulting population, but that is just an exhibit of microevolution within species in response to conditions, sort of like creation of new breeds of dogs, or new population of humans resulting from intermixing of different previously isolated populations.

If the hybrids are not fertile or viable, then that proves our classification of them as different species to have been correct, and brown and polar bears are of different species. Their offspring with either die before mating, will not be able to mate, or will sire no offspring from any mating attempt. In this case, the presence of hybrid polar and brown bears is evidence of a threat to the continued existence of both species because because each act of such mating wastes the parents' mating capacity in producing hybrid offspring that can not carry on the species past their own lifetimes, but will potentially still compete with really viable and fertile offsprings for resource.