invert_nexus said:
I did read it, but must have missed it or forgotten it after reading everything else. I did come to the thread late and had to read to catch up, it's difficult sometimes to not miss something. I'll try harder next time.
Don't feel so bad. It's tough keeping up with these threads. Some of them spurt from two pages to six if you don't check them for a few days. Who's got enough time to read all that?
I suppose a lot of what I contributed is somewhat off-topic, but I think it's important to understand the process of domestication to have a better understanding of the reverse process.
If you're interested in the process of domestication, you should study the psittacines (the order of parrots). We used to breed them and there is some incredible stuff going on.
In the wild, like most birds, many different species of parrots will flock together and eat side by side. Yet when it comes breeding season, they all mate with members of their own species. Only when populations dwindle and they can't find one of their own kind, they might consider crossbreeding.
At which point the stranest thing happens, at least with conures (the Brits and Aussies confuse us by calling them New World parakeets, but they're similar and closely related to the mini-macaws). Two species of conures come into contact and interbreed. Since conures are rather colorful, even for parrots, they produce some amazing colored hybrid offspring. Then in a few years when the offspring reach sexual maturity, they will only choose other hybrids that look like them, rather than members of either ancestral species. If there's more than one type of hybrid around, they will even avoid each other!
But in captivity, none of this happens. Hybridized parrots, macaws, cockatoos and parakeets are abundant. Most domestic parrots are taken from their nests when their eyes open after about seven days, and are hand-fed by humans. They then do what is called "imprinting", meaning they think that they are one of whatever species raises them. But this is a classic case of cognitive dissonance. Even though they can't see themselves very well, somewhere in their brain they know not only that they are a parrot, but more specifically a blue-and-gold macaw or a red-lored Amazon or a whatever. When they see another member of their species, they recognize it.
But. . . . domestically bred parrots have no taboos about interspecies dating. You raise a male blue-and-gold macaw with a female scarlet macaw so they get used to playing together, and chances are they will mate when the time comes. You get a rather gorgeous hybrid that's been named the Catalina macaw. The offspring are similarly unbound by tradition and will mate with another just like them, or a member of the ancestral species, or a different species. Breed a Catalina macaw back to a Scarlet and you get a "Camelot" macaw that is bright orange. Breed that one back to another Scarlet and you get a lovely Lavender macaw. At seven years per generation nobody's gotten to the next level yet. But they sure play havoc with our traditional concept of the "color wheel"!
The Greens (people, not parrots) freak out when they see us doing stuff like this. They scream that these hybrid birds might get loose in the rain forest and pollute the gene pool. They don't seem to understand that their natural habitat has already shrunk so badly that for quite a few species, there are more breeding pairs in American hobbyist and commercial aviaries than there are in the wild. The future of these birds is in domestic life.
The gene pools we have to work with are so small that it's healthy to interbreed them. You don't get the weakness that comes with inbreeding that way. And anything you can do to make them even more popular as pets means that their domestic population will continue to increase, assuring their survival. I think that's more important than keeping the extremely minor differences between closely related species purely defined.
Besides, these birds do hybridize outside of captivity: among the populations that have less fear of humans and hang out on the edges of human settlements, taking up the easy life of scavenging. Animals that can adapt comfortably to proximity to other species such as humans and dogs are the curious, adventurous ones that are more likely to be interested in interspecies dating. Check out the macaws that dive bomb your table and steal your Big Mac at the Iguassu McDonald's (goddess I hope there isn't really one there but you get my point) and you're likely to see some riotously colorful hybrids that the ornithologists never see because they go way out into the forest where the bird population has a different attitude.
Many animals seem to more readily interbreed in proximity to human settlements, I think my theory that if you can stand hanging out near a city you're probably also curious about other species of mates is true. Wolves and coyotes have hybridized in the northeastern USA, the first region to be heavily populated and drive off the individuals who were shy about multi-species socialization. So have many kinds of birds. The western black-headed grosbeak and the eastern rose-breasted grosbeak run into each other near the Mississippi river, now that the forest that used to separate their habitats has been replaced by farms. They interbreed rather commonly. We spotted a hybrid of the two species at our bird feeder -- in Los Angeles! Two thousand miles west of the place where they first met, and clear on the other side of the Rocky Mountains. It must have taken fifty generations of migration and interbreeding for that bird to show up that far away from his pure-species ancestors.
