What Is A Hybrid?

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default What Is A Hybrid?

Post  FinchG on Tue Nov 27, 2012 10:53 am

What is a hybrid?
A hybrid is the offspring of two different species. It is not the same as a mutation, which is a genetic variation within a species. Hybrids vary depending on how closely related the parent species where. If the parent species are not closely related they cannot produce any offspring together at all (e.g. dogs and cats). Some crosses will produce hybrid offpring but those hybrids will be sterile (e.g. horses and zebras will make a sterile "zebroid"). This is because the genes are too out of sync to make a viable reproductive system. If the parent species are very closely related the hybrids will be fertile (e.g. dogs, wolves, coyotes). Other things are still out of sync though. Behaviors in particular will be muddled. For instance, the way that lovebirds carry nesting materials is genetically determined. For those of you who don’t work with lovebirds, these small parrots will weave basket nests inside their nestboxes. They will strip pieces of newspaper, gather leaves and other items and carry them back to the nest. Each species has their own method of carrying materials and when hybridized the offspring have no idea how to do this correctly:

The Yellow-collared Lovebird carries one strip of nesting material at a time in its bill, but the related Rosy-faced Lovebird tucks the ends of several strips beneath its rump feathers and flies to the nest with the strips in tow. Hybrids between these two species try to tuck strips into their rump feathers but cannot do so correctly. Sometimes the hybrids fail to complete the tuck; more often they hold the stip by the middle instead of the end, fail to let go of the strip after tucking it, or tuck it into the wrong place; many strips do not reach the nest box. The hybrid’s genetic program for carrying nesting material apparently contains conflicting instructions.
- from Ornithology by Frank B. Gill

Genes carry a vast amount of information about what an organism looks like and how it will act. Genetically speaking, humans and chimps are only a tiny fraction different from each other, yet look at the huge difference that tiny fraction makes! Hybrids, even closely-related ones, mix up the differences between species at the genetic level. The lovebird example above shows how behavior can be affected. Health too can be an issue, as illustrated by my green-cheek conure hybrid. There is an even greater problem aviculture faces though- the loss of genetically pure stock.

Why Hybrids Should be Avoided
In the early 1990's the Wild Bird Conservation Act was passed. This restricted the export and import of virtually all birds. Backed by animal rights groups, this act was promoted to halt collecting and poaching of wild populations, some of which were dwindling due to over collecting. It was a well-meaning act that unfortunately did more bad than good. Many wild birds came from unindustrialized countries where export of native species was THE economy. Cutting off the demand forced them to look at other ways to get income- usually cattle ranching, in which rainforests were destroyed to provide room for the livestock. So the birds couldn’t be exported into captivity and instead faced extinction from deforestation. But I digress. The WBCA has greatly affected aviculture. No new birds can be imported to replace stock. Brotogeris, known as "pocket parakeets," used to be imported in huge numbers. Few breeders bothered with this genus because they were difficult to breed and too inexpensive to bother with. Now you can’t even find them, their captive numbers are so low.

Why not just get captive birds from other countries? The WBCA also restricts that. Breeders of captive bred stock have huge difficulties trading birds with other countries and few consider it worth the headache. With no new bloodlines being introduced, the risk of hybridization and inbreeding among the rarer species is great. Many of the greater/lesser/citron cockatoos have been hybridized and unscrupulous breeders may even sell them as pure stock. Once a bloodline has been tainted with hybrid genes, purity can never be restored. Hybrids are not like mutations- they cannot be bred out.

Ethically, hybridization is a touchy issue. A few breeders actually promote it, most of us condemn it. Whatever your stance may be, you should NOT purposely breed hybrids and intentionally try to pass them off as pure birds. If it happens accidently or unwillingly like in this case, any offspring should be sold as pets and banded with bands marked "hybrid." You should make any buyers fully aware that the offspring are hybrids and that because of this they should not be bred as they may carry potential defects. If you have one of the rarer species you should not be hybridizing at all. Instead, do everything you can to find the bird a pure mate, either by trading or collaborating with another breeder and participating in a loan.

Breed vs. Hybrid
Many people confuse these two terms. A breed is a man made variation within a species. Domestic dogs have thousands of breeds, from the doberman to husky to terrier, but all of these are the same species. Breeds arise during domestication, the process by which man breeds an animal for specific characteristics until it becomes a seperate species from the original wild population. Parrots aren't really domesticated, though some, like budgies, are getting there. You can already see two breeds developing within the budgie species: English (show) and American (pet). Breeds are made through selective breeding, the same way you would select birds to isolate a color mutation.


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