breeding

[icebread]

wot is it that stops animals breeding with other animals say...dog and sheep or cat and a monkey ect ect and humans and birds and so on so on I would like you to explain it but with not too many big words thank you for your time

[willowoak]

Genetic material is stored in DNA, this is found in pairs of Chromosomes. Different species have different numbers / sizes of chromosomes. Humans have 23 pairs, while dogs have 39 pairs. For breeding the size and number of these must match as one of each pair comes from each parent. All dogs have 39 chromosomes so different breeds of dog can breed as they are the same species, but not with a human (or sheep who have 27 pairs)

hope this helps

[icebread]

if thay were together in the lab, are there any species close enough to each other with the pairs thing you told me about ( thanks ) any species that could be put or together to be able to get a odd sort of species?

[dundurn]

It depends how closely related the two animals are in a genetic sense.

All dogs can interbreed because no matter how different they look thay are all the same species.

Dogs can interbreed with wolves because although they are different species dogs were domesticated from wolves and have the same number of chromosomes.

Horses can interbreed with donkeys but they have different numbers of chromosomes; 64 in the horse to 62 in the donkey. As a result their offspring (with 63 chromosomes)are neither horses nor donkeys, but mules or hinnies and are almost always infertile.

Lions and tigers can interbreed but again their offspring have trouble in reproducing - the males are sterile, so any further breeding can only take place with male lions or tigers.

[Clanad]

But, of course, the animals don't know from chromosomes, do they? The more pedantic answer to you question is the inherent sexual stimulants, especially smells, from one species to another just don't register. The fact that if the animals did mate no progeny would result is as the other posters suggest. However, the more basic non-interaction question has garnered a lot of study.

A lot of work has been done on pheromones, for example. Many of these seem to be low key chemical induced actions from one sex to another... sometimes hardly identifiable (such as in humans), while others are more overt, especially the vivid colors seen in birds. At any rate, many factors inhibit such reactions, but most appear, at least for now, to be genetically linked...

[jake-the-peg]

But it's not so easy.

The old idea was a species was defined by the fact that animals of the same species can mate and have fertile young.

But take dundurn's lions and tigers.

You can have ligers and tions but only the males are sterile so you can have li-tions and ti-tions and ...well you get the idea.

Some nice pics here: http://www.hemmy.net/2006/06/19/top-10-hybrid- animals/ )
There are also a number of "species" that can interbrede and have fertile young dogs are the classic example with wolves, cyotes but also Polar bears and Grisley bears and some seals as I recall.

As Clanad suggests there may be many more but they just - well - don't fancy each other!

[dundurn]

Another problem is what's called oestrus (or estrus in the USA). Lots of female animals are sexually active only when they're fertile so even if the (random) male in the equation found the (similarly random) female "fanciable", she would very probably run a mile unless she was just about to ovulate.