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What makes two different living beings two different animals?

JAR

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J
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What makes two different animals two different animals?

The concept that two different animals are two different animals because they can't breed with each other has one problem. Two animals that can't breed with each other are not necessarily two different animals. Two male guinea pigs can't breed with each other, but they are both considered to be the same type of animal. Another factor is sterility, which can make it impossible for two animals to breed with each other.

Also, some times two animals can breed with each other, but complications will arise. Among humans there is the Rh factor which can make it impossible for a Rh negative woman to breed with a Rh positive man, but it doesn't always happen. These days, there's some type of thing physicians can do to stop a Rh negative woman's immune system from developing an immunity to Rh positive blood. This fixes the problem. Rh negative blood is mainly found among the Basques, Canary Islanders, and inhabitants of the Atlas Mountains.
 
They have different social security numbers.

I take it your point is that "species" is a human classification, rather than a "natural" category?

No argument from me. You may find the creationists a harder nut to crack.
 
You forgot mules, they are bred but do not produce offspring. While it has it's flaws it is the best definition os species goin.

It is probably illegal in most states to bred two male hamsters.
 
davidhorman said:
Call me sceptical, heh, but does anyone else think that looks like a tiger's face pasted on top of another animal's body?
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It does indeed look strange, but I don't believe it's a tiger head, since tigers have black stripes on their heads, not spots. The body itself looks like the body of a lion, but it has spots like a leopard.

I found another site with some better pictures and info:

http://members.aol.com/jshartwell/hybrid-bigcats.html

Peter :)
 
Hybrid animals are cool. In jr. high I always said I was going to become a geneticist and breed an anaconda/rattlesnake hybrid. My dream has yet to be achieved. :( ;)

Any genticists want take my idea and run with it?
 
The important question is can you breed a pot-bellied pig with an elephant? (I heard somewhere that their DNA won't splice.)
 
Segnosaur said:
The important question is can you breed a pot-bellied pig with an elephant? (I heard somewhere that their DNA won't splice.)
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Yeah, but how many butts can you grow on em?
 
given that some are fertile could these constitute transitional species in any sense?is this a stupid question?why?
 
hgc said:

Is this a veiled reference to the famed 5 butt monkey?
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Which was a response to another south park reference.

Edit-

"Now I know how all those white women felt."
 
The biological species concept at times can get a little tricky. The most empirical definition involves similar chromosome number and the ability to reproduce & produce viable offspring as has been mentioned. I don't know if gender applies to any arguement about a species concept. In fact, I know in the early 20th century many bird "species" were refuted after finding that they were different sexes of the same species.

As I mentioned, though, the species concept can get a little gray. Included in the reproductive isolation definition is not only that two organisms can't reproduce, but they don't reproduce. This could include geographic separation or behavioral differences (i.e. mating ritual recognition) that cause two different things not to mate even though they genetically could pull it off.

When it comes to plants, particularly herbaceous flowering plants it can get real ugly. Many genra such as Lupinus can exist in a polyploid situation. Other criteria such as geographic distribution and morphology may be included.

In short, trying not to oversimplify, sometimes it just depends on what everyone agrees on.
 
Included in the reproductive isolation definition is not only that two organisms can't reproduce, but they don't reproduce.
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Or even that they could but they can't, like if the separation is caused by time; there are several members of the Hominid family with whom modern humans might be able to breed, but obviously can't.

It would seem wierd to declare two populations of some organism to suddenly be two different species just because of the sudden appearance of a geographic barrier which separated them. But it would also seem weird to withold the species distinction until the production of viable offspring is absolutely impossible, despite obvious morphological differences.

This kind of fuzziness can be frustrating, but it really only arises when two species are closely related. You might observe a cell under a microscope, and say, "Here is a single cell", and then return later to find that the cell had divided and say, "Here are two cells". But a fourth of the way through the process, or halfway, it would be difficult to make such a definitive statement.
 
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