The definition of species involves the abilty of individual within the group to produce? offspring?

Question

The definition of species involves the abilty of individual within the group to produce? offspring?

Answer 1

...to produce fertile offspring.

Answer 2

Of course, the definition requiring the ability to reproduce is a bit inadequate for a number of reasons.

1.  If an individual does not reproduce or has not reproduced, does this mean that it is not part of the species?  That is, is a chaste nun or a six year old child part of the human species if it has not had children?

2.  Does the definition depend on geography?  For example, if an organism becomes isolated from all other organisms with which it can breed, does it cease to be a member of that species because it can no longer breed with them?  

3.  How can one determine the species of organisms that are dead or are fossils?

Answer 3

The biological definition of a species is the ability to produce fertile offspring.  Sterile offspring are evolutionary dead ends (e.g. a horse and a donkey giving birth to a sterile mule).

But remember there are many other ways to assign species as well.