Evolution question: How does speciation take place?

Answer 1

All speciation is a result of a *branching* (or *splitting*) of one species into two. There are many ways this can occur, but the most common way is something called 'allopatric speciation' ... and it works like this:

In any species there can be many subpopulations. As long as there is occasional contact between members of the species in adjoining territories, they will exchange genetics, and continue to interbreed.

But as often happens, some event can occur where a subpopulation becomes geographically isolated from the rest of the species. E.g. a lake with a species of fish can get dried up into two lakes. Or a river can cut through a valley. Or a flood, or a drought, or a migration following a bad winter, or continental drift ... any of a number of things.

If this genetic isolation is for many generations, then the two subpopulations accumulate enough genetic differences to where they can no longer interbreed, even if they do come in contact again. At that point they are officially *two* species (defined by the fact that they cannot interbreed). Once they are two species, they can never become one species again (regain the ability to interbreed). So as they cannot exchange genetic material, the two species will continue to get more and more different from each other.

Answer 2

small mutations over a long period of time will often lead to a change in allele frequency which can lead to speciation.
Other things will also lead to speciation:
- Isolation over time and space eg. Geographical isolation, a popluation moves into a new area, mountains, seas, rivers may separate populations, also mountains may cause separation over altitude as new habitats are opened up (some species become adapted to higher altitudes, while others remain at lower alts.)
- members may begin to flower or be fertile at different times and preventing fetilisation with other members of a population due to changes in climate or being in a different area (eg southern/northern hemisphere).
Basically they will all be unable to mate or produce fertile offspring with members of the orignal population.

polyploidy in plants can lead to an immediate new species, by being unable to breed with other members of the population ( this will be caused during meiosis, where chromosomes non-disjunction occurs)/

Answer 3

speciation is when one species evolves into a completely different species. It is when the new species evolved would not/will not be able to mate with the species from before.

It takes place when the species is put into a different environment, and through natural selection, the population evolves into a different species.

Answer 4

If you get a bunch of cats, say, and they live in the desert or something? Ok so their population increases and they spread out. Some of them stay in the desert, some go live in the next desert over.

Eventually you've got multiple populations of cats living in seperate locations, some of them now completely cut off from the others, so there's little or no interbreeding between populations.

Over generations of successive, independent mutation in response to local conditions, the seperate populations may come to be so unlike each other that they can no longer interbreed to create fertiile offspring. They have become seperate species.

That's how they explained it to me in school.

Answer 5

As a species evolves, it undergoes several changes in its morphology which over generations are reproduced to such an extent among the members of that species that species that a time comes when some members differ very markedly from their ancestors and hence cannot be classed as the same species.

A new species is thus born.