Are newly evolved species believed to emerge from single individuals?

Question

Or from multiple individuals of this new species born at the same time, or from multiple individuals of different newly evovled kinds that still share a similar enough form to reproduce with each other? And if multiple new examples of the same new species what is the process of this emergence outside of creatures that have multiple births per litter. (Please use simple people's terms. Thanks.)

Answer 1

In short, multiple individuals.

The most common mechanism for speciation (called 'allopatric speciation') is where a subpopulation of a species becomes geographically isolated from the rest of the species. If this isolation is long enough (at least hundreds of generations), any changes accumulated during that time will make them genetically incompatible with members of the base species (who have also been accumulating changes in that time). Then even if members of the two groups do come in contact with each other, they will have little desire to interbreed, and eventually will lose the ability to interbreed at all ... they are now, by definition, two separate species.

There are other mechanisms for speciation ... peripatric, parapatric, and sympatric (see source) ... but in all cases, it is a *population* that ends up being the foundation for the new branch that is the new species.

Now it is possible that some genetic mutation may begin to propagate into a population, and this may become the foundation event for speciation (see sympatric speciation). And that mutation may be traceable to a single individual. But that mutation may have lived for generations in the general population without it becoming a new species.

In short, don't ever get the idea that there is some individual, all of whose offspring are now a new species, completely reproductively incompatible with the foundation species. It is *possible* for that to happen. But that is very far from the most common way for speciation to occur.

--- {re: labscimas' post about Dawkins} ----

Be careful with misinterpreting Dawkins' point. (I don't have my copy of Ancestor's Tale on me, or I would try to find the exact quote you are referring to.) I'm pretty sure he was talking about the most recent common ancestor (MRCA) of a species ... but that does NOT mean that the entire species is thought to emerge from a single individual. E.g. if a subpopulation X of 100 individuals gets geographically isolated due to a drought that makes X a foundation population for a new species ... we can then trace back all the members of X to a common ancestor A, many, many generations before the drought. However, that hardly means that the new species emerged from individual A. Notice that A probably had a lot of other descendants that were NOT a member of population X.

Answer 2

The process works like this: A mutation will change the genetic structure in one offspring, and will cause it to be somewhat different from its parents. But it cannot change too much, as it must be cross-fertile with other (unmutated) members of the species so that it can reproduce and propagate the mutated genes to the next generation. It will take a series of mutations to result in a type which is no longer cross-fertile with the original -- which by the time these have happened, the original may have already gone extinct.

Answer 3

In most (multicellular) cases, populations evolve... not individuals.

Further, the term speciation can have a few (slightly) different meanings depending on who uses the word: but I will assume you mean in its most general way that it refers to two individuals that can not (or, sometimes, will not) reproduce together.

This is usually a slow process (dozens to hundreds or thousands of generations) where a particular trait, often gained by mutation within one (rarely more) individual, is passed on and selected for within a population.

Over the course of several generations, and favorable selection, all individuals will have the new trait - this is basic evolution.

Speciation occurs most often when part of a population is genetically isolated from its other half (often by geographic barriers but there are other ways), and each population begins to accumulate several new traits in the way described above. There will come a generation that can no longer reproduce with the latter - they have become a new species.

Answer 4

Richard Dawkins in his book "The Ancestor's Tale" puts it quite well. To paraphrase - " there has to be a moment, when there are two siblings of say, our common ancestor with the apes, that one of the siblings will be our direct ancestor, and the other one won't."
This must have occur on many occasions, that an individual, in which an advantageous gene mutation has occurred, will introduce that mutation into the gene pool, and it will remain and become more prevalent. It may have him or her become the dominant male or female in the group, thus ensuring more offspring, and so on. And it may lead to separation from other groups. As this occurrs over many generations, differences between the groups, particularly if they are geographically separate, will continue, as different environmental and other pressures are applied.
This is the basis of formation of divergence into different species.

Answer 5

evolution works very slowly, so the changes are within a group in the species and as changes are strenghten and accumulated they split off and form a different species.that's why the tendency is for kind to be attracted kind.
all this takes place over thousands or millions of years.
for anything to be sudden in evolutionary terms would be over hundreds of years.
God bless,
gabe

Answer 6

It may just be a mutant gene. Then that mutant goes and has new life created and the gene is passed on. And so on creating a new species

Answer 7

No, even in the case of polyploid speciation events.