Thread: Specation and reproduction

The definition of specation is that one animal has evolved to another animal that cannot breed with the animal it evolved from.

So my question is this...

When specation occurs, how does the new specie survive/reproduce? Does groups of the same specie evolve to a new one, or does it happen randomly making it difficult for the new specie to reproduce?

Speciation does not usually happen to a single organism, with the exception of things like polyploidism, where a mistake in the generation of gametes results in offspring with twice or three times etc as many copies of chromosomes as its parents. This mostly happens in plants, and in this case usually some crossbreeding with the parent species can still occur.

When it comes to animals, for the most part speciation happens to a sub-population of animals, that from generation to generation are only breeding with each other with no intermixing with other populations of the parent species. Any changes in gene frequency (aka evolution) that happen to this population do not get spread to the rest of the parent species, and vice versa. There are a lot of different reasons for why the sub-population has become genetically separate from the parent population, and different factors will also effect the speed with which the two populations become unable to breed with each other. But this is the gist of it.

think ring species, just like the gull species that span the arctic - each adjacent part of the ring species can interbreed , but where the western part of the ring meets the eastern part of the ring they're too different to interbreed

imagine a similar situation over time with populations gradually drifting apart after being geographically separated, and you get a picture picture of how speciation really happens

I'm glad I got that out of my mind ^^

I knew there was a simple answer, but I wasn't sure what it was

Thanks for the help :wink:

Originally Posted by Obviously

The definition of specation is that one animal has evolved to another animal that cannot breed with the animal it evolved from.

So my question is this...

When specation occurs, how does the new specie survive/reproduce? Does groups of the same specie evolve to a new one, or does it happen randomly making it difficult for the new specie to reproduce?

I can answer your question.

The evolution happened in honor of a new environmental condition it had adapted to.

It will only be a matter of time before the type of species it adapted from is extinct.

Sometimes survival in the fitness/environment sense takes the backseat to mate selection. Im pretty sure some birds with colorful feathers and fancy-not-so-good-for-flying tails have no advantage for their own survival as opposed to being more likely to have offsprings than those better fit for strict survival but less attractive (or those that are camouflaged but take less care of their offspring).

Also, we evaluate with our eyes, if all animals look the same (or humans) we tend to think of a monolithic 'species' when a whole range of tiny differences that have nothing to to with appearance comes into play.

For example, a small proportion of people with European descent have mutated T-cells which makes them immune to HIV virus, you cant tell whose got that gene by looking at people, a lot of people have that mutation without realizing it. People have an array of various mutations and tiny variations that have no visible effect until some event makes them relevant(detrimental or helpful). So at any point in time theres usually not 1 individual that is new or different, but many that are different without it being noticable.

Originally Posted by Obviously

The definition of specation is that one animal has evolved to another animal that cannot breed with the animal it evolved from.

No, it isn't

What SPurious means (approximately) is that speciation occurs when members of the separate species generally do not interbreed. They may be able to do so, as is the case with lions and tigers, but their offspring will typically be sterile. Or there is the classic case of the herring gull and black gull in western Europe - two clearly distinct species that do not interbreeed - yet if we follow colonies of the black backed gull around the arctic circle we find them gradually transforming into the herring gull.

Originally Posted by Ophiolite

What SPurious means (approximately) is that speciation occurs when members of the separate species generally do not interbreed. They may be able to do so, as is the case with lions and tigers, but their offspring will typically be sterile.

Differences in mating behaviors can also keep species from interbreeding as well. To further paraphrase, different species are not necessarily 100% incapable of having fertile offspring, but there exists a barrier to their sharing of genes. (Which is why ring species are so controversial - the genes do eventually get passed from one species to the other.) The barrier can be geographical distance, anatomical mismatching, incompatible mating rituals, etc. The general rule I like to go by is that if they couldn't or wouldn't interbreed in their natural environment, then it's likely that they're different species. This would have to be corroborated by other evidence of course, but it helps.

I agree completely with your amendments. I did not mean to imply that geographical isolation was the only thing preventing interbreeding, simply that it is one of the possible barriers. Behaviour in general is another one.

Sorry for my weak definition of specation then I don't have much knowledge within biology, just trying to learn :wink:

There is no absolutely agreed definition, that I am aware of. This reflects the fact that the concept of species is, like many classification systems, an artifical one that does not exactly fit reality.
The definition you used has been used in the past, inlcusing - I think - by biologists. It just wouldn't be considered accurate enough today.

Don't apologise for not knowing something - its the people who don't know things, don't know they don't know, and are stubbornly unapologetic who should apologise.

"populations who normally don't mate with each other in their natural state" is as good a rule of thumb for recognising currently living species

just remember that :
a) the boundaries can at times be fuzzy
b) it's sometimes not clear whether separate populations can mate with each other because they never meet in the wild

Species has been defined in many different ways which leaves it open to abuse by non-scientists who want to confuse other non-scientists.

The original poster of course had no ill intentions here. And my apologies if my answer was a bit short.

I will now give you a longer answer.

Speciation is artificial. It does not exist as such in reality. It is an event we mark in hindsight. I emphasized hindsight, because it is really important in understanding evolution.

We are standing at a specific point in evolutionary time. We are looking back. This gives the false impression that everything what came before us led to us. That's only because we are looking back.

The human ancestor (a concept that can only be derived from looking back) had no clue that we would be here right now. Evolution had no clue. Nor any intention to produce humans.

Every single generation struggled for life. Every generation had to perform. Every generation was meaningful. Every single generation was part of a 'species'.

In hindsight though we split this lineage up in rather distinct species. It is a useful concept for categorizing life. It is not reality. Keep this in mind. Speciation on an evolutionary time line is therefore also not a real event. Every generation means evolutionary change, speciation is merely a large change, a classification based on hindsight.

This for instance also means that technically there are no transitional forms between species. Each generation was just there for itself. Not to give rise to a new species. The labeling of transitional is therefore artificial, albeit useful to scientists. This is not always clear to the general audience. It is a manner of labeling that facilitates doing research. It is not reality. There is no transitional forms between the chimp and the human. They are indeed connected by a common ancestor though! And there were intermediate generations between ancestor and human. All steps are equal though. Is the difference becoming clear? Because it is an very important lesson in evolutionary thinking.

Whether or not a species can interbreed with another is absolutely irrelevant to evolutionary reality. They are each part of a lineage that separated at one point: common ancestor. And if they would interbreed again that would be perfectly fine too. It wouldn't be the first time in evolution, nor the last.

When thinking about evolution you should be extremely careful about building your thinking on the concept of species. A species is a category, a classification. A logical argument against evolution based on examining the species concept is fruitless since the classification is merely a tool for scientists. And the definition of species can vary a lot because of that. It just depends on what kind of research you are doing.

I hope I managed to convey some of the reserve you should use when discussing species and evolution.

Nicely structured post Spurious. Of course what adds to the confusion is that Darwin, while providing the initial insight into the reality and mechanisms of evolution, did so in a book called On the Origin of Species.

[My emphasis.]

Bravo, monk. One criticism though, I think you neglected to emphasize that change can be variable (when environment change is rapid an organism will tend to change quicker/generations and vice versa). You'll have people arguing that evolution is at a set pace.

Originally Posted by GhostofMaxwell

You'll have people arguing that evolution is at a set pace.

All that glitters is not Gould. 8)

Originally Posted by Ophiolite

Originally Posted by GhostofMaxwell

You'll have people arguing that evolution is at a set pace.

All that glitters is not Gould. 8)

Is he one of the punctuated slelubyjubby guys? Im not familiar.

I agree, good post Spurious. Definitely something I'm going to keep in mind next time I find myself explaining species concepts to someone.

What silly beings we humans are, always trying to categorize things. This is this and that is that! Perhaps easier to understand, but blurs reality.

Originally Posted by paralith

What silly beings we humans are, always trying to categorize things. This is this and that is that! Perhaps easier to understand, but blurs reality.

There's nothing silly about it, as long as you understand that it IS just a tool. When people try to assign more meaning to it than the actual scientists who use that tool is when we run into problems.

Originally Posted by GhostofMaxwell

Originally Posted by Ophiolite

Originally Posted by GhostofMaxwell

You'll have people arguing that evolution is at a set pace.

All that glitters is not Gould. 8)

Is he one of the punctuated slelubyjubby guys? Im not familiar.

Indeed yes. Stephen J.Gould and Niles Eldridge were the two originators of the idea of punctuated equilibrium. Gould died four (?) years ago having completed the brilliant, if convoluted, and extensively parenthtetical, though always erudite and informative, The Structure of Evolutionary Theory.

I've never really thought there was much wrong with Darwinian evolution that the neo-Darwinist's needed to elaborate on.

Evolution always means "Darwin" to me, despite the latter day refinements.

for one thing, Darwin never got to the bottom of what created variation + never got to grips with inheritance
clever though, that despite these major gaps his theory still stands tall