In evolution process, when do two varieties of same species become two different species?
Two
varieties of same species have small difference in chromosome and two
species have different chromosome number. When does that happen
following evolution process?
__________________
You ask about when and not about how. So...When?, sometimes the answer is just "when the disparate chromosome structures avoid producing offspring together". I explain it bellow.
It is a terrific question that can't be answered so easily. In animals that share the same geographical territory the moment is a undefined period of time when animals of the future species clearly prefer to mate among then rather than with the other fraction of the current species.
But the process of speciation doesn't need to be a question of once and forever. The variety of probabilities in nature is madly overhelming. We are talking about many factors, individuals and time.
To put you one very intriguing example, let's look to ourselves, the process of speciation of human beings. We have genetic similarities with both chimps and bonobos, suggesting common ancestors (Take into account that we are talking of common ancestors of both humans and chimps, chimps are not the ancestors of humans). Genetic analysis point that humans and chimpanzees speciated apart 4.1 million years ago.But, and it is a giant but...
more about this possible hybridation: Human and Chimp Ancestors Might Have Interbred
Bear in mind that we are taling about proto-humans, not humans. However, if this emntioned 2006 genetic study is correct...in our own species there wasn't a clear event of separation...but...but...
Now, in your question details you tell that different species have different number of chromosomes. It is not a neccessary requisite, as you have been told in other answers. There is a terrific study made in two species of flycatchers ( European pied flycatcher and the collared flycatcher, these two species occur together on the Baltic islands of Öland and Gotland, and are still able of hybridizing), here is the link: http://www.sciencedaily.c
Ok, the scientific of the university of Upssala sequenced the whole genome of the two secies found out that:
So...When?, sometimes the answer is just "when the disparate chromosome structures avoid producing offspring together".
Sometimes. I was only speaking about animals. If you find them (us) complicated, you wouldn't believe what kind of tricks can plants do.
It is a terrific question that can't be answered so easily. In animals that share the same geographical territory the moment is a undefined period of time when animals of the future species clearly prefer to mate among then rather than with the other fraction of the current species.
But the process of speciation doesn't need to be a question of once and forever. The variety of probabilities in nature is madly overhelming. We are talking about many factors, individuals and time.
To put you one very intriguing example, let's look to ourselves, the process of speciation of human beings. We have genetic similarities with both chimps and bonobos, suggesting common ancestors (Take into account that we are talking of common ancestors of both humans and chimps, chimps are not the ancestors of humans). Genetic analysis point that humans and chimpanzees speciated apart 4.1 million years ago.But, and it is a giant but...
Analysis of the two species' genes in 2006 provides evidence that after human ancestors had started to diverge from chimpanzees, interspecies mating between "proto-human" and "proto-chimps" nonetheless occurred regularly enough to change certain genes in the new gene pool:
A new comparison of the human and chimp genomes suggests that after the two lineages separated, they may have begun interbreeding... A principal finding is that the X chromosomes of humans and chimps appear to have diverged about 1.2 million years more recently than the other chromosomes.
The research suggests:
Source: Human evolutionThere were in fact two splits between the human and chimp lineages, with the first being followed by interbreeding between the two populations and then a second split. The suggestion of a hybridization has startled paleoanthropologists, who nonetheless are treating the new genetic data seriously.
more about this possible hybridation: Human and Chimp Ancestors Might Have Interbred
Bear in mind that we are taling about proto-humans, not humans. However, if this emntioned 2006 genetic study is correct...in our own species there wasn't a clear event of separation...but...but...
Now, in your question details you tell that different species have different number of chromosomes. It is not a neccessary requisite, as you have been told in other answers. There is a terrific study made in two species of flycatchers ( European pied flycatcher and the collared flycatcher, these two species occur together on the Baltic islands of Öland and Gotland, and are still able of hybridizing), here is the link: http://www.sciencedaily.c
Ok, the scientific of the university of Upssala sequenced the whole genome of the two secies found out that:
The scientists have now managed to identify the regions in the respective flycatchers' genomes that are most clearly different. It turns out that it is a matter of one or a few regions per chromosome, and these regions coincide with the chromosome parts that are involved in meiosis and the production of gender cells (centromeres). This indicates that what underlies the separation of the species it is the disparate chromosome structures rather than different adaptations in individual genes.They also point out that this same process can happen in more events of speciation.
So...When?, sometimes the answer is just "when the disparate chromosome structures avoid producing offspring together".
Sometimes. I was only speaking about animals. If you find them (us) complicated, you wouldn't believe what kind of tricks can plants do.
No hay comentarios:
Publicar un comentario