https://www.science.org/doi/10.1126/science.ade2833
https://phys.org/news/2023-09-explosion-fish-biodiversity-due-genetic.html
Apparently the diversification of cichlids in Lake Victoria occurred
within a 16,000 year period in the last 20,000 years after a dry period
when the lake dried up. All the species evolved since then.
They sequenced over 400 cichlid species.
Around a 150,000 years ago two different species hybridized and formed a >mixed population with genetic variation from both species segregating
within the new hybrid species.
16,000 years is nothing in terms of population genetics. The Phys Org >article notes that it took millions of years for the Galapagos finches
to diversify into less than 20 species. There should be greater >differentiation between African and non African human populations, but
these fish diversified into the amazing number of species in a geologic
eye blink. They did it by segregating the genetic variation of the two >original species into functional nuclear genomes that were better
adapted to particular environments. These new nuclear genomes did not
have the full set of genetic variation from the two original species,
but by chance and selection would have created novel subsets that
consisted of only some of that original genetic variation. These new >"species" would themselves hybridize with other populations that
segregated the original genetic variation into other subsets that were
better adapted to other specific environments. In this way you could
recycle the variation and combine subsets to form new combinations that
would be adapted to new environmental conditions.
It is pretty amazing that the genetic variation of the two original
species could be mixed up and recombined into all the novel outcomes
that have been produced so far.
On Sun, 1 Oct 2023 15:28:30 -0500, the following appeared in
talk.origins, posted by RonO <rokimoto@cox.net>:
https://www.science.org/doi/10.1126/science.ade2833It is indeed. But, assuming that cichlids were the *only*
https://phys.org/news/2023-09-explosion-fish-biodiversity-due-genetic.html >>
Apparently the diversification of cichlids in Lake Victoria occurred
within a 16,000 year period in the last 20,000 years after a dry period
when the lake dried up. All the species evolved since then.
They sequenced over 400 cichlid species.
Around a 150,000 years ago two different species hybridized and formed a
mixed population with genetic variation from both species segregating
within the new hybrid species.
16,000 years is nothing in terms of population genetics. The Phys Org
article notes that it took millions of years for the Galapagos finches
to diversify into less than 20 species. There should be greater
differentiation between African and non African human populations, but
these fish diversified into the amazing number of species in a geologic
eye blink. They did it by segregating the genetic variation of the two
original species into functional nuclear genomes that were better
adapted to particular environments. These new nuclear genomes did not
have the full set of genetic variation from the two original species,
but by chance and selection would have created novel subsets that
consisted of only some of that original genetic variation. These new
"species" would themselves hybridize with other populations that
segregated the original genetic variation into other subsets that were
better adapted to other specific environments. In this way you could
recycle the variation and combine subsets to form new combinations that
would be adapted to new environmental conditions.
It is pretty amazing that the genetic variation of the two original
species could be mixed up and recombined into all the novel outcomes
that have been produced so far.
surviving species of the "drying event", there would have
been quite a few empty niches to be filled, which I'd think
would have "supercharged" adaptation and subsequent
speciation. Correct?
On 10/2/2023 10:04 AM, Bob Casanova wrote:
On Sun, 1 Oct 2023 15:28:30 -0500, the following appeared in
talk.origins, posted by RonO <rokimoto@cox.net>:
https://www.science.org/doi/10.1126/science.ade2833It is indeed. But, assuming that cichlids were the *only*
https://phys.org/news/2023-09-explosion-fish-biodiversity-due-genetic.html >>>
Apparently the diversification of cichlids in Lake Victoria occurred
within a 16,000 year period in the last 20,000 years after a dry period
when the lake dried up. All the species evolved since then.
They sequenced over 400 cichlid species.
Around a 150,000 years ago two different species hybridized and formed a >>> mixed population with genetic variation from both species segregating
within the new hybrid species.
16,000 years is nothing in terms of population genetics. The Phys Org
article notes that it took millions of years for the Galapagos finches
to diversify into less than 20 species. There should be greater
differentiation between African and non African human populations, but
these fish diversified into the amazing number of species in a geologic
eye blink. They did it by segregating the genetic variation of the two
original species into functional nuclear genomes that were better
adapted to particular environments. These new nuclear genomes did not
have the full set of genetic variation from the two original species,
but by chance and selection would have created novel subsets that
consisted of only some of that original genetic variation. These new
"species" would themselves hybridize with other populations that
segregated the original genetic variation into other subsets that were
better adapted to other specific environments. In this way you could
recycle the variation and combine subsets to form new combinations that
would be adapted to new environmental conditions.
It is pretty amazing that the genetic variation of the two original
species could be mixed up and recombined into all the novel outcomes
that have been produced so far.
surviving species of the "drying event", there would have
been quite a few empty niches to be filled, which I'd think
would have "supercharged" adaptation and subsequent
speciation. Correct?
When the lake filled all the existing habitats formed, so there were
plenty of new niches to fill. Apparently fish best adapted to the
available niches settled there and adapted to them, and as the new
nuclear genomes formed they hybridized with the surrounding populations >creating even more diverse subsets of the two original genomes. What
seems to be glossed over is how a Congo species interbred with a Nile
species when they are different drainage systems. They do note
mitochondrial lineage spread across the continental divide. I guess
fish can be carried by birds or sucked up by cyclones or tornados, but
the cichlids were able to cross the continental divide, probably more
than once.
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