Change in allele frequency results in genetic degradation and species extinction
https://cosmosmagazine.com/biology/darwin-s-finches-continue-to-inform-and-confuseWhile the story of Darwin’s finches is often framed as a “eureka moment” in his understanding of the way organisms transform through natural selection, nothing could be further from the truth.
Darwin arrived at the Galápagos islands in September of 1835. The black lava of the island and the terrible heat caused him some distress, and he was only selectively attentive to the wonders around him.
He was captivated by the local mockingbirds that varied from island to island, but ignored the island-specific tortoises, preferring instead to shoot and eat them in serious numbers. He even rode on the back of one of the larger specimens for fun.
He had noticed the many finches in the dense growth of the islands’ lowlands but the variation in size, colour and habit left him in a state of “inexplicable confusion”. He collected samples of six species from three islands and stored and labelled them rather haphazardly.
On his return to England, he dumped this mess in the lap of the talented artist and ornithologist John Gould of the Zoological Society of London, and it was he that figured out (in only six days) that Darwin’s finches were actually a complexly interrelated group of 12 different species.
Now it seems the finches, including some of the specimens Darwin himself collected in 1835, are helping science to understand the complexities of the process of extinction.
One of the common ways to test whether a population or species is likely to go extinct is to measure its genetic diversity: such testing is quick, easy and cheap. Each gene comes in a number of different forms, called alleles.
Genetic diversity refers to the number of different alleles in a population or species; greater diversity is thought to mean that the population or species will have the capacity to adapt should environmental conditions change.
With more diversity comes a higher likelihood that alleles exist in the population that will provide certain individuals with an advantage in changed conditions. These individuals will then outbreed the rest of the population and over time these alleles will become typical of the population or species. This is basically how evolution works. (My comment: This is how it was thought to work.)
"Typically, we would expect populations with high genetic diversity to have a greater potential for long-term survival," says Lawson. "Meanwhile, the low-diversity populations would be more likely to go extinct because that's a common pattern as populations decline to few individuals."
She and her colleagues set out to explore this indicator using Darwin’s finches, which provide a rare opportunity to test whether genetic diversity really is a predictor of extinction.
By looking at the genetic diversity of 212 tissue samples taken from both museum specimens and living birds, they could compare these to the reality that has played out in the islands’ finches, where “many populations went extinct, but far more persisted” over the last 100 years or so. The trio’s hypothesis was “that genetic variation was lower in populations that ultimately went extinct, relative to those that are still extant”.
What they found was the opposite.
Only one of the extinct finch populations, a species called the vegetarian finch, had lower genetic diversity compared to modern survivors. To make matters more confusing, most of the now extinct populations had indications of higher genetic diversity compared to surviving populations that migrated to other islands.
My comment: Change in allele frequency means just different repertoires of genetic errors. Despite of scientists' efforts to explain away these inconvenient findings, Darwin's Finches prove that genetic mutations never result in any kind of evolution. Adaptation and variation within organisms is based on epigenetic modifications that cause minor genetic errors. High genetic diversity means a higher rate of harmful DNA mutations. Along the needs of adaptation these genetic errors are silenced by epigenetic mechanisms. This can be observed as higher amounts of heterochromatin. Further, if population size decreases, gene pool is reduced to a critical level and the final step is extinction.
There is no mechanism for evolution. Any change in organisms is based on epigenetic regulation of pre-existing biological information OR corruption of information. Don't get lost.
There is no mechanism for evolution. Any change in organisms is based on epigenetic regulation of pre-existing biological information OR corruption of information. Don't get lost.
