When my husband studied to obtain his Master of Science Degree in Biology, his two favorite courses were Molecular Biology of the Cell and Population Genetics. He said that both classes proved that evolution was an impossibility and violated most, if not all, of the basic laws of true biology.
Population genetics clearly displays that natural selection generally does one of two things. It either causes a population to genetically stabilize and remain constant or it drives a population to extinction. Neither of these results are friends to evolution which is based on ever changing population genetics, not stabilization or extinction.
Today’s cheetah population is an example of natural selection driving a species to extinction. Research has revealed that many of the wild cheetah’s have little to no genetic variation left, which makes them less able to adapt to any changes, especially environmental.
Allow me to explain. By genetic variation, it means containing both dominant and recessive traits. For example, the genetic variability within a large population will generally remain fairly stable. For the sake of the example, this large population has 1000 genes that are heterozygous (Aa, Bb, Cc, etc.) and 9000 genes that are homozygous, (XX, xx, YY, yy, ZZ, zz, etc.). The only genetic variation exists in the 1000 heterozygous genes. The homozygous genes are fixed and are not variable. As the numerous individuals within that population continue to interbreed, the various genetic traits found in the 1000 heterozygous genes will be equally shared and dispersed throughout the population, thus preserving the overall genetic and physical make up of that population.
However, if a small group of individuals from that population breaks away and moves to another location and no longer intermingles with the larger population, the amount of genetic variability can be reduced. Perhaps the individuals in the new population only have 950 heterozygous genes and 9050 homozygous genes. If this new population no longer interbreeds with the larger population, then only those genetic traits that they carried with them will be passed down to the offspring of the new population. Eventually, this new smaller population may or may not exhibit physical or behavioral differences from the parent population. If the differences are significant enough so that the two populations can no longer interbreed and produce viable offspring, it may be enough to declare the new population to be a separate species. But note that the formation of the new species is caused by the reduction in genetic variability not an increase.
With each new population that breaks off from the parent population, it continues to reduce the amount of genetic variability in the new populations. The more variability a population loses, the less likely they are to survive any changes to their environment. Eventually, a population may lose so much of their variability that their chances of surviving any type of environmental change are extremely poor, increasing the likelihood of their eventual extinction.
Some scientists are suggesting trying to extract DNA from historical cheetah remains and attempting to introduce it into today’s population in order to restore some of the variability and give the cheetah’s a chance of survival. Without the addition of more genetic variation, most scientists agree that cheetahs are doomed to extinction. Definitely not what evolution is based upon.
A recent study now lead some scientists to believe this is what happened to some of the wooly mammoth populations and why they are not alive today:
“The shaggy megafauna that roamed Siberia and North America together with our ancestors captivate the imagination, but now it looks like they’re giving us a practical lesson in genetics that could help inform conservation efforts.”
“Scientists compared the DNA of two mammoths: a member of a dwindling island population with an individual from the booming herds of the more distant past. Their findings, published Thursday in the journal PLOS Genetics, provided some of the first concrete proof of the genetic theories describing how population size affects genetic fitness. ‘Genomic meltdown’ may have doomed the last herd of mammoths, a conclusion that on its face suggests dire consequences for modern endangered species, but that could also offer valuable insight into how to best keep today’s rarest creatures from crossing the threshold into extinction.”
Natural selection is real and operating in the world we live in. It works to keep large herds of zebras – zebras. It also works to force small and diminishing populations like wooly mammoths to go extinct. It’s also pushing the world’s few remaining cheetahs towards inevitable extinct. Natural selection – yes. Evolution – NO!