Muddled theory.

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Dogs Evolution Is Muddled by Genetic Rift

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Dogs are the most revered household pet. Ranging in all facets of size coupled with a loyalty that stands the test of time, dogs easily take the face for the Human household animal. Yet the exact origins of this most adored animal generates a dog fight between biologists who hold differing breeds of thought. In one corner stands the idea that dogs were domesticated in an agricultural setting. In the other corner stands the idea that dogs were domesticated by hunter-gatherers. Yet in all facets of life, there exists multiple shades of gray between an opposing spectrum. Since the dogs evolution is muddled by genetic rift and interbreeding, it is difficult to pinpoint the precise origins of dogs.

A recent study published in PLOS Genetics gives credence to the view that dogs were domesticated by hunter- gatherers approximately 11,000 to 16,000 years ago. Traditionally, the lineage of dogs could be classified by comparing the proportions of their distinct nasal cavities and skulls. In biology, the classification of organisms in accordance to their features is known as taxonomy. It is one way that Charles Darwin illustrated that all animals share a common ancestor in the Origin of Species. Yet the diagrams provided by taxonomy have been cross-confirmed by a more recent and advanced field of biology known as molecular genetics.

By unraveling the dogs genome, the team of researchers looked for clues regarding the dogs precise origins. The scientists examined the genome of two dog breeds; the dingo from Australia and the Basenji whose origins trace back to Africa. The researchers also examined the genomes of three distinct wolves living in separate regions including Israel, Coratia and China. The wolves were selected on the grounds that each lived in a location that was a top candidate for the exact origins of dogs.

The difficulty is that the dogs evolution is muddled by genetic rift. In particular, dogs and wolves have been interbreeding and swapping genetic traits in recent times. Due to this, it is difficult to determine whether dogs are descended from wolves, or whether wolves and dogs both evolved from a common ancestor. Through careful genetic analysis, the team of researchers concluded the latter is more likely the case. In particular, researchers concluded that dogs and wolves co-evolved from a more ancient ancestor that is now extinct. More specifically, however, unraveling the genome of the dog gave biologists positive reasons for thinking that dogs were domesticated by hunter-gatherers.

The researchers discovered that most dogs have a greater amount of amylase genes than most wolves. Amylase genes are essential to efficiently digesting starch. The idea is that dogs originally lived in a terrain in close proximity to agricultural settlements. Due to environmental pressures, dogs gradually adapted to consume agricultural waste.

Although the dogs evolution is muddled by genetic rift, the insights of the study can help clear the air. Understanding where these creatures first evolved can help strengthen the future of our domestic relation, such as determining a proper diet for dogs as well as healthy breeding sizes.

By Nathan Cranford

Sources:

NBC News
LA Times
Fast Co Design

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Genetic Drift and Natural Selection

Home > Population Genetics & Statistics > Population Theory > Hardy-Weinberg Principle > Genetic Drift and Natural Selection
Genetic Drift

Allele  ( each of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome )  frequencies in small populations do not generally reflect those of larger populations since too small of a set of individuals cannot represent all of the alleles for the entire population. Genetic drift occurs when the population size is limited and therefore by chance, certain alleles increase or decrease in frequency. This can result in a shift away from Hardy-Weinberg equilibrium (HWE). Unlike natural selection, genetic drift is random and rarely produces adaptations to the environment.

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Natural Selection

Although population genetics by itself is important, one of the objectives of this field is to assess how changes in allele frequencies affect the evolution of a population. Evolution in its modern form was first explored by Charles Darwin in 1859. In his book On the Origin of Species, Darwin outlined what he called “descent with modification” and what we now refer to as evolution. He speculated that all species evolved from a common ancestor. Over time, faced with new environments and habitats, populations of species acquired modifications, which allowed them to better adapt to their environment.

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Darwin Monkey

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Darwin termed these changes within populations, natural selection, and he proposed the idea of “survival of the fittest.” Individual variations which proved beneficial would be preserved within a population, whereas variations that were lethal to the organism would be destroyed. Under natural selection, some individuals in a population have modifications that allow them to more successfully survive and reproduce, making their adaptations more common as a whole due to their increased reproductive success. Over a long period of time, this change in the characteristics of a population can lead to the production of a new species.

 

Darwin ‘s theory of evolution can be summarized in three main principles:

  1. Principle of variation: Among individuals within any population, there is variation in morphology, physiology, and behavior.
  2. Principle of heredity: Offspring resemble their parents more than they resemble unrelated individuals.
  3. Principle of selection: Some forms are more successful at surviving and reproducing than other forms in a given environment.

It is important to remember that evolution occurs at the population level, not at the individual level.

To see an example of mutation and natural selection at work, consider the case of the peppered moth. Prior to the Industrial Revolution in England, the peppered moth was found almost entirely in its light colored form. Its color provided camouflage against the lichen-covered trees, preventing the moths being seen by predators. The pollution from the industrial revolution caused much of the lichen on the trees to die. As a result, the light moths became more visible to birds, whereas the dark colored moths (which arose from a mutation) were able to blend in better with the trees and avoid being eaten.

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moth

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The result was that the population of dark moths, which was about 1% in 1848, increased to about 90% by 1959!

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Personally I think Mr Cranford is barking up the wrong family tree  !!! He is just trying to prove wrong, a long held belief that dogs Evolved from Wolves.  He shall “never” prove this to be wrong.

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