Genetic Changes Within The Populations : The Consequences Of Selection

Michael Nachmann, from the University of Arizona, was fascinated with the fact that he can look into the animals' genes and discover the genes which are responsible for the evolution of one animal species to the other. In the Pinacate Desert of Arizona, rock pocket mouse are easy pickings for predators which are foxes, coyotes, owls an rattlesnakes; unlike other organisms, the rock pocket mouse’s defence mechanism is camouflage – a protective coloration that some animals use to blend into their environment in order to avoid being seen by predators. The Pinacate Desert’s environment is not entirely uniform – a part of the desert is dominated by light rocks while other parts of the desert are full of dark rocks. Similar to Darwinian concept of evolution, the mice, which have light fur, that thrive on areas dominated by dark rocks have evolved a dark-colour fur. So, Nachmann look into the DNA of the mice in light of determining the reason behind the evolution of mice. According to Nachmann’s findings, a mutation has occurred in the DNA of the mice which is responsible in the change of fur colour of the mice living in areas full of dark lava and

The Rock Pocket Mouses’ coat color is extremely important because the mice use it as a mean of camouflage if the mice are a different color of fur than its environment, their overall fitness, how well an organism can survive and reproduce in its environment, decreases. Due to a volcanic eruption, most of the environment has turned from a sandy-colored soil to black soil; therefore making it very difficult for the unmutated, pale mice to survive. The dark fur color of the Rock Pocket’s population occurred due to a random mutation, a mistake made in the DNA whether it is good or bad, known as the MC1R gene. Because of this, variation among the mice was created, making some mice dark-colored and others to stay light-colored. Dark-colored mice

In order for natural selection to take effect with coat coloration of rock pocket mice that live on New Mexico’s Valley of Fire’s lava flows, conditions were met that are necessary and sufficient for evolutionary change. These conditions relate with variation. With variation, the coats of the mice must be heritable, and have a distinctive mortality (Study Week 4). The variation occurs here with the two different colours of fur; dark and light. These colours came from slightly different genes over time that controls their pigment. This mutation has heritability because the dark mice coat has enough of an advantage for staying alive that their offspring had more offspring and so on; eventually leading to natural selection weeding out the mice

With natural selection depending on the environment conditions, the phenotype confers can advantage or disadvantage the the indicidual with the phenotype relative to the other phenotypes in the popultion. If it is an advantage, then the individual will most likely have more offsprings that the individuals with the other phenotypes, and this will mean the the allele behind the phenotype will have greater representation in the next generation.

Theories of evolution have been created by many people. As more theories come along, we can identify that genetics is related to evolution. Rodents that are immune to effects of poison warfarin are called “super mice”, which are thought to be influenced by evolution. This poison is now no longer as effective as it once was. In this report, the theories of transformation by Lamarck and natural selection by Darwin are explored to provide a recommendation for which theory best supports how super mice came around.

The results of this simulation are a demonstration of natural selection since the data showed that as each generation passed, hairless bunnies which have have the recessive allele trait started to become extinct. This proves that the environment easily triggered natural selection into making sure the bunnies have fur in order to

Three examples of this can be counterfactual accounts, manipulability accounts, and a controlled experiment account, but only two will be discussed in further detail (Millstein, 2006). For each example heritable difference in physical traits can be seen, along with notable differences in the reproductive success, as well (Millstein, 2006). Counterfactual accounts show heritable differences and how these differences are not altered by the differences in the reproductive rates (Millstein, 2006). In this instance natural selection would favor the counterfactual account because there were no heritable differences in characteristics among individuals in the population (Millstein, 2006). If this is the case it would mean that natural selection had nothing to favor, and all of the organisms in the population would have the same genotypes, according to this model (Millstein, 2006). The manipulability account involves changing the heritable difference of the organisms within the population (Millstein, 2006). If this was done, then there would be a visible change in the reproductive success of the individuals (Millstein, 2006). With the example of the beetles studied in this particular case, they were trying to withstand different temperatures that the scientists subjected them to (Millstein, 2006). From this experiment a new beetle genotype emerged and could withstand a broader range of temperatures compared to the previous generations (Millstein, 2006). Since this occurred, according to the model, there would be an expected decrease in the reproductive rate of these particular beetles with the new genotype (Millstein,

Evolution is the process by which an organism branches off from an ancestor and changes due to modifications caused by natural selection, mutation, genetic drift, and gene flow. In the case of the squirrel population a dominant long tooth gene came about. Depending on whether the long tooth trait is favored in the environment will determine what happens to the litter of squirrels. Suppose the gene is favored, this would give the litter of squirrels an advantage over the others when it came to either getting more mates or having more success on getting different types of food. This would eventually change the allelic frequencies and over generations make the long tooth gene an advantageous trait. However, if having long teeth is a disadvantage

What Darwin Never Knew (2009) mentions a few examples of how Darwin’s theory influenced their studies. Michael Nachman of the University of Arizona concluded that natural selection was present in pocket mice of the Pinacate Desert – gene mutations gave mice living in the sandy desert tan fur, whilst the mice that lived on darker rocks had black fur.

Animal breeder has considered it as a simple ‘aggregate’ of the traits of the group’s that is constituent by individuals, nevertheless some other scholars had imagination that group traits were often ‘emergent’ and might be undefined at the individual level (Salt, 1979; Grantham, 1995). Secondly, a similar type of ambiguity arises over the actual concept of group fitness. Typically, it has been defined that the group with greater number of daughter individuals would considered as most fittest group, however, an alternative approach clearly disagree the concept in the context of variable group size (Damuth and Heisler, 1988; Sober, 1993; Okasha, 2006; Rainey & Kerr, 2011). Lastly, there was a doubt regarding how to carry out the multilevel selection analysis, as multilevel selection 1 (MLS-1) was mostly responsible for describing the change in the frequencies of different types of individual and multilevel selection 2 (MLS-2) explained about the change in the frequencies of different types of groups (Michod, 2011; Rainey and Kerr, 2011). Moreover, MLS theory did not take care of the problems engaged with class structure, i.e., when different groups differ from others in terms of non-genetic reasons (West et al. 2008; Gardner and Grafen, 2009; Frank,

The Theory of Natural Selection was first proposed by Charles Darwin in his work titled On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for life published in 1859. Darwin’s theory states that because of competition for finite resources within a habitat individuals must compete for survival and those more adapted to their specific environments have a greater success in surviving to maturity which enables them the opportunity to successfully reproduce. Individuals that successfully reproduce will pass down to their offspring the traits that gave then an advantage in survival to maturity and over long periods of time this can cause transformation within a species. (Houk 2013: 2-2) In

The gray squirrels were increasing in population while the black were staying the same. The number alleles increased in gray squirrels compared to scenario one.

In the 20th century, with the development of the science of genetics biologists began understanding the mechanics of how traits are passed down to different generations and how they are altered through the discovery of DNA and its major importance. They learned that parts of DNA from each parent are passed down to the offspring. Mutations of DNA, which cause alterations of species, can also occur when traits are being passed down to the offspring. Mutations in DNA can cause the offspring to have difficulties surviving and eventually lead to the extinction of the species. On the other hand, mutation of DNA can affect the offspring positively and change its traits to be stronger and a better survivor in that certain environment which would eventually lead to a growth in population of the certain species. Mutations in DNA can also be neutral and have no effect of the offspring’s traits. This battle with nature and survival through DNA lead to the foundation of the idea of Natural Selection (Alberto 2008).

Biological evolution, gene-based changes in a population that is inherited over time, (Hull, 2001:53) is dependent on biological variation within a population in order to come about. The biological variation within a population is the utmost necessity to ensure that natural selection can occur. It is what enables a species to withstand environmental pressures, as they are not all similar, and each organism within a population has its own unique probability to survive in the

Relative fitness. The relative fitness of a genotype (w) equals to its absolute fitness when get normalized. In the most common normalization, the absolute fitness of each genotype is divided by the absolute fitness of the fittest genotype (Barton and Turelli, 1989), such that the fittest genotype has a relative fitness of one. We can also define a selection coefficient (s), a measure of how much ‘worse’ the A2 allele is than A1. Mathematically,