Draft Essay3 Influential Changes: Environment, Mutation and Inheritance

Influential changes: Environment, Mutations and Inheritance

Long before the science of genetics formally began with the great work of Mendel, many intellectuals began wondering about patterns of similarities observed in nature. Scientists observed that there were similarities among groups of organisms, but there was a common belief that all organisms were created by God, and that He brought them to Earth the way they are today.  People believed that God’s creations were perfect, and that they would never change from the original form designed by the Creator.  The theory of evolution brought great controversy to this belief.  Evolution refers to the genetic changes in a population that, can lead to the development of new species throughout time.  This major scientific theory explained to many scientists, who were searching for answers, why there were groups of organisms that looked alike.  The theory of evolution provided a mechanism that demonstrated how the species changed.  Environment, mutations and inheritance are factors that drive natural selection and other evolutionary forces to cause evolution.

For each species there is a proper habitat.  The space, or niche in which species live, contain favorable conditions that allows them to survive.  All of the organisms living in that space are adapted to the conditions that are present, i.e. temperature, light, nutrients (Pidwirny, M.).  For instance, the point of reproduction for a species of birds known as the great tits is affected by the changes in temperature. If the temperature is to cold, it causes the birds to lay the eggs earlier but if the conditions are to warm then it causes a delay in laying eggs (Visser et. al).  Changes that occur in conditions that are favorable for a certain species can affect greatly how it develops. Adapting to the changes in environment is critical for the survival of a species.  The great 19^th century naturalist, Charles Darwin in his book The Origin of Species wrote: “As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.”(page 5)

Although Darwin did not know much about the mechanisms of inheritance, in his studies he observed that certain characteristics were more frequent than others.  In order for new characteristics to occur genetics changes known as mutations must occur.  There are always some mutations occurring, so the genetic material is constantly provided with change.  Genetic changes are critical for the propagation of species; the genetic material of a species must be variable in order for the species to adapt to the changes in the environment.  The frequency of mutations that occur in a species could be a key factor that determines the rate in which the species is adapting and therefore evolving(Stebbins and Ayala).  A species that contains the same genetic material for many generations will most likely become extinct, since its gene variants may no longer be favored by the new environmental conditions.  

One of the leading evolutionary biologist of the 20^th century, G.L. Stebbins ,along with professor Francisco J. Ayala of the University of California wrote: “Genetic changes underlie the evolution of organisms; mutations are the ultimate source of the genetic variation that makes possible the evolutionary process” (page 967).

Mutations that occur on genes create new forms called alleles. These new forms are passed down through generations.  The inheritance of the new alleles can benefit survival of the species but other alleles can carry detrimental effects.  For example, research showed that 46,880 years ago dogs carried a mutation for black coat color and recently, scientist have found that wolves that live in forested areas have inherited the allele (Anderson et al.).  Acquiring this melanistic allele benefited wolves who hunt in dark forests.  Dr. Anderson from Stanford University addresses the benefit of melanism in wolves.  “The potential selective value of dark versus light coat color has been suggested to include concealment during predation and/or indirect effects due to pleiotropy, but remains unresolved because the underlying gene(s) have not been identified”.  The inheritance of black coat allele has propagated quickly in wolf populations across North America.  Natural selection has increased the frequency of the allele but still the value of this adaptation is not understood (Anderson et al.).

The environment provides the pressure on the genetic material (the DNA), and during cellular division, mistakes happen in DNA replication (mutations).  These mutations can be passed on to the next generation (inheritance).  While some of them are harmful, others can provide advantage and increase survival and reproduction of the species (selection).  Natural selection works on mutations that already exist in the population.  Evolution occurs when mutations are selected and passed on through generations.

Work Cited

Ande

Anderson, T. M., et al. "Molecular and Evolutionary History of Melanism in North American Gray Wolves." Science 323.5919 (2009): 1339-43.

Pidwirny, M. (2006). "Concept of Ecological Niche". Fundamentals of Physical Geography, 2nd Edition. Date Viewed. http://www.physicalgeography.net/fundamentals/9g.html

Stebbins, G. L., and F. J. Ayala. "Is a New Evolutionary Synthesis Necessary?" Science 213.4511 (1981): 967-71.

Visser, M. E., L. J.M. Holleman, and S. P. Caro. "Temperature Has a Causal Effect on Avian Timing of Reproduction." Proceedings of the Royal Society B: Biological Sciences 276.1665 (2009): 2323-331. Print