Genetic variations
Variations in gene composition in any population are what cause evolution. However, the Hardy-Weinberg Law provides some conditions which when fulfilled, genetic changes will not occur in any sexually reproducing population. Genetic variations therefore occur when these conditions are violated. According to Hardy and Weinberg, a stable population can only be maintained if the following conditions are met failure to which variations would occur.
The first condition is for the alleles to be stable a condition which allows zero net mutation (for a zero net mutation to occur, the rate of forward mutation must equal that of the backward mutation). This condition is violated when the rate of forward mutation is not counteracted by the backward mutation rate resulting to net mutation which contributes to genetic variations and evolution.
The second condition is neutrality of the alleles towards each other such that they are all passed from one generation to another in the same proportion with similar abilities to survive and reproduce in any particular environment. Violation of this condition involves natural selection where one of the alleles adapt better than the other alleles thus possessing the advantages of reproducing and passing its copies to offspring over the other alleles.
The third condition is the effective closure of a population where no individuals leave a particular population or enter a new one. When this condition is violated, the population is opened allowing individuals to move from one population to another hence creating a net flow of genes which results to genetic variations and consequently, to evolution. The fourth condition requires the population to be large enough since it is based on statistics. This is because large populations are less subjected to deviations from the expected sampling. This condition is violated when a certain population is small to allow deviations from the normal frequency of reproducing parental genes.
These deviations resulting from errors in sampling are referred to as genetic drift and are contributing factors to genetic variations. This condition further maintains that fusion if gametes occur randomly according to the frequency of the genotypes available, a condition known as panmixis. In addition, genetic drift may result due to death or meeting of different genotypes by chance (Okasha, 2006, p. 1).
Genetic inheritance on behavior
All animals including human beings have in-built forces which enable them behave in a certain manner. Genes play an important role in determining an individual’s behavior. Though not directly involved, genes govern the development and functioning of the nervous system which in turn causes and controls the way than an individual behaves. Genes contribute only a little towards an animal’s behavior as environmental factors are the most determinant factors.
Different environments provide the opportunity for individuals to behave in a certain manner to the point of adapting that particular behavior. These adaptive characteristics may even e passed on to other generations. The behavior of the off spring will therefore be determined by the traits inherited from the parents. Some of the most common behaviors that are inherited include specific cognitive abilities which determine an individual’s ability to perform academically. Genetic research on animal and human behavior shows that genetic influence involves not only some few major genes but multiple of genes.
It is also possible that certain families have unique genes that are responsible for some behaviors especially health disorders such as the Huntington’s disorder. Behavior development is, in most cases, disrupted by few or minor genes such that their effects cannot be striking in a few individuals (Plomin, 2000, p. 1).
Caenorhabditis elegans as a model organism
C. elegans has been used to study the different functions of genes as well as mutations that cause diseases in man. Its gene structure has been used by researchers to identify and locate genes and mutations in the human genome to help understand many of the human disorders. For instance, C. elegans has long been used to study a genetic human condition of the kidney, the polycystic kidney disease, which involves growth of sacs in the human kidney filled with fluid. C. elegans has been used as a model organism to identify the pathways that lead to the growth of the cysts as well as understanding the protein mutations that result to development of the disease (Adams, 2008, p. 1).
Other animal models besides Caenorhabditis elegans include: Drosophila melanogaster, a fruit fly which is easily cultivated in the lab. Used commonly because it can be easily mutated and they grow fast allowing rapid generations. It is also large enough to see many of its body parts with the naked eyes. Another most used animal is Arbacia puntualata, a sea urchin used to study embryology. Hydra has been used to study regeneration and differentiation in animals as well as body symmetry. Besides vertebrates, invertebrates have also been used as model animals such as the Guinea pig, dogs and even cats among many others.
Developmental biologists have over the past decades used the nematode, Caenorhabditis elegans as a model animal to study the biological development of a cell. It has been the most preferred model organism/animal over the others because it has certain advantages that make the study work a lot easier and efficient. To start with, it is very transparent allowing the scientists to easily observe the cell that they are studying using a simple dissecting microscope.
It is also advantageous in that it has a small body which makes it easy to grow in large numbers in a cell culture. Its short life cycle of approximately three days allows scientists to produce as many generations as they desire for their studies. Breeding of the nematode is easy since it has both male and hermaphrodite sexes which means that males can mate with the hermaphrodites or in the absence of the males, the hermaphrodite can self-fertilize hence fertilization is always ensured. Advanced microscopes and other study tools such as antibodies can be used on the nematode. Its efficiency is added by the fact that it has a genome which has been sequenced making it much easier for scientists to identify the specific gene of interest (Brenner, 2010, p. 1).
Disadvantages of C. elegans
Besides being advantageous in scientific research, C. elegans has some disadvantages over the other model organisms. For instance, its small body is a disadvantage on the part of the animal in that it can easily be preyed on by other larger organisms. Similarly, its short life cycle may be a disadvantage when many of the nematodes die before breeding something which when repeated may deplete the nematode’s generation. Since many of the nematodes are hermaphrodites with only a few males, variations are not likely to occur because of self fertilization. As a result, certain genetic diseases will keep on being passed from generation to generation due to lack of gene varieties (Johnson, 2011, p. 1).
Reference List
Adams, J. (2008). C. elegans: Model Organisms in the Discovery of PKD. Web.
Brenner, S. (2010). A good organism to use for genetic research. Web.
Johnson, T. (2011). Advantages and disadvantages of Caenorhabditis elegans for aging research. Web.
Plomin, R. (2000). The Role of Inheritance in Behavior. Web.
Okasha, S.(2006). Population Genetics. Web.