Spotlight on Students: Mendelian Genetics

The following is a post that features the exemplary work of one of my Anthropology 102: Introduction to Physical Anthropology students.  In this assignment he was tasked with addressing a problem involving Mendelian Genetics of Inheritance.  The background of this assignment was that students were tasked with discovery the parentage of a mystery alien individual from a group of alien species.  

Kerbori, canine-like aliens, featured in this assignment.  Picture illustrated by Kathryn Barker.

By: Robert Stolting

The crew of the SS Adventurer, including myself, have been tasked to explore deep space in the search for life and more importantly advanced culture. In this search to find life and culture and to document it we found an occupied planet known as Zanku by the local population in the Circinus Galaxy. Zanku is a planet inhabited by the Kerbori, a species of intelligent beings that have canine like features. The Kerbori are covered in fur and have dog like tails and ears.

The leaders of the Kerbori, Morgan and his wife Buu, extended their hand in friendship and hosted a party in honor of the crew of the SS Adventurer. Shortly into the festivities two Kerbori began fighting with each other over the relationship to a Kerbori boy named Seth. Seth is the son of Kittsa, who is the daughter of Morgan and Buu. The two Kerbori males asserted that they are Seth's father and vow a fight to the death to determine who is the father. Kittsa was unsure of who the father was and confirmed either could be Seth’s father.

The Captain of the SS Adventurer, in an attempt to prevent bloodshed, tasked me, the team's Physical Anthropologist in determining the father and restoring order. I retreated to the University to determine what traits of the Kerbori are inherited through mendelian genetics.  Mendelian genetics are the phenotypical (physical) expression of pairs of genes known as alleles that make up an individual's genotype for a specific inherited trait (Jurmain et al. 81). Mendelian traits can either be homozygous, they have two of the same allele, or heterozygous where the alleles in the pair are the same (Jurmain et al. 80). Traits that are dominate will be expressed in the phenotype if they are homozygous or heterozygous. Recessive traits are only expressed when both alleles are recessive, or homozygous recessive (Jurmain et al. 79, 80).

At the university I discovered that ear shape, fur color, and tail shape are traits inherited through mendelian genetics in the Kerbori. I also learned from the family that for at least 15 generations the royal family have always had large ears, a dominate trait and presumably a homozygous trait because of the number of generations without small ears.

The first trait that was analyzed was ear shape. Kittsa was determined to have a homozygous trait for large ears because of the before mentioned family linage. Potential father one has large ears and could be either homozygous or heterozygous for large ears. Potential father two has small ears and must be homozygous small because it is a recessive trait. Seth has large ears so Punnett Squares were performed with the above information to determine which father with Kittsa could produce large ears in Seth. Punnett Squares are a tool used to separate the parent genotypes and figure out the probability of children for any given trait (Jurmain et al. 81). The punnett squares for the trait of large ears in Seth were inconclusive. Either father could have produced offspring with Kittsa that would result in children with large ears (Figure 1).

The next trait investigated was the trait for tail shape. I had learned in the University that straight tails are the dominant phenotype for tails and that nubs are recessive. There is a third shape curly that is recessive to straight but dominant to nub. Kittsa has a nub tail and must be homozygous recessive for the trait because nub tails are only expressed in the phenotype if both alleles are for nub shaped tails. Potential Father 1 has a curly tail and must be either homozygous or heterozygous for curly. If he is heterozygous then the other allele besides curly must be nub.  If it was straight then the straight trait would be present in the genotype. Potential Father 2 has a straight tail and can be either homozygous or heterozygous for straight. The receiver can be

either nub or curly because they would not be expressed in the phenotype. Seth the son has a straight tail. So punnett squares were created to see which father could produce offspring with a straight tail.

The results from the punnett squares related to the type of tail present in Seth conclusively answered who is the father of Seth. Potential Father 2 is the father. Seth has a straight tail. Potential Father 2 has a straight tail and straight tails are the most dominate tail type and could produce the phenotype for a straight tail. Potential Father 1 had a curly tail. This trait is dominant to the nub type but recessive to straight. Kittsa is homozygous for nub and this combination of nub and curly could not produce an offspring with a straight tail. This conclusively proves that Potential Father 2 is that father of Seth (Figure 2).

 The final trait fur color was not used. Both fathers had blue hair and it was impossible to determine if either was homozygous or heterozygous for the the trait. The punnett squares would look the same for both fathers and was not useful in determining the father. The father must be heterozygous for the trait and carry the allele for white fur because Seth is homozygous white, a recessive trait.

Presenting this report to the Captain of the SS Adventurer and to the leaders of the Kerbori Morgan, Buu, their daughter Kittsa, and the potential fathers prevented bloodshed. All parties agreed with the results that Potential Father 2 was the father of Seth. This act has brought the relationship between the Kerbori and Humans closer and initiates what will be sure to become a rewarding partnership. The mission of the SS adventurer has been advanced as much knowledge has been gained of another culture in the vast universe.

References Cited

Jurmain, Robert, Lynn Kilgore, Wenda Trevathan, and Russell L. Ciochon. Introduction to Physical Anthropology ., 2014. Print.