Why some phenotypes are more common in a population than others?

Why some phenotypes are more common in a population than others?

Whether or not a trait is common has to do with how many copies of that gene version (or allele) are in the population. It has little or nothing to do with whether the trait is dominant or recessive. The brown allele of OCA2 is dominant over the not-brown allele. Nearly everyone in most of Africa has brown eyes.

Are dominant phenotypes always the most common in a population?

A widespread misconception is that traits due to dominant alleles are the most common in the population. While this is sometimes true, it is not always the case. For example, the allele for Huntington’s Disease is dominant, while the allele for not developing this disorder is recessive.

What determines the phenotypes found in a population?

An organism’s phenotype results from two basic factors: the expression of an organism’s genetic code, or its genotype, and the influence of environmental factors. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic.

Which trait is more common in the general population?

Dominant traits are the most common traits in a population.

Is phenotype dominant or recessive?

Some alleles are considered dominant, meaning if you get one allele for the trait, that’s going to be your phenotype. Other traits are recessive. They are masked by the dominant phenotype, and you need to get two copies of that trait to see it in your phenotype.

What are the possible causes of phenotypic variations?

Phenotypes can be caused by genes, environmental factors, or a combination of both. Phenotypic variation, then, is the variability in phenotypes that exists in a population. For example, people come in all shapes and sizes: height, weight, and body shape are phenotypes that vary.

Why recessive traits are more common?

Recessive disease mutations are much more common than those that are harmful even in a single copy, because such “dominant” mutations are more easily eliminated by natural selection.

What is the relationship between phenotype and genotype?

The genotype of an organism is defined as the sum of all its genes. The phenotype of an organism is the observable physical or biochemical characteristics of an organism, determined by both genetic make-up and environmental influences.

Does phenotype depend entirely on genotype?

The genotype of an organism is the genetic code in its cells. This genetic constitution of an individual influences – but is not solely responsible for – many of its traits. The phenotype depends upon the genotype but can also be influenced by environmental factors. …

What’s the difference between a genotype and a phenotype?

The sum of an organism’s observable characteristics is their phenotype. A key difference between phenotype and genotype is that, whilst genotype is inherited from an organism’s parents, the phenotype is not. Whilst a phenotype is influenced the genotype, genotype does not equal phenotype.

What makes a trait common in a population?

Whether or not a trait is common has to do with how many copies of that gene version (or allele) are in the population. It has little or nothing to do with whether the trait is dominant or recessive.

Can a trait become more common if it is dominant?

Whether an allele is dominant or not does not affect how common a trait is. Now of course traits can become more common over time. The changes just don’t have anything to do with whether the trait is dominant or not. If brown eyes gave an advantage, then it would start to become more common.

Are there genetic differences between different human populations?

The proportion of human genetic variation due to differences between populations is modest, and individuals from different populations can be genetically more similar than individuals from the same population. Yet sufficient genetic data can permit accurate classification of individuals into populations.