Describe how selection at a locus can result in a loss of polymorphism surrounding the locus.

Verified step by step guidance

1. Understand that a locus is a specific location on a chromosome where a particular gene or genetic marker is situated.
2. Recognize that polymorphism refers to the presence of two or more variants (alleles) at a locus within a population.
3. Consider the concept of natural selection, which can favor certain alleles at a locus, leading to an increase in their frequency in the population.
4. Realize that when selection strongly favors a particular allele, it can lead to a 'selective sweep,' where the advantageous allele becomes fixed in the population.
5. Acknowledge that as the favored allele becomes fixed, the genetic variation (polymorphism) at and around the locus decreases, as other alleles are lost due to the selective sweep.

Key Concepts

Genetic Polymorphism

Genetic polymorphism refers to the occurrence of two or more distinct alleles at a locus within a population. This variation is crucial for the adaptability and evolution of species, as it provides a genetic reservoir that can be acted upon by natural selection. When polymorphism is high, it indicates a diverse gene pool, which can enhance survival in changing environments.

Selection Pressure

Selection pressure is the environmental factor that influences the survival and reproduction of individuals within a population. It can be natural, sexual, or artificial, and it favors certain traits over others. When selection pressure is applied to a specific locus, alleles that confer advantageous traits may increase in frequency, while less favorable alleles may diminish, leading to a reduction in overall genetic diversity.

Genetic Hitchhiking

Genetic hitchhiking occurs when an allele at one locus increases in frequency due to selection for a nearby beneficial allele, even if the hitchhiked allele itself is neutral or deleterious. This phenomenon can lead to a loss of polymorphism around the selected locus, as alleles linked to the advantageous trait are also swept along, reducing genetic variation in that region of the genome.