Describe artificial selection (selective breeding) with reference to: (a) selection by humans of animals or plants with desirable features (b) crossing these to produce the next generation (c) selection of offspring showing the desirable features (d) repetition over many generations

SouravNovember 4, 2024

Answer

Artificial selection, also known as selective breeding, is a process in which humans intentionally select for specific traits in animals or plants to enhance desirable characteristics. This method has been used for thousands of years to improve agricultural crops and livestock. Here’s a detailed explanation of the process, broken down into key steps:

(a) Selection by Humans of Animals or Plants with Desirable Features

• Identifying Desirable Traits: Humans identify specific traits that are beneficial or desirable for their needs. For example, farmers may select plants that produce larger fruits, have better disease resistance, or exhibit faster growth rates. Similarly, animal breeders might choose dogs with particular temperaments, physical characteristics, or abilities (such as herding or hunting).
• Examples: In agriculture, crops like corn have been selectively bred for higher yields and better nutritional content. In livestock, cattle may be selected for traits such as size, milk production, or meat quality.

(b) Crossing These to Produce the Next Generation

• Controlled Breeding: Once desired traits are identified, breeders cross individuals that exhibit these traits to produce the next generation. This can involve controlled mating between specific plants or animals to ensure that the offspring inherit the desired characteristics.
• Techniques: Breeders may use various methods to facilitate this process, such as artificial insemination in animals or controlled pollination in plants.

(c) Selection of Offspring Showing the Desirable Features

• Evaluating Offspring: After the offspring are produced, breeders assess them for the presence of the desired traits. This evaluation can include physical examinations, performance tests, and other assessments relevant to the traits being selected.
• Choosing the Best Individuals: Only those offspring that exhibit the desired features are selected for further breeding. For example, in a batch of puppies, only those that show the desired coat color or temperament might be kept for future breeding.

(d) Repetition Over Many Generations

• Generational Breeding: The process of selecting and breeding continues over many generations. Each generation provides an opportunity to refine and enhance the desirable traits further.
• Cumulative Effect: With each cycle of selection and breeding, the frequency of desirable alleles increases within the population. Over time, this can lead to significant changes in the characteristics of the species being bred.
• Long-Term Goals: For example, through generations of selective breeding, certain dog breeds have been developed with specific physical traits and temperaments suited for particular roles (e.g., herding dogs, guard dogs).