Wrights Approach in Contrast to Malecots Estimation Parameters and Measurements | Animal Husbandry & Veterinary Science Optional for UPSC PDF Download

Wright's Approach vs. Malecot's Estimation

• Wright and Malecot provided differing perspectives on inbreeding effects.
• Wright emphasized increasing homozygosity due to inbreeding, highlighting genetic consequences.
• Malecot defined inbreeding as the probability of alleles at a locus being identical by descent.

Parameters and Measurements

Coefficient of Inbreeding:

• The coefficient indicates increased homozygosity from mating closely related individuals.
• It ranges from 0 to 1 or as a percentage (0.1% to 100%).

Calculation of Inbreeding Coefficient:

• Wright introduced the concept in 1921 to quantify the level of inbreeding in populations.
• It reflects the probable increase in homozygosity due to related individuals mating.

Genetic Impact of Inbreeding:

• Inbreeding leads to more homozygosity, affecting the proportion of heterozygotes in the population.
• Malecot's definition focuses on the probability of two alleles at a locus being identical by descent.

Interpretation and Examples

Inbreeding Coefficient Determination:

• Calculating the probability that an individual received identical genes from a common ancestor.
• Probability of homozygosity increases with inbreeding, impacting genetic diversity.

Pathways and Probability:

• Examining gene transmission probabilities in inbred populations.
• Probability calculations based on the relatedness of individuals and common ancestry.

Inbreeding Coefficient Calculation

Definition of IAS:

• IAS (Inbreeding Coefficient of Individual X): It is calculated as the sum of all the paths of inheritance connecting the sire and dam of individual X.

Components of IAS:

• Fx (Inbreeding Coefficient of Individual X): This represents the inbreeding coefficient of individual X.
• Σ (Summation of All Paths): It signifies the sum of all paths of inheritance that connect the sire and dam of X.
• n (Number of Segregations): Represents the number of segregations in a specific path between the sire and dam of X.
• Finbreeding Coefficient of Common Ancestor: This is the inbreeding coefficient of the common ancestor for each path.

Explanation with Example:

• Example: 
  Consider a scenario where individual X has a sire and dam with multiple paths of inheritance. The inbreeding coefficient is calculated by considering all these paths and the number of segregations in each path, along with the inbreeding coefficient of the common ancestor for each path.