Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경

Sanders 3rd Edition

Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels

문제 34c

20장, 문제 34c

Evaluate the following pedigree, and answer the questions below. Calculate F for any inbred members of this family.

검증된 단계별 안내

Step 1: Understand the concept of inbreeding coefficient (F). The inbreeding coefficient measures the probability that two alleles at a locus are identical by descent. It is calculated using the formula:

F = \sum p_{i} F_{a}

, where

p_{i}

is the probability of a specific path and

F_{a}

is the inbreeding coefficient of the common ancestor.

Step 2: Identify the inbred members in the pedigree. Look for individuals whose parents are related (e.g., cousins, siblings, or other relatives). These individuals are likely to have an inbreeding coefficient greater than zero.

Step 3: Trace all possible paths through which alleles could be inherited from a common ancestor to the inbred individual. For each path, calculate the probability of inheritance using the rules of Mendelian genetics. For example, if the common ancestor is a grandparent, the probability of inheritance through one path is

\frac{1}{4}

Step 4: Sum the probabilities of all paths leading to the inbred individual. Multiply this sum by the inbreeding coefficient of the common ancestor (if the ancestor is not inbred, their coefficient is 0). This gives the inbreeding coefficient for the individual.

Step 5: Repeat the calculation for each inbred member of the family. Ensure that you account for all possible paths and common ancestors for each individual.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Pedigree Analysis

Pedigree analysis is a method used to study the inheritance patterns of traits in families. It involves creating a diagram that represents family relationships and the occurrence of specific genetic traits across generations. This visual representation helps identify whether traits are dominant, recessive, or linked to sex, which is crucial for understanding genetic inheritance.

Inbreeding Coefficient (F)

The inbreeding coefficient (F) quantifies the probability that two alleles at a locus are identical by descent due to inbreeding. It ranges from 0 (no inbreeding) to 1 (complete inbreeding). Calculating F involves analyzing the pedigree to determine the degree of relatedness between individuals, which is essential for assessing the genetic health of a population.

Genetic Relatedness

Genetic relatedness refers to the proportion of shared genetic material between individuals, often expressed as a percentage. In pedigree analysis, relatedness helps determine the likelihood of inheriting specific alleles from common ancestors. Understanding genetic relatedness is vital for calculating the inbreeding coefficient and evaluating the potential risks of inbreeding depression in a family.