Question

In ants, which employ a haplodiploid mating system, the coefficient of relatedness, \(r,\) for fathers and sons is equal to a. 0. d. 0.5 b. 0.125 e. 0.75 c. 0.25

Short answer

The coefficient of relatedness, \(r,\) for fathers and sons in ants which employ a haplodiploid mating system is 0.

Step-by-step solution

Understand the Haplodiploid Mating System

In the Haplodiploid Mating System of ants, females develop from fertilized eggs and are diploid, meaning they have two sets of chromosomes. On the other hand, males develop from unfertilized eggs and are haploid, meaning they have one set of chromosomes which they get from their mother. Fathers contribute to the genetic material of their daughters, not their sons.

Determine the Coefficient of Relatedness

The coefficient of relatedness, denoted by \( r \), is a measure of genetic relatedness or identity between different individuals. Given that fathers do not contribute any genetic material to their sons in this mating system, the coefficient of relatedness between them is 0.

Key concepts

Coefficient of Relatedness

The idea of the 'coefficient of relatedness', often symbolized as \(r\), is central to understanding family genetics. It is a numerical value that reflects the probability that two individuals share the same alleles due to their descent. The coefficient value ranges from 0 to 1, where 0 indicates no genetic relationship and 1 denotes an identical genetic makeup, as with clones or identical twins.

When dealing with haplodiploid species like ants, the calculation of \(r\) takes a unique turn due to their distinct reproductive mechanism. Remember, the equation to find \(r\) is typically based on how many genes are shared due to common ancestry. However, in haplodiploid systems, males are produced by unfertilized eggs and have no fathers genetically, thereby mothers pass on all their genes to their sons. On the flip side, sons do not receive any genetic material from their fathers. Hence, the coefficient of relatedness between fathers and sons is 0.

Genetic Relatedness

Genetic relatedness extends beyond simple percentages; it's fundamental to the study of evolutionary biology and social behaviors within animal species. It pertains to the proportion of genes that two individuals share, and these shared genes are typically inherited from common ancestors. The higher the genetic relatedness among individuals, the more likely they are to exhibit altruistic behaviors towards each other. This is explained through a theory known as 'inclusive fitness', where organisms act not only for their personal reproductive success but also for the passing of shared genes within their family group.

In the case of the haplodiploid mating system found in ants and other insects like bees and wasps, this system influences social structures, leading to complex behaviors and colony dynamics. For example, because of their genetic makeup, female worker ants are often more closely related to their sisters than they would be to their own offspring, leading to the evolution of eusociality, where individuals cooperate in the upbringing of the young, often foregoing their own reproduction.

Diploid and Haploid

Understanding the terms 'diploid' and 'haploid' is important for grasping the intricacies of genetic inheritance. 'Diploid' refers to cells that contain two complete sets of chromosomes, one from each parent. Most animals, including humans, are diploid organisms, meaning their body cells have two sets of chromosomes, and this genetic information is mixed during sexual reproduction.

'Haploid', on the other hand, describes cells with only one set of chromosomes. These are found in gametes, which are reproductive cells like sperm and eggs in humans. In the haplodiploid system, a key distinction is that males are haploid; they only inherit their genetic material from their mothers, as they originate from unfertilized eggs. Contrarily, females are diploid, with genetics derived from both parents. This unique system plays a pivotal role in the social structure of species that exhibit it, as the reproductive and genetic roles of each sex are fundamentally different.