Variation among organism

Continuous variation

Is the variation which shows intermediate form between any two extremes i.e there is no clear-cut distinction between two extremes.

Example in group length ranges from shortest to tallest with several intermediaries continuous variation arises from interaction between genes and environment.

Discontinuous variation

Is the variation which shows clear-cut distinction from one form to another form.

Example: In human population an individual is either a male or a female, ability to roll the tongue, albinism, blood group (A, AB, O) and rhesus factor.

Environment does not influence the characteristics that show discontinuous variation.

Example blood group can not be altered by environment.

Environment factors

Food: lack of food of a certain diet leads to deficiency diseases such as Kwashiorkor. Lack of enough food causes starvation. In addition, pathogens causes diseases in organism making the individual different from the normal ones.

Genetic factors

Meiosis – during meiosis there is segregation of different gametes. This reduces the chance of pairs of chromosomes producing a wide variety of different gametes. This reduces the chance of individuals being the same.

Fertilization: during fertilization the nuclei of male and female gametes fuse.

1. This permits parental genes to be brought together in different combinations.
2. This may lead to desirable and undesirable qualities of parents be combined in the offspring.

Mutation: This is a sudden change in gene which can be inherited are caused by mutagens such as x-rays, cosmic rays, chemicals as mustard gas. The individual is called a mutant after undergoing mutation and appears different from the rest of the population.

Migration

As species are not normally informally distributed but occurs in small isolated population called demes. If members from the deme migrate and mate with members of another deme the offspring that results have characteristics that are different from those of both parents.

1. Basis for evolution

• Variations provide the raw material for evolution. Through natural selection, favorable traits are passed on to future generations, leading to the development of new species over time.

2. Adaptation to changing environments

• Variations allow organisms to adapt to changes in their environment.
• Example: Genetic variation in peppered moths allowed darker moths to survive in polluted areas during the Industrial Revolution, demonstrating environmental adaptation.

3. Increased survival chances

• In populations with high genetic diversity, some individuals are more likely to possess traits that help them survive threats such as diseases, predators, or climate changes.
• Example: Genetic variation in humans has led to resistance to diseases like malaria in populations with sickle-cell traits.

4. Avoidance of extinction

• A species with more variation is less likely to go extinct because some members may survive drastic environmental changes.
• Example: Genetic diversity in crop plants can protect against widespread loss from pests or diseases.

5. Maintaining biodiversity

• Variation within and among species contributes to the rich biodiversity of life on Earth, ensuring ecological balance.

6. Improvement through artificial selection

• Humans exploit natural variations in plants and animals to improve desirable traits through artificial selection.
• Example: Breeding high-yield crops, disease-resistant livestock, or faster racehorses relies on genetic variation.

7. Formation of new traits

• Variations lead to the development of unique traits, which might give individuals a competitive advantage in survival or reproduction.
• Example: Camouflage in animals like chameleons helps them evade predators.