- Reproduction is the production of offspring that are biologically similar to the parent organism.
- An individual organism does not need reproduction to maintain its own life, but it is necessary for the existence and continuity of each species. Therefore, an organism expends significant energy to create more individuals.
DO ORGANISMS CREATE EXACT COPIES OF THEMSELVES?
- Chromosomes in the cell nucleus contain DNA (Deoxyribonucleic Acid). It holds the information (blueprints) for body designs that are inherited from parents to offspring.
- DNA is the information source for making proteins. If the information is changed, different proteins will be made, leading to changes in body designs. Therefore, the creation of a DNA copy is the basic event in reproduction.
- A reproducing cell creates two DNA copies and additional cellular apparatus. Then, they separate, and the cell divides into two.
- In each process of DNA copying, some variations are created. As a result, DNA copies will be similar but not identical to the original.
- If large variations occur, the new DNA copy may not work with the cellular apparatus, causing the newborn cell to die. If variations are mild, cells can survive.
- Variation during reproduction is the basis of evolution.
THE IMPORTANCE OF VARIATION
- Consistent DNA copying maintains body design, helping the organism to use a particular niche. Thus, reproduction is linked to the stability of populations of species.
- Niches can change due to many reasons, such as changes in temperature, water levels, or meteorite impacts.
- If a niche is drastically altered, the population not suited to that niche may be wiped out. Individuals with variations may survive. For example, consider a bacterial population in temperate waters. If the water temperature increases due to global warming, most bacteria die, but the few variants resistant to heat survive. Variation is thus useful for the survival of species over time.