WHAT IS ORGANIC EVOLUTION? - BIOLOGY - 2025

The organic evolution, also known as biological evolution is the result of genetic changes in populations of certain species that have been inheritances over several generations.

These changes can be both large and small, obvious or not so obvious, minimal or substantial; that is, slight changes in a species or alterations that lead to the diversification of a type of organism in several subspecies or in unique and different species.

Biological evolution is not simply about changes over time. Many organisms show changes over time such as the loss of leaves in trees, weight loss in mammals, the metamorphoses of insects or the skin changes of some reptiles.

These are not considered evolutionary changes because there is no genetic change that is being passed on to the next generation.

Evolution transcends the simple life cycle of a single individual organism; encompasses the inheritance of genetic information between generations.

Organic evolution: microevolution and macroevolution

For these events to be truly considered an evolutionary step, the changes have to occur at the genetic level in a population and be passed on to offspring. These small-scale changes are defined as micro evolution.

The definition of macro evolution considers that all living organisms are connected in an evolutionary history, and can be traced back many generations to a common ancestor.

Organic evolution as a theory and natural selection

Evolution involves modifications to existing species, not the development of new species. This idea was developed and proposed by Charles Darwin as a scientific theory based on observations and experiments.

This theory tries to explain how events related to living organisms in the natural world work and it was called Darwinism or the General Theory of Evolution.

Darwinism states that the struggle of the species to exist and survive was forcing the systems of their body to adapt to the conditions, acquiring new characteristics that responded to the needs of the environment.

Different conditions can trigger an adaptation process and eventually an evolutionary genetic change in a species, such as climate, terrain, environment, temperature, pressure, excess or lack of food, excess or absence of predators, isolation, etc.

According to Darwin, the set of these processes is called natural selection and acts in populations, not in individuals.

The first traces of change can occur in a single individual. If that change helps it survive where another of the same species does not, by transmitting it to subsequent generations, the change ends up being written in the DNA of other individuals and eventually in entire populations.

Natural selection

Genetic variations that occur in a population occur randomly, but the process of natural selection does not. Natural selection is the result of the interactions between genetic changes in a population and the conditions of the environment or environment.

The environment determines which variation is more favorable. Individuals that have more favorable characteristics in their environment will survive to reproduce and give life to other individuals.

Consequently, the most optimal traits are transmitted to the population as a whole. The following conditions must occur for the processes of evolutionary change to occur in species populations:

1- Individuals in a population must produce more offspring than environmental conditions can support

This increases the survival chances of individuals of the same species, since at least a small portion of the offspring would reach maturity to reproduce and pass on their genes.

2- Individuals when mating must have different characteristics

Changes in organisms arise from DNA mutations in a mixture of genetic information during sexual reproduction, in a process called genetic recombination.

This occurs during meiosis that provides a way to produce new combinations of alleles on a single chromosome. Sexual reproduction also allows the removal of unfavorable gene combinations in a population.

Organisms that reproduce asexually do not bring evolutionary changes, since the process simply produces exact copies of the same individual.

3- The offspring must inherit the characteristics of the parents with the transmission of genes

4- Organisms with the most suitable characteristics for their environment have a better chance of surviving and reproducing

This point is the heart of natural selection. If there is competition for survival and all organisms are not equal, those with the best traits will have the upper hand.

If those traits are passed on, then the next generation will show more of these advantages.

If these four conditions are met, the following generations will always be different from previous individuals in frequency and distribution of genetic traits; then we could say that a species has evolved satisfactorily.

Cetaceans as an example of organic evolution

But its life cycle was completely dissociated from the mainland millions of years ago. Their limbs were adapted by developing fins for swimming and their bodies to offer the least possible resistance when moving through the water.

The way they store and distribute oxygen within their body systems allows them to submerge and even stay underwater for a long time. They can decrease your rate of oxygen consumption under immersion conditions by almost 30%.

Muscle tissues can store 50% oxygen and blood 40%, and your lungs exchange gases more efficiently.

With the exhalations, they manage to eliminate up to 90% of the carbon dioxide from the alveoli, where a terrestrial mammal only achieves 20%.

The nostrils were adapted to become a nostril that moved to the upper part of the skull, thus facilitating air intake by simply showing the upper part of the head on the surface.

References

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