What is evolution?

Yesterday was National STEM (Science, Technology, Engineering, and Math) Day!! So we’re going to cover a basic scientific concept that everyone should understand, but unfortunately many do not. The facts are most people who understand evolution accept it and most who don’t understand evolution strongly deny it. So lets get started with evolution 101:

What is evolution?

In biology, evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection.

The theory of evolution is based on the idea that all species? are related and gradually change over time.

Evolution relies on there being genetic variation? (This is differences in DNA. Variation between individuals in their DNA is what makes them different. ) in a population which affects the physical characteristics (phenotype) of an organism.

Some of these characteristics may give the individual an advantage over other individuals which they can then pass on to their offspring.

What is natural selection?

Charles Darwin’s theory of evolution states that evolution happens by natural selection.

Individuals in a species show variation in physical characteristics. This variation is because of differences in their genes?(Section of DNA within the genome that carries the information to make a molecule, usually a protein. They contain the instructions for our individual characteristics, like eye and hair colour. In humans and other complex organisms, genes are split into coding (exons) and non-coding sequences (introns). These split sections allow some genes to make more than one type of protein.

Individuals with characteristics best suited to their environment are more likely to survive, finding food, avoiding predators and resisting disease. These individuals are more likely to reproduce and pass their genes on to their children.

Individuals that are poorly adapted to their environment are less likely to survive and reproduce. Therefore their genes are less likely to be passed on to the next generation.

As a consequence those individuals most suited to their environment survive and, given enough time, the species will gradually evolve.

Different types of evolution:

Convergent evolution:

When the same adaptations evolve independently, under similar selection pressures.

For example, flying insects, birds and bats have all evolved the ability to fly, but independently of each other.

Co-evolution:

When two species or groups of species have evolved alongside each other where one adapts to changes in the other.

For example, flowering plants and pollinating insects such as bees.

Adaptive radiation:

When a species splits into a number of new forms when a change in the environment makes new resources available or creates new environmental challenges.

For example, finches on the Galapagos Islands have developed different shaped beaks to take advantage of the different kinds of food available on different islands. (See image)

Source: https://www.yourgenome.org

Image: Sketches of the heads of finches from the Galapagos Islands showing the differences in their beak shapes due to evolution.

Image credit: John Gould (14.Sep.1804 – 3.Feb.1881) – From “Voyage of the Beagle”

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