Biology - natural selection and evolution

What is natural selection?

A process where organisms with favourable, heritable traits for a particular environment are more likely to survive, reproduce and transmit these traits through generations.

Give an example of natural selection

The peppered moth:

• Normally white with black speckles across the wings, well camouflaged against lichen-covered tree trunks

• A naturally occurring genetic mutation causes some moths to have almost black wings.

• They are not as well camouflaged, so are more likely to be eaten by predators.

• Therefore, fewer black forms survive to breed, and are less common in the population than paler forms.

• In 19th century Industrial Revolution, darker moths became predominant due to pollution from factories which darkened tree bark and killed the lichens.

• White moths were easier to see for predators, while dark moths were camouflaged, and more likely to survive and produce offspring.

• Over generations, black moths outnumbered the pale forms.

What is an adaptation?

A heritable feature, trait or characteristic that gives an organism an advantage and better chance of survival in a specific environment.

What are the 3 types of adaptations?

1. STRUCTURAL - physical (ears, feet)

2. BEHAVIOURAL - actions organisms perform (hibernation, migration)

3. PSYCHOLOGICAL - internal bodily proceses or functions (venom, temperature regulation)

What is evolution?

A scientific theory that explains how life changes and diversifies over time through genetic changes that are passed down from one generation to the next.

What is biological evolution?

Scientific process of heritable genetic changes in populations of organisms over successive generations.

It explains how species develop, adapt, and go extinct over time.

It can lead to the development of new species if genes change enough.

Process through which modern organisms descended from ancient ones. 

What is genetic variation?

The presence of differences in sequences of genes between individual organisms of a species.

What is speciation?

The evolutionary process by which a single ancestral species diverges into 2 or more distinct species.

How does speciation occur?

When a group within a species separates from other members of its species and develops its own unique traits over time.

What is common ancestry?

Scientific concept that a group of organisms shares a shared ancentral group of organisms, tracing their evolution back to a single ancestral lineage.

All living organisms descended from a common ancestor.

Which means that genetic information is shared and common amongst all living things.

State the 5 evidences for evolution

1. Anatomy

2. Molecular biology

3. Biogeography

4. Fossils

5. Direct observation

What is artificial selection?

Process in which humans consciously select for or against particular features/traits in organisms.

Breeding species with favourable traits to produce offspring of the same.