Evolution & Natural Selection

What is natural selection?

The primary mechanism of evolution where organisms better adapted to their environment are more likely to survive and reproduce.

What conditions are required for natural selection to occur?

It occurs wen environment favours certain traits over others. E.G. Phenotypic variation, differential reproduction, heredity, and time.

What is adaptation?

The physical or behavioural characteristic that helps an organism survive and reproduce in its environment. E.G. animal’s camouflage.

How does adaptation improve survival?

By directly solving challenges like finding food, avoiding predators, or handling extreme weather, individuals with advantageous traits survive longer and pass these genes to future generations.

Define fitness biologically

It is an organism’s ability to survive, reproduce, and pass its genes on to the next generation.

How do traits affect fitness?

Traits that help an organism to avoid predators, resist diseases, or tolerate harsh climates ensure they live long enough to reproduce.

How are fossils evidence for evolution?

By showing how life on Earth has changed over billions of years.

How are DNA similarities evidence for evolution?

By showing that all life shares a common ancestor with the universal four-letter DNA alphabet (A, T, C, G).

How are structural similarities evidence for evolution?

By showing that different species share common ancestors. E.G. similar embryonic development.

How are developmental simliarities evidence for evolution?

By revealing shared ancestry. Organisms inherit their developmental programs from their ancestors and closely related species go through similar embryonic stages.

What is a species

The most fundamental unit of biological classification, representing a group of organisms that share common characteristics and can interbreed to produce offspring.

What is speciation?

The evolutionary process by which a single ancestral population splits into two or more distinct, independently evolving species from reproductive isolation.

How do new species form?

From speciation, where due to different environmental pressures, makes it impossible for them to interbreed and produce offspring.

What is geographical isolation?

The primary lead of allopatric speciation. When a species is divided, the seperated populations face different environmental pressures, food sources, and predators.

What is temporal isolation?

A biological concept where two or more closely related species are unable to interbreed because they reproduce at different times. E.G. American toad and Fowler’s toad are closely related but American toad mates early summer, and Fowler’s mate late summer.

What is behavioural isolation?

An evolutionary mechanism that prevents different species from mating through differences in communication or behaviours. E.G. Eastern and Western meadowlark birds look identical but use different songs to attract mates which prevents crossbreeding.

How does environmental change affect population?

By driving forced migration, increasing death rates, and limiting access to vital resources like food and water.

How does population change over time?

By people being born, dying, or moving.