Evolution

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Analogous structures

Different anatomies, similar function | In dudes in similar environments

Homologous structures

Similar structure, different function | In closely related dudes

Vestigial structures

Left over body part important in organism’s ancestor but no more

Hardy-Weinberg Law

p² + 2pq + q² = 1, & p + q = 1

Evolution

Changes in the frequency of alleles

Hardy-Weinberg Law is for

Easily determining whether evolution is occurring because equilibrium cannot exist

Sedimentary rock

Where fossils are found

Lamarck’s Theory

Acquired trait passed to offspring

Things Darwin observed on the Galápagos Islands

Variation, overproduction, struggle and different reproductive success

Descent with modification

Offspring maybe slightly different from parent

Natural selection

Process where environment causes only strong to reproduce

Adaptation

Beneficial mutation

Fitness

Ability to survive and reproduce well

Evolution process

Accumulation of inherited changes within populations over time

Genetic drift

Change in allele frequency

Bottle neck affect

Most of pop is wiped out by natural disaster and random few are less

Founder effect

Small group randomly find different place to live

Types of natural selection

Stabilising selection, Directional selection and disruptive selection

Stabilising Selection

Medium variety has an advantage

Directional Selection

Environment favours one extreme

Disruptive Selection

Environment favours both extremes

Speciation

When a species diverges into two new species

Species

Members are able to reproduce, having fertile offspring

Types of reproductive isolation

Pre-zygotic (egg never fertilised) and post-zygotic (egg fertilised-may get feeble or sterile offspring)

Pre-zygotic barriers

Behavioural, Temporal, Gametic, Mechanical and Geographic/allopatric

Post zygotic barriers

Reduced hybrid and hybrid sterility

Mechanisms of speciation

Allopathic speciation and sympathetic speciation

Sympatric speciation

Behavioural, temporal, gametic and mechanical

Punctuated equilibria

Quick change→ 2 species

Gradual equilibria

Slow change, intermediate steps → 2 species