Evolution by Natural Selection

Part 1: Darwin

Part 2: Adaptations

Who is Charles Darwin?

Part 1

An English naturalist in the 1800’s– Studied to be a minister

Did most of his research while working on the HMS Beagle as the science officer– Voyage took 7 years

– Sailed along the coast of South America

– Explored the Galapagos Island chain

– Collected thousands of specimens (plants and animals), collected data on weather and ocean currents

Darwin’s Theory

Proposed The Theory of Evolution By Natural Selection– Based on 5 key observations

• those organisms best adapted to the environment will most likely survive; “survival of the fittest”

• those organisms that survive will mostly likely reproduce

• genetic traits are passed on from parents to offspring who usually look similar to parents

• more offspring are produced than can survive – the idea of overproduction to ensure some will survive to reproduce

• organisms compete for needed resources:• a. food• b. water• c. shelter

d. space / territory e. mates 

What are Adaptations?

Part 2

Traits that help an organism survive – Helpful, positive physical or behavioral

characteristics

Allow organisms to:

1. get food

2. protect themselves

3. reproduce/find a mate

4. withstand environment

Types of Adaptations

structural:– a body part or coloration that aids survival

1.) wings, beak shapes, long legs, antlers, etc.

2.) camouflage or protective coloration * allows an organism to blend in or

hide in its surroundings

3.) mimicry or protective resemblance * organism looks like or acts like

something it’s not

Physiological– the ability to control life functions to

aid survival

1.) hibernation (slowing down metabolism, breathing, heart rate)

2.) marine mammals holding breath for long time

3.) certain plants in extreme conditions (salty, dry, underwater)

Behavioral:– actions that aid survival

learned behaviors1.) behaviors taught to or learned by

experience2.) example: knowing where the water

hole is or knowing what to eat Instincts

1.) behaviors genetically inherited from parents; “just know how”2.) example: knowing when to migrate,

sensing danger, mating season