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

What are Adaptations?

Part 2

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

characteristics

¨ Purpose of Adaptations:

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

¨ Instincts1.) behaviors genetically inherited from

parents; “just know how”2.) example: knowing when to

migrate, sensing danger, mating season