Charles Darwin, Charles Darwin, Natural Selection Natural Selection and Animal and Animal AdaptationsAdaptations

Charles Charles DarwinDarwinCharles Darwin was born on February 12, 1809 in Shrewsbury, England.In 1825, he left for the University Of Edinburgh to study medicine. His father was a doctor…he was going to follow in Dad’s footsteps.

He gave up medicine after one year…the blood and surgery were too much for him to handle.

He instead started studying NATURAL HISTORY…the science of organizing and classifying organisms.

Charles Charles DarwinDarwinIn 1831, he received an offer to be the naturalist on a ship named the HMS Beagle.

The ship was going on a 5 year voyage around South America to accurately map the coastlines.

Darwin’s job was to collect as many animal species as he could.

Galapagos Galapagos IslandsIslandsOn September 15 1835, after four years, the Beagle reached the GALAPAGOS ISLANDS.

There are 13 main islands that are all volcanic. They are between 5 and 10 million years old.

The islands are 600 miles West of South America. That’s pretty remote…just like Jurassic Park, the animals are isolated from the mainland.

Galapagos Galapagos IslandsIslandsOn the islands Darwin observed animals such as:

Marine Iguanas

Mockingbirds

Finches

Tortoises

Galapagos Galapagos IslandsIslandsWhile on the islands, two things stood out as important to Darwin…The first was that the tortoises’ shells differed from island to island in shape and size.

The second main observation was that the finches of the Galapagos Islands had slightly different beaks depending on the islands they live on…just like the tortoises and their shells. The Finch beaks VARIEDVARIED in size and shape.

What Darwin observed were GENETIC VARIATIONSVARIATIONS (small differences in an organism caused by genetic mutations or environmental change) that can be passed on from parent to offspring.

Darwin proposed that these ADAPTATIONSADAPTATIONS (any inherited genetic characteristic, or trait, that increases an organisms chance of survival) were the cause of the variations from island to island.

One of his conclusions was that organisms that are better suited for their environment survive and reproduce much more effectively.

Darwin explained this by describing it as SURVIVAL OF SURVIVAL OF THE FITTESTTHE FITTEST.

He also referred to it as NATURAL SELECTIONNATURAL SELECTION. Nature “selects” which organisms will live and pass on their genes and which ones will die out.

Theory Of Theory Of EvolutionEvolutionEventually, Darwin would organize all of his findings into his THEORY THEORY OF EVOLUTIONOF EVOLUTION.

The theory could be summarized in five parts:Part One: All organisms contain small GENETIC VARIATIONS, or differences that can be inherited and passed on.

Part Two: Organisms will produce more offspring than can survive due to predators and competition.

Basically, animals produce more offspring knowing that all the genetic traits might not be passed down. The more offspring the greater the probability of their traits surviving to the next generation. Most of these baby spiders will die out…only the strongest and fittest will survive to reproduce.

Part Three: Organisms that are better able to survive and ADAPT in their environment will live to reproduce.

BIRDS

Feathers/Wings: Feathers are made from dead cells and keratin(like our hair and fingernails.They are lightweight, aid in flight, act as camouflage, repel water,and provide warmth. Aerodynamic wings make flight possible.Birds have two sets of feathers:

Primary feathers = Forward motion (thrust)Secondary feathers = Up and down motion (lift)Tail feathers = Steering, balancing, breaking

Beaks: Are used for eating different foods.

Hollow Bones: Weightlessness for flying.

Eggs: Provide stability for developing offspring.Feet: Different uses of various types of feet (web, talon, etc.)

Part Four: Over time, the successful traits in a population will increase and the unsuccessful traits will decrease.

Does fish’s coloration acts as camouflage?

What behaviors and structures help a fish reproduce?

What would happen to a fish that didn’t reproduce? Would its genetic trait get passed on?

Part Five: Species alive today are descended from species in the past that best adapted to their environments.

ANY QUESTIONS?