Download Name: Evolution: the Process Date: Taxonomy—Naming and

Name: ______________________________
Evolution: the Process
Date: _______________________________
Taxonomy—Naming and Classifying the Diverse Forms of Life
-Prior to Charles Darwin’s publication of On the Origin of Species by Means of Natural Selection (1859),
Swedish physician and botanist, Carolus Linnaeus (1707-1778), developed his system of naming and
classifying organisms based on structural similarities between organisms.

Later Darwin would use this taxonomic system in support of his theory.
We will return to Taxonomy therefore, after we examine Evolution. Remember: BIG PICTURE THINKING!
Introduction to Evolution
First, let’s clarify what we mean by “evolution”

The process of evolution: Organisms naturally change over time due to a number of observable
factors
vs.

Theory of Evolution: A big picture idea that attempts to explain several observed
phenomena at once
-Charles Darwin (1809-1882) was a naturalist who developed what would eventually be called
Darwinism, a broad theory of evolution based on his own scientific observations, as well as existing
theories about the natural world at the time:
(NOTE: Darwinism differs from modern evolutionary theories, or Neo-Darwinism, particularly because
an understanding of genetics hadn’t been developed yet)

Sailed the Southern Hemisphere from 1831—1836 on the HMS Beagle, a ship set to survey
and chart the coastline of South America
o Collected numerous specimens, made extensive observations on geology and organisms
o Saw and read about fossils of ancient animals
o Amazed by diversity of life
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Name: ______________________________
Evolution: the Process
Date: _______________________________
o Saw many different ways in which organisms survive and produce offspring, in a
wide variety of different geographical environments


Ex. Galapagos’ finches
Observed what he called “Artificial Selection” with plant and animal breeders
o They couldn’t cause variations to occur, but when one did occur naturally, they
could use it to their advantage


Ex. Scrawny bulls or cows that didn’t produce enough milk would not
be allowed to mate. Superior cows and bulls were mated often.
Read scientific journals and influences by revolutionary thinkers
o Jean-Baptiste Lamarck (1744-1829) on use and disuse inheritance—favourable
traits are passed on to offspring
o Charles Lyell’s (1797-1875) arguments in favour of a very old Earth that has
always been changing—evolution from ancient ancestors can only occur if Earth
has been around long enough
o Thomas Malthus (1766-1834) ideas on population growth—high birth rates force
organisms to struggle to survive against competition and the environment

Ex. Maple trees produce thousands of seeds per year, but the planet
isn’t covered by maple trees
His theory began to come together:

Most animals and plants have body parts and behaviours to do certain things very well.
The physical traits and behaviours that enable organisms to survive and reproduce in
their given environment give them what Darwin called “fitness.”
o Ex. A giraffe’s long neck, camouflaged markings

He asked: How did organisms develop these body parts and behaviours? And, why are there
so many different techniques for survival?
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Name: ______________________________
Evolution: the Process
Date: _______________________________
Years later, in his famous book, he proposed two main points:

Modern organisms descended from ancient organisms
o Darwin argued that each species has evolved (changed) from other species very slowly
over time, and if you look back far enough in time, you will see that all species have
shared or common ancestors

“Natural Selection” is the mechanism that drives this change over time
o Successful adaptations enable organisms to become better suited to their environment,
better able to survive and reproduce: “Survival of the Fittest”
o Certain adaptive traits increase an organism’s chance of survival, and therefore the
chance to pass on its favourable traits to its offspring—and so on

Favourable traits occur through natural variation in populations, as well as due to
genetic mutation (though Darwin didn’t know this)

The environment plays a crucial role in this process, as it “selects” from among
populations of species who is more likely to succeed
 As such, the process of evolution can occur quite fast if the environment
is changed due to natural events or human intervention
o Ex. Peppered moth during the Industrial Revolution
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