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Evolution Notes
The Theory of Evolution
In science, theories are statements or models that have been tested and confirmed many times.
Theories have some important properties:
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They explain a wide variety of data and observations
They can be used to make predictions
They are not absolute, they serve as a model of understanding the world and can be changed as the world view changes
In science, the term “Theory” does not express doubt.
In science, the term theory is used to represent ideas and explanations that have been confirmed through tests and observations
The theory of evolution remains one of the most useful theories in biology because it explains many questions and observations.
Some questions that can be answered by evolution.
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Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale?
Why do organisms have structures they no longer use, like the appendix in a human? Non functioning wings in penguins
Why are there bones and fossil evidence of creatures that no longer exist? What happened to these creatures?
Why do so many organisms’ morphology and anatomy follow the same plan?
Why is the sequence of DNA very similar in some groups of organisms but not in others?
Why do the embryos of animals look very similar at an early stage?
The Theory of Evolution is considered a Unifying Theory of Biology, because it answers many of these questions and offers and explanation for the
data.
Lamarke’s Theory of Acquired Characteristics
Some thought that you would gain or lose features if you overused or didn’t use them, and you could pass these new
traits onto your offspring.
This was known as the Inheritance of Acquired Characteristics
 A lizard that didn’t use it legs would eventually not have legs and its offspring wouldn’t have legs
 A giraffe stretched its neck to reach higher leaves, and this stretched neck would be a trait inherited by its offspring
Lamarke’s Theory was eventually discarded – PROVEN TO BE WRONG!
Why? Logically it doesn’t work. Imagine if you were in a car accident and had a leg amputed. This does not mean that
your children will only have one leg. Features gained during life are not passed on to children.
Darwin’s Theory of Evolution by Natural Selection
Darwin was a naturalist who observed many species. He is famous for his trips to the Galapagos Islands, his
observations of the finches (and other animals) and the book he wrote: “The Origin of Species:
1. Variation exists among individuals in a species.
2. Individuals of species will compete for resources (food and space)
3. Some competition would lead to the death of some individuals while others would survive
4. Individuals that had advantageous variations are more likely to survive and reproduce.
Taxonomy
Taxonomy – the science of classifying organisms
Why do we need a system to classify and name organisms?
Here are some common names:
spider monkey
sea monkey
sea horse
gray wolf
firefly
crayfish
mud puppy
horned toad
ringworm
black bear
jellyfish
spiny anteater
These names can vary by region and can also be misleading. Is a sea horse really a horse?
Naming Organisms:
Organisms have common & scientific name -all organisms have only 1 scientific name
-usually Latin or Greek
-developed by Carolus Linnaeus
This two-word naming system is called…..
Binomial Nomenclature
-written in italics (or underlined)
-1st word is Capitalized –Genus
-2nd word is lowercase —species
Examples: Felis concolor, Ursus arctos, Homo sapiens, Panthera leo , Panthera tigris. These can also be abbreviated as (P. tigris or P. leo)
Linneaus also devised the system we use to organize animals. This system uses large groups divided into subgroups (like the way you organize folders on your computer)
Kingdom — Phylum — Class — Order — Family — Genus — Species
Human
Lion
Animalia
Animalia Animalia
Animalia
Phylum/DivisionChordata
Chordata Chordata
Chordata
Kingdom
Tiger
Pintail Duck
Class
Mammalia MammaliaMammalia Aves
Order
Primate
Family
Homindae Felidae
Genus
Homo
Panthera Panthera
Anas
Species
sapiens
leo
acuta
Carnivora Carnivora
Felidae
tigris
Anseriformes
Anatidae
Each organism has a group and subgroups. The organisms with the most similar groups will be most closely related. Note that both the lion and the tiger are in the same
genus, but are considered to be separate species.
There are currently 6 kingdoms – organisms are placed into the kingdoms based on the number and type of cells they have, and their nutritional needs.
number
of Cells
energy
cell
type
examples
archaebacteria unicellular
some
autotrophic, most chemotrophic prokaryote “extremophiles”
eubacteria
unicellular
autotrophic
and heterotrophic
fungae
most
multicellular heterotrophic
bacteria,
prokaryote E. coli
mushrooms,
eukaryote yeast
plantae
multicellular autotrophic
trees,
eukaryote grass
animalia
multicellular heterotrophic
humans,
eukaryote insects, worms
protista
most
unicellular
ameba,
eukaryote paramecium, algae
heterotrophic
or autotrophic