Download Evolution Notes - Spring Branch ISD

Evolution Notes:
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Aristotle- around 230 BCE. Ranked the natural world into a scale or hierarchy called “Scala
Natura” (The scale of Nature) this listed things in terms of importance or complexity. It was a
Ladder type of idea or the natural world.
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Carolus Linnaeus- around 1770 Wrote the “Systema Naturae” which classified plants by very
specific characteristics and grouped them into families. This was more like a tree or branching
model (not a ladder or scale like Aristotle)
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Jean Baptiste Lamarck- around 1820 Believed organisms change through Use and Disuse.
Meaning that a Giraffe gains a longer neck through use and passes on that trait to his offspring
His idea has been discounted through observation, and genetic understanding.
WHO IS CHARLES DARWIN?
Darwin was a naturalist that voyaged on the HMS Beagle (a ship) in the 1830’s. It
traveld around the globe. From his voyage observations he wrote “Origin of Species” In
the “Origin of Species” he explained his theory of Evolution. It had four main points:
1. Individuals in a species are varied (no two individuals are identical)
2. Organism that produce the most offspring that survive to maturity have better
successes.
3. In an ecosystem in equilibrium, a population tends to stay fairly constant.
4. Some traits and adaptations can be passed onto offspring.
Evidence for Evolution:
FOSSIL RECORD- fossils are imprints or petrified remains of organisms
from the past.
Relative Dating- arranging or sequencing the age of fossils based
on their placement in the soil. The oldest fossils would be found
on the bottom. Species that existed at similar times would be
found in an equal position in the rock layers.
Radioactive Dating- finding the exact age of a fossil by measuring
the amount of specific elements in the sample based on the
know length of atom decay of that substance.
HOMOLOGOUS STRUCTURES -structure in different organisms that
have similar structures, this implies a common ancestor
Vestigial Structures- structures on an organism that no longer serve a
purpose, Ex: Appendix, tail bone
Analogous Structure- structures with similar function but different
structure Ex: Insect Wing and Bird Wing
EMBRYOLOGY
Comparing the similarity in embryos (developing- unborn young) and
the genes that are present and activated shows similarity among various animals (not just mammals)
BIOGEOGRAPHY
similarity of organism in geographically isolated parts that have common
structures and behaviors
DNA SEQUENCEING
Compairing the genetic code of organisms
Humans and Chimps have a 1% difference in their genetic code.
Natural Selection: the survival of a species based on its ability to adapt and survive.
The struggle to survive in nature.
Survival of Competition: the Fittest: The organisms with the greatest “fitness” will survive long enough
to reproduce and pass of their traits.
Artificial Selection: When the traits that are passed are selected by humans for purposes other than
survival. Ex: Dog breeding and Horse Breeding
Decent with Modification: changes that have occurred in species that originated with a common
ancestor.
Adaptation- a structural or behavioral change that is a benefit to the
survival of the species. Passed on through inheritance.
Causes- Mutation, Migration, Recombination of chromosomes,
interbreeding amount a genetic line of a population