Download Chapter #12.2

Evolution &
Classification
The Theory of Evolution
 Charles Darwin (1809-1882)
Joined the crew of the HMS Beagle as a naturalist
responsible for collecting specimens as the ship sailed
around the world
Visited the Galapagos Islands and noticed that animals
varied from island to island
 noted both similarities and differences between the
islands and other parts of the world
Began working on an idea that new organisms develop
from preexisting organisms over time
 This is the traditional definition for evolution
The Theory of Evolution (2)
Modern Scientists Evolution is…
Heritable change in characteristics in a
population from one generation to the next
REMEMBER – a Theory is a well-supported
explanation for some aspect of the natural world
that incorporates many observations,
inferences, and hypothesis
Changing ideas in the 1700’s & 1800’s
 TRADITIONAL THOUGHT
Most scientists thought that species were permanent
and unchanging
The earth was only several thousand years old
 ROLE OF GEOLOGY
George Cuvier (1769-1832)
 Catistrophism – sudden geologic catastrophes cause
mass extinctions (explains some the findings in fossils)
Charles Lyell (1797-1875)
 Uniformitarianism – processes shaping the earth are the
same as those in the past (logic for the earth being much
older than thought at the time)
Shifting Ideas
With many in the scientific community
researching species and the age of the
earth, it set the stage for ideas of
evolution.
Jean Baptiste Lamarck
Charles Darwin
Alfred Russel Wallace
Jean Baptiste Lamarck (1744-1829)
 French biologist
 Supported the idea that organisms change over
time
 Theory of Inheritance of Acquired
Characteristics – traits acquired during one’s
lifetime are pass on to the next generation
 WRONG, WRONG, WRONG!!!!!! Why?
Charles Darwin
Published book On the Origin of Species
by Means of Natural Selection
Wanted to present:
Large amount of evidence he compiled during his
voyage that supported evolution
An explanation for the variety and distribution of
organisms present today as a result of naturally
occurring processes
Darwin (2)
 Coined the phrase “decent with modification” to
describe the process of evolution
Concluded that all species today must have descended
from a common ancestor
Species can change over time – if the change is great
enough then a “new” species can emerge
Alfred Wallace – had similar idea, however Darwin
published his work first
Darwin’s Voyage aboard HMS Beagle
The Galapagos Islands
Darwin and the Galapagos Finches
Darwin’s Proposed Theory
The Theory of Natural Selection
This is the mechanism by which decent with
modification can occur
Natural Selection occurs because of…
 Overproduction
More offspring are produced than survive to adulthood
 Genetic Variation
Individuals within a population have different traits
inherited from their parents some may survive
longer/better than others as a result
 Struggle to Survive
Individuals must compete with each other; some
variations (adaptations) may increase survival and
reproduction
 Differential Reproduction
Individuals with the best adaptations are most likely to
reproduce and pass on their adaptations (genes)
Some misconceptions
Natural Selection is not a “guiding hand”
It does not produce perfection
It does not provide organisms with what they
“need” or “want”
Natural Selection is not random
Genetic variation DOES occur
So, what does it all boil down to?
Natural Selection is…
A process that results from variation (genes)
within a population
About being “good enough” not necessarily the
best
Anything that allows an organism to survive and
pass on it’s genes to the next generation
Evidence for Evolution (natural selection)
Fossil Record
Transitional Species
Biogeography
Studying the location of organism around the
world
Anatomy
Study of structure
Embryology
Study of development
EMBRYOLOGY
 Branch of biology that
studies the formation,
early growth and
development of an
organism
MORPHOLOGY
 Branch of biology that
deals with the form
and structure of an
organism without
consideration of the
function
The wing of a bat is
more similar to the leg
of a human than a wing
of a bird
PHYLOGENETICS
The analysis of the evolutionary or
ancestral relationships among organisms
DNA analysis (gel electrophoresis)
Chromosome # (karyotypes)
Gene location
Protein similarities
3 “types” of Evolution
Convergent Evolution
Different species evolve similar traits
Divergent Evolution
Descendants of a single ancestor diversify into
species that each fit different parts of the
environment
Adaptive Radiation
A new population in a new environment
develops into a new species
“Man-Made” Evolution
Artificial Selection
The selection of individuals by humans to
create the next generation
Horse Breeds
Dog Breeds
High-Yield Foods (corn, wheat etc.)
Population Genetics
Ch #16
What is Population Genetics?
 The study of evolution from one generation to
the next (microevolution) caused by variation
 What causes the variation?
Environmental factors
Heredity
 Mutation
 Recombination
 Random paring of gametes
What do Population Geneticists Study?
Gene Pool
Total genetic information in the population
Allele Frequency
Percentage of an allele in a population
Phenotype Frequency
Percentage of individuals with a specific trait
within a population
Hardy-Weinberg Equilibrium
 Mathematical way of calculating if allele
frequencies are changing in a population
 Assumption can be made that if a population is
NOT evolving then:
No mutations are occurring
No individuals enter or leave the population
The population is large
All mating is random
Selection does not occur
Is this likely to happen?
Factors that change a population
 Mutation
Production of new alleles
 Gene Flow
Process of genes moving from one population to
another
 Immigration = movement of individuals INTO a population
 Emigration = movement of individuals OUT of a population
 Genetic Drift
Change in allele frequencies as a result of random
events
 Sexual Selection
Selecting mates based on some criteria
CLASSIFICATION
The grouping of objects or information
based on similarities
Classification of Organisms
Ch #17
TAXONOMY
Branch of biology concerned with the
grouping and naming of organisms
Taxonomist – biologist who study
taxonomy
ARISTOTLE’S SYSTEM
Greek philosopher
First to develop a classification scheme
Plants
Herbs, shrubs, trees
Animals
Land, air, water
Linnaeus’ Classification System
Swedish botanist (1700’s)
Used physical characteristics of the
organisms
Classification based on the evolutionary
context of a species
Developed 2 name system
binomial nomenclature
Levels of Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
The Three Domains of Life
Eubacteria
Single-cell prokaryotic organisms
Archaea
Prokaryotes that can live in extreme
environments
Eukarya
All Eukaryotes
The Six Kingdoms
 Eubacteria – aligns w/ Domain Bacteria(Archaea)
 Archaebacteria – Aligns w/ Archaea
 Protista – eukaryotes that are not plants, animals or
fungi
 most unicellular
 Fungi – eukaryotes, heterotrophs –
 most multicellular
 Plantae – eukaryotes, autotrophs
 multicellular
 Animalia – eukaryotes,heterotrophs – develop from
embryos
 Multicellular
BINOMIAL NOMENCLATURE
 Genus – group of closely related species
 Species – group of organisms that can mate and
produce viable offspring
 Binomial name = genus species
Capitalize genus name
When typed, the name should be in italics
 Ex. Homo sapiens
BINOMIAL NOMENCLATURE (2)
Linnaeus chose Latin as the language for
the system
Dead Language (does not change)
Universal understanding
Common names lead to confusion…
Honey Badger
Common names lead to confusion…
 North American
Badger
Common names lead to confusion…
 Eurasian Badger
Common names lead to confusion…
 Stink Badger
LINNAEUS AND SYSTEMATICS
 Systematics – classifying organisms in terms of
their natural relationships
 Linnaeus
Grouped according to visual similarities
 Modern Biologists
Visible similarities
Embryos
Chromosomes
Proteins
DNA
IDENTIFYING AN UNKNOWN
ORGANISM
Dichotomous Key
A written form of a branch diagram that is used
to identify an organism based on physical
characteristics
To create a dichotomous key…
Design a branch diagram
Transfer the diagram to written form
THERE MUST ALWAYS BE 2 CHOICES FOR
EVERY STATEMENT