Please enable JavaScript.
Coggle requires JavaScript to display documents.
Evolution - Coggle Diagram
Evolution
Evolution Ch 22 and 23
History and Context Ch 22
Old Beliefs
Fixed Species
Aristotle viewed life as a ladder
Old Testament said species were designed perfect
Young Earth
Earth was only a few thousand years old
Key Scientists
Carolus Linnaeus
Created naming system
Grouped similar species together
Georges Cuvier
Studied fossils in rock layers
Proposed Catastrophism
Hutton and Lyell
Studied Geology
Said Earth changes very slowly
Lamarck
Proposed Use and Disuse
Thought acquired traits are inherited
He was wrong but had the first idea
Charles Darwin
The Voyage
Traveled on HMS Beagle
Visited Galapagos Islands
Studied finch beaks
The Big Idea
Descent with Modification
Tree of Life logic
Unity of Life
Natural Selection Rules Ch 22
Darwin Observations
Variation
Individuals in a group are different
Traits come from parents
Overproduction
Too many babies are born
Resources are limited
Inferences
Unequal Survival
Best traits help you survive
Accumulation
Good traits pile up over time
Important Limits
Populations Evolve
Individuals do not evolve
Heritable Traits Only
Must be in the genes
Context Matters
Good traits depend on environment
Evidence for Evolution Ch 22
Direct Observation
Soapberry Bugs
Beak size changed for new fruit
Happened in less than 35 years
Bacteria
MRSA resists antibiotics
Penicillinase enzyme destroys medicine
Homology
Anatomical
Same arm bones in humans and bats
Vestigial structures like snake legs
Molecular
All life uses DNA
Convergent Evolution
Analogous structures
Similar job but different ancestor
Example flying squirrel and sugar glider
Fossils
The Record
Shows past extinction
Shows origin of new groups
Transitions
Whales from land animals
Biogeography
Geography
Pangea split continents
Explains species location
Islands
Endemic species found nowhere else
Related to mainland species
Measuring Populations Ch 23
Definitions
Microevolution
Change in allele frequency
Population
Group of same species in one place
Gene Pool
All alleles in the group
Genetic Variation
Mutation\
Makes new alleles
Source of change
Sexual Reproduction
Mixes existing alleles
Recombination
Hardy Weinberg
Purpose
Tests if evolution is happening
Equilibrium means NO change
The 5 Conditions
No mutations allowed
Mating must be random
No natural selection allowed
Population must be extremely large
No migration allowed
How Populations Change Ch 23\
Natural Selection
Adaptive Evolution
Only consistent mechanism
Modes of Selection
Directional
Moves to one extreme
Disruptive
Favors both extremes
Stabilizing
Favors the middle
Removes extremes
Sexual Selection
Intrasexual is competition
Intersexual is mate choice
Genetic Drift
Basics
Chance events
Big effect on small groups
Types
Founder Effect
Small group starts new colony
Bottleneck Effect
Disaster shrinks population
Gene Flow
Basics
Transfer of alleles
Migration in or out
Mixes populations
Preserving Variation Ch 23
Why It Matters
Variation allows evolution
Diploidy
Two Sets
Organisms have two gene copies
Hiding Genes
Recessive alleles hide in heterozygotes
Keeps bad genes safe
Balancing Selection
Definition
Keeps two or more forms
Heterozygote Advantage
Heterozygotes survive better
Example Sickle Cell and Malaria
Frequency Dependent
Fitness depends on how common it is