Course Intro: 

Observation law refers to what?

∙ Scientific Method

o Only method humans have to provide us with reliable knowledge  o Observation -> Hypothesis -> Test -> Theory -> Test Theory ->  Law

∙ Important aspects of science

o Falsifiable; Guided by Natural Law; Single variable tested; Proper  control; Replication/Sample size; Repeatability; Peer-review;  Open methodology; Use statistics to determine differences;  Conclusions are tentative

Natural Selection: 

∙ Darwin’s two ideas:

o Descent with modification

 Slow gradual accumulation of differences

 Inheritance of “good” traits by offspring

 Overtime accumulation of new traits causes differentiation  of new species

Falsifiable is what?

 More closely related species are, the more similar they are  Relationship of all living things

 Saw history of life as a branching tree

 Closer the relationship, more similar the appearance

o Natural Selection

 Mechanism that species adapt to environment We also discuss several other topics like Hyperbolic space is how many degrees?

 Individual variation, heritability, and differential survival  lead to a selective pressure for variants that confer an  

advantage

 Over time beneficial variations will proportionately increase in population

o Darwin’s Observations and Inferences

o 1.  

 Reproduction potential is high

 Population size relatively constant

 Resources are limited

 Not every individual born survives

What is darwin’s two ideas?

 There is a struggle for existence

o 2.  

 Individual variation in populations  

 Some variation is heritable

 Variation in individuals confers differential survival If you want to learn more check out What are the types of hazards?

 More favorable traits will accumulate over time

o Five things required for Natural Selection to happen

 Variability  

 More offspring born than survive

 Some form of selective pressure

 Heredity

 Time

∙ Important influences on Darwin:

o Lyell

 Principles of Geology (1830) Don't forget about the age old question of Are chickens today so large because they’re given hormones?

 Uniformitarianism

∙ Laws of Physics and Chemistry unchangeable

∙ Helped explain how the features we see today on the Earth could have happened without divine  

intervention

o Lamark

 French naturalist that attempted to derive a theory of how  life changes through tine by passing on traits (incorrect)  Believed individuals would experience various needs  o Cuvier

 Studied fossils in rocks and found extinct species

o Erasmus Darwin

 Charles Darwin’s grandfather

 Darwin used much of his grandpas research  

 Similar ideas to Lamark

∙ Important Aspects of Darwin’s Life:

o What subject did he quit studying?

 Medicine

o What subject did he like studying?

 Natural science

o Major important things he saw on the Beagle:

 Slow and fast geologic processes

∙ Gradualism was clearly visible in erosion and  If you want to learn more check out What are religions of the world?

volcanism

∙ Saw volcanic eruptions that provided evidence that  We also discuss several other topics like What is variolation?
We also discuss several other topics like What is the theory of knowledge?

some geology happens in quick spurts

 Fossils

∙ Found fossil remains of Megatherium on the shores of South America

 Galapagos plants and animals

∙ Finches  

o Wallace and his discoveries

 Came up with the idea of natural selection while in  

Indonesia

∙ What is Evolution?

o Organisms changing and adapting overtime  

∙ Modern Synthesis

o Merging natural selectin with Mendel’s inheritance

o Brought the understanding of how changes at the molecular  (DNA) level can have profound effects at the  

indivicual/population level

o Linked genetics with natural selection

Microevolution: 

∙ Microevolution: Changes in gene frequency

o Polymorphism: Occurrence of different allele forms in a  population

o Gene Pool: The total of all allele types in a population

o Gene (allele) Frequencies: Frequency of a particular allele in a  population

∙ Hardy Weinberg Equilibrium

o Formula

 1=p^2 + 2pq + q^2

 Frequencies of alleles and genotypes in a population  

remains constant from generation to generation

o Factors that throw a population out of HWE:

 Mutations

∙ Not a common source of evolutionary change

 Genetic Drift/Founder Effect/Bottleneck

∙ Which sperm/egg combo occurs is random

∙ Possible for sperm of only one allele to fertilize

∙ Genetic drift associated with small populations is  

Genetic Bottleneck  

 Non-random Mating

∙ Positive Assortive Mating

o Individuals frequency of homozygous  

genotypes

o Decreases frequency of heterozygous

∙ Preferential Mating among relatives

o Inbreeding increases homozygosity

o Inbreeding affects all traits, not just preferred  

one

o Leads to increased recessive disease

 Migration/Dispersal

∙ Prevents distant populations from diverging

∙ Acts to keep entire population in HWE

∙ Very little migration required to maintain HWE

 Gene Flow

∙ Movement of genes form one population to another

∙ Genes only move when individuals with that genetic  

makeup move to another population

 Natural Selection

∙ Selection acts on entire individual  

∙ May lead to genetic drift where an allele combination

disappears from population

∙ Mendel:

o First and Second Medelian Inheritance Laws

 1. Law of Segregation:  

∙ Expression dependent on completeness of  

dominance in trait

∙ Some traits have Incomplete Dominance

 2. Law of Independent Assortment:

∙ Genes on different pairs of homologous  

chromosomes assort independently during meiosis

Macroevolution: 

∙ Macroevolution: Origins a new structures, evolutionary trends, adaptive radiation, and speciation and extinction events

∙ Methods of Speciation (allopatric/Sympatric)

o Allopatric: Gene flow is interrupted by physical separation of  populations leading to differentiation

o Sympatric: Differentiation and isolation of populations while  being in the same location

∙ Autopolypploidy: Multiple chromosomes that are derived from the  same species (4n)

∙ Allopolyploidy: Multiple chromosomes that are derived from different  species (2n)

∙ Hybrid Zone and Outcomes

o As time goes by the isolated population will accumulate changes  because there is no gene flow to maintain the status quo

o Outcomes:  

 Reinforcement of barrier will keep the 2 populations  

separate and will gradually diminish the hybrid zon until  

there is total divergence

 Weakening of the barrier will allow the isolated population  to come back together with the original population and any new traits in the isolated population can be incorporated  

into population as a whole

 Can be maintained where the 2 populations don’t  

completely isolate and a hybrid zone can remain

∙ Effects of Selection (Directional, Disruptive, Stabilizing Selection) ∙ Gradualism vs Punctuated Equilibrium

o Gradualism: Change slowly through time; Follows Lyell’s geologic gradualism; Small continuous changes that accumulate over

large amounts of time; Gradual change occurs at the population  level; Phenotypic change occurs at the individual level

o Punctuated: Stephen J. Gould and Niles Eldrige; Species evolve  rapidly then experience long periods of stasis; Change associated with rapid environmental change

∙ Mutations and what they are

∙ Biological Species Concept

o Group of populations whose members have the potential to  interbreed in nature and produce viable, fertile offspring

o Reproductive isolation is critical  

o Even low-levels of gene flow connect distant populations ∙ Mechanisms of isolating reproduction:

o Habitat Isolation- Live in different habitats and never encounter  each other

o Temporal- Come out at different times

o Behavioral- Courtship displays does not provoke breeding o Mechanical- Reproductive organs are wrong size/shape

o Gametic- Sperm does not work with egg of other species o Hybrid Infertility- Although breeding produces offspring, the  offspring is infertile

Life on Earth: 

∙ Major Time Periods of Earth and the main thing happening: o Hadean: Molten Earth, High Impact Rate, High Volcano Activity,  Reducing Atmosphere, Molecular Evolution (RNA World)

o Archaean: Planet Calms down, Bacterial Evolution, Stromatolites  and Oxygen production/photosynthesis

o Proterozoic: Eukaryote evolution

o Cambrian: Modern phyla evolution, “explosion” of  

multicellular/complex life

o Silurian: Primitive plants invade land

o Devonian: Woody Plants evolve, Animals invade land

o Carboniferous: Massive plant growth (source of most petroleum),  increased oxygen, Vertebrates invade land

o Permian: Massive Extinction, Animals evolve water tight egg and  can leave land

o Mesozoic: Time of the dinosaurs, consists of  

Triassic/Jurassic/Cretaceous, Impact event kills dinos

o Paleocene: Rise of mammals, Terror Birds

o Pliocene: First Hominids, Cooler and Drier Earth, American  Interchange

o Pleistocene: Glacial cycles, giant mammals,  

∙ Continental Drift: Gradual movement of continents across earth

∙ Hox Control Genes: help lay out the basic body forms of many animals, including humans, flies, and worms. They set up the head-to-tail  organization. 

Phylogeny: 

∙ How to read and interpret a phylogenetic tree

o Nodes, sister taxa, polytomy, Monopyletic, Paraphyletic,  Polyphyletic

o Data used to make phylogenetic tree

o Parsimony

 Tree with the least number of steps is likely the correct tree ∙ Orthologous vs Paralogous genes

o Orthologous: Conserved genes

o Paralogous: Duplicated within a species; Room for lots of new  changes because there are multiple copies of the original gene