Evolution

  • A genetically based change in a line of descent over time

    • Two types

      1. Micro Evolution 

      2. Macro Evolution



  • Micro Evolution - happens (non controversial)

    • Small changes overtime

      • Recently occurred

      • Visible changes

      • Plentiful & obvious evidence

    • Ex. human height, mottled moth (black and white allele frequency shifts)



  • Macro Evolution - occurred in early stages of creation (controversial)

    • Major changes over time

      • Occurred very long ago 

      • Evidence is sparse (due to flaws in carbon dating)

      • No defined intermediates to believe

      • You have to trust historical data in order to base any beliefs 

    • When assessing data or any of its probability of being “correct” the probability must outweigh the possibility

      • Can not view any evidence of Macro Evolution as objective (always estimated)



  • Evolution Comes in Multiple Forms

    • Majority fall under Micro Evolution



  • Convergent Evolution

    • Occurs when superficially similar traits evolve independently in different species 

      • Ex. Wings 



  • Co - Evolution 

    • When an adaptation in one species leads to adaptation in another species in which it interacts with

      • Coyotes develop heightened smell in order to efficiently hunt rabbits

      • Rabbits in turn develop super hearing in order to escape coyotes



  • Cultural Evolution 

    • A learned behavior that is passed down from parent to offspring



  • Evidence of Evolution



  • Geologic 

    • Fossils -  Remains of organisms that no longer exist

      • Certain fossils only appear in a certain kind of rock

    • Soil Stratification

      • Formation of distinct layers in rock

      • Thought to take millions of years (subjective idea)

        • Fossils made after Mt St Helen eruption



  • Comparative Anatomy

    • Homologous Structures 

      • Structures that have the same internal anatomy yet different functions

    • Analogous Structures 

      • Structures with similar functions yet different anatomy 

    • Vestigial Structures 

      • Structures with no apparent purpose

      • Ex. Remains of whale pelvis bone, molars in bats, humans with tails, gill slits, and webbing

    • Comparative Embryology

      • The embryo of mans vertebrates are nearly identical at early stages of development

    • Comparative Biochemistry

      • All organisms use the same ATP, 20AA, DNA, RNA



  • Evolution of Life

    • Many theories surround this outlook on the history of life



  1. Pre-Biotic Synthesis Theories 

    1. All life evolved from primordial soup

    2. Early atmosphere contained CO2, Ammonia, Methane, HCL, H2SO4

    3. 1953 Stanley Miller originated theories of early organic compounds



  1. Monomer Evolution

    1. Consists of 3 main theories

      1. Outer Space

      2. Reactions in the Atmosphere

      3. Reactions at deep thermal oceanic vents



  1. Polymer Evolution 

    1. Protein First Hypothesis

      1. Catalyst (Protein) governs all reactions

      2. Would be needed before other operations in the process

    2. Polypeptides & RNA raise together

    3. RNA First hypothesis 

      1. Simpler than DNA



  1. Cellular Evolution

    1. Endosymbiotic Theory

      1. Ex. A phagocytic cell engulfed by photosynthetic bacteria



  • Macro Evolution



  1. Gradualistic Module 

    1. Speciation occurs after species become isolated with each group slowly continuing on its own evolutionary pathway

      1. Hard to identify & no transitional lines



  1. Punctuated Equilibrium Module 

    1. Periods of equilibrium are punctuated by speciation

      1. Species appears in existence and is unchanged



  1. Artificial selection

    1. Breeding of organisms with a particular desired outcome

      1. Non-Natural 

      2. Destroys theories of evolution

      3. Ex. Human selection of specific traits in dogs



Population Genetics

  • Evolution is an inevitable consequence of the nature of living things

-Individuals do not evolve, it occurs over generations

  • Evolution is the change in genetics of a population over many generations



  • Deals with frequency, distribution, and inheritance of alleles in a population

    • Alleles: what makes up genetics (same strands but different)



  • Gene Pool

    • The total of all the alleles for that gene in a population

  • Total Gene Pool

    • The total of all alleles for all genes in a population

  • Allele Frequency

    • The relative proportion of different alleles 

      • Ex. Gene pool = 60 White Flowers, 140 Purple Flowers 

        • Frequency = Purple - 70%

          White - 30%

  • Evolutions affects on population genetics 

    • Only micro evolution, macro evolution cannot be tracked



  • Four points on evolution

  1. Natural selection does not cause changes in individuals 

    1. Organisms do NOT willfully change

  2. Natural selection befalls individuals but evolution occurs in populations

  3. Evolution is change in the allele frequency of a population, owing to differential reproduction among unrelated individuals

    1. Fitness of an organism determines its measure of reproductive success

  4. Evolutionary changes are not defined as good or bad in any real sense

    1. Favorable phenotypes depend on the environment



  • Hardy - Weinberg Equilibrium

    • Defined a way to mathematically plot population genetics 



  • Equilibrium Populations 

    • Populations in which allele frequency and distribution of genotypes remain constant from one generation to the next



  • To obtain or be an equilibrium population:

    • No mutation

    • No migration

    • Population must be large

    • Mating must be random

    • All genotypes must reproduce equally 



  1. Mutations 

    1. 100% at random (non goal directed)



  1. Migration 

    1. Flow of genes between populations 

      1. ALL organisms 

    2. 2 types 

  1. Emigration (leaving)

  2. Immigration (entering)

    c. Effects

    i. Helps to spread advantageous alleles throughout a population

ii. Helps maintain large populations as 1 species

     3.  Population Size 

  1. Reproductions depends on fitness

  2. To be in equilibrium population must be large

    1. A change in small populations can be devastating

    2. Same change in large populations can go unnoticed



  • Genetic Drift 

    • Changes in allele frequencies of a small population by chance

    • Two main cases

  1. Population Bottleneck - drastic reduction (leaves few to contribute genes to future generations)

  • Ex. Elephant Seal hunted, forced to stop when there was 20 left, moved to 30,000 in species, all genetically the same

  1. Founder Effect - Occurs in isolated populations founded by few individuals 

  • Ex. Amish Migrated to US 1720-1770, one carrier of ievc spread



4. All mating must be random

  1. Hardly ever occurs

    1. Limited mobility

    2. Nearby members



Three main types of breeding

  • Hareem, Sexual Selection, Assortative Selection



Hareem Mating

  • One Male, Multiple Females

  • Good way to put best genes forward

Assortative Selection

  • Choosing mates w/ traits similar to themselves 

    • Black bear w/ black bears



Sexual Selection 

  • Selecting is “always” done by one sex (majority female)

  • Males display virtues for breeding

  • Humans fall under both Sexual and Assortative Selection



5. All Reproduce Equally 

  • This means no natural selection 

  • NEVER occurs



Natural Selection

  • “Fittest” is one that is best adapted to its environment



Directional Selection

  • Selects for one extreme against the average and the other extreme



Stabilizing Selection 

  • Selects for the average and against the extremes



Disruptive Selection 

  • Selects for both extremes and against the average 

    • Leads to speciation



Balanced Polymorphism 

  • When 2 or more alleles are maintained in a population because each is favored by a distinct selective force 

    • Sickle cell





Microorganisms

  • Commonly seen negatively

  • Ex. Ebola, Swine Flu, Bird Flu, Bubonic Plague, Covid



  • Without Microbes, Humans Cannot Survive

  • Nitrogen Fixing Bacteria

  • Converts 97% of all usable nitrogen 



  • Protists 

    • Major photosynthetic group on earth



  • Stomach Microbes 

    • Helps remnant animals dissect cellulose 

      • Insects (termites)



  • Breakdown Bacteria 

    • Renew dead material 

    • These bacteria free up unheld quantities of nutrients/elements that otherwise would remain trapped and unusable are released into the ecosystem



  • Bacteria

    • Single prokaryotic cells

      • 0.2-10 microns

        • Micron = One millionth of meter

    • Bacteria Classifications 

      • Color

      • Shape

      • Locomotion


  1. Color

    1. Based on staining

  2. Shape 

    1. Baicilli - Red Like

    2. Cocci - Spheres

    3. Spirilla - Spirals

  3. Locomotion

    1. Flagella 

      1. Long whiplike extension of the plasma membrane

      2. Used for propulsion

        1. Primarily for rapid disposal

    2. Magnetotactic bacteria

      1. Containing magnetosomes 

        1. Cause them to align with the earths magnetic fields

    3. Spores 

      1. Provide a mechanism for travel

      2. Protect the bacteria in bad environments



  • Almost all bacteria encased in a porous rigid cell wall

    • Provides three different shapes

  1. Capsules

    1. Surround cell wall

    2. Help bacteria escape detection of immune system

  2. Slime Layers

    1. Helps bacteria adhere to surfaces

      1. Ex. Fuzzy tooth feeling

  3. Pill 

    1. Fuzz that helps them attach to surfaces



Bacterial Reproduction

  1. Asexual 

    1. Known as Bacterial Fission 

    2. Produces an identical copy of the bacteria 

    3. 1 Bacteria in one day can reproduce 

      1. 1x10^21 offspring

  2. Sexual

    1. Known as bacterial conjugation

    2. They transfer genetic material through a tube

  • Curates diversity and a more prone ability to reproduce



Bacteria Habitats 

  • Everywhere 

    • Habitat specifics 

      • Can only live in environments they are specific for

      • Gives Humans an edge



Bacterial Nutrition 

  • Diet = Also extremely specific 

    • Blue/Green bacteria = Photosynthetic 

    • Chemosynthetic 

    • Anaerobic (No oxygen)

    • Cellulose breakdown 



Bacteria & Human Health 

  • Pathogen 

    • Cause disease/disease like symptoms

    • Synthesize toxins that cause

      • Ex. 

        • Tetanus 

          • Attacks nervous system

          • Tetanus bacteria requires iron

        • Botulism 

          • Neural toxin 

          • 1 gram WILL kill 14 million people 

          • Ex. Botox = Injecting botulism to paralyze an area

        • Strepococcus Pneumonia

        • Tuberculosis

        • Leprosy