Evolution

Evolution

1. change in frequency in a population's gene pool

   • happens to gene pool (species), not inds.
     • ORIGIN OF LIFE
       • all living things come from common ancestor
         • CHEMICAL EVOLUTION
           • mix of inorganic molecules reacting to form organic molecules
             • glucose, amino acids, nucleotides, etc.
         • BIOLOGICAL EVOLUTION
           • first protocells arise
           • deep sea, meteors, hydrothermal vents
             • MILLER-UREY EXPERIMENT
               • synthesized organic compounds from inorganic
                 • H2O, CH4, NH4, H2 sealed in container and other has water which is heated
                   • electric shocks = lightning with the atmosphere composition
                     • atmosphere was cooled to be condensed again
                       • solution was purified to be tested for amino acids
               • Criticisms
                 • atmosphere had different composition
                   • experiment was done again w/ CO2, CO, N2, but results were same
                 • ignored presence of O2 which would've oxidized org. compounds

2. BIOGEOGRAPHY

   • geographical distribution of species
     • ISLAND ANIMALS EVOLVE FR. MAINLAND ANIMALS/MIGRANTS
       • species adapt over time, as they adjust to new environmental conditions, selective pressures
         • geographically close species > more related than geo. separate (even if conditions are similar)
     • ISLANDS
       • Volcanic Islands
         • species swim, fly, float from mainland
       • Islands Breaking Off fr. Continental Land Mass
         • same species on mainlands evolve when isolated
           • become endemic

3. THEORY OF NATURAL SELECTION

   • OVERPRODUCTION
     • overpopulation of species leads to competition within species
   • COMPETITION
     • individuals compete for resources
   • VARIATION
     • individuals have variation in DNA leading to different traits and characteristics
   • ADAPTATION
     • any trait increasing an organism's chance of survival
       • types
         • structural adaptations
           • outside appearance, body shapes, colouration, etc.
           • mimicry: organisms mimic other organisms/objects
         • physiological adaptations
           • associated w/ function of organism
         • behavioral adaptations
           • change in animal behavior; can be learned/innate
   • NATURAL SELECTION
     • individuals w/ beneficial adaptations are more likely to pass genes to next gen.
     • How does natural selection occur?
       • reproduction
         • individuals able to reproduce to pass genes to next gen
       • heredity
         • genes of parents combine to produce genes of offspring
         • adv. traits stay in gene pool by reproduction/heredity
       • varitaion
         • in characteristics
           • variety among species
             • if none, there's no competition/no change
         • in fitness
           • ability to live long enough to pass genes
             • traits allow certain individuals to grow and reproduce
             • variation of alleles better suited to environment
     • ARTIFICIAL SELECTION
       • humans control trait selection
         • breed organisms w/ desirable traits (non-random mating)
         • controlled mating
     • Types of Selection
       • STABILIZING SELECTION
         • favor average trait//select against lowest/highest extreme
           • keeps frequency on average
           • human birth weight, select against small/big babies
       • DIRECTIONAL SELECTION
         • favors inds. w/ extreme distribution//select against average/other extreme
           • operate on env. change
           • industrial melanism
       • DISRUPTIVE SELECTION
         • favors both extreme ends//select against average
           • allele frequencies can change
           • shell color, light/dark survive not tan
   • SPECIATION
     • when 1 species arise from common ancestor
       • can happen by:
         • TRANSFORMATION
           • changes accumulate over time
         • DIVERGENCE
           • one or more species arise from parent species that continue to exist
       • occur when barrier prevents organism from mating
         • GEOGRAPHICAL BARRIER
           • populations are physically separated
             • river, mountain, etc.
           • ALLOPATRIC SPECIATION
             • occurs when pt. of pop. become gradually isolated fr. parent pop.
         • BIOLOGICAL BARRIER
           • populations can't reproduce even tho ranges overlap
             • behavioural isolation
               • song of bird, pheromones, colouration
           • SYMPATRIC SPECIATION
             • reproductive isolation happens even if there's no barrier
               • muations, non-random mating
             • Polyploidy
               • (error in cell division) cause extra set of chromosomes
             • Hybridization
               • species can interbreed to form hybrids
             • Cichlids
               • each have feature making them unique; parent pops. had diff. diets
         • reproductively isolated
           • can't interbreed, when there's enough genetic differences accumulated

4. OTHER THEORIESTS

   • Charles Lyell
     • a Geologist > studies changes in earth over time
       • influence Darwin's ideas about evolution through gradualism
   • Jean-Baptiste Lamarck
     • proposed environmental influences change in animals
       • use and disuse
         • organs develop on usage
       • inheritance of acquired characteristics
         • acquisition/losses passed on to next gen.

5. TYPES OF EVOLUTION

   • MACROEVOLUTION
     • large-scale, long-term, lead to speciation
       • can be adaptive radiation
         • evolution of many different species to specific niches
           • short time frame, organisms closely related
   • MICROEVOLUTION
     • single species, no speciation, includes natural selection
       • change in allele frequency
         • industrial melanism
   • DIVERGENT EVOLUTION
     • when 2 or more species diverge from common ancestor, become diff. from each other
       • change, adapt under different selective pressures
       • great white shark, giant manta ray
         • common ancestors, but one hunts and other is filter feeder
     • HOMOLOGOUS STRUCTURES
       • similar structure, differing function, from common ancestor
         • killer whale, fruit bat > fins, wings
   • CONVERGENT EVOLUTION
     • dolphin, great white shark
       • not from common ancestors, but both are hunters due to water env.
     • echolocation in bats and dolphins
       • not from common ancestors, but similar dark env.
     • when unrelated species, coming from diff. ancestors share similar traits
       • adapt under similar selective pressures
     • ANALOGOUS STRUCTURES
       • differing structure, similar function, not from common ancestor
         • bird wing, bee wing
   • COEVOLUTION
     • when 2 organisms evolve gradually together, responding to changes in each other
       • birds and plants
         • poor sense of smell = bright petals

6. GENETIC EQUILIBRIUM

   • no change in allele frequency in population's gene pool
     • large population
     • random mating
     • no immigration
     • no mutation
     • no natural selection
   • mathematical model, dealing w/ frequency of alleles in gene pool
     • p2 + 2pq + q2 = 1

7. WHY DO SPECIES EVOLVE?

   • Small Population/Population Shrinks
     • change can take over
       • alleles of small population get passed down
   • Non-Random Mating
     • mate choice
   • Mutation
     • changes allele frequency > can be passed down
   • Gene Flow
     • immigration/emigration
       • get rid of/introduce alelles
   • Adaptation
     • inds. w/ beneficial trait more likely to pass genes

8. EVOLUTIONARY PACE

   • GRADUALISM THEORY
     • theory that change occurs slowly w/in lineage
       • slow & steady > small changes lead to big change over time
   • PUNCTUATED EQUILIBRIUM THEORY
     • proposes that there's a long period of time of no change followed by periods of divergence speciation
       • species undergo most change after separating fr. parent species
         • species won't change if selective pressures don't change