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Evolution - Coggle Diagram

- - - - mating calls, feeding strategies
  - - - Natural selection: helpful alleles become more common and harmful alleles become less common
      - Genetic drift: bottleneck and founder effect
      - Gene flow: alleles enter or leave a population when individuals migrate.
      - Mutations: new alleles appear when DNA changes
      - selective mating: if organisms choose mates based on certain trait then certain alleles get passed on more often
  - - - Evolution happens at the population level, not the individual level.
  - - - random changes in DNA sequences create new alleles
      - primary reason for genetic variation, w/o mutations new alleles would not be possible nor evolution can happen
      - can be as tiny as swapping one base for another or as big as adding or deleting whole sections of chromosomes
      - happens in 2 main places
        
        In somatic cells which only affects the individual, not passed on
        
        In the gametes which are heritable
        
        these are the ones that matter for evolution to occur
      - types of mutations and there effects
        
        point mutations
        
        A single base changes
        
        silent: no effect on protein
        
        missense: changes one amino acid
        
        Nonsense: creates a stop codon creating a short nonfunctional protein
        
        frameshift mutations
        
        Insertion or deletion shifts the reading frame, usually causing severe effects
        
        gene duplication
        
        A gene gets copied twice and one copy can mutate freely and evolve new functions.
    - - Sex mixes alleles in new combinations
      - Crossing over (chromosomes swap pieces during meiosis)
      - Independent assortment (chromosomes line up randomly)
        
        This means each gamete gets a random mix of maternal and paternal chromosomes.
        
        Ex: You have 2 chromosome pairs. Pair 1: A (from mom) / a (from dad) Pair 2: B (from mom) / b (from dad)
        
        AB,Ab, aB, ab are all equally possible bc the pairs assort independently
      - Random fertilization, any sperm can meet any egg
    - - when individuals move into or out of a population, they bring new alleles
    - - common in bacteria and viruses
      - fast reproduction = more mutations = more variation.
  - - - Ex: silent mutations, harmless differences in hair texture, eye color in many environments.
      - When the environment is stable
      - If no trait gives an advantage, natural selection has nothing to act on.
  - - - No mutations
      - Random mating
      - All individuals survive and reproduce equally.
      - Very large population size
      - No gene flow
    - - p= dominant allele frequency q= recessive allele frequency p^2= homozygous dominant 2pq=heterozygous q^2=homozygous recessive
  - - - Can increase or decrease certain alleles randomly
      - reduces genetic gene diversity
      - Ex: A storm kills majority of a beetle population, leaving mostly green beetles by chance
      - is a random change in allele frequencies due to chance.
    - - The movement of alleles into or out of a population when individual organisms migrate and reproduce
      - Increases genetic diversity
      - Makes populations more genetically similar
      - Can introduce new alleles
  - - - Can be worse because loss of genetic diversity, harmful alleles become common hindering the ability to adapt too, increase in inbreeding
      - although rare, can be beneficial if the population happen to have individuals with traits well suited to their new environment, or the harmful alleles were left behind
  - - - The bottle neck effect can make a population worse most of the time because harmful alleles become more commonn and loss of genetic diversity
        
        With less variation, the population is more vulnerable to disease, climate shifts, and predators
        
        Ex: A past bottleneck left cheetahs with low genetic diversity causing them to be able to accept skin grafts from each other
      - Although rare, the bottleneck effect can make a population better off if harmful alleles are eliminated, the survivors have traits well suited to the environment or if the environment changed and the survivors fit the new conditions
  - - - One extreme version of a trait is favored.
      - The populations average shifts toward that particular extreme
      - Ex: If larger beaks help birds crack tougher seeds during a drought, birds with larger beaks survive more then the population shifts toward larger beaks.
    - - The average trait is favored, and extremes are selected against.
      - The environment stays stable
      - Variation decreases
      - Extremes become rare
      - Ex: very light weight and heavy weight infants have higher mortality compared to average weight babies
    - - Both extremes are favored, and the average is selected against.
      - The environment has two different that conditions that favor opposite traits.
      - The population splits into two groups
      - can lead to new species forming
      - Ex: Birds in an environment with only large seeds and tiny seeds
- - - - geologist who suggested gradual change in earths features
      - . This helped Darwin realize that if Earth changes gradually over long periods, then living organisms could also change gradually through evolution.
    - - expanded Hutton’s ideas and argued that the same natural processes we see today (erosion, sedimentation, volcanic activity) have been shaping Earth for a very long time.
      - Darwin realized that if Earth changes slowly, life could also change slowly through natural processes.
    - - suggested that species change over time through the mechanism: inheritance of acquired traits
        
        Why is his mechanism wrong?
        
        Because he thought organisms could change their bodies by using them, we now know that changing your body during your lifetime does not alter your DNA.
        A body change is not genetic.
        
        He thought acquired traits were inherited, we now know only genetic changes in reproductive cells get passed on.
        
        Ex:a bodybuilder building muscle isn't going to be passed down to their children
      - he introduced the concept of evolution
    - - wrote about how human populations grow faster than food supplies causing competition, struggle, and survival pressure.
      - This inspired Darwin’s idea of “struggle for existence”
        
        What connection did Darwin make between malthus’s idea and how natural selection works?
        
        Darwin realized that because organisms produce more offspring than the environment can support, they must compete for limited resources.
        
        struggle for existence meaning individuals with advantageous traits are more likely to survive and reproduce. Overtime, those traits become more common.
  - - - Darwin saw fossils of extinct animals that resembled living species in the same regions.
    - - Species on the Galápagos Islands resembled species from the south american mainland, not from similar islands elsewhere.
      - Each island had its own version of finches and mockingbirds
      - This supported his theory that species adapt to their environments and diverge from common ancestors
    - - observed how breeders could dramatically change animals by selecting which individuals reproduced
      - this showed him selection can change a species
  - - - Species were not fixed, they change over time and adapt to their environment
  - - - We choose which organisms get to reproduce.
      - Happens quickly because humans control the breeding.
    - - Nature decides which organisms survive and reproduce.
      - Happens slowly over many generations.
  - - - Ex: Human arm, cat leg, whale flipper, and bat wing
        All have the same bone structure
    - - Ex: sugar gliders (marsupial)s and flying squirrels (placental mammals) both have skin flaps that let them glide.
        
        Flying squirrels ancestors didn't glide, they just lived in similar forest environments, and faced similar challenges, therefore natural selection pushed them toward the same solution: gliding
    - - unrelated species evolve similar traits because they live in similar environments or face similar selective pressures
  - - - Believed species were created by God and were unchanging.This belief dominated western people thinking.
      - Organized life into a “Scala Naturae” ranking organisms from simple to complex
    - - Founder of paleontology
      - Noticed that older rock layers had different fossils than upper layers.
      - Proposed that sudden disasters wiped out species and new ones appeared afterward
      - Did not believed species evolved
      - His work with fossils showed that life changes over time despite his beliefs
    - - botanist who sought to classify life’s diversity for the greater glory of God.
      - developed the two-part, or binomial, format for naming species
      - used a nested classification system, grouping similar species into increasingly inclusive categories
      - did not ascribe the resemblances among species to evolutionary ties but to the pattern of their creation
      - despite his beliefs, his classification systems revealed the pattern of relateness among organisms