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Evolution (What are species? (Reproductive isolation could impede member…

- - - - no way to evaluate the reproductive isolation of fossils
      - does not apply to organisms that reproduce asexually
      - Gene flow is not always absent
  - - - impeding members of diff. species from mating
      - unsuccessful mating
      - hindring fertilization
        
        Habitat isolation two species might not encounter each other at all
        
        temporal isolation is when species have different mating season
        
        mechanical isolation is when morphological differences prevent from successful completion
        
        behavioral isolation mate recognition is unrecognized within other species
        
        gametic isolation when some species can't work w/ egg and sperm
    - - may reduce survival among hybrid embryos
        
        reduces hybrid viability is when the genes of both of the parents may affect the hybrids chances of survival
        
        reduces hybrid fertility is is when the chromosomes of both parents may fail to produce normal gametes
        
        hybrid breakdown is when the first-generation hybrids is fertile but when they try to reproduce with one of their parents the make a feeble hybrid
      - problems after birth may cause hybrids to be infertile or not live long enough to reproduce
  - - - applies to asexual and sexual organisms
      - w/o info of gene flow
  - - - allopatric speciation is the aftermath of geographical isolation where the species adapt to the environment and can no longer reproduce
- - - - Example: flower color, height, # of species
    - - if they affect reproduction
      - affect survival before mating
    - - one of the possible forms of a gene
        
        Locus is a fixed position of a gene
        
        Loci is important in genetic variation
  - - - No mutations occur
      - No gene flow in population
      - Population must be very large
      - Mating must be random
      - Natural selection Is not changing the population
      - Allele is not sex-linked
    - - p = frequency of the dominant allele
      - q - frequency of recessive allele
      - p^2 = frequency of homozygous dominant individuals
      - 2pq = frequency of heterozygous individuals
      - q^2 = frequency of homozygous recessive individuals
  - - - directional selection where the environment favors the one that will survive the most
      - disruptive selection is when the environment favors extreme phenotypes than those with intermediate phenotypes
      - stabilizing selection acts against both extreme phenotypes and favors certain intermediate traits
      - sexual selection
        
        intrasexual: 2 males fight to get the attention of a female
        
        intersexual is the mate's choice
- - - - Observation: there is variation in every species
      - Inference: Best adaptations/traits tend to survive the highest
      - Observation: more offspring that the environment can support
      - Inference: species adapt to the environment
    - - Lamark proposed the theory of transmutation of species (species turn into something else)
      - Lyell published the principles of geology (fossils), which inspired Darwin to think of gradual evolution
    - - Famous observation was the Galapagos finches (demonstrated that birds adapt to their environment for better survival)
      - here he studied and observed nature for approx. 5 years
  - - - This can increase the frequency of adaptations that are favorable in a given environment
      - if environment changes, natural selections will adapt to these new conditions, which sometimes leads to a new species
  - - - demonstrated Darwin's inference and observations of descent with modification
    - - Ex: Us humans, have a tail bone but we don't use it because we don't need it to survive in our environmen
      - structures that have lost all/most of its function
    - - development of diff, species of organisms based upon their descent from a common evolutionary ancestor
      - Ex: the structure of forelimbs of humans, bats, deer are all very similar
      - Homologous structures
        
        same structures diff. function
        
        We all come from the same ancestor!
    - - Catalog that shows the diff. between past life forms to the present day
      - In the geological Strata, fossils showed that new species would appear while older ones would disappear (survival of the fittest)
    - - unrelated species are adapting to similar environments in similar ways
      - Ex: sugar gliders and flying squirrels
      - analogous structures
        
        features share similar functions, but not common ancestor
        
        We adapt to the environment, regardless of our ancestor