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evolution (what are species (species concepts (phylogenetic concept, small…

- - - - members in this concept reproduce b/c of their compatibility
      - b/c of their compatibility, reproductive isolation
    - - it also applies to sexual and asexual organisms
      - this concept is basically subjective criteria making that a disadvantage
    - - it also applies to sexual and asexual organisms
    - - determined by comparing morphology, molecular sequences with other organisms
      - the concept distinguishes organisms that are different and considered them to be separated species
      - a disadvantage is that it can tell how much of a difference there is for the species to be considered separated
  - - - it can also occur with having geographic isolation, b/c some organisms can colonize remote areas and that could be a way they get geographically isolated
      - geographic separation causes divergence in gene pools, mutation arise, natural selection, genetic drift can change allele frequencies
      - ex:mosquito fish pg.505
    - - it also occurs when gene flow is reduced, by polyploidy, sexual selection, & habitat differentiation
        
        1) polyploidy, an organism get an extra set of chromosomes b/c during cell division there was an accident
        
        2) autopolyploid, organisms has more than two chromosome sets from a single parent
        
        3) allopolyploid, is when sterile hybrids change into a fertile polyploid. b/c allopolyploid are fertile when they mate together but cant interbreed with parent species
        
        this also occurs when two species interbreed resulting in a hybrid
        
        sexual selection, occurred in cichlid. the females choose the males based on appearance in this case color
        
        pundamilia pudamilia are blue-tinged, and the pundamilia nyererei are red-tinged back
        
        b/c females only mated with the color in their habitat causing reproductive barrier keeping the gene pool of the species separate
        
        habitat differentiation, is another way that sympatric speciation occurs. exploitation a habitat or resource that is not used by the parent population
        
        ex:the apple maggot fly, original habitat was hawthorn tree but some colonized apple trees. they feed on or near the host plant
        
        b/c the flies use this it results in prezygotic barrier between the populations
  - - - prezygotic barriers should be stronger so that hybrids formation is reduced which is called reinforcement
      - two species are able to come in contact, the reproductive barriers have weaken b/c of too much gene flow and they become alike this is called fusion (ex: lake Victoria cichlids fish)
      - stability, the zone continues to produce hybrids. this takes place b/c hybrids survive & reproduce better than the parent population in certain habitat and years
- - - - resemblance of arrangement but have different functions. assuming that there had been a structural theme in a common ancestor (homologous structures)
    - - (ex: snakes retain pelvic bones and leg bones of ancestors)
  - - - they also show evolutionary changes occurring in various groups
- - - - characters that vary this way they are determined by a single gene locus
      - or some phenotypic differences vary in gradation along a continuum, results from the influence of two or more genes on a single phenotypic character
      - some phenotypic variation don't result from genetic differences in individual ex: muscles
    - - which evolution depends originates when mutation, gene duplication, or process produce new alleles and genes
        
        new alleles can arise by mutations, meaning a change in the DNA nucleotide
        
        a change in one base pair can result in a point mutation which can have an impact on phenotype
        
        mutations that alter phenotype are least slightly harmful, so natural selection removes those alleles
        
        diploid organisms with harmful recessive alleles, these alleles can be hidden from natural selection
        
        but there are some mutation aren't always harmful. the point mutations in these non-coding regions result in neutral variation
        
        neutral variation, there is no advantage or disadvantage if there are differences in DNA sequences
      - altering gene number or position
        
        chromosome changes that delete, disrupt, or rearrange are harmful
        
        translocation of one chromosome to a different one, linking genes that can have a positive effect.
        
        so a source a variation is the duplication of the genes b/c their was an error in meiosis, or slippage during DNA replication, or activities of transposable elements
  - - - favoring alleles over other ones NS causes adaptive evolution (better match between organisms and environment)
    - - ex: founder effect, organisms isolated from a large population, establish a new population differing the genes from the source (members are blown by a storm to a new island)
        
        this causes genetic drift to happen
        
        founder effect higher possibility of inherited disorders
      - ex: bottleneck effect, sudden change in the environment reduces population size. fire,flood
        
        alleles become either overrepresented in survivors, or underrepresented, or some completely absent
        
        genetic drift affects the gene pool until the population can get large again so chance events have less impact
    - - b/c alleles are transferred, gene flow reduces genetic differences between populations
      - gene flow can combine two populations into one having a common gene pool
      - alleles transferred affect the population and how they are adapted to their environment
      - gene flow also transfer alleles that improve the ability of the population to adapt to the local conditions (insecticide-resistant alleles)
      - gene flow is important for evolutionary change in humans (we move freely, so exchanging of alleles and having less genetic drift between population)
- - - - he had describe that organisms had features that made them suited for their environment
      - ex: the Galapagos finches, different sized beaks because of their type of food they had
      - Darwin observed adaptions in animals as it enhanced their survival and reproduction
  - - - Darwin had evidence on 3 observations about nature
        
        unity of life, diversity of life, match between organisms and their environments resulted from descent with modification by natural selection
        
        unity of life, organism had an ancestor
        
        descendants of ancestral organism lived in various habitats, and adapted
    - - selective breeding called artificial breeding
        
        selecting & breeding based on desired traits
        
        ex: dog breeders
      - Darwin's observations and inferences
        
        observation 1,members of a population vary in inherited traits
        
        2, offspring are overproduced in an environment, fail to survive & reproduce
        
        inference 1, inherited traits that give a higher chance at surviving & reproducing leave more offspring than those who dont
        
        2, unequal ability to survive, causing favorable traits to accumulate
    - - NS can diminish or amplify heritable traits that differ among individuals in a populations
      - environmental factor change place to place & over time
        
        traits are favored depends on which the species lives and mates
        
        traits can useless or detrimental depending on the environment