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Speciation (Types of speciation (Intraspecific speciation (Allopatric…

- - - - genetic drift
        
        variation in gene frequencies within populations that occur by chance rather than natural selection
        
        phenomena
        
        Founder principle
        
        new colony,occur when a few individuals from a large population colonize a new habitat
        
        genetic viability is low compared to large original population
        
        continuous breeding within individuals in the new population will produce a different population from the original one
        
        Bottleneck effect
        
        certain alleles over represent while some of the allele being eliminated or under represented
        
        small surviving population do not represent the original populations
        
        due to drastic reduction in population size,cause by disasters
      - hybridisation
        
        production of hybrid through interbreeding between two different species (allopolyploidy)
        
        allopolyploidy will overcome sterility by doubling number of chromosome producing fertile organisms
      - isolation
        
        Separation process which lead to speciation by prevent interbreeding between individual
        
        isolating mechanisms
        
        producing or maintaining reproductive isolation within a population to prevent interbreeding
        
        Types
        
        prezygotic barrier
        
        prevent mating between individuals or prevent fertilization
        
        Habitat isolation
        
        1 more item...
        
        behavioral isolation
        
        3 more items...
        
        temporal/ seasonal isolation
        
        2 more items...
        
        mechanical isolation
        
        4 more items...
        
        gametic isolation
        
        2 more items...
        
        postzygotic barrier
        
        reduce hybrid fertility
        
        hybrid fail to produce gametes caused by the failure of meiosis due to chromosomes of the parents differ in number or sturcture (eg. crossing between donkey (2n= 66) and horse (2n=60)
        
        hybrid breakdown
        
        hybrid F1 generation are viable and fertile but F2 generation fail to develop or sterile (eg. cotton)
        
        reduce hybrid viability
        
        hybrid is occurred but fail to develop (eg. mating between northern leopard frog and southern leopard frog)
      - adaptative radiation
        
        group of individuals share a homologous structure which is modified to perform a variety of function
        
        homologous structure is the structure in different species that are similar because originated from the common ancestors
        
        importance
        
        formation of a new species
        
        enables organisms to be isolated physically and reproductively
        
        brings about divergent evolution
        
        enable the organisms to occupy the niche even though they are living together
  - - - occurs when one population of a species is divided into two separated populations by physical or geographical barriers
    - - occurs when members of a species of a species population in a same habitat develop genetic differences (although they are not geographically isolated)