Theory of Evolution

• Evidence supporting the theory of evolution? Fossils, anatomy, biogeography, embryology, natural selection
• Anatomical similarities between species that are evident of evolution? Vestigial structures, structures have the same plan but different uses (modified)
• Embryological evidence comes from the embryo stage being very similar, but structures are lost in later development
• Biogeography: Position of the continents change over time, altering climate and placing different environmental pressures on life.

  This can explain similarities and differences in biota
• 1 gene carries 2 alleles. It can be either heterozygous or homozygous (2 of the same, or one of each).
• Term for genetic make-up? Genotype
• Term for appearance? Phenotype
• How does variation arise? Genetic drift and natural selection
• Phenotype natural selection graph:

  Phenotype near the mean favoured (more likely to survive) over the original population or the evolved population? Stabilising Selection

  Phenotype towards one end favoured, freqeuncy shifts in one direction? Directional Selection

  Both extremes are the most fit, the middle is not? Diversifying Selection
• Term: The process by which new species are formed? Speciation
• Speciation term:

  Geographic barries separate populations, followed by evolution change and reproductive isolation. Allopatric
• Speciation term:

  No geographical isolation. Arises from meiotic error. Generally reproductively isolated from parental species (different chromosome numbers inhibit successful mating). Sympatric
• The two main mechanisms of speciation are allopatric and sympatric.
• Relevance of evolution?

  Pest control, antibiotic resistance, inbreeding, if population is driven low their numbers may recover quickly but genetic diversity will not