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Biological Evolution (Inheritance (Mendel's first law of segregation -…

- - - - Migration of animals due to climate changes, shifting of range towards the poles and introducing new habitats the species need to adapt to
    - - Loss of habitats and saltwater intrusion strains land and water supply forcing the animals to adapt to gain a selective advantage
    - - Loss of habitat acts as a selection pressure to adapt to new environments, natural selection occurs and the species evolves
  - - - Water stress
        
        Morphological
        
        Leaf size and shape influence diffusion shells of water
        
        Leaf curling, wilting and shedding reduce water loss by transpiration
        
        Increased allocation of carbon to root production for increased water uptake
        
        Physiological
        
        C3 plants form 3-carbon PGA first, while C4 plants that are better adapted to increase photosynthetic rate produce 4-carbon OAA first, in order to survive in hot dry climates
    - - Extended geographical ranges to counter the effects of harsh selection pressures (e.g. Colorado potato beetles, shrubs in northern Alaska USA)
      - Increase in overwintering success presents less selection pressure on the populations
      - Increased length of development seasons and annual generations allows greater survival of a species
      - Changed synchrony in pest-host relations lead to changes in selection pressures and thus the natural selection of the fitter phenotypes
    - - Energy efficiency
        
        Decrease in average body size of endothermic animal species as a smaller body size is more energetically efficient in a warmer climate
        
        Ectotherms' metabolic activity increases exponentially rather than linearly with temperature
  - - - Loss of genetic diversity, reduction in variance of genotypes and phenotypes leading to populations more susceptible to extinction
      - Loss of species diversity due to extinction of species caused by climate change, such as mismatch in plant and pollinator populations
      - Loss of ecosystem diversity and hence different types of selection pressures that act on populations to result in evolution
- - - - Accumulation of mutations in the genetic sequences of organisms allow the determination of phylogeny and evolutionary relationships
      - Gene mutations
        
        Immediately brings about changes in the gene pool of population by substituting one allele for another
        
        Random mutations within pre-existing genes are a source of new alleles that are new heritable variations which other evolutionary processes can act on
      - Chromosomal abberations
        
        Deletion, disruption or rearrangement of loci of chromosome
        
        Duplication of genes due to error in meiosis or slippage during DNA replication duplicate large chromosome segments
        
        Result in an expanded genome with new genes that may take on new functions
        
        E.g. Single gene for detecting odors -> duplicated in humans to give 350 functional olfactory receptor genes
    - - Alignment of homologous sequences such as in cytochrome C of ETC and haemoglobin allow comparison for quantitative analysis