4.2.2 - classification and evolution

• Classification is the process of naming and organising organisms into groups based on their characteristics.
• What is classification?

  process of naming and organising organisms into groups based on their characteristics
• The eight groups an organism can be classified into are:

  domain

  kingdom

  phylum

  class

  order

  family

  genus

  species
• The two components to a binomial name are the

  genus the organism belongs to (with a capital first letter) and the species name

  eg Homo sapiens
• An advantage of the binomial naming system is that an organisms binomial name is the same everywhere in the world
• The three domains are:

  bacteria

  archaea

  eukaryota
• The five kingdoms are

  prokaryote

  protoctista

  fungi

  plantae

  animalia
• Organisms are classified into kingdoms based on similarities in observable characteristics
• The domain system of classification was developed by analysing molecular differences between organisms to determine their evolutionary relationships. (Phylogeny)
• The phylogenic definition of a species is:

  a group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics.
• the difference between classification and phylogeny is that classification is sorting organisms but phylogeny investigates evolutionary relationships between organisms.
• Natural selection results in evolution because:

  • random mutations result in new alleles
  • some alleles provide an advantage against selection pressures making an individual more likely to survive and reproduce
  • their offspring receive the new allele and are said to have ‘evolved’ a new characteristic
• Darwin and Wallace contributed to the theory of evolution. They observed that birds have many different beak shapes and concluded that birds with beak shapes most suited to the food they eat are more likely to survive and pass this beak shape onto their offspring.
• Evidence for the theory of evolution includes:

  fossils

  genomic dna

  molecular evidence
• fossils provide evidence for the theory of evolution as they allow us to compare extinct organisms to todays organisms
• genomic DNA provides evidence for the theory of evolution as sequencing of genomes has shown how closely related we are to primates
• Molecular evidence for the theory of evolution shows that differences in amino acid sequences could be linked to how closely related two individuals are
• Two things cause variation:

  genetic = mutations, random fertilisation

  environmental = climate, diet
• intraspecific variation is variation within the same species
• interspecific variation is variation between different species
• Continuous variation is when variation exists as gradual changes over a range

  eg, height
• discontinuous variation is when variation exists as distinct categories

  eg, blood group
• We may carry out the Spear man’s rank correlation coefficient to measure the correlation between two variables.

  the extent to which changing one variable affects the other variable
• Spearmans rank results are interpreted as:

  closer to 1 : more positive correlation

  closer to -1 : more negative correlation

  Around 0 : no correlation
• The three types of adaptation are

  anatomical

  physiological

  behavioural
• anatomical adaptations are changes to body structure

  eg, oily fur
• physiological adaptations are changes to bodily processes

  eg, venom production
• Behavioural adaptations are changes to actions

  eg, hibernation
• Organisms froom different taxonomic groups might show similar features because they adapted to similar environments so share Similar anatomical features
• Implications of evolution for humans include:

  bacterial antibiotic resistance means infections are harder to treat

  pesticide resistance means entire crops could be destroyed