taxonomy and diversity

• Two organisms belong to the same species if they are able to produce living fertile offspring
• Linnaeus Binomial system (printed in italics or underlined if written)

  First name = genus

  second name = species [if unknown sp. can be written]

  e.g. Homo sapiens
• courtship rituals are a sequence of actions which are unique to each species important to ensure mating is successful and offspring have the maximum chance of survival
• importance of courtship:

  • recognise members of their own species (for fertile offspring)
  • synchronise mating (maximum probability of sperm and egg meeting)
  • become able to breed (opposite sex into physiological state for breeding)
• during courtship animals use signals to communicate typically there is a chain of actions = same for all members of a species
• principles of classification:

  • artificial classification
  • phylogenetic classification
• artificial classification divides organisms into groups based on observable characteristics, not evolutionary relationships (like birds and butterfly both have wings but they originated in different ways)
• Phylogenetic classification attempts to arrange species into groups based on their evolutionary origins and relationships.

  • It uses a hierarchy in which smaller groups are placed within larger groups, with no overlap between groups. Each group is called a taxon
• 3 features of the phylogenetic classification:

  • based on evolutionary relationships between organism and their ancestors
  • classifies species into groups using shared features derived from their ancestors
  • arranges the groups into a hierarchy in which the groups are contained with larger composite taxa and no overlap
• The grouping of organisms according to their characteristics is called taxonomy. There are eight different taxonomic groups used to classify organisms.

  • domain (bacteria, archaea and eukarya)
  • kingdom
  • phylum
  • class
  • order
  • family
  • genus
  • species
• courtship rituals genetically determined, so the more similar a species is the more similar DNA base sequence is
• evolutionary relationship determined by the hierarchical order of taxonomic ranks is known as phylogeny
• phylogenetic relationships of different species usually represented by phylogenetic tree

  
• species diversity is the number of different species and the number of individuals of each species within any one community
• genetic diversity is the variety of genes possessed by individuals that make up a population of species
• species richness is a measure of the number of different species in a community (variety of species)
• index of diversity is the relationship between the number of species in a community and the number of individuals in each species
• calculating index of diversity:

  N = total number of organisms of ALL species

  n = total number of organisms of each species

  A) N

  B) n

  C) -

  
• farmers often select species for a particular quality

  = number of species and genetic variety of alleles are reduced

  = smaller area for other species

  = other species compete for space and resources

  = pesticides used to kill other species as they compete

  REDUCTION OF SPECIES DIVERSITY
• Farming practises that directly remove habitats and reduce species diversity:

  • removal of hedgerows
  • creating monoculture
  • filling in ponds and draining marshes
  • over-grazing of land
• farming practises that indirectly remove habitats and reduce species diversity:

  • use of pesticides and inorganic fertilisers
  • escape of effluent from silage stores and slurry tanks into water courses
  • absence of crop rotation and lack of intercropping
• examples of conservation techniques:

  • maintain and plant hedgerows in an A shape
  • use organic rather than inorganic fertilisers
  • use crop rotation and intercropping rather than fertilisers and herbicides
• dna determines the proteins of an organism inlcuding enzymes and features of a species so...

  • changes in the features of a species are due to changes in its DNA
• comparison of observable characteristics:

  • limitations = given large number of observable characteristics are coded for by more than one gene (polygene)
  • limitations = characteristics can also be modified by the environmental conditions rather than different alleles
• inferring dna differences from observable characteristics has been replaced by directly observing dna sequences themselves - gene technology
• comparison of DNA base sequence:

  • each nucleotide can be tagged with a different coloured dye (adenine = green etc) producing series of coloured bands each representing one of the four nucleotide bases

  analysis of these patterns allows us to compare one species with another or one individual with another to determine how diverse they are
• comparison of mRNA base sequences:

  mRNA is coded for by DNA and the base sequence on mRNA is complementary to strand of dna

  • compare the base sequence of mRNA to measure DNA diversity = genetic diversity
• comparison of amino acid sequence in proteins:

  sequence of amino acid in proteins determines by mRNA which is determined by DNA

  • comparing amino acid sequence of proteins to observe genetic diversity

  the degree of similarity in the amino acid sequence in two species reflects hoe closely related they are