biodiversity

• Polymorphism


  The presence of more than one form or type of organism within a single species
• Polymorphism


  • Result of multiple alleles for a gene
  • Assessed by determining the number of alleles and the proportion of individuals with that allele
• Assessing genetic diversity


  1. Counting every allele in a population is difficult

  2. Analysis of base sequences in DNA can be carried out on samples of the population to look for variation between individuals

  3. The larger the variation, the higher the genetic diversity
• Biodiversity


  The number of different species (species richness) and the number of individuals of each species (species evenness) in a given environment
• Biodiversity varies spatially


  The closer to the equator, the more biodiversity there is
• Biodiversity varies temporally


  Through time biodiversity has varied, e.g. mass extinctions reduce biodiversity
• Human activities


  Affect biodiversity, e.g. through habitat destruction and climate change
• Assessing biodiversity in field work

  1. Grid an area and use a random number generator to select co-ordinates at which to place quadrats

  2. Count the number of different species and the number of individuals of each species in the quadrat

  3. Repeat 10 times to improve reliability

  4. Calculate Simpson's diversity index
• Simpson's diversity index


  Reduces species richness and evenness to a single number so that different areas can be compared
• Other methods for assessing biodiversity

  1. Kick sampling can be used in rivers

  2. The Lincoln index can be used to estimate populations of mobile organisms
• Natural selection


  • All individuals in a species have genetic variation (through mutation) that can be inherited
  • Some variants have a selective advantage
  • These variants survive, reproduce and pass their advantageous alleles to their offspring
• Adaptations


  • Morphological
  • Physiological
  • Behavioural
• Adaptations of the jerboa

  • Large ears to aid heat loss (morphological)
  • Long loop of Henle to reabsorb the maximum volume of water from urine (physiological)
  • Crepuscular activity (dawn and dusk), burrowing to avoid the heat of the day and cold nights (behavioural)
• Phylogenetic

  Reflecting evolutionary relatedness
• Hierarchy

  A system of ranking in which small groups are components of larger groups
• Taxon

  A group within a system of classification
• Hierarchy of Biological Classification

  Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
• Why classify?

  • Groups are easier to deal with than individuals
  • To identify any individual
  • To organise biological thought
  • Phylogenetic relationships - Allow us to suggest evolutionary links
• 3 Domains:

  • Eubacteria - Bacteria, They are prokaryotic
  • Archaea - Bacteria with unusual metabolism
  • Eukaryota - Plantae, Animalia, Fungi, Protoctista
• 5 Kingdoms

  • Prokaryotae - Prokaryotic organisms, single celled
  • Protoctista - Eukaryotic organisms, single celled
  • Fungi - yeast and moulds
  • Animalia
  • Plantae
• Phylum

  sub-group of a kingdom
• Genus

  A group of similar organisms
• Species

  A group of organisms showing a large number of physical features and are able to interbreed to make fertile offspring
• Homologous structures

  Structures in different species with a similar anatomical position and development origin, derived from a common ancestor
• Divergent evolution

  Common ancestral structure has evolved and performs different functions
• Analogous structures

  Have a corresponding function and similar shape, but with different development origin
• Assessing relatedness with genetic evidence

  • DNA sequences
  • DNA hybridization
  • Amino acid sequences
  • Immunology
• DNA sequences

  More closely related species show more similarity in their DNA base sequence than more distantly related species. This is because as organisms evolve their DNA base sequence changes as their genes change.
• DNA hybridization

  DNA is extracted, separated and cut into fragments using enzymes. The fragments of 2 species are mixed together. Where there are complementary base pairs, the fragments will hybridise. The greater the hybridisation the more closely related 2 species are
• Amino acid sequence

  DNA determines the amino acid sequence. The closely related 2 species are, the greater degree of similarity in the amino acid seaquence
• Immunology

  Allows antibodies of one species to recognise the antigens of another. When the antigen and antibody interact they form a precipitate. The closer the 2 species are the greater the degree of interaction and the more precipitate formed
• Binomial system

  The system of giving organisms a unique name, the genus and the species
• Biodiversity

  The number of species and the number of individuals in each species in a given environment
• Lincon index

  Used for estimating the number of motile organisms in an environment