4. biodiversity & classification

• due to developments in microscopes, biochemistry and genomes we have 5 classification kingdoms: animals, fungi, plants, protists (malaria), prokaryotes
• carl linneaus

  • first classification system- based on structure and characteristics
  • binomial naming system
• taxonomic groups:

  • domain
  • kingdom
  • phylum
  • class
  • order
  • family
  • genus
  • species
• species- a group of similar organisms that can successfully breed together to produce fertile offsprings
• hierarchy- large groups split into smaller groups but there is no overlap between groups
• courtship behaviours

  • release chemicals- pheromones
  • sound- calls
  • colour/ visual displays- colour represent physical fitness
  • dancing
  • build shelters- can provide and protect offsprings
• more closely related species have more similar courtship behaviours
• phylogeny- grouping of organisms based on their evolutionary relationships using common ancestry
• Darwin was limited as he didn’t know about genetics
• advantages of phylogenetic classification over hierarchical

  • P based on evolutionary relationships not characteristics
  • P allows a continuum rather than discrete groups, shows change over time
  • P better description of variety in groups
• extracting and analysing differences in DNA code through genome sequencing improved classifications
• Classification methods:

  1. compare base sequence of DNA/ mRNA- higher similarity in base sequence more closely related
• Classification methods:

  2. compare amino acid sequence of proteins- DNA base sequence affect mRNA affects amino acid sequence. Look at specific proteins
• Classification methods:

  3. immunological comparison- similar proteins should bind to similar antibodies
• how phylogenetic system differs from a hierarchy (3)

  • hierarchy based on common characteristics
  • phylogenetic based on evolution from common ancestor
  • eg. shows reptiles and birds more closely related than mammals
• How biologists classify organisms into groups (3)

  • hierarchal system where large groups are divided into smaller groups with no overlap
  • groups have a common ancestor
  • based on evolution from common ancestor
• Ecosystem- community of organisms interact with the non-living, abiotic factors
• Habitat- abiotic (non-living)

  Community- biotic (living)
• -Within a community all species depend on each other

  -Creates a complex interdependence between species
• Biodiversity

  • measure variety of all species in a particular ecosystem
  • High biodiversity generally good for stability
• Human affect on biodiversity

  • biodiversity reduced due to habitat loss, flooding, drought, climate change
  • biodiversity increases our natural resources
• Deforestation

  • provide land for farmland (cattle= methane)/ growing crops (monocultures)
  • more CO2 in atmosphere cause global warming as forests are a carbon sink
• Quadrats

  • use random number generator to generate coordinates
  • place 10-20 quadrats so more accurate
  • count the number of daisys in quadrats
  • calculate mean
  • estimate population size = sampled area/ total area x number of organisms
• quadrats= T-test, statistical test, measure differences in means

  transects= spearman's rank, look at correlation
• Biodiversity- the variety of living organisms in an area
• stable community- all species and environmental factors are balanced so populations size remains constant. Drastic change in the number of organisms can largely impact unstable communities
• genetic diversity- variety of genes that make up an organisms

  -take into account the different alleles

  -greater genetic biodiversity, more likely to survive and reproduce
• species richness- number of different species living in an area

  -measured with transect

  -takes no account of number of individuals of each species present
• index of diversity- takes into account species richness and abundance

  -higher index of diversity more diverse an area

  -compare biodiversity of two habitats and link it to a factor
• Human impact on biodiversity

  • deforestation- remove habitat and food sources
  • hedgerow removal- increase farmland area, hedges source of pests and weeds- decrease yield
  • pesticides- kill insects so increase yield
  • herbicides- spray unwanted plants which could compete with crops
  • monocultures- reduce biodiversity
• species- a group of organisms with similar features that can successfully breed together to produce fertile offsprings
• species diversity- number of different species in a community
• economic argument for maintaining biodiversity

  • tourism
  • medicine
  • agriculture
• index of diversity rather than record number of species present

  • measure number of individual species
  • and the number of species
  • some species are only present in small numbers
• standard deviation

  • tell you the variation of values in a sample about the mean
  • low S.D = little variation
  • high S.D = lots of variation
• random sampling

  • use random number generator to get grid coordinates to place quadrats
  • use 10-20 quadrats
  • count all species in each quadrat
• standard deviation

  • no overlap of standard deviation
  • so there is a significant difference between species
  • therefore it is not due to chance
• T-test

  • look at differences between measurements of the same variable from different samples
  • random sampling
  • degrees of freedom = (n1 + n2) - 2
  • t value less/ greater than critical value, then there's 5% probability that means are/ not due to chance. We accept/ reject null hypothesis
• Spearman's rank correlation

  • see strength of correlation between 2 sets of data
  • transect
  • degrees of freedom = n
  • if calculated number is same or higher than critical value then correlation is significant and reject null hypothesis
• Chi-Squared Test

  • compare observed results with theoretical expected results
  • degrees of freedom = (n-1)
  • value greater/ less than critical value at 0.005 level then accept/ reject null hypothesis