BIODIVERSITY

SPECIES: group of rganisms with similar characteristics capable of breeding to produce living, fertile offspring

COURTSHIP BEHAVIOUR

behaviour of species that allows them to...

• recognise members of own species
• identify a mate capable of breeding (sexual maturity)
• form a pair born
• synchronise mating (through fertility cycles)
• become able to breed (physiological state for mating)

CLASSIFICATION: the grouping of organisms

ARTIFICIAL CLASSIFICATION.

• classifies organisms based on characteristics that are useful at the time
• ANALOGOUS characteristics - same function but different evolutionary origins

PHYLOGENETIC CLASSIFICATION.

• classifies organisms based on shared features derived from ancestors (HOMOLOGOUS characteristics - similar evolutionary origins regardless of function)
• arranges groups into hierarchy with small groups contained within larger composite ones with no overlap

PHYLOGENY.

• evolutionary relationship between organisms 
• phylogenetic tree - shows different common ancestors of organisms

TAXONOMY.

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

DOMAINS.

• BACTERIA - lack membrane bound organelles, unicellular, 70S ribosomes, murein cell walls, single loop of DNA with no proteins
• ARCHAEA - more eukaryotic DNA, membranes of fatty acids + glycerol, no murein in cell walls, complex RNA polymerase
• EUKARYA - membrane bound organelles, membranes containing fatty acids + glycerol, where cell walls are present there is no murein, 80S ribosomes

SPECIES DIVERSITY: number of different species AND number of individuals 

GENETIC DIVERSITY: variety of different alleles making up a population of a species

ECOSYSTEM DIVERSITY: range of different habitats present in a location

SPECIES RICHNESS: number of different species in a particular area at a given time

INDEX OF DIVERSITY.

d = N(N-1) / En(n-1)

N = total number of organisms

n = number of organisms of each species

higher the index, higher the diversity.

AGRICULTURE.

• farmers select for particular characteristics, reducing the number of alleles a species posesses
• economic value means number of individuals of one species needs to be large
• area can only support so much biomass
• large area supports one species = not much area for other species, creates competition that reduces species richness
• pesticides exclude species as they compete for light, ions, water + food
• overall, species diversity is reduced

SPECIFIC PRACTICES.

• removal of hedgerows
• creating monocultures - replacing natural medows with cereal crops or grass for sileage
• filling in ponds, draining marsh + wetland
• overgrazing of land, preventing regenerated of woodland
• use of pesticides + inorganic fertisilers
• leakage of silage + slurry into water sources
• absence of crop rotation, lack of intercropping

CONSERVATION TECHNIQUES.

• maintain existing hedgerows
• use hedges to separate fields, not fences
• maintain existing ponds, create new ones
• reduce use of pesticides
• use organic fertilisers
• use crop-rotation with nitrogen-fixing crop to improve soil fertility
• create natural meadows and use hay for silage
• use intercropping instead of herbicides to control weeds - multiple crops in close proximity

OBSERVABLE CHARACTERISTICS.

• each observable characteristic determined by genes
• BUT characteristics coded for by multipel different genes + characteristics modified by environment

DNA BASE SEQUENCES.

• similar species have similar DNA as new species arise from genetic mutations
• can also compare base sequences of mRNA as this is coded for by DNA
• can also compare amino acids as these are coded for by DNA (HOWEVER code is degenerate so this is less accurate)

IMMUNOLOGY.

• serum from A + serum from B, species B produces antibodies specific to antigens from species A
• serum from species B containing antibodies injected into species C
• precipitate forms - more precipitate = more complexes = more similar antigens = more closely related

RANDOM SAMPLING.

• sampling bias - selection process is affected by investigators' choices
• chance - even random sample may be unrepresentative

method...

divide area into grid, use random numbers to obtain coordinates, take samples at intersections of coordinates.

• use large sample size - reduces effect of anomalous extremes on overall result
• analyse results through statistical testing to ensure results have not occurred due to chance