Definition of phylogenetic classification
Grouping organisms together to reflect evolutionary history, closely related organisms grouped together. Groups have a more recent common ancestor so will share physical properties
Phylogenetic tree
Branch points represent common ancestors of organisms in branches above
Taxa are..
Levels of classification
Classification order
Domain Kingdom Phylum Class Order Family Genus Species
Largest taxon?
Domain
3 types of Domain
Eubacteria
Archaea
Eukaryota
Eubacteria
Prokaryotes, familiar bacteria like e.coli and salmonella
Archaea
Prokaryotes, bacteria with unusual metabolisms, ‘extremophiles’
Eukaryota
Eukaryotes like plantae, fungi, animalia, protoctista
5 types of Kingdom
Prokaryota Protoctista Animalia Plantae Fungi
Prokaryota
Bacteria/Cyanobacteria, microscopic, single called organisms with no membrane bound organelles , prokaryotes with murein/peptidoglycan cell walls
Protoctista
Eukaryotes, unicellular, can be multicellular but with no tissue differentiation e.g amoeba, algae, slime moulds
Fungi
Eukaryotes with chitin cell walls, heterotrophic, reproduce using spores
Plantae
Autotrophic, multicellular eukaryotes with cellulose cell walls, photosynthetic (e.g chloroplasts contain chlorophyll)
Animalia
Heterotrophic, multicellular eukaryotes with no cell walls, nervous coordination
Autotrophic
Take simple inorganic molecules and convert into complex organic molecules to use as an energy source
Heterotrophic
Require ready made complex organic molecules to use as food/energy source
Homologous structures
Similar arrangement of component parts and similar developmental structure but different functions
(Same basic structure, different function)
Shows existence of common ancestry
Analogous structures
Corresponding function but different developmental origin
(Same function, different structure)
Shows no evidence for common ancestor
Convergent evolution
Unrelated species evolve similar features to overcome similar problems
DNA base sequences
Evolution, DNA base sequence changes in species, considered a different species, closely related species have similar DNA base sequences
DNA hybridisation
DNA extracted and cut into fragments
Fragments from 2 species mixed, where there are complimentary base pairs they hybridise together
Heat to 95 (hydrogen bonds break)
Combine strands
Cool down and hybrid DNA forms
Heat up, will break at less than 95 as fewer hydrogen bonds to break (DNA strands won’t have identical base sequences)
Amino acid sequence
Determined by DNA base sequence
Similarity of proteins shows how closely related they are
Can produce evolutionary tree
Count amount of amino acid sequences in common, most in common=most closely related so have most common ancestor
Immunology
Antigens of one species mix with antibodies of another forming a precipitate
More they react, more precipitate made, more closely related
Species definition (reproductive definition)
Organisms are in same species if they can interbreed and produce fertile offspring
Taxonomy definition and what it allows
Identification & naming of organism allows description and discovery of biodiversity, investigate evolutionary relationships and classifications to reflect them
Why is binomial system used?
Latin = universal language
2 names= Genus species [must be underlined] (name is unique and specific)
Biodiversity
Number of species and number of individuals of each species in a given area
Simpsons index of biodiversity
S = 1 - sigma n(n-1) divided by N(N-1)
n = number of individuals N = number of organisms sampled
‘Gene pool’
All genes and alleles present in a population
Polymorphism
Many different phenotype a in population e.g blood types
98% alleles recessive compared to 50% recessive
Lower biodiversity in 98%
Evolution
Process by which new species formed from pre existing species over long periods of time
Natural selection stages
Mutation Variation Competitive advantage Survival of the fittest Reproduction Pass advantageous gene to offspring
Who has different opinion to missing links and creation?
Eldridge and Gould
Anatomical traits
E.g. Sharks, Dolphins, penguins have streamlined bodies to catch food/ escape predators
Some plants have nectar/honey guides on flowers to attract more pollinators
Physiological traits
Mammals and birds endothermic
Polar bears however reset body temp hibernating so as not to waste energy
Leaves fall off in autumn to reduce water loss
Behavioural traits
Plants flower in spring when pollinating insects emerge
Mating rituals
