[10.1] species and taxonomy Flashcards
what is phylogeny?
the study of the evolutionary history of groups of organisms
what does a phyogenetic tree show? (draw one!)
- how closely related organisms are
- ‘divergence points’ (branch points) which are common ancestors that organisms came from, which are now extinct
- also shows when organisms diverged eg. reptiles and birds diverged before mammals
how can you use DNA evidence to calculate the time of divergence?
- some genes or protein sequences accumulate mutations at a relatively constant rate (eg. 1% per million years)
- scientists can use this to calculate the time of divergence
- this is called the molecular clock
which is the use of DNA evidence to calculate the time of divergence limited?
- rate of change can differ between groups of organisms
- rate of change can vary between different genes and proteins
- over long periods of time, earlier changes may be reversed by later changes
what is taxonomy?
the process of classifying organisms into smaller and smaller groups based on homologous features (shared characteristics) or molecular information
what is a hierarchy?
a structure which places smaller groups within larger groups with no overlap between groups
what is the binomial system?
- all organisms are given on internationally accepted scientific name
- generic name: denotes which genus organism belongs to
- specific name: denotes which species organism belongs to
- printed in italics, underlined if handwritten
- 1st letter of generic name is uppercase, rest is lowercase
what are the taxonomic ranks in the classification system?
- domain
- phylum
- class
- order
- family
- genus
- species
the further down the classification system you go the smaller the groups and the more evolutionarily similar they are
archaea
- unicellular
- cell wall without peptidoglycan
- no nucleus
- no membrane-bound organelles
- not sensitive to antibiotics that affect bacteria but are sensitive to antibiotics that affect eukarya
bacteria
- unicellular
- cell wall with peptidoglycan
- no nucleus
- no membrane-bound organelles
- sensitive to antibacterial antibiotics, resistant to most antibiotics that affect eukarya
eukarya
- multicellular
- plant and fungi have cell wall, animals do not
- have membrane-bound nucleus
- have membrane-bound organelles
- resistant to traditional antibiotics but sensitive to antibiotics that affect eukaryotic cells
what is courtship behaviour?
- members of the same species need to mate with other members of the same species
- they have evolved to develop species specific courtship behaviour that are a sign stimulus that attracts a mate only of the same species to breed with
- we can observe these courtship behaviours and use them to classify animals into species
- species with closely related courtship behaviour are more closely related
what does courtship behaviour allow individuals to do?
- recognise members of their own species so mating only takes place between members of the same species
- identify a mate that is capable of breeding because both partners need to be sexually mature, fertile and receptive to mating
- form a pair bond that will lead to successful mating and raising of offspring
- synchronise mating so that it takes place when there is the maximum probability of the sperm and egg meeting
- become able to breed by bringing a member of the opposite sex into a physiological state that allows breeding to occur
- determine whether female is at receptive stage, around the time when they produce eggs
what are the 2 types of biological classifications?
- artificial classification
- phylogenetic classification
what is artificial classification
- divides organisms in way that is useful at the time
> eg. colour, size, number of legs, leaf shape etc. - these are described as analogous characteristics where they have the same function but do not have the same evolutionary origins
eg. wings of butterflies and birds are both used for flight but originated in different ways
