10.1 - Species and taxonomy Flashcards
what is classification
- The organisation of living organisms into groups
- it IS NOT a random process, but based on a number of accepted principles
what is a species
basic unit of classification
what do members of a single species all have in common
- they are capable of breeding to produce living, fertile offspring
–> therefore when a species reproduces sexually, any of the genes of its individuals can, in theory, be combined with any other
who came up with the binomial system
Swedish botanist Linnaeus
describe how animals are identified with the binomial system
Given 2 names
describe the 2 names given in the binomial system
- it’s a universal system based on Latin/Greek names
- the first name (generic name), denotes the genus which the organism belongs.
- the second name (specific name), denotes the species which and organism belongs. It is never shared by other species within the genus.
describe the rules for the binomial system
- the names are printed in italics, but if they’re handwritten = underlined. This is to indicate that they’re scientific names
- the fist letter of the generic name is upper case, but the first letter of the specific name is lower case
- if the specific name is unkown, you can just write ‘sp’, e.g ‘Felix sp.’
Because members of the same species have the same genes, what does this mean?
- resemble each other physically and biochemically
- this is the same for their behaviour, which has evolved along with their own genes
- this evolved behaviour is courtship and helps with ensuring mating
how does courtship behaviour help to achieve reproduction
enables individuals to:
- recognise members of their own species (ensures that mating only occurs with members of the same species, so that offspring are fertile)
- 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)
- become able to breed (by bringing a member of the opposite sex into a physiological state that allows breeding to occur)
describe courtship behaviour for females
- they undergo a cycle of sexual activity in which they can only conceive during a very short time
- they are only receptive to mating for a period around the time when they produce eggs
describe courtship behaviour for males
- used to determine whether the female is at a receptive stage
- if she responds with the appropriate behavioural response, courtship continues and is likely to result in the production of offspring
- is she isn’t receptive, she exhibits a different pattern of behaviour and the male ceases to court her, turning his attention elsewhere.
how are members of the same species able to recognise each other for courtship
- animals use signals to communicate with a potential mate and with members of their own sex
- typically there is a chain of actions between male and female
- this chain of actions is the same for all members of the same species. And therefore varies between species
- this allows individuals to recognise if their partner is of the same species or not
what is classification
the grouping of organisms
what is taxonomy
the theory and practise of biological classification
what are the 2 main forms of classification
- artificial classification
- phylogenetic classification
what is artificial classification
- it divides organisms according to differences that are useful at the time
- such features may include: colour, size, no. of legs, leaf shape, etc
- these are described as analogous characteristics where they have the same function but don’t have the same evolutionary origins (e.g. wings on butterflies and birds)
what is phylogenetic classification
- is based upon the evolutionary relationships between organisms and their ancestors
-classifies species into groups using shared features derived from their ancestors - Arranges the groups into a hierarchy, in which the groups are contained within larger composite groups with no overlap
what are relationships in a phylogenetic classification based on
- homologous characteristics
- HCs have similar evolutionary origins regardless of their functions in the adult of a species
what is each group within a phylogenetic biological classification called
taxon (plural: taxa)
what is taxonomy
- the study of taxa and their position in a hierarchical order, where they are known as taxonomic ranks
- these are based upon the evolutionary line of descent of the group members
what is the highest taxonomic rank (what is this rank made up of)
- Domain (made up of 3)
1) Bacteria
2) Archaea
3) Eukarya
what are bacteria
group of single-celled prokaryotes
what are the features of bacteria
- the absence of membrane-bounded organelles such as nuclei or mitochondria
- unicellular, although cells may occur in chains or clusters
- ribosomes are smaller (70S) than in eukaryotic cells
- cell walls are present and made of murein (never chitin or cellulose)
- single loop of naked DNA made up of nucleic acids but no histones
what are Archaea
a group of single-celled prokaryotes that were originally classified as bacteria which they resemble in appearance
what are the features of Archaea that makes them differ from bacteria
- their genes and protein synthesis are more similar to eukaryotes (they contain introns)
- their membranes contain fatty acid chains attached to glycerol by ether linkages
- there is no murein in their cell walls
- they have a more complex form of RNA polymerase (to deal with the introns)
what are Eukarya
a group of organisms made up of 1 or more eukaryotic cells
what are the features of Eukarya
- their cells possess membrane-bound organelles such as mitochondria and chloroplasts
- they have membranes containing fatty acid chains attached to glycerol by ester linkages
- not all possess cells with a cell wall, but where they do it contains no murein
- ribosomes are larger (80S) than in bacteria and archaea
what are the 4 kingdoms that the Eukarya domain is divided into
- Protoctista
- Fungi
- Plantae
- Animalia
what are the different taxonomic ranks
- Domain
- Kingdom
- phylum
- class
- order
- family
- genus
- species
what is the phylogeny of an organism
it reflects the evolutionary branch that led up to it (its evolutionary line of descent)
how is the phylogenetic relationships of different species usually represented
- a tree-like diagram called:
- a phylogenetic tree
- in these diagrams: the oldest species is at the base of the tree, and the most recent ones are represented by the ends of the branches
why might there be difficulty in defining a species
- species are not fixed, but change and evolve over time. In time, some individuals may develop into a new species
- within a species there can be considerable variation among individuals. All dogs, for example, belong to the same species, but artificial selection has led to a variety of different breeds
- Many species are extinct and most of these have left no fossil record
- some species rarely, if ever, produce sexually
- members of different populations of the same species may be isolated, e.g. oceans, so never got the chance to meet and therefore never got the chance to interbreed
- some types of organism are sterile
