Species and taxonomy Flashcards
Define species
A group of organisms with similar characteristics that can interbreed to produce fertile offspring
How are organisms identified (named)?
Through the binomial system.
First name = Genus (must be capital letter)
Second name = species (must be lowercase)
What is courtship behaviour?
The behaviour of members of the same species is more alike than that of members of a different species - this allows individuals to recognise members of their species by the way they act, leading to mating and reproduction
Genetically determined and will evolve over time to increase chances of survival.
Why is courtship behaviour important?
- species recognition
- mating compatibility
- pair bond formation
- synchronised mating
What is the importance of species recognition?
ensures that mating can only take place between members of the same species, so fertile offspring will be produced
What is the importance of mating compatibility?
Differences in size/shape may make mating physically impossible
What is the importance of pair bond formation?
Gives offspring the best possible chance of survival, will lead to successful mating and raising of offspring
What is the importance of synchronised mating?
Females will only be receptive to courtship behaviour when they are fertile, which allows the male to determine whether breeding will occur or not
What is the stimulus-response chain of courtship behaviour?
Stimulus - the male will carry out an action which acts as a stimulus to the female
Response - the female will respond with an action of her own. This acts as a stimulus to the male to carry out a further action
Chain - this generates a chain of stimuli and responses. Chains are the same for members of the same species, so both individuals can identify if they are from the same species and that they are ready to mate
The longer the courtship sequence, the more likely that mating will result. An inappropriate response will end the chain
If the female does not exhibit typical courtship behaviour, what does this suggest?
- not fertile
- from a different species
What is artificial classification?
Divides organisms according to differences that are useful at the time eg. colour, size, number of legs etc.
Described as analogous characteristics (same function but different evolutionary origins) eg. wings that originated in different ways
What is phylogenetic classification?
- based upon evolutionary relationships between organisms and their ancestors
What is a domain?
The highest taxonomic rank
What are the three recognised domains?
- bacteria
- archaea
- eukarya
What is the order of taxonomic ranks?
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
(dear king philip came over for good soup)
What do phylogenetic trees show?
The oldest species (common ancestor) is found at the base of the tree
The most recent species are represented by the ends of branches
The closer the branches, the closer the evolutionary relationship between species
What is species diversity?
the number of different species and number of individuals of each species within a community
What is species richness?
the number of different species within a community at a given time
How do you calculate index of diversity?
d= N(N-1)/En(n-1)
d = index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
E = sum of
Why is it difficult for biologists to take measurements?
- living things may be motile so difficult to count
- multiple control factors to consider
- difficult to measure every single organism of a species so samples need to be taken
Why might samples not be completely representative?
- can’t represent all factors at once
- sampling bias
- chance (individuals may not be representative by chance)
What are the stages of random sampling eg. in a field of daisies?
- place 2 tape measures perpendicular to each other to create an axis
- use a random number generator to generate random coordinates to avoid bias
- place down a quadrat and count the number of daisies
- repeat at least 20 times - needs a large sample size to be more representative
- find a mean and multiply by area of field
How would you measure to see if the number of daisies in 2 fields is significantly different?
Use 2 standard deviations for 95% certainty. If the ranges overlap then they are not significantly different
How can you measure motile organisms?
using traps - use a large number of traps for a more representative sample
How can we reduce the effects of chance?
- large sample size (lots of quadrats and find a mean)
- use statistical tests to analyse the data
What is a community?
all the organisms of all species in a particular habitat
What is a population?
all the organisms of one species in a habitat
What is an ecosystem?
the interaction of living organisms and their environment
How can species diversity be reduced?
- deforestation
- monoculture (growing only one type of crop)
- removal of hedgerows
- road building
- use of agrochemicals
How can diversity be investigated?
- observable characteristics
- comparison of DNA base sequences
- comparison of mRNA base sequences
- comparison of amino acid sequences
How can diversity be investigated through observable characteristics?
- each characteristic is determined by genes
- variety within characteristics depends on the variety of alleles within a gene
- difficult because characteristics can also be determined by environmental factors
How can diversity be investigated through DNA base sequences?
- the more similar the base sequence of DNA, the more closely related the species
How can diversity be investigated through mRNA base sequence?
- the more similar the base sequence of mRNA, the more closely related the species
How can diversity be investigated through comparison of amino acid sequences?
- the amino acid sequence is what codes for DNA base sequence
- therefore the more similar the sequence of amino acids, the more closely related the species
What is interspecific variation?
one species differing from another species
What is intraspecific variation?
members of the same species differing from one another
What is a normal distribution curve?
The mean, mode and median all have the same values
What is hierarchal classification?
- groups within groups
- no overlap between groups
- each group is called a taxon
