Biology - classification and biodiversity Flashcards
(revise biology)
Phylogenic classification is …
grouping closely related organisms together
Close together is …
sharing a common ancestor
Closely related is …
show physical similarities
Classification is …
putting things into groups
Phylogenic is …
reflecting evolutionary relatedness (showing how organisms are related to each other through common ancestors)
Phylogenic tree is …
picture of how organisms are related to their common ancestor, that is related to it’s common ancestor, that is related to its common ancestor all the way back to LUCA
Phylogenic tree is also ….
a diagram showing descent with living organisms at the tips of the tree and ancestral species in the branches and trunk with branch points representing common ancestors. The lengths of the branches indicate the time between branch points.
Phylogenic tree is also also …..
traversing from the tips of the tree (the species that are alive now) down the tree through the ancestors is also going back in time
LUCA
last universal common ancestor. This is the organism at the root of the phylogenic tree, it’s the ancestor of EVERYTHING
Natural classification
grouping organisms based on common ancestors
Artificial classification
grouping organisms not by common ancestor but, for example, by colour, or by number of legs etc.
Hierarchy
a system of ranking in which small groups are nested components of large groups e.g. small groups such as cats and dogs come under the larger group of “mammal” which itself comes under the larger group “chordate” which itself comes under the large group called “animal”
Taxon (plural taxa)
any group within a system of classification i.e. when classifying animals “cats” is a taxon as is “dogs” as is “mammal” as is “chordate” as is “animal”
THE HIERARCHY OF BIOLOGICAL CLASSIFICATION
DOMAIN > KINGDOM > PHYLUM > CLASS > ORDER > FAMILY > GENUS > SPECIES
(Do Kings Put Clay Oranges For Green Spaniards)
Example of biological classification
Domain - Eukaryota,
Kingdom - Animalia,
Phylum - Chordata,
Class - mammalia,
Order - Primates,
Family - Hominidae,
Genus - Homo,
Species - Sapiens
Taxa are discrete
a thing can only be in one Taxon
Classification, why?
it’s part of human psychology
Classification, why?
phylogenetic classification allows us to infer evolutionary relationships
Classification, why?
can predict features of new species from characteristics of the new species that are found in members of an existing taxon. I.e. if we find a new animal with a beak and feathers we may group it as a bird and therefore infer other characteristics that belong to birds
Classification, why?
easy to communicate with group names rather than having to use the description of members of the group i.e. easier to say “bird” than “vertebrated eff laying biped with a beak and feathers’
Classification, why?
when describing the health of an ecosystem or he rate of extinction in the geological record, conservationists often find it more useful to count families than species (i.e over long periods of time it’s easier to count the bigger groups of things than the smaller groups of things)
Tentative nature
we can only classify what we know, the system of classification can therefore change if we discover new organisms that don’t fit into current groups, making us add new groups
Three domain system
domain is the largest biological grouping, everything fits into three domains, they are Eubacteria, Archaea, Eukaryota
Domain of Eubacteria
bacteria such as E.coli, they are prokaryotes
Doman of Archaea
bacteria that often have unusual metabolism, e.g. generate methane or live in extreme conditions
Doman of Eukaryota
Plantae, Animalia, Fungi and Protoctista
Five kingdoms
underneath Domains are five kingdoms, they are Prokaryota, Protoctista, Fungi, Plantae, Animalia
Domains of Eubacteria and Archaea kingdom is …
Prokaryota
Domain of Eukaryota kingdoms are …
Prokaryota, Protoctista, Fungi, Plantae and Animalia
A Phylem is ..
subgroup of Kingdom, each member has a distinct body plan
A Class is …
subgroup of Phylem i.e. mammalia are a class with the phylum Chordata
An Order is …
subgroup of class e.g. lepidopera is an order containing butterflies in the class Insecta
A Family is …
subgroup of order e.g. flower family Rosaceae contains roses
A Species is …
subgroup of family, they share a large number of physical features and can interbreed to make fertile offspring.
Genus
a group (taxon) containing organisms whith many similarities but enough differences that they cannot interbreed to produce fertile offspring i.e.lions and tigers, both are similar but if they breed the offspring (tigon or liger) aren’t fertile
Prokaryota (description of members)
no membrane bound organelles, microscopic
Protoctista (description of members)
single cells or all similar celsl animal or plant-like
Plants (description of members)
Autotrophs containing chlorophyll, cellulose cell walls.
ferns, mosses, horsetails have spores, everything else has seeds
Fungi (description of members)
saprotophs, chitin cell walls, hyphae
Animals (description of members)
heterotrophs, no cell walls, nervious co-ordination
Homologous structures
Structures in different species with a similar anatomical position and developmental origin derived from a common ancestor
Pentadactyl
Having five digits
Divergent evolution
the development of different structures over long periods of time from the equivalent structures in related organisms
What does the theory of evolution suggest?
That organisms evolve from a common ancestor, we share common ancestors
How do you tell how closely two organisms are related?
By looking for homologous structures
How can you assess how related organisms are?
By their physical features and with genetic evidence
Convergent evolution
The development of similar features in unrelated organisms over long periods of time
Analogous structures
structures with a corresponding function and similar shape but have a different developmental origin
Just because things have the same features doesn’t mean they are related -
For example a bat, a butterfly and a sparrow all have wings but one is a mammal, one and insect and one a bird. This shows convergent evolution i.e. they all evolved wings but they’re not related organisms
Generic evidence for relatedness
can use DNA sequences, DNA hybridisation, Amino acid sequences, Immunology
DNA sequences
as organisms evolve their base DNA changes. The more similar your base DNA is to another species means you’re more closely related to them. DNA analysis has been used to correct mistakes made in classification of some organisms that were originally based on physical characteristics
DNA hybridisation
compare the DNA base sequence of two species. Seperate the DNA into single strands and cut the strands into fragments.Mix the fragments from the two species together.
When the two species are closely related the DNA fragments hybridize together. The higher the percentage of hybridization the more closely related the two species are.
Amino acid sequences
amino acid sequences in proteins are determined by the DNA base sequence. If the amino acids of one species are similar to another species it means it’s more closely related.
Immunology
if you mix the antigens of one species with antibodies of another the antigens and antibodies coagulate. The closer the species are related the more they coagulate.
Species - morphological definition
if two species look the same they’re likely to be the same species. The sex of the organism may cause some differences i.e. male lions have a mane, this should be taken into account
Species - reproductive definition
same species can interbreed and produce fertile offspring. Different species may interbreed but their offspring are not fertile.
Taxonomy is
the identification and naming of organisms
Taxonomy allows you to…
discover and describe biological diversity
investigate evolutionary relationships between organisms
classify organisms to reflect ehri evolutionary relationships
Binomial system
the system for naming organisms that gives them two names so that:
naming is unambiguous
based on latin (which was scholarly and used around the world when this was all made up in 1753)
implies that two species sharing part of the name are closely related eg Panthera leo and Panthera tigris show that the tiger and lion are closely related but two different species
Using the binomial system
The two names are the genus and it’s species
Genus is first and has a captial letter
Species is second and does not have a capital letter
The first time a name is used in a scientific text it’s written in full, after that it may be abbreviated
Both names are printed in italics or underlined if hand-written
Biodiversity is …
the number of species in an environment (species richness)
The number of organisms within each species in an environment (species evenness)
Biodiversity is ….
not constant
Spatial variation
biodiversity depends on environment. Biodiversity hotspots occur around the equator and tropics because light is high intensity which means more plants, which means more herbivores which means more carnivores. Also it’s warmer which means more energy which means more of everything as well
Biodiveristy can increase or decrease because of ….
Succession. Organisms change their habitat which makes it more suitable for them and other species. This change is called “succession”. It increases animal biodiversity but decreases plant biodiversity
Biodiveristy can increase or decrease because of ….
Natural selection … it just does, ok
Biodiveristy can increase or decrease because of ….
Human influence. Human activity affects habitats usually decreasing biodiversity and often leading to extinction of species.
e.g.
Logging and road building in tropical rain forests
Over fishing the oceans
Misuse of land leading to desertification
Polution of rivers with chemicals
Humans can improve biodiversity but this only usually happens as a by product of humans wanting something for themselves. i.e. when the Thames was so poluted with sewage in 1858 people built sewers because they couldn’t stand the smell. This had the effect of also increasing the biodiversity of the river as it was cleaned up but the people didn’t directly clean the river to save species, they did it because they didn’t like the smell.
Reduced biodiversity means …
less food types to eat
less plants and fungi to make new medicines from
less organisms to produce important raw materials i.e. rubber, cotton
Humans are ….
the biggest threat to biodiversity.
As we decrease biodiveristy we reduce sources of new foods and sources of characteristics to help with crops, medicine, building/making stuff.
Assessing biodiversity at the population level
is done using a biodiversity index
A biodiversity index is …
some way of meansuring the biodiversity in an environment
An example biodiversity index is …
Simpsons Diversity Index which meansures the biodiversity of motile organisms such as invertibrates in a stream
Simpsons Diversity Index formula is …
D (diversit index) = 1 - sum of n (n-1) / N (N-1)
so D equals ONE minus the sum of the number of species multiplied by the number of species minus one divided by the number of organisms multiplied by the number of organisms minus one
where:
n = number of species
N = number of organisms
Assess biodiversity at the generic level using polymorphic loci
examine the genes and alleles in the gene pool of a population.
A genes position on a chromosome is called its locus
A locus is polymorphic if it has two or more alleles
A gene has more biodiversity if it has more alleles
Molecular assessment of biodiversity using DNA fingerprinting
Organisms that are related have DNA base sequences that are more similar
DNA does not all code for protein
Non-coding sequences undergo mutation and individuals get different base sequences
Sometimes only one base differents, these single differences are called SPNs (snips) which stands for single nucleotide polymorphisms
Other regions of DNA, about 20-40 base sequences that repeat many times. These are HVR (hyper variable regions) or STRs (short tandem sequeces)
You can see these differences in DNA fingerprints (also called genetic fingerprints, genetic profiles or DNA profiles).
You can compare the number and position of the bands in DNA profiles to see how similar the DNA sequences are. The more similar, the more related.
The more differences in SNPs and HVRs means an increase in biodiversity.
In a biodiverse population there is a lot of differences between the DNA fingerprints
Natural selection and biodiversity
mutations cause differences providing the raw material for natural selection
mutation causes differences in DNA
this causes variation which can be seen in different physical appearence or biochemical function or behaviour
some mutations give a competative advantage
those with an advantage survive better
They reproduce more and pass the advantagous allells to their offspring
more variation means a more biodiverse environment
Natural selection can. ….
reduce biodiversity.
If a preditor evolves and is super good at killing things it kills all the things and reduces the biodiversity
Natural selection can …
increase biodiversity.
As environments change organisms evolve to cope with the new environment. This often means you have organisms that coped well with the old environment, organsims that cope well with the new environment and organisms inbetween giving you a biodiverse set of organisms in the environment
Adaptation is …
the change in a species as a useful characteristic becomes more common
An Adaptive Trait is …
a useful characteristic that lets an organism have an advantage in it’s environment that it didn’t have before. i.e. the organism adapts to its environment
Adaptive traits can be …
Anatomical
The physical form of the organism adapts to gain an advantage
Adaptive traits can be …
Phsyiological
e.g. hibernating hedgehogs lower their body temperature to expend less energy during hibernation
leaves fall off trees so that they don’t lose moisture by transpiration
Adaptive traits can be …
Behavioural
plants flower in spring when there are lots of insects about to do the pollination
Extravigant mating rituals (peacock tails and flamingo dances) increase the changes of reproducing
