Classification and biodiversity Flashcards
Phylogenetic
refelcting evolutionary relatedness
Phylogenetic tree
Diagram showing evolutionary descet wiht living orgaisms at the tip of the branches ancestral species in the branches and trunk and branch points representing common ancestors
What is the phylogenetic method
- Bilogists use a method that reflects an organism’s revolutionary history
- grouping closely related organisms togehter
What do organisms in the same group in the phylogenetic method have in common
- organisms in same group have more recent common ancestor with each other than with organisms not in their group
- if there closely related they may show physical similarities
Taxonomy
The identification and naming of organisms
Classification
Putting items into groups
Hierarchy
A system of ranking in which small group are nested componenets of larger groups
What is a taxon
Any group within a system of classification
what can you see with small groups that are contained within bigger groups
- members of each group are more similar to each other than to members of other groups.
What is a hierarchical system
- syste in which smaller groups are componenets of larger groups
- has been devised for living organisms
- each grouping in the system is a taxon (plural = taxa)
- Bigger taxa contain smaller taxa
- Within each taxon organisms are more similar to each other and more closely related than to organisms outside the taxon
Wha is the hierarchy of biological classification
- domain
- kingdon
- phylum
- class
- order
- family
- genus
- species
What happens as you move down the hierarchy
- from domain to species organisms in a taxon are more closely related
- moving up hierarchy from specides to domain members of a taxon are less closely related
What are taxa
- taxa are discrete at any level of classification and organism belongs in one taxon and in no other
- discrete is individually seperate and distinct
Why do we need a classification system
- a phylogenetic classification system allows us to infer evolutionary relationships. If two organisms are so similar that we put them in the same taxon, we infer that they are closely related
- if a new animal is discovered with a beak and feathers we predict ome of its other characterisistics based on our general understanding of birds
- when we communicate it is wuicker to same bird than to say the full name
- when describing the helathy of an ecoystem or the rate of extinction in the geological record, conservation soften find it more useful to count families than species
What is a problem with the classification systen
- it is tentative
- clasification depends on our current knowledge
What is the three domain system
- it’s the largest taxon and all living things belong in one of three domains
- domain were originally defined on the basis of rRNA base sequences
- more modern methods of analysis also conider similariies in the DNA sequence
What are the three different domains
- eubascteria: these are the familiar bacteria such as e coli and salmonella they’re prokaryotes
- archar: thee are bacteria and often have unusual metabolism for example some generate methane and live in marginal habitat and are also prokaryotes
- eukaryota: plantae, animalia, fungi and protoctista
Wha is the five kindom system
classifies organisms on the basis of their physical appearance
What are the five different kingdoms
- all bacterua eubacteria and archae are in one kindom the prokaryota and the other four kindoms conain eukaryote organisms
What is a phylum
- Is a sub group kindom
- member of each phylum have a distinct body plan
- eg members of the phylim annelida are soft bodiesd and segmented members of the arthropoad jave chitinious exosskeleton and jointed limbs the phylum chordata contains vertebrates
What is a class
- is a subgroup of a phylum eg mammalia form a class within the phylum chordata insecta are a class within the phylum rthropoda
What is a species
- is a group of organisms sharing a large number of physical features and able to interbreed to make fertile offspring
What are prokaryota (prokaryotes)
- prokaryote are microscopic
- this kingsom contains all the bacteria and cyanobacteria
What are protoctista (protoctists)
- some have only one cell and these are major component of planktom others are colonia
- some have many similarcells like seaweeds and algae
What are fungi
- yeasts are single celled
- moulds such as penicllium and mushrooms uch as amanita musscaria have hyphae which weave together to form the body of the fungus a mycelium
- in some cross cell wall called septa sub divide the hyphae
What are plantae (plants)
- mosses, horsetails,and ferns reproduce with spores
- conifers and flowering plants which reproduce with seeds
Describe prokaryota
- organisation - prokaryotic and single celled
- no nucleus
- have a mesosome
- they are photosynthetic and have llamalae in some
- 70s ribsomoes
- no ER
- no vacuole
- peptidoglycan cell wall
- nutrition - saprotrophic, parasitic and autotrophic
- no nervous coordination
Describe protoctista
- Eukaryotic
- single celled or multicellular
- have a nucleus
- have mitochondria
- some contain chloroplast
- 80s ribsomes in cytoplasm
- have endoplasmic reticulum
- some contain a vacuole
- some contain a cellulose cell wall
- some contain no cells walls
- some autotrophic
- some are hetrotrophic
- no nervous coordination
Describe planta
- Eukaryotic
- multicellular
- contain a nucleus
- contain mitochondria
- contain chloroplasts
- contain 80 s ribosomes in cytoplasm
- have an endoplamsic reticiculum
- large central permanent vacuole
- celluloe cell wall
- autotrophic
- no nervous co ordination
Describe fungi
- Eukaryotic
- single celled or hyphal
- contain a nucleus
- contain mitochondria
- contain no chloroplasts
- contain 80s ribosomes in cytoplasm
- contain endoplasmic reticulum
- contain large central permanent vacuole
- chitin cell wall
- saprotrophic or parasititc
- no nervous co ordination
Describe animalia
- Euakryotic
- multicellular
- contain a nucleus
- contain mitochondira
- contain no chloroplast
- contain 80s ribsomes in cytoplasm
- contain endoplasmic reticulum
- contain small scattered temporary vacoules
- no cell wall
- heterotrophic
- has a nervous co ordination
What does the theory of evolution suggest
- that widely seperated groups of organisms share a common ancestor
- therfore it would be expected that they share basic features so their similarities should indicate how closely related they are
- the more similar two organisms are the more recently they are assumed to have diverged
- groups with little in common presumably diverged from a common ancestor much earlier
Homologous structures
Structures in different species with a similar anatomical position and development origin derived from a common ancestor
Pendactyl
Having five digits
Divergent evolution
The development of different structures over long periods of time from the equivalent structures in related organisms
Convergent evolution
The development of similar featuress in unrelated organisms over long periods of time related to natural selection of similar features in a common environment
Analogous structures
Have a corresponding function and similar shape but have a different devolpment origin
How do you decide how closely related two organisms are
- a biologist looks for homologous structures
- they may have different functions but have a similar form and development origin
- an example is a pentadactyl limb of the vertebrate. It’s basic structure is the same in all four classes of terrestrial vertebrates amphibians reptiles birds and mammals
- However the limbs of different vertebrates have adapted and have different functions like grasping walking swimming and flying
- This provides an example of divergent evolution where a common ancestral structure has evolved and performs different functions
How do you decide if two organisms are not closely related
- Two animals may look similar but it does not mean that they’re closely related such as a butterfly, a sparrow and a bat
- they all have wings and fly but one is an insect and one is a bird and one is a mammal
- they do not ave a recent common ancestor with wings but because their ancestors adapted to a similar environment they all evolved wings which perform the ame function
- this is an example of convergent evolution in which structures evolve similar properties but have different development originss such structures are analogous so they are not suitable criteria for classifying organisms
How are DNA sequences used to assess relatedness in organisms
- during the course of evolution sspecies undergo changes in their DNA base sequences which accumulate until the organisms are so different that they are considered to be different species
- more closely related species show more similarity in their DNA base sequences than those more distantly related
- DNA analysis has confirmed evolutionary relationships and corrected mistakes made in classification based on physical characteristics
How does DNA hybridisation assess relatedness between organisms
- involves comparint the DNA base sequences of two species
- to work out how closely related two species of primates are eg humans and chimpanzee
- DNA from both are is extracted seperated into ssingle strands and cut into fragments
- the fragments from the two species are mixed and where they have complementary base sequences they hybridise together
- this shown that chimpanzees and chimanzees have at least 95% of their DNA in common whereas humans and monkeys have 93% of DNA in common
How do you assess relatedness with genetic evidence
- DNA sequences
- DNA hybridisation
- Amino acid sequences
- Immunology
How do amino acid sequences assess relatedness between organisms
- the sequence of amino acids in protein is determined bu the DNA base sequences
- the degree of similarity in the smino acid sequence of the same protein in two species will reflect how closely related they are
- fibrinogen is a plasma glycoprotein contributing to blood clotting in vertebratess
- part of the molecule of various mammal species jas been compaed and differences in the amino acid sequences have allowed scientist to propose an evolutionary tree for mammals
How does immunology assess the relatedness between organisms
- the proteins of different species can be compared using immunological techniques
- if you mix the antigens of one species such as the blood protein albumin with specific anitbodies of another the antigens and antibodies cogulate the closer the evolitionary relationship the more cogulation occurs
What are the steps of immunology
- human serum injected into rabbit
- rabbit serum containing anti human antibodies is extractted
- rabbit serum added to serum of other species
- increasing amount of precipitation showing a closer evolutionary relationship
What is the morphological definition of species
- if two organisms look very similar they are likely to be the same species there mau ne differences s uch as the presence of a mane on male lions but not females
- this is sexual dimorphism must be taken into account when deciding if two organisms are the same species
What is the reproductive definition for species
- another way of defininf a species stae that two organisms are in the same species if they can interbreed to make fertile offpring
- dissimilar organisims may have a different number of chromosomes or incompatible physiology or biochemistry so a hybrid would no be viable
What is taxonomy
- is the identification and naming of organisms
- this allows use to discover and describe biological diversity
- investigate evolutionary relationships between organisms
- classify organisms to reflect their evolutionary relationships
What are the advantages of the binomial system
- unambiguous naming
- based on latin the scholarly language so could be used all over the worl
- implies that two species sharing part of their name are closely related
How do you use the binomial system
- each organism has two names it genus and it species
- the genus name is the first word and has a capital letter
- the species name combes second and does not have a capital letter
- the firt time the scientific name is used in a text it is written in full eg Panthera tigris
- if used again the genus may be abbreviated P.tigris
- both names are printed in italic or underlined when hand written
Taxonomy
The identification and naming of organisms
Biodiversity
The number of species and the number of individuals in each species in a specified region
Binomial system
the sytem of giving organisms a unique name with two parts a genus and species
What does the term biodiversity refers to
- two aspects of organisms in a given environment
- the number of species someimes called species richness
- the number of organisms within each species sometimes called species evenness
- biodiveristy is not constant
What does the number of species and the number of orgainsms depend on
- the environment
- more plants grow at high light intensity than at low light intenssity so a bright environment can support more herbivores and therefore more carnivored than a dull one
- more energy flowing through an ecosystem produces more species and more individuals this means hat equatorial regions have a much higher biodiveristy than polar regions
How can biodiveristy increase of decrease
- succesion - over time a community of organisms changes is habitat making it more suitbale for other sspeices
- the change in the composition of a community over time is called succession
- it increases animal animal biodiversity but ultimatley decreases plant biodiverisity
- natural selection - this carn generate and change biodiverity
- human influence - in many areas of the owlrd human activity has ade the environemen less hospitable to living organissms this has decreased there biodiveristy and led to extinction
how does human activities decrease biodiverisity
- in tropical rain forests of Brazil and Costa rica farming roads and industry have destroyed habitats reduced the numbers of individuals and driven to extincioyion and many species found nowhere else in the world
- in the oceans over fishing has depleted fissh stocks and some very productive diverse areas such as in corral reefs and estuaries are severly stressed. Trawlers dredging the ocean floor disrupt habitat damaging the population of invertebrates, fish and sea mammals
- Missuse of land such as tampling by cattle accompanied by the increase temperature related to climate change has increased the area of deserts the sahara desert has expanded and large areas of Australia and North America are vulnerable
- rivers are polluted with industrial chemicals the problems of river dolvins were made worse by capture and by collisions with river traffic and was declared extinct later
How are many different plants and animals used to supprt human civilisation
- small number of plant species provide staple foods eg wheat and rice for humans worldwide
- medicinal drugs are derived from plants and fungi eg aspirins, statin and anitbiotics
- living organissms provide important raw materials eg rubber and cotton
What happens when biodiversity decreases
- we lose potential new foods and sources of new useful characteristic to breed into cropps such as disease resistance
- in addition the potential for discovering new raw materials is compromised
- thi argument is selfissh because it is human centred
- the non selfish argument for protecting biodiversity is that each species in unique and we have an obligation to preserve that uniqueess as it has its’ own intrinsic values
How do we assess biodiversity
- assessing biodiverisity at the population level produce a biodiversity incex which can be ussed to monitor the biodiversity of a habitat over timeand to compare biodiversity in different habitats
What is the simpson’s diversity index
describes the diversitty of moile organisms such as inverbrates in a stream the commenest way of calculating the index gives a numerical number and the higher the value the higher the biodiversity
How does the number of alleles show biodiversity
- a genes position on a chromosomr is its locus
- a locus shows polymorphisms if it has two or more alleles with the rarer alleles at frequencies greater than would occur by mutation alone
- if a gene has more alleles and its locus is more polymorphic that if there were fewer alleles
How do the number of allleles in some plants determine biodiversity
- Gene T controls height and there are two different alleles
- Gene S controls wether of not pollen can germinae on the stigma of a flower of the same species in one species of poppy gene S has 31 different alleles
- Gene s has a greater biodiversity than gene T as more pheontypes are possible for Gene s than Gene T
Polymorphism
The occurence of more than one pheontype in a population with the rarer pheontypes at frequencies greater than can be accounted for by mutation alone
How does the proportion of alleles determine biodiversity
- if we considered the whole gene pool 98% of all alleles of a particular gene are the same recessive allele there is a low biodiversity for that gee but if only 50% of the alleles in the gene pool were recessive 50% would be other alleles so the biodiversity for that gene woild be higher
How does DNA fingerprinting assess biodiversity
- organisms that are more closely related to each other have DNA base sequences that are more similar
- The DNA of organisms does not code for protein like all DNA non coding equences undergo mutation so individuals acquire different base sequences
- Sometimes it is onluone base that differs these single base differenecess are calles SNP pronounces snips which stands for single nucleotide polymorphisms
- There are also regions of DNA that vary generally about 20 - 40 base sequences long often repeated many times
- these unique lengths of non coding DNA are called hyper variable regions (HVR) or short tandem repeats (STRs)
How can differences of biodiversity be determined by DNA fingerprinting
- these differences can be seen in genetic or DNA fingerprints or profile including the number of times that the lengths of non coding DNA are repeated
- Comparing the number and position of the bands in DNA profiles of a population indicated how similar or different their DNA sequences are. The more different NPs and HVRs a population has the more differences there are in its DNA fingerprints more differences indicate a greater biodiversity
- In a biodiverse population DNA fingerprints show a lot of variation
Genetic or DNA fingerprint or profile
terms for pattern unique for each individual related to the base sequences of their DNA
Natural selection
The gradual process in which inherited characteristics become more or less common in a population in responsee to the environment determining the breeding success of individuals possessing those characteristics
What do mutation in organisms do
- mutations cause differences between organsisms providing raw material for natural selection
What is the process of natural selection
- mutation - differences in DNA
- variation - different physical appearance biochemical function or behaviour
- competitive advantage - some are more suited to the environment that others and out compete rivals for resources
- survival of the fittest -those more suited to the environment survive better
- reproduction - those more suited to the environment have more offspring
- pass advantageous alleles to offspring - offspring inherit the advantageous alleles so they are also more suites to the environment
What is the effect of natural selection on biodiversity
- it can decrease biodiversity
- thi may happen when a elective insecticide kills all the aphid in a habitat or when an asteroid crashes into the earth throwing dust into the atmossphere reducing light intensity so plants cannot survive
- then the herbivores die so then the carnivored die
What is adaptation
- the change in a species as a useful characteristic becomes more common
- the useful characterisitic is refferred to as an adaptive trait every aspect of an organisms is ubject to adaptation and adaptive traits may be seen in many features
What are anatomical traits
- sharks , dolphins and penguins have streamlines bodies without this body hape they would be less efficient at catching food or escaping predators
- some plants have flowers with honey or nectar guids sometimes called beelines they indicate the centre of the flower he source of nectar and pollen for visiting insects a flower without these lines would attract fewer pollintations
What are physiological traits
- mammals and birds are endothermic and must avoid wasting energy trying to maintain body temperature in the cold during hibernation a hedgehog for example resetss it body thermostaat it body temperature drops from its normal to a lower temperature and so the hibernating hedgehog requires less energy
- the leaves fall off deciduous plants when the temperature and light intesity decrease in autumn this way they do not lose water by transpiration and rik dehydration throughout the winter when water may be frozen and so they survive the cold weather
What are behaavioural traits
- like many plants the hawthorn, flowers in springs when its pollinating insects have emerged if it flowered earlier it would not be pollinated
- mating rituals in animals include the displaying of a peacocks tail or the elaborate dances performed by birds such as flaminogs they increase the animals chance of reproducing
