Module 4.2.2 - Classification and evolution Flashcards
Why do biologists classify organisms?
To identify organisms easily and to scientifically organize knowledge
Why is it important to give organisms scientific names?
Only has 1 unique name to avoid confusion
What does biological classification mean?
Organization of living and extinct organisms into systematic groups based on similarities/differences between species
Why must every species be studied in detail before being correctly placed in a group of similar organisms?
- convenience
- identify species
- predict characteristics
- find evolutionary links
What is taxonomy?
The study and practice of naming and classifying species and groups of species within the hierarchical classification scheme
Name the taxonomy
Domain, kingdom, phylum, class, order, family, genus, species
What is the binomial system?
A system of naming species in which each species has 2 names : a generic name and a specific description
What were the issues with grouping organisms based on similar characteristics before classification systems were used?
- same organisms may have a completely different common name in different parts of 1 country or other countries
- translation of languages/dialects may give different names
- same common name could be used for a different species in another part of the world
Name the 5 kingdoms
Prokaryote
Protist
Fungi
Plantae
Animalia
Describe prokaryotes
- mostly unicellular
- have no nucleus
- have a loop of DNA that’s not arranged in a linear chromosome autotrophic and heterotrophic
- no membrane bound organelles
- have smaller ribosomes than in other groups (70s)
- cells smaller than eukaryotes
- can be free living or parasitic
What did early classification rely on?
Observable features only to place organisms into groups such as appearance and anatomy
Describe protists
- eukaryotic
- mostly single celled (many algae are multicellular)
- have wide variety of forms
- show various plant like and animal like features
- mostly free living
- have autotrophic or heterotrophic nutrition
Describe fungi
- eukaryotic
- can exist as single cells (yeasts) or have a mycelium that consists of hyphae
- cell walls made of chitin
- cytoplasm is multinucleate
- mostly free living and saprophytic (cause decay of organic matter)
Describe plantae
- eukaryotic
- multicellular
- cell walls made of cellulose
- contain chlorophyll
- autotrophic
Describe animalia
- eukaryotic
- multicellular
- heterotrophic
- usually motile
What are examples of prokaryotes?
Bacteria, cyanobacteria
What are examples of protists?
Unicellular eukaryotes, algae, protozoa
What are examples of fungi?
Yeasts, molds, mushrooms
What are examples of plantae?
Mosses, ferns, flowering plants
What does autotrophic mean?
Absorb simple molecules and build into larger molecules
What are examples of animalia?
Mammals, birds, reptiles, fish, insects, mollusks, nematodes
What does heterotrophic mean?
Digest larger molecules to form smaller molecules for absorption
What is artificial classification?
- done for convenience
- only based on a few characteristics
- doesn’t reflect evolutionary relationships
- stable
- provides limited amount of info
What is natural classification?
- involves a more detailed study of individuals in a species
- uses many characteristics
- reflects evolutionary relationships
- based on homology
- provides a lot of useful info
- may change with advancing knowledge
What is homology?
The existence of shared features that are inherited from a common ancestor. The shared featured may not be used for the same thing.
E.g. pentadactyl limb
What does phylogeny mean?
The study of evolutionary relationships between organisms
What are the benefits of phylogeny?
- can be done without referring to the Linnaean classification
- provides a continuous tree whereas classification requires discrete taxonomical groups
- not as misleading as hierarchical classification of the Linnaean system
What is the biological species concept?
The ability of 2 individuals to successfully produce viable, fertile offspring
What is the phylogenetic species concept?
How closely related individuals are evolutionarily, the concept of a species as an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining or derived traits
What is the morphological species concept?
Whether individuals look similar
What is the ecological species concept?
Whether the individuals use or can use the same set of biological resources
What does GENIE stand for in evidence of evolution?
G - genetic variation
E - environment
N - natural selection
I - inheritance
E - evolution
What were Darwin’s contributions to evidence of evolution?
- Proposed the mechanism of natural selection for the theory of evolution
- his ideas were developed during observations he made in Galapagos Islands
What were Darwin’s 4 main observations?
- offspring generally appear similar to their parents
- no 2 individuals were identical
- organisms have ability to produce large numbers of offspring
- populations in nature tend to remain fairly stable size
What were Wallace’s contributions to evidence of evolution?
- developed theory of natural selection independently to Darwin
- collected evidence and many many observations in parts of the world
What were Wallace’s 3 main observations?
- some organisms had advantageous adaptations evolved by natural selection
- geographical boundaries often marked species boundaries
- most individuals found in habitats were best fitted for that environment
What can be used as evidence for evolution?
- fossils
- comparative anatomy
- comparative biochemistry
What are fossils?
The mineralised or preserved remains of an animal, plant or microorganism. May also consist of other traces of organisms such as footprints, burrows and faeces
Due to the fossil record being incomplete, what does this create?
issues with evidence of evolution
How are fossils formed?
Animal or plant dies - organism becomes buried under sediment - high temp and pressure turns sediment into stone - the remains dissolve and leave behind a space - minerals crystalize in the space and forms a fossil/cast
What is the homologous structure?
Structure that appears superficially different in different organisms but has the same underlying structure
What does the pentadactyl limb do?
Provides evidence for divergent evolution and would most likely be due to migration or loss of habitat
What is comparative biochemistry?
- study of similarities and differences in proteins and other molecules that control life processes
- some important molecules are highly conserved among species
- slight changes that occur in the molecules can help identify evolutionary links
How does DNA give evidence for evolution?
- differences in sequence of DNA molecule would be due to mutations as genetic code is universal, so a particular sequence of DNA codes for the same sequence of amino acids in both animals, plants or bacterium
- more similar the sequence in the part of DNA, the more closely related the species
- more differences in sequence of part of the DNA, the earlier the evolution of the 2 species and so less closely related they are
What is cytochrome C?
A short protein used in respiration and is found in many species. But the amino acid sequence for cytochrome C can have variations between species
If the sequence for cytochrome C is the same…
2 species must be closely related
If the sequence for cytochrome C is different…
2 species aren’t closely related
The more differences found between the sequences in a species…
The less closely related they are
What is variation?
Difference between species and the differences within the species
What is intraspecific variation?
Variation between members of the same species
What is intraspecific variation used for?
- To study natural selection and evolution
-phenotypic variation between individual are more often difficult to detect - selective breeding often results in variation not often visible in wild population
What is interspecific variation?
Differences between species
What is interspecific variation used for?
Used to identify different species and to classify them
What are the features of continuous variation?
- can also be known as quantitative variation
- any features that can be measure
- no distinct categories
- characteristics aren’t controlled by a single gene, but by a number of genes known as polygenes
- these features are known as polygenic
What is continuous variation?
Variation in a feature that shows a range of phenotypes between 2 extremes with many intermediates
What is discontinuous variation?
Variation in a feature that only has discrete categories without any intermediates
What are the features of discontinuous variation?
- can also be known as qualitative or discrete variation
- are distinct categories
- characteristics are usually controlled by a single gene and the environment usually has no effect on the expression of the genes in the phenotype
- this can be presented as a bar chart or pie chart
What are the 2 types of variation?
Genetic
Environmental
How does genetics cause variation?
Alleles - genes have different versions and the individuals in a species population may inherit different alleles of a gene
Mutations - changes to the DNA sequence and therefore genes can lead to changes in the protein coded for and this cam affect the physical and metabolic characteristics
Meiosis - formation of gametes and the process of independent assortment and crossing over to ‘mix up’ the genetic material
Sexual reproduction
Chance p– random fertilisation as a result of which gametes combine
How does the environment cause variation?
- environmental variation can be due to climate, food, lifestyle etc…
- characteristics controlled by environmental factors can change over an organisms life
When can genetic and environmental variation happen at the same time?
Not all genes are active at any 1 time, e.g. puberty
Changes in environment can also directly affect genes being active, e.g. melanin production
What can you investigate variation with?
Statistical tests but you must first come up with a null hypothesis
What are characteristics of normal distribution?
- mean, median and mode are the same
- distribution has a characteristic ‘bell shape’ which is symmetrical about the mean
What does it mean if there is a high or low standard deviation?
High - data is more spread out, less reliable
Low - data is closer to the mean, more reliable
What is standard deviation?
measure of spread of data around a mean
What is the standard deviation equation?
√ Σ(x-x̅)^2
————–
√n-1
What is the equation for Spearman’s rank?
1 - 6Σ D^2
———-
n(n^2 -1)
If spearman’s rank is equal or greater than the critical value for appropriate n, then…
There’s significant correlation and null hypothesis is rejected and alternative hypothesis is accepted
If spearman’s rank is less than the critical value for appropriate n, then…
There’s no significance and the null hypothesis is accepted
What is an unpaired t-test?
- samples can be different sizes
- compare mean from 2 different categories/individuals
- data not linked to each other
What is the unpaired t-test equation?
t = x̄ (a) - x̄ (b)
—————-
√ sd^2 (a) sd^2 (b)
———– + ————-
√ n (a) n (b)
What is a paired t-test?
- same sample size
- compare data from same individuals before and after event
- each individual in data set has a ‘pair’ of data
What is the paired t-test equation?
t = mean √n
————–
standard deviation
What are the 3 types of adaptations?
- behavioural
- physiological
- anatomical
What does adaptation mean?
The way a structure, function or an aspect of behaviour helps an organism to survive in its environment or perform activity
What is behavioural adaptation?
Ways an organism acts to increase chances of survival, can be inherited or learnt from their parents
What are example of behavioural adaptation?
- survival behaviour
- courtship behaviour
- seasonal behaviour
What are example of physiological adaptation?
- poison production
- antibiotic production
- water holding
What is physiological adaptation?
Processes inside an organisms body that increases the chances of survival
What is anatomical adaptation?
Structural features to increase the chances of survival
What are example of anatomical adaptation?
- body covering
- camouflage
- teeth
- mimicry
What are anatomical adaptations of marram grass?
- long roots spread over wide area
- curled leaves with lower epidermis covered in hairs and folded to create pits to hold stomata
What are behavioural adaptations of marram grass?
- rolls leaves more tightly when there’s shortage of water and closes stomata
- grow faster to reach sunlight when covered by sand
What are physiological adaptations of marram grass?
- can roll leaf due to action of specialised hinge cells in lower epidermis
- not very slat tolerant but maintains a cell water potential lower than other plants
What is convergent evolution?
Organisms evolve similarities because the organisms adapt to similar environments or other selection pressures
What is analogous evolution?
Have adopted to perform the same function but have different origin
What is natural selection?
Process by which organisms best suited to their environment survive and reproduce, passing on their characteristics to their offspring through their genes
What were Darwin’s contributions to the changing population characteristics?
- all organisms reproduce to give for more offspring than are going to survive
- population of organisms fluctuate but don’t tend to increase or decrease significantly overtime as the numbers are mostly consistent
- variation in characteristics among individuals within a species
- offspring resemble their parents features and are transmitted from 1 generation to the next
What is the process of natural selection?
- mutation creates alternative versions of a gene
- this creates genetic variation between individuals of a species
- There’s a selection pressure such as predation, disease or competition that creates a struggle for survival
- Individuals with an advantageous characteristic are more likely to survive and have reproductive success
- Therefore these individuals will pass on their advantageous characteristics
- The next gen will have higher proportion of individuals with the successful characteristic, overtime the proportion of the population possessing the advantageous adaptations increase
- Over generations this leads to evolution of a new species if genetic variation occurs
What are the consequences of antibiotic resistance?
- serious and of great concern to medical authorities
- new antibiotics have to be created/discovered
- some strains of bacteria are now untreatable using antibiotics
What are the steps that can be used to reduce antibiotic resistance?
- only prescribe when necessary
- ensure course of antibiotics is finished
- rotate use of antibiotics so1 type isn’t used continuously for a certain disease
- keep some antibiotics as a ‘last resort’
- invest in further research to find new antibiotics
