Unit 2.1 - All organisms are related through their evolutionary history Flashcards
What do ALL organisms one from and when?
A common ancestor, billions of years ago
What does the way organisms are named reflect?
That they all came from a common ancestor billions of years ago
Taxonomy
The branch of science concerned with classification
The branch of science concerned with classification
Taxonomy
Phylogenetic
Methods of classification that reflect an organism’s evolutionary history
Phylogenetic
Evolutionary relatedness
Evolutionary relatedness
Phylogenetic
What are grouped together under phylogenetic classification?
Closely related organisms
What does it mean if organisms are in the same group?
More recent common ancestor, and may show physical similarities
Who and when does the system of classification we now use originate from?
Carl Linnaeus in the 18th century
What type of methods of classification reflect on an organism’s evolutionary history?
Phylogenetic methods of classification
Taxa
Levels of classification
Levels of classification
Taxa
What so large Taxa contain?
Smaller taxonomic groups
What contains smaller taxonomic groups?
Large Taxa
Whats the pattern in relatedness of organisms in terms of the taxonomic groups?
Animals become more related as you move down the taxonomic groups
What happens to organisms as you move down the taxonomic groups?
They become more closely related
Largest taxonomic group
Domain
Smallest taxonomic group
Species
List the taxonomic groups
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
List the taxonomic groups of humans from top to bottom
Domain - eukaryotes
Kingdom - animalia
Phylum - Chordata
Class - mammalian
Order - primates
Family - hominidae
Genus - homo
Species - sapiens
Back bone phylum
Cordata
Cordata
Back bone phylum
Can an animal belong to more than 1 taxon at any level? What’s the word for this?
No - Taxa are discrete
What do you call the diagrams frequently used to show the genetic relatedness of species?
Phylogenetic trees
What does the point at which 2 species cross over on a phylogenetic tree represent?
A common ancestor for 2 organisms
What represent a common ancestor for 2 organisms?
The point where the points cross on a phylogenetic tree
What does it mean if 2 species evolved more recently from another organism?
More closely related and therefore share a lot more of the same DNA
What do organisms that are closely related share a lot of?
The same DNA
What did we depend on in the past for classification?
Comparative anatomy
What do we depend on now for classification and why?
Biochemical, DNA comparisons
More reliable
Why is the fact that DNA is shred between closely related species a useful fact for classification of previously Iiving organisms?
We’re able to extract DNA from old archeological samples
Why are we able to extract DNA from old archeological samples?
It remains stable due to its structure, so it remains in good condition for thousands of years
What does more time passing usually mean in terms of DNA?
More time for DNA to change = more changes
What do genes change via during evolution?
Via mutation and natural selection
Why do genes change during evolution?
Evolutionary pressures were different in new environments
What do ALL living species belong to 1 out of 3 possible groups?
1 out of 3 of the groups in the domain system
What was the domain system originally defined on the basis of?
rRNA base sequences
What is the domain system now defined on the basis of?
DNA base sequences
3 domains
Eubacteria
Archaea
Eukaryota
Description of eubacteria domain
Familiar bacteria (e.g - E. Coli, salmonella, strep A)
Prokaryotes
2 prokaryote domains
Eubacteria and archaea
Archaea domain description
Also bacteria, but often have unusual metabolism (e.g - generate methane)
Live in marginal (extreme) environments
Prokaryotes
Which domain lives in extreme environments and give examples of these?
Archaea
Frozen soil in the Antarctic
In geothermal springs
Eukaryota domain description
Included plantae, animalia, fungi and protoctista
Eukaryotes
Features of Eukaryota domain
Membrane bound organelles, DNA in a nucleus with a nuclear envelope..
What’s the kingdom system based on?
Morphological similarities between organisms, not DNA analysis
Which group is based n morphological similarities between organisms, not on DNA analysis?
Th kingdom system
Main features of the prokaryotae kingdom
Includes all bacteria (eubacteria and archaea) and Cyanobacteria
Microscopic, single called organisms with no membrane bound organelles
Cell wall made from pectidoglycan or Murein (not cellulose)
What are the 5 kingdoms?
Prokaryotae
Protoctista
Fungi
Plantae
Animalia
Protoctista kingdom main features
Eukaryotic organisms
Single celled
No tissue differentiation
(E.g - amoeba, paramecium, paracytes)
Fungi kingdom main features
Heterophobic eukaryotes
Cell wall made up of chitin
Reproduce by spores
Grow in long threads called hyphae (together = mycelium)
Plantae kingdom features
Multicellular eukaryotes
Photosynthetic
Cellulose cell walls
Animalia kingdom main features
Multicellular eukaryotes
Heterophobic
No cell wall
Nervous coordination
Which kingdom is known as the “dustbin group” and why?
Protoctista as it’s such a diverse group that anything that doesn’t fit into the others goes into
Heterophobic
Have to consume complex organic molecules made by other organisms (don’t photosynthesise)
Name 2 heterophobic kingdoms
Animalia and fungi
Differences between Plantae and fungi kingdoms
(Plantae first, then fungi)
Cellulose cell wall, chitin cell wall
Reproduce by seeds, reproduce by spores
Photosynthetic, heterophobic
Photosynthetic
Use energy from sunlight to make complex organic compounds (e.g - carbohydrates) from simple, inorganic molecules (CO2, H20)
Name a good piece of evidence for evolutionary relationships and give an example
The presence of homologous structures
e.g - the pentadactyl limb in vertebrates
What’s comparative anatomy evidence of?
Common ancestry
Homologous structures + example
Same evolutionary origin (common ancestor) but have very different functions
(e.g - the wing of a bat and the flipper of a whale)
Analogous structures + example
Different evolutionary origins but have similar biological functions
(e.g - the wing of a bird and the wing of an insect)
What type of evolution do homologous structures result from?
Divergent evolution
What type of structures does divergent evolution lead to?
Homologous structures
What do analogous structures result from?
Convergent evolution
What type of structures does convergent evolution result in?
Analogous
Divergent evolution
When a population is split in 2 by geographical barriers and develop different traits under their respective selective pressures
(Have a common ancestor)
Convergent evolution
Species from different evolutionary origins occupying similar adaptations to similar selective pressures
(Adapted separately from different starting points, but reach the same end point - converge)
Example of convergent evolution + explanation
Dolphins and sharks
Dolphins - evolved from land mammals
Sharks - evolved from fish
Similar body shapes, but would need to track back million of years to find a common ancestor
What are the 4 methods of indicating how closely relate species are?
- DNA base sequence
- DNA hybridisation
- Amino acid sequence
- Immunology
What happens to DNA base sequences during evolution?
Species undergo changes in their DNA base sequences, which accumulate until the organisms are so different that they’re considered to be different species
Relationship between relatedness and DNA base sequence
More closely related = more similar DNA base sequence
Which method has confirmed evolutionary relationships in the past and corrected mistakes made in classification based on physical appearances?
DNA base sequencing
DNA sequencing
Reading the sequence of bases in a DNA molecule
What occurs during DNA base sequencing and why?
Specific sequences of DNA are targeted (e.g - a specific gene)
We can then compare that gene between species
(Remember that DNA is extraordinarily long)
What’s the issue with DNA base sequencing of only one gene?
The data is not representative of the whole DNA and so 2 species could appear more closely related then they really are
What does DNA hybridisation involve?
Comparing the DNA base sequence of 2 species
Describe the stages of DNA hybridisation
- DNA is extracted from both species
- DNA is heated to separate the 2 strands
- DNA is cut into fragments
- Fragments from 2 species are mixed
- Where they have complementary base sequences, they hybridise together
What has to be done to get a result from DNA hybridisation and what is this result?
Has to be heated -
The higher the temperature required to separate the new hybrid DNA molecules, the more similar the DNA due to the hydrogen bonds formed
What does 1 degree Celsius difference in desaturation temperature for DNA hybdridisation result in?
1% difference in DNA sequence
Even though humans and chimpanzees have 95% of their DNA in common, they have huge differences in appearance and behaviour. Why?
Due to gene regulation between the 2 species
Gene regulation
A process used to control the timing, location and amount in which genes are released
How is amino aid sequencing done?
The sequence of amino acid sin protein is determined by the DNA base equence
The degree of similarity in amino acid sequence reflects how closely related 2 organisms are
Example of amino acid sequencing that’s led to evolutionary trees
Part of the fibrinogen molecule of various mammal species have been compared
Their differences have led to evolutionary trees
What’s the problem with observing the amino acid sequence to indicate how closely related species are?
Can have differences in the DNA sequence that don’t cause differences in the amino acid (different codons of amino acids)
(Not as sensitive as using the DNA base sequence)
What’s not as sensitive as using the DNA base sequence for indicating how closely related species are?
Using the amino acid sequence
What does immunology do?
Compare proteins of different species
Describe the process of immunology
Antigen of one species
+
Specific antibodies of another
Mixed
Form a precipitate
What would show a closer evolutionary relationship during immunology?
The antigen and antibody reacting more to make more precipitate
Example of an antigen used during immunology
Blood protein albumin
Why is biological classification said to have a “tentative nature”?
Classification can change over time as more techniques and information become available
What is a species defined as?
A group of organisms able to interbreed to produce fertile offspring
Which domain includes extremophiles?
Archaea
Extremophiles
Bacteria living in extreme environments
Examples of extreme environments that extremophiles can endure
Very high and very low temperatures (e.g - geothermal springs, frozen ice)
High salinity
Acidic + alkaline
High pressure
Extremophiles living in very high temperatures
Thermophiles
Extremophiles living in an area of high salinity
Halophiles
Extremophiles living in very low temperatures
Psychrophiles
What do you call the groups in which fungi grow?
Hyphae (together - mycelium)
Name the kingdoms with photosynthetic organisms
Prokaryotae
Plantae
Protoctista
What are the photosynthetic pigments of plantae attached to?
Thylakoids
Hierarchical
Each group is subdivided into smaller groups
Ribosomes of eukaryotes vs prokaryotes
80s vs 70s
What changes genes?
Mutations
What’s the name of the system used when naming organisms?
Binomial system
What’s the names of the first and second names used in the binomial system?
Genus + species
How do we correctly write out a binomial name?
Genus name starting with an uppercase letter
Species name in lowercase
Which names for organisms can be misleading?
Common names
What’s the purpose of the binomial system?
Avoids confusion
Can accurately identify species internationally
Each scientific name is distinct
When a scientist discovers a new species, which part of the binomial name can they choose and which part must they not choose randomly and why?
Choose - species name
Keep - Genus name (if there are other species in the genus)
What can a scientist that discovers a new species do?
Choose the species name of an organism
Species definition
A group of organisms that can interbreed to produce fertile offspring
Give an example of two closely related species that interbreed to produce a hybrid - what’s the same between them both?
Zebra and donkey
Have the same GENUS
What is a zebronkey?
A hybrid of a male zebra and a female donkey
What’s the problem with hybrids from closely related species?
They’re infertile and cannot produce offspring
What type of offspring are infertile?
Hybrids
Why are hybrids infertile?
The number of chromosomes in the parents are different
Egg and sperm DO combine, but the zygote has an uneven amount of chromosomes
Cannot form homologous pairs during meiosis
Cannot form viable gametes
=infertile
What’s the difference between a domestic dog and a wolf?
Different SUB species
Give an example of two species that the only difference is a sub-species and discuss whether they can therefore interbreed to produce fertile offspring
Domestic dog + wolf
They CAN still interbreed to produce fertile offspring - it’s only the SUB-species that’s different
What does evolutionary change occur due to?
Natural selection
Describe and explain how an evolutionary change occurs/ natural selection
- Genetic variation exists due to spontaneous mutations
- Competition between organisms (limited resources)
- A mutation may give an organism a selective advantage
- Organism is better adapted to the environment and survives
- Organism reproduces, passing on its beneficial alleles
- Frequency of advantageous alleles increase
Why does genetic variation exist?
Due to spontaneous mutations
What could a mutation give to an organism that’s good?
A selective advantage
What adapts to new environments?
The entire population, not just individuals
What does it mean if an organism has a “selective advantage” during natural selection?
It’s better adapted, so it can out-compete other species
What are the 3 types of biodiversity?
Genetic
Species
Ecosystem
Genetic diversity
Count the gene forms in a population
Species diversity
Count the species in a community
Ecosystem diversity
Count the ecosystem types in a landscape
What are the 2 aspects to biodiversity?
The species richness - the number of species in a given environment
The species evenness - the number of individual organisms within each species
Species richness
The number of species in a given environment (local or wide-ranging)
What’s the word for the fact that biodiversity varies depending on where you are?
Varies spatially
What’s the general pattern with biodiversity in terms of the equator?
More biodiversity close to the equator
List some factors that affect biodiversity across the globe (4)
UV light
Humidity + rainfall (water availability)
Temperature
Amount of species and individuals
How does UV light affect biodiversity?
Causes a higher rate of mutation - leads to rapid evolution
How does a stable temperature affect biodiversity?
Favourable conditions for plants to grow - biodiversity of animals generally depends on plant life
How does humidity/rainfall (water availability) affect biodiversity?
Provide favourable conditions for plants to grow - the biodiversity of animals generally depends on plant life
Niches
Food types
Word for food types
Niches
How does having more species types affect biodiversity?
More habitats and niches (food types)
How does having more species and individuals affect biodiversity?
Competition is high, so individuals are more specialised and narrow the exploitation of niches, making it difficult to move out of the area
When is it difficult for a species to move out of an area?
When there’s more species and individuals, and so competition is high, so individuals are more specialised and narrow the exploitation of niches
Give 4 examples of different habitats
Rainforests
Deserts
Coral reefs
The Antarctic
What are the pros and cons of the desert environment?
High light intensity
Low rain fall /humidity, so no plants, so no basis for ecosystems to grow, so very few animals
Why are plants important for biodiversity?
Provide the basis for ecosystems to grow, so without them there’s also few animals
What makes coral reefs have large amounts of biodiversity?
Nutrient loops
Are there many plants in the Antarctic? Why?
There’s obviously a lot of water, but its frozen, so its not available for plants to row, so no, there’s virtually no plants in the Antarctic
Where abouts to species that live in the Antarctic live and why?
Near the coast as they depend on plant and marine life in the sea
What are the cases of biodiversity changing over time?
Succession
Natural selection
Human influence
Succession
Over time, a community of organisms changes its habitat
Community
A number of organisms of different species living together in the same environment and interacting with one another. They can influence and change a habitat together.
What forms at the bottom of a pond during succession when bits of dead plants and leaves sink there?
Detritus
Detritus
Dead bits of plants and leaves that have sank to the bottom of a pond
What happens as detritus forms at the bottom of a pond?
More plants grow from it and it gets deeper, causing the pond to become shallower until eventually, the habitat has changed
How does the habitat of a pond change?
Through succession
Detritus form from bits of plants and leaves dying
Sink to the bottom
More plants grow from it
Detritus gets deeper
Pond becomes shallower
Habitat has eventually changed
What can happen to plants once the habitat of a pond has changed via succession?
Different types of plants can grow there
What does succession do to animal biodiversity (in general)?
Increases it
What doe succession do to plant biodiversity (in general)?
Decreases it
Climax community
The last stable stage of succession
The last stable stage of succession
The climax community
What is usually the climax community?
Forest
What is a climax community usually dominated by?
1 plant type
Why does plant biodiversity decrease with succession?
A climax community (the last stable stage of succession) is usually dominated by 1 plant type
What did Darwin come up with?
The theory of evolution through natural selection
What’s a good example of natural selection causing biodiversity?
Darwin’s finches
What did Darwin’s finches help him do?
Come up with the theory of evolution through natural selection
What had the Galapagos finches adapted for?
Adapted to be suitable for their diets
How did Darwin use the finches to come up with the theory of evolution through natural selection?
He travelled the world collecting bird samples and carefully documented the environments that they lived in to see the relationship between the beak shape and their diets
How did biodiversity come about with the Galapagos finches?
Ancestral finch landed on one of the islands, breaded and grew the population which spread out to different habitats which they adapted to
Therefore, over time, natural selection led to an increase in Biodiversity
Adaptive radiation
1 type of organism adapts to different types
Why is it initially strange to think of the fact that there’s so much Biodiversity in the Galápagos Islands?
-formed fairly recently - they’re volcanic islands that emerged from volcanic eruptions in fairly recent geological time
-hundreds of miles from the nearest mainland - any animal/plant there must have come from the mainland, which would happen rarely due to the distance
What type of islands are the Galápagos Islands?
Volcanic islands that emerged from volcanic eruptions in fairly recent geological time
Why is there so much biodiversity in the Galápagos Islands?
Include dozens of islands with different habitats and Environments
Mountainous, dry, lush vegetation, rocky
So, they provide habitats for many different organisms
Give 4 types of habitats present in the Galápagos Islands
Mountainous
Dry
Lush vegetation
Rocky
Genetic diversity
The total number of genetic characterises in the genetic makeup of a species
Genetic variability
The tendency of genetic characteristics to vary
What does genetic diversity serve as?
A way for populations to adapt to changing environments
Polymorphism
Describes the presences of several different forms or types of individuals among the members of a single species. Polymorphism results from the presence of polymorphic genes (i.e - multiple alleles of the same gene)
Polymorphic genes
Multiple alleles of the same gene
2 examples of species demonstrating clear polymorphism
Domestic dogs
Snails with different shells
Describe the differences in a particular snail species and explain why this is advantageous
Genetically determined factors give them unique colours and patterns that help them blend into new environments
How can biodiversity be assessed within a species at a genetic level?
By looking at the variety of alleles in the gene pool of a population (i.e - the proportion of polymeric loci across the genome)
Gene pool
The number of different alleles within the genome
Genome
Total genes of a population
What’s the same for all domestic dogs?
Genome
What’s an example of polymorphic alleles in humans?
Blood groups
Which is the recessive blood group in humans?
O
How can biodiversity be assessed at a molecular level?
Using DNA fingerprinting and sequencing
What do researchers do instead of counting every single allele (which would be very difficult) in a population to look for variation between individuasls?
Collect samples of DNA and analyse the base sequences
Why do researchers collect samples of DNA and analyse base sequences to look for variations between individuals?
Because there’s difficulty involved in counting every single allele in a population
A greater variation in WHAT implies a greater genetic diversity of a species?
Greater variation in the base sequences in the DNA samples of different individuals
What are many plants and animals used to support?
Human civilisation
What could each species represent?
An important human asset
List 4 reasons why biodiversity is important
A potential source of food
Essential raw materials (cotton, rubber, wood…)
Useful chemicals and pharmaceuticals
Disease resistant genes which can be spliced into new genomes to produce useful GM crops
Do many plant species provide stable foods for humans worldwide? Why is this an issue?
No, few do, such as wheat and rice
A low biodiversity like this is risky - climate change or other factors could lead to the disappearance of these supplies, and then what?
Essential raw materials we get from nature
Cotton
Rubber
Wood
Examples of useful chemicals and pharmaceuticals produced by plants
Antibiotics, aspirin and many drugs used to treat heart disease
What do pretty much all drugs come from?
Plants and fungi
What can disease resistance genes be used for?
Can be spliced Ito new genomes to produce useful GM crops
What could lead to an incalculable loss in terms of biodiversity?
Extinction of a plant species before its chemical properties have been investigated
What is essential that we do to protect biodiversity?
Conservation
What does more space usually lead to in terms of biodiversity?
More biodiversity
Why is conservation essential?
Extinction of a plant species before its chemical properties have been investigated would amount to an incalculable loss
What has climate change caused throughout evolutionary history?
Mass extinctions
What’s been the cause of mass extinctions in the past?
Climate change
What have previous mass extinctions caused by climate change been followed by?
Rapid expansion and diversification of species
What are there fears currently that human activities are leading towards?
A sixth mass extinction event, with a massive loss of biodiversity
What would be the cause of a sixth mass extinction event with a massive loss of biodiversity?
Human activities
What would happen to biodiversity under a mass extinction event?
Huge losses
Give 2 examples of habitats with high numbers of species
Rainforest
Coral reef
What must we count when measuring biodiversity?
the number of different species (species richness)
the number of individuals of each species (species evenness)
Species richness
the number of different species
What are the 2 ways in which an area can be sampled?
gridding
sampling along a line (transect)
When is gridding used? include an example
Where 2 areas can be compared (e.g - mown or unmown grass)
When are transects used? Include an example
where there is a gradual change in the enviornment (e.g - under a tree to into the open)
What do we place on our grid or transetcs?
Quadrats
What are quadrats used especially for?
measuring plant biodiversity
How are quadrats used?
The area to be samples is divided up into a grid pattern with indexed coordinates
Quadrats are placed on the coordinates on a random basis - this can be achieved by using a random number table
How can quadrats be placed on a random basis?
by using a random number table
Why are quadrats useful?
They give you a specific and consistent area that’s repeatable
What can we do with the data we have after counting the number of plant species within a quadrat?
We can expand the data to represent the whole field
What must samples be in order to collect reliable data?
Random
Representable
Why must samples be random?
to reduce bias
Why must samples be representative?
They must be large enough to be an accurate estimate
Why must samples be both random and representative?
in order to collect reliable data
Where should you place quadrats and why?
In multiple various positions in order to get more reliable data that’s representative of the entire field
What’s an alternative method of sampling used in aquatic ecosystems?
Kick sampling
Describe the method of kick sampling
- Place the bottom edge of the net on the stream bed on the downstream side of the sample point
- Kick into the stones upstream of the net
- empty contents into a tray of stream water
- identify and count invertebrates
- return invertebrates gently into the stream
Give 6 variable that we need to control between 2 streams when doing kick sampling
depth of water
temperature
speed of current
oxygen and ion concentration
light intensity
time of year
Give 4 factors to control to ensure standardisation of sampling when doing kick sampling
same sampling area
same mesh size
same distance from bank
same time spent kicking
Why would the values obtained be underestimates when using kick sampling?
Animals not caught in net
animals not dislodged from bank
uneven kicking
animals too small to identify
How would we improve our confidence in a sample taken?
Take more samples
What does the Simpson Diversity index give us?
An overall measure of the species richness in an ecosystem
What are the steps in calculating the Simpson Diversity index of an ecosystem?
- collect random sample for organisms
- Identify each of the organisms found
- Count the total number of organisms
- calculate D (the index)
What’s ‘n’ in the Simpson Diversity index calculation?
the number of individuals per species
What’s N in the Simpson diversity index calcilation?
The total number of organisms
What do we need to obtain from our sample in order to calculate the Simpson Diversity index?
the number of species and the number of individuals of each species
Do we need to actually be able to identify each individual species in order to calculate a Simpson Diversity index?
no, just distinguish between the,
What is the Simpson Diversity index generally rounded up to?
Usually to 1d.p
What’s the relationship between the value of the Simpson diversity index and the biodiversity of an ecosystem?
The closer to 1 the value is, the higher the biodiversity of the area
What is the value of the Simpson diversity index always less than?
1
What does the Simpson Diversity index take into account?
Both the variety of species and how many there are of each one
What does having more evenly distributed species lead to?
higher biodiversity
What is the Simpson Diversity index particularly useful for?
Comparing different habitats which may have similar conditions except for 1 factor, for example pollution or being near a road
What are some sources of error when investigating the biodiversity of animals?
Possibility of recounting as they move
Some are camouflaged
Some are easier to catch than others
Can misidentify
What are possible sou
Polymorphism actual definition
More alleles for a specific gene than can be explained by mutation alone
What are the 3 main ways of classifying adaptations?
Structural
Behavioural
Physiological
Structural adaptations + example
Physical differences (e.g - giraffe neck)
Behavioural adaptations + example
Differences in patterns of activity (e.g - tortoises hibernating)
Physiological adaptations + example
Variations in detection and response by vital organs (e.g - elephants with ears sensitive to lower frequencies)
What is it that’s we’re comparing the similarity of during DNA hybridisation?
DNA base sequence
(Not just DNA in general)
What does the lowest different in separation temperature between 2 organisms compares to others mean?
They have the most recent common ancestor
What’s it important to ensure when assessing the biodiversity of an area?
That we have a low range in our results
That we survey a large enough area
How many decimal places is Simpson’s Diversity Index usually rounded to?
2
What do you need to remember to include in hazard and risk questions?
When this risk is there
How do we assess diversity within 1 species?
look at the number of alleles for a specific gene
