Easter Flashcards
What is biodiversity?
The different kinds of species and life found in an area
How do humans effect biodiversity?
- 20-40% of primary productivity effects
- Biofuels generates further stress
How is mapping of biodiversity achieved?
Species range mapping
1. Sample
2. Analyse
3. Map or model
Describe the degree of biodiversity around the world
Poles - low
Tropics - high
Mountain ranges
- High due to elevation gradient, change in environment within short distances
- Isolation of areas, leading to speciation
What governing body regulates and targets biodiversity and extinctions? Give examples of what they do
The International Union of Conservation of Nature (IUCN)
- Generate red lists to mark endangered animals
What does the Millennium Ecosystem Assessment show?
- Mankind has increased the rate of extinctions
- Done by mapping changes in the number of species, using fossils and models to also predict future changes
Why is the rate of extinction not as great as expected?
- Species- area relationship
- Shows a slope of 0.25, suggesting that changing area occurs much faster than its effect and change in rate of extinction - Extinction takes time
- there may not be a viable population however it can take time for them to fully die out
- 0.2 - 0.5% species per year
What can be done to tackle the effects of anthropogenic actions on biodiversity? (3)
- Identify areas at risk (by mapping)
- Inform and promote governments to act (e.g. Dasgupta review, COP panels)
- Develop protected networks (put into legislation)
How can deforestation rates be quantified?
- Satellite imaging, detecting reflectance of different surfaces
- e.g. Landsat 1972, at 30m resolution - Ground based imaging
What is the difference between Euchromatin and Heterochromatin?
- Structure
- Euchromatin is less condensed, more accessible, less DNA methylation - Transcriptional activity
- Euchromatin - transcriptionally active
- Hetero - inactive - Genetic content
- Hetero - contains lots of repetitive DNA sequences - Function
- Hetero - gene silencing, maintenance of structure
Euchromatin- active gene expression
What is the Normalised Difference Vegetation Index (NDVI)?
- Used to asses the density and health of vegetation
- Can be used to monitor changes over time
- Measures the near infrared reflectance band and red reflectance band
NDVI = (NIR-R)/(NIR+R) - Used by farmers, habitat managers etc.
What is the value range for NDVI and what do they mean?
Range from -1 to 1
1 = densely vegetated and healthy
-1 = signifies no vegetation e.g. rock
0 = minimal vegetation e.g. soil or urban areas
What is an example of deforestation tracking?
Deforestation tracking in Chile
Echeverria et al., 2006
- Showed an increase in deforestation and fragmentation
How can fragmentation be quantified?
Lidar imaging using a plane
- Can be used to monito number of patches and patch size
- As well as changing size of the core area
- Can be used to produce a 3D image of the forest area
What are the 4 key consequences of fragmentation?
- Increased access
- Increases deforestation
- Illegal logging
- Settlement formation
- Farming/ pasture land formation
- Overexploitation, bushmeat and orchids - Increased edges
- Increased mortality of trees - Negative effect on carbon emissions
- Disconnection effect on habitats and ecology
- increased extinction rates, theory of Island biogeography developed by McArthur and Wilson in 1967
What are some studies into the effects of fragmentation?
Laurence at al., 2000
- Death of large trees in the edge border between 0-300m in
- Greater percentage of death of trees with a larger radius
Putz el at., 2014
- Carbon loss due to fragmentation is equivalent to 9-24% of carbon emissions of deforestation
How can fragmentation be minimised or dealt with?
- Produce larger fragment areas that remain as core areas
- Ensure the fragments are still in close proximity
- Formation of corridors to connect different fragments e.g. land buying in the USA and Mexico to avoid disjoint over state lines and border lines
How can different forest types be identified?
Hyperspectral data collection
- Use a plane and collect reflectance of a variety of different wavelengths that are reflected from different forest types
How can the history of vegetation be constructed?
- Pollen analysis
Shows abundance and types of plants - Fossils
How has the landscape of the UK changed since 130,000 Ya?
Used to be Savannah like with low density due to the presence of large animals
- After interglacial period
More grasslands and woodlands developed
- Then humans began to change the landscape ~2000
- An account was taken in the Doomsday book
- Continual decrease in biodiversity due to settlement expansion and conversion of land to arable land
What is arable land?
Land that can be used to grow crops
What is a woodland?
Land that contains a shrub layer and woody trees, however not as dense as a forest
- can be exploited for timber
What are pastures and meadows?
Pasture- area of land for grazing livestock
Meadows - area of land cut for hay
How has nature protection been established in the UK?
Introduction of national reserves in 1949
- 224 national nature reserves (NNRs)
- Sites of Special scientific interest (SSSI) that are protected
What are calcaerous grasslands? How have they changed?
Calcaerous grasslands are grass areas grown on calcaerous rock
- Have a high pH of around 7-8
Changes = Decrease in presence due to conversion to arable land and settlement expansion
Why is grazing important?
- Increases biodiversity by allowing other plants to grow
- Prevents full succession to woodlands
- Helps plants build up resilience
- Nutrient recycling
What types of species are found in woodlands?
Spring ephemeral - bluebells and Oxlip
- bloom in early spring to avoid shading from taller trees
Trees- oak, beech and maple
Shrubs- hawthorn
How can woodlands be managed?
Rewilding
- Reduce fragmentation
- re-introduce species
Management of wildlife
Selective logging
What are linked traits and what is crossover recombination?
Linked traits- genes that are found on the same chromosome
Crossover recombination - Crossover of chromosomes, resulting in splitting of linked traits
What are the characteristics of cereals that make them good crops (3)?
- High protein and starch content
- Storable
- Germinate every year
How was the hexaploid wheat genome formed?
- Hybridization of 3 diploid progenitors
- Contributing to A, B and D genomes
What is conscious and unconscious selection?
Conscious selection - targeted selection, e.g. via CRISPR e.g. Sr gene for stem rust resistance, DREB genes
Unconscious selection - selection that is not controlled e.g. natural selection e.g. Ph1, B and Q gene
What is the role of the Ph1 gene? What are the effects of ph1 mutation?
Regulates homologous pairing during meiosis
- Carried out by regulating CDK which controls cell cycle progression
- Ensures that homeologues don’t pair up
MUTANT = Infertile
What are the roles of the Br, Q and tg gene?
Br = brittle, mutation reduces brittleness, causing retention of grain
Q and tg = cause soft shell
What genetic changes occurred in the green revolution and who pioneered it?
1960s Norman Borlaug
- Rht gene causes reduced height
- Regulates DELLA and GA signalling
DELLA = inhibits growth
GA = inhibits DELLA by ubiquitination
Give an example of disease resistance in wheat
Sr gene conferring resistance against most variants of stem rust fungus
- Except Ug99
How can genetic diversity be reintroduced to wheat?
Find extant progenitors that are related to Triticum
- Generate synthetic wheat
- Within the genome will be wild genes
Compare and contrast conscious and unconscious selection in crop domestication, providing examples.
Time - Conscious is more rapid, Unconscious occurs over long tie and many generations
Scale - Conscious targets a specific species e.g. crop, while unconscious can target a whole ecosystem
Intent- Conscious aims to increase yield and economic value of plant, while unconscious increases survival chances e.g. shattering seeds
Describe a gene that has been selected for crop domestication
Rht
- Rht represses GA, and preserves DELLA that inhibits growth
- Achieved by removing N terminus so GA + GID-1 can’t bind
- This causes reduced height
- Increases yield and reduces lodging
- Developed by Norman Borlaug, via unconscious selection
Q gene
- Alters shape and size of the flower by altering APETALA
- Leads to greater ease of threshing, decreased fragility of rachis
- Increases yield, by greater efficiency of farming and reduced lodging
- Unconscious selection
What are the uses of hybrid vigour?
- Crossing of ecotypes and different species to generate a fitter offspring
- Can be used to introduce wild genes, increasing genetic diversity
- This can be used to develop disease resistance
- A form of supercrop can be formed with all the desired phenotypes
What is genetic bottlenecking? What are the disadvantages and how can it occur?
- Inbreeding/ continuous selection of plants that results in a reduction of genetic diversity
- Can be done to acquire a desired phenotype
- Decreased disease resistance
OCCURRENCE - Isolation, fragmentation
- Overhunting
- Natural disasters
What are the uses of CRISPR in the lab?
- Generate inducible second knockouts/mutations
- These may be lethal and so need to be induced into a plant that already contains one mutation, as growth of double mutant may not occur
State some uses of genetic screens and mutant lines (5)
Discover/ Monitor
- Flower time
- Leaf development
- Hormone signalling
- Metabolism
- Circadian rhythms
Describe EMS as a chemical mutagen
Causes C:G to switch to A:T
- Results in amino acid change
- Premature stop codon
What is QTL analysis used for?
Analyse of quantitative traits
- Affected by multiple genes
- Often show normal distribution
How does skewed crossover occur?
- Crossing over of individuals, showing uneven spread of phenotype
- Some degree of linkage drag
- Some regions show low recombination (e.g. transposon and DNA methylated rich)
Describe marker assisted selection
- Use marker such as SNP and microsatellites
- Markers are linked with traits
- Monitor presence of markers, assist for selection
= Increases efficiency of introgression
What is heterosis?
When F1 population shows better phenotypes that the parents, opposite of inbreeding depression
What are the 3 reasons for heterosis?
- Complementation - cross inhibits deleterious gene from being expressed
- Overdominance - heterozygous mix is better than homozygous e.g. Single flower truss in tomatoes
- Epistasis - interactions between other alleles more beneficial
How can male sterility be engineered?
- Spray with N-acetyl phosphinothricin
- Forms toxin that destroys tapetum
- Lack of tapetum prevent pollen development
What is apomixis?
Asexual reproduction
- used to generate clone descendant
- Naturally carried out by blackberries and dandelions
1. Bypasses meiosis
2. Bypasses fertilisation
What are 2 genes that generate lab induced apomixis?
- Baby boom TF
- Stops the need for fertilisation - MiMe
- Converts meiosis to mitosis
- Removes a round of division
- Generates diploid daughter
What is somaclonal variation? Provide an example
Phenotypes are different in clones due to epigenetics
- Lamarckian evolution suggests that the environment can alter genes
e.g. Karma transposon that is methylated, to generate a deleterious phenotype
What are the two ways in which clones can be generated?
- Vegetative propagation
- Stem and root cuttings planted and form new plants - Cloning in the lab
- Grow plant tissues on plates
What are 3 ways in which nutrient uptake can be engineered to be better?
- Change in transporter expression
- e.g. Pht5 overexpression - Nodulation changes
- generate crops that can symbiosis with rhizobia - Plant artificial chromosomes
- introduce beneficial genes
What are transposons?
Mobile elements that move in the genome
- Discovered by Barbara McClintock in maize
- Heavily methylated regions
- Able to disrupt genes
What are 3 ways in which photosynthesis efficiency can be increased?
- Engineering active site of Rubisco (affinity)
- C4 plants
- Developmental regulation
- optimise factors by changing architecture
- Develop tolerance to certain conditions such as sub1 (flooding)
Describe the advantages of producing clones versus hybrids during crop breeding.
- Genetic uniformity
- Desirable traits are kept
- Rapid multiplication (via cuttings and lack of breeding required)
- Heterosis (hybrid vigour)
- Genetic diversity (for pathogen resistance)
What is cytoplasmic male sterility (cms)? Give some examples
Lack of male organs due to mutations or changes to mitochondrial or chloroplast genome
- Leads to lack of ability for self fertilisation
- T-urf13 in Maize
- Boro II in rice, increase ROS so lack of pollen
What is co-suppression?
Integration of transgene led to endogenous gene silencing
e.g. changes in pigmentation in Petunia
What are TALENs?
Transcription Activator Like Effector Nucleases
- Repeat variable diresidues (RVD), bind specifically to DNA and regulate expression
- used to study effects of knockouts
Give examples of conscious and unconscious selection in wheat
Conscious - Sr gene for stem rust resistance,
Unconscious - Br and Q gene, Ph1 (homologous not homeologous recombination)
Give examples of post-translational modifications that occur in plants
NRT1.1 - phosphorylation = HA, dephosphorylation LA
TPK1: Activated by Ca2+ and 14-3-3 proteins
H+ ATPase: Pi and 14-3-3 binding
What are the various roles of suberin?
- Wound healing
- Casparian strip formation, controlling apoplastic movement (e.g. of Fe2+)
- Drought and salinity tolerance
