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1
Q

What is the importance of species definitions? 5

A
  1. species must be defined before we can measure biodiversity 2. definitions aid classification of organisms into discrete groups of similar organisms 3. allow us to understand how discrete groups arise 4. represent products of evolutionary history 5. quantify and explain the variety of organisms that exist
2
Q

Define the different species concepts. 6

A
  1. none work perfectly but some are better than others 2. biological species - groups of actual/potentially interbreeding organisms isolated reproductively from other groups - problematic for plants, microbes and insects - can hybridise 3. evolutionary species - a single lineage of organisms that maintain a separate identity from other organisms/lineages with own evolutionary tendancies and histories 4. phylogenetic species - distinct, irreducable cluster of organisms with common ancestry and descent/the smallest monophyletic group of common ancestry 5. genealogical species - exclusive group of organisms more closely related to each other than organisms outside group 6. recognition species - the most inclusive population of biparental individuals sharing a common fertile system
3
Q

How can we estimate species biodiversity? 5

A
  1. species number/richness 2. species abundance - how many of each species 3. tells of relationship between species 4. heterogeneity (evenness) of species numbers 5. Greater heterogeneity means more diversity, as deaths have less impact
4
Q

What is the Shannon-Wiener diversity measurement.

A
  1. Predicts how difficult it is to predict the species of next individual sampled 2. The easier it is, the lower diversity 3. Range is from 0 to log2s
  2. Comparisons between communities are unadvisable with this
  3. Larger value means more uncertainty.
5
Q

What is Simpson’s index of diversity? 5

A
  1. Depends on species richness
  2. Can compare communities with some species richness.
  3. Finds probability that 2 specimens picked at random are different species
  4. More weight given to common species
6
Q

What are the three scales of species biodiversity? 3

A
  1. alpha diversity - diversity within a habitat
  2. beta diversity - diversity between habitats/how similar they are
  3. gamma diversity - total landscape diversity eg. flora of british isles
7
Q

What are the global terrestrial diversity trends? 3

A
  1. Above ground, diversity increases with decreasing latitude
  2. the tropics support higher biodiversity
  3. this applies for plants and animals
8
Q

What are the factors contributing to diversity gradients? 8

A
  1. history - more time permits more colonisation and evolution of species
  2. habitat heterogeneity - complex habitats mean more niches
  3. competition reduces niche size
  4. predation prevents competitive exclusion
  5. climate - unfavourable tolerated by fewer species
  6. climate variability - fewer species adapted for this
  7. productivity - more productive supports more species
  8. disturbance - moderate disturbance prevents competitive exclusion
9
Q

What are the soil diversity gradients? 7

A
  1. tropic trend not followed
  2. overall, common findings in a scottish field are common globally
  3. High nematode diversity at tropics but peaks in temperate zones
  4. but could be artefact of sampling efforts
  5. doesn’t explain all off trends but will contribute
  6. overall, still significant peak in tropics for nematodes
  7. above ground trends mirror below for some things
10
Q

What is the intermediate disturbance hypothesis? 5

A
  1. Disturbance of succession at midpoint promotes both pioneer and competitive species
  2. Particularly in tropical grassland
  3. examples of disturbance include fire, tree fall, landslides
  4. in soil, disturbance reduces diversity
  5. eg. making space in soil by root pushing
11
Q

What is habitat heterogeneity? 1

A
  1. Less heterogeneity means more complex, so more niches, so more species
12
Q

Describe the landscape diversity of soil bacteria. 4

A
  1. countryside survey audits UK land use
  2. carried out every few years
  3. information on flora, fauna and environmental variables collected
  4. last survey included analysis of soil bacterial communities from 1000 cores across the uk
13
Q

Describe the bacterial biogeography of british soils, as described by Griffiths et al., 2007. 8

A
  1. bacterial communities associated with most environmental factors measured
  2. broadly follows same patterns as plant communities
  3. pH major factor in determining diversity and community structure
  4. relationship shanges depending on scale measured
  5. positive relationship between alpha and gamma diversity and pH
  6. negative relationship between beta diversity and pH
  7. more alkaline soils are more similar
  8. within site, diversity increases as alkalinity increases
14
Q

What are the seasonal assemblages of arbuscular mycorrhizal fungi, according to dumbell at al., 2011? 6

A
  1. Single site study of arbuscular mycorrhizal fungi on plant roots from a temperate grassland
  2. change in communities over time
  3. summer and winter communities very different
  4. negative relationship between temp. and diversity
  5. higher diversity in winter
  6. may be due to increased competition for scarce resources
15
Q

How can we measure soil diversity? 3

A
  1. Very difficult
  2. need to define what counts as species/individual
  3. how do you measure richness and abundance without them?
16
Q

What is arbuscular mycorrhizal fungi? 5

A
  1. very abundant with global distribution
  2. form symbiotic associations with most land plants
  3. asexual conal lineages - taxonomy defined by clonal isolates
  4. ecological characteristics differ between isolates
  5. no formal species concept
17
Q

Describe AMF (arbuscular mycorrhizal fungi) species definitions. 4

A
  1. taxonomy can also be based on morphology of resting, asexual spores
  2. limited by distinguishing features
  3. very few described species but large diversity revealed by molecular approaches
  4. diversity within and between isolates
18
Q

What is the significance of the rhizobium leguminosarum bacteria genome? 7

A
  1. One circular chromosome and several large plasmids
  2. these are the two main components of the genome
  3. core genes are conserved
  4. accessory geners more labile
  5. different evolutionary histories and trajectories
  6. form nitrogen fixing nodules with legumes
  7. horizontal gene transmission violates phylogenetic species concept
19
Q

Talk about Sinorhizobium medicae bacteria phylogeny. 2

A
  1. different parts of the genome have different histories
  2. isolate position in network changes based on what part of the genome is used
20
Q

How can we measure microbial diversity? 4

A
  1. traditionally used culture techniques
  2. count number of distinct colonies
  3. only able to culture 0.3% of microbial soil diversity
  4. molecular techniques now used
21
Q

How can we separate microbe species with phenotypic analysis? 5

A
  1. Phospholipid fatty acid analysis (PLFA)
  2. Phospholipids are in the membranes of all living cells
  3. different compounds in different microbial communities
  4. measures living component
  5. relative abundance of broad taxonomic groups (bacteria not fungi)
22
Q

How can we determine abundance of microbes using genotypic analysis? 6

A
  1. DNA sequences very more among species than within species
  2. can use PCR based techniques to look at phylogenetic and functional diversity, community diversity and species composition
  3. if 97% similar, isolates classed as same species
  4. we do this with denaturant gradient gel electrophoresis, using terminal restriction fragment length polymorphism (T-RFLP)
  5. Sequencing technologies used
  6. Good for species richness but not abundance
23
Q

Ecology. C. Krebs. 2014.

What are the difficulties in measuring biodiversity? 3

A
  1. finding no species in a community can be difficult because species counts depend on sample size
  2. communities have more rare species than common species
  3. many communities show some abundance curves
24
Q

Ecology. C. Krebs. 2014.

What are some inconsistencies in diversity gradients? 3

A
  1. some fauna eg. those that are seals/sea lions do not increase in diversity at tropics
  2. in USA, many mammals more diverse in temperate zones eg. shrews and pocket gophers
  3. Areas of sudden change often include mountains
25
Q

Ecology. C. Krebs. 2014.

What is the evolutionary speed hypothesis? 2

A
  1. older communities have more species richness - particularly non-interrrupted ones
  2. more diverse may equal fast evolution and low extinction
26
Q

Ecology. C. Krebs. 2014.

Describe some interspecific interactions. 5

A
  1. competition and predation may be keener in tropics - smaller niches
  2. polar/temperature populations more ompacted by environmental factors
  3. does not explain alpha diversity of plants - few limiting factors
  4. more niche overlap means more species - may apply to tropic
  5. important in animals, especially predation
27
Q

Ecology. C. Krebs. 2014.

What is the ambient energy hypothesis? 4

A
  1. Availability of energy is important in maintaining species rich habitats, and creates gradients
  2. lots of evidence to support this
  3. energy includes light, temperature and water
  4. Only explains large gradients, not small ones
28
Q

Ecology. C. Krebs. 2014.

What is the productivity hypothesis? 2

A
  1. thought that greater productivity means greater biodiversity, but no supporting evidence has been found
  2. productivity in plants leads to lower local biodiversity
29
Q

Fundamentals of Ecology. Odum and Barrett. 2005.

What are the types of biodiversity? 4

A
  1. larger areas have more diversity
  2. pattern diversity - due to zonation, patchiness etc
  3. genetic diversity - genetic variability
  4. habitat diversity
30
Q

Fundamentals of Ecology. Odum and Barrett. 2005.

What is the relationship between diversity and stability? 3

A
  1. more stable communities are more diverse
  2. not necessarily causal
  3. in community parts, trophic levels are influential over species diversity