Patterns in Biodiversity

Question 1

What are communities?

Answer 1

Groups of interacting species that occur together at the same time and place

Question 2

Elaborate on communities

Answer 2

Interactions among these species and their physical environment give communities their character and function.
The relative importance of species interactions and the environment can vary.

Question 3

Describe the subsets of defining communities

Answer 3

1. Evolutionary lineage or taxonomic affinity (e.g. just all the birds in a forest)
2. Guild, when species are taxonomically distinct but are using the same resource
3. Functional group, when species are different but function in similar ways.

Question 4

What does species diversity combine?

Answer 4

Number of species (richness) and abundance of species in comparison to other species (evenness)

Question 5

Describe the Sudden Oak Death case study

Answer 5

Phytopthora ramorum is the oomycete causing SOD. Carried out the oak removal experiment in New York to see the repercussions of losing oaks from the community.
Studied ants as there are lots of different species

Question 6

Describe rank-abundance diagrams

Answer 6

Typically lazy-J shape. Abundance measured against rank. Species richness is the number of bars on the RAD

Question 7

Describe the Rabinowitz rarity criteria

Answer 7

1. Size of geographic range (large/small)
2. Habitat specificity (generalised/specialised)
3. Local population density (dense/sparse)
   Species rare by all criteria are the most vulnerable to extinction.

Question 8

Describe diversity indices

Answer 8

Focus on one aspect of the taxa abundance and emphasise either:
richess (weighting towards uncommon taxa) or dominance (weighting towards abundant taxa)

Question 9

Quantifying biodiversity: species richness

Answer 9

Sestimated = Sobserved + Sundiscovered

Question 10

Describe professor Chazon’s work.

Answer 10

Costa Rican Forest - Soil samples, germinating seeds, 34 different species. Seed bank produced a RAD - species not even due to interactions with environment around them

Question 11

Describe species accumulation curves

Answer 11

Initially, each new individual sampled can add a new species. Eventually, further accumulation reveals few or no new species

Question 12

Describe estimating ‘undiscovered species.’

Answer 12

Assuming that the species accumulation curve saturates monotonically, extrapolate to a flat-line and estimate Sundiscovered

Question 13

Describe Chao1 Estimator

Answer 13

Sundiscovered = a2 / 2b
a = number of species represented by a single individual
b = the number of species represented by two individuals

Question 14

Describe Species-abundance distribution

Answer 14

Description of the commonness and rarity of species in a community by means of a frequency distribution of a species abundances

Question 15

What is the Neutral Theory neutrality assumption?

Answer 15

all individuals within a particular trophic level have the same chances of reproduction and death regardless of their species identity

Question 16

Describe neutral theory

Answer 16

Classic neutral theory has a metacommunity (well-mixed source pool of potential immigrants) and a local community. Within the local community, local extinction and immigration from the metacommunity are in equilibrium

Highlights importance of dispersal limitation, speciation and ecological drift in the natural world

Provides quantitative null models for assessing the role of adaptation and natural selection