Final Exam Review Flashcards
What was the 1992 Rio Earth Summit?
Conference with over 100 countries participating on Environment and Development
What is Agenda 21?
The product of the Rio Earth Summit, it’s a document which outlines the international plan of action for sustainable development and key policies for environment and sustainability
- Became the blueprint for sustainability and forms the basis
for sustainable development strategies
UN Definition of “Biodiversity”
“the variability among living organisms from all sources, including, inter alia, terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems” (UN 1992)
when did the word “Biodiversity” first appear?
First published appearance in 1988 by E.O Wilson as a contraction of “biological” and “diversity”
Is there a single definition of Biodiversity?
No, there are actually more than 25 definitions
- “the totality of genes, species, and ecosystems in a region or the world”
- “functional diversity ‐ thevariety of different responses to environmental change, especially the diverse space and time scales with which organisms react to each other and the environment”
Basic definition of Biodiversity
Biodiversity is the variety of life in all its manifestations
Examples of biodiversity
Species diversity, genetic diversity, molecular diversity, ecological diversity, etc.
How many species are there on earth?
We don’t really know, estimates are around 10-100 million
Can we make accurate predictions of the number of species?
Mora et al. (2011) showed how higher taxonomic classification of species follows a consistent and predictable pattern from which the total number of species in a taxonomic group
can be estimated
- Linear increasing line
Have most species been discovered already?
No, most species actually have not been discovered. The majority of them being insects (most) and bacteria
What is the correlation of description date with species geographic region (carnivores and primates)?
Date of description vs geographic range is correlated in that species with a very large geographic range were described earliest, and rarer/smaller geographic range species have only been described more recently.
What are the distinctive attributes of ‘newly discovered’ species?
- geographically restricted
- small body size
- live in difficult to access locations
- small population size
- high risk of extinction
- hard to distinguish morphologically
- nocturnal
- Symbiont with another organism we already know of
- probably an insect or beetle
Global species richness is difficult to measure, how could you estimate species richness?
Chao et al., 2011 - The simplest non-parametric estimator of true species richness in a community (= asymptote of species accumulation curve)
S(est) = S(obs) + a^2/2b
what is a species abundance distribution (SAD)?
A species abundance distribution graphs the number of species (y axis) by the number of individuals represented in sample (x axis)
what is a rank abundance distribution?
A rank abundance distribution graphs the abundance of individuals (y axis) by the species rank (usually from most abundant to least) on the x axis.
(usually looks like a decreasing exponential graph)
what is the advantage of modelling species richness as a log series?
species richness (S) can be estimated simply as
S = alpha*ln(1+N/alpha)
where N = number of individuals sampled
alpha = Fischer’s alpha (calculated from ur data set)
what is Fischer’s alpha?
Fixed values calculated for the number of species (S) and number of individuals minus number of species (N-S) in a sample
what is Preston’s log-normal distribution of species abundance?
- If you sampled all the species in an area, they would graph a log-normal distribution on # of species (y axis) by log abundance (x axis).
- however, it requires extensive sampling before the log‐normal distribution becomes evident or accurate
what is Preston’s Veil Line?
There are always a few rare species that are missed in sampling, so you must do extensive sampling to remove this veil on the very rare species to achieve more accurate richness
what is alpha in Preston’s log-normal distribution?
‘a’ represents the equitability of species and is typically ≈ 0.2
what are Whittaker’s spatial levels of diversity?
An hierarchical structure composed of alpha diversity, beta diversity, and gamma diversity
what is Alpha Diversity?
Local diversity within a community
what is Beta Diversity?
Diversity between communities
- When you have two communities, there may be some overlap in the species present in both. Beta diversity would be the remaining species that are NOT in both samples (species which are not overlapping)
what is Gamma Diversity?
Total diversity within a region (basically result of combining alpha and beta diversity)
what does Jaccard’s formula measure?
This formula can be used to measure beta diversity using presence-absence data
what does Sorensen’s formula measure?
Another way to measure beta diversity using presence-absence data
- Tends to give higher estimates
what is Nestedness?
a pattern of biodiversity which represents the species in a site may be a subset of a larger group of species present in another site
what is Turnover?
Turnover is a pattern of biodiversity which indicates replacement and occurs when the loss of species is counterbalanced by the gain of new others in a site
How does Nestedness and Turnover relate to Beta Diversity?
These two are additive components of biodiversity which together reflect the two basic mechanisms underlying the overall change in species identities across the landscape (the replacement of species or their loss) and how much overlap there is between sites.
What does Sorensen Dissimilarity Index (Bsor) measure?
Bsor incorporates both spatial turnover and differences in richness to measure beta diversity
What does Simpson Dissimilarity Index (Bsim) measure?
Bsim measures the species turnover without the influence of richness gradients
How can you calculate Nestedness?
you can combine Bsor and Bsim to get the formula
Bnes = Bsor - Bsim
What are the variables a, b and c in terms of sites and overlap?
a = overlap between sites b and c
b = # of species in site b
c = # of species in site c
what does Bray-Curtis Dissimilarity measure?
This accounts for abundances of species in measuring beta diversity between two sites
Cij = the sum of the lesser values for the species common to both sites
Si and Sj = total number of individuals counted at both sites respectively (all individuals of all species summed)
what are the primary determinants of species richness?
- Theory of island biogeography
- Emigration and immigration rates
- Climate and environmental pressures
What is MacArther & Wilson’s (1967) equilibrium theory of island biogeography?
Theory that there is a dynamic equilibrium between the immigration of new species to an island and the extinction of species previously established on that island
- Graph shows number of species present (x axis) and rate of change in number of species (y axis) where immigration and extinction lines intersect at the equilibrium point
Theory of Island Biogeography - How does distance of the island from mainland impact equilibrium?
Islands closer to the mainland may have higher rates of immigration
Those farther away have much lower rates of immigration
Theory of Island Biogeography - How does size of the island impact equilibrium?
Larger islands tend to have lower rates of extinction because they can support more species
Small islands have less space and higher rates of extinction
Theory of Island Biogeography - How do environmental/climatic factors impact equilibrium?
Wind/sea currents, dispersal abilities of species, island climates, etc. can all impact the rates of immigration and extinction
Theory of Island Biogeography - Species-Area Relationship formula?
S = CA^z
S = number of species present
C = constant which varies with the taxonomic group under study
A = area of the island
z = constant (island situations usually around 0.3)
Theory of Island Biogeography - What does the Species-Area Relationship demonstrate?
This formula shows the relationship between area of the island and the number of species it supports
what is the SLOSS debate?
SLOSS = Single Large Or Several Small (areas)
- Since species richness increases with area, a larger block of habitat would support more species than any of the smaller blocks and would therefore be preferable to conserve
what is Z in species-area curves?
Z is the slope on a graph of number of species by area, giving the percentage of species expected to go extinct
- Values of Z seem to lower for mainland systems compared to islands (or small geographic areas)
What happens to species richness if you increase area?
Species richness increases fairly linearly with habitat area (log scale)
define Evenness (of species)
Evenness is a description of the distribution of abundance across the species in a community. Species evenness is highest when all species in a sample have the same abundance
why is evenness an important component of biodiversity?
more even species abundance distribution means a more diverse community
what is Shannon’s Diversity Index (H) ?
a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species.
- it is particularly useful when comparing ecosystems or habitats
what is the usual range of Shannon’s Diversity Index?
Typically in the range of 1.5 (low richness and evenness) to 3.5 (high evenness and richness)
what is Simpson’s concentration index (λ) ?
A weighted arithmetic mean of proportional abundance and measures the probability that two individuals randomly selected from a sample will belong to the same species
- given by λ (lambda)
what do small versus large values of λ mean for Simpson’s concentration index?
small values of λ = dataset with high diversity
large values of λ = dataset with low diversity
What is 1-λ (Simpson’s concentration index)?
1-λ = the probability that two individuals taken at random are from different species
What is Berger and Parker’s dominance index?
Measures inverse dominance, so that the more dominant the most abundant species, the lower the index.
d = P1
P1 value equals the relative abundance of the most abundant species
what is in common between all the diversity measures (Species richness, Shannon, Simpson, Berger & Parker)?
- They all combine species relative abundances to yield a sum
- They give different weights to relative abundances by raising them to different powers
What is entropy? In relation to diversity?
Entropy is the quantitative measure of disorder in a system
- Entropy/diversity is maximized (for a fixed n) when all the species occur in equal abundance
What is Renyi Entropy?
Renyi entropy is a generalized entropy measure of order a which, when calculated, gives the “effective” number of species
How does ‘a’ influence the Renyi Entropy value?
The higher the order a, the stronger the relative influence of the commonest species and the smaller the sample size necessary to obtain a reliable estimate
What does Renyi entropy return when at order a=1?
at a=1, Renyi entropy returns Shannon (H)
What is Multiplicative partitioning of diversity?
gamma = alpha x beta (diversity)
What is Additive partitioning of diversity?
gamma = mean alpha + beta (diversity)
- mean alpha and beta diversity adds up to gamma diversity
what is Hill’s Diversity Number?
Hill’s diversity mumber = Sa
is the geometric mean of alpha diversity