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GEOG0020: Ecological Patterns and Processes > Biodiversity & Island Biogeography > Flashcards

Biodiversity & Island Biogeography Flashcards

1
Q

when was the term biodiversity coined

A

1986

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2
Q

how was biodiversity initially defined

A

“Biological diversity“ means the
variability among living organisms from all sources … and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.

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3
Q

define species diversity

A

number of species present

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4
Q

define species density

A

number of species per area

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5
Q

define species evenness

A

Degree of equality in the
distribution
(Pielou 1975)
maximum evenness = all species have the same number of individuals (same cover, biomass, etc.) in a given area

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6
Q

define alpha diversity

A

richness of the community in number of species

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7
Q

define beta diversity

A

extent of species replacement or biotic change along environmental gradients

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8
Q

define gamma diversity

A

richness in species of a range of habitats (a landscape, a geographic area, an island),

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9
Q

who came up with alpha beta and gamma diversity

A

whittaker 1972

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10
Q

list the 8 biomes

A 
tundra, 
taiga, 
steppe & cold desert, 
temperate deciduous forests
mediterranean shrubland,
hot desert, 
tropical grasslands and savannah,
tropical rainforest
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11
Q

5 ways to express alpha diversity

A

1) the number of species
2) Berger-Parker-Index (Dominance)
3) Simpson‘s Index
4) Fisher‘s alpha
5) The Shannon-Wienert (-Wiener /-Weaver) Index

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12
Q

what is the idea behind the berger-parker index

A

What is the proportion of the most dominant species in the sample?

so, the greatest value indicates equal distribution

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13
Q

what is the idea behind Simpson’s index

A

Probability that two individuals drawn from the
same population represent the same species

so, the greatest value indicates equal distribution

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14
Q

advantages and disadvantages of recording a diversity by counting number of species

A

Advantage: Very easy to use and understand
Disadvantages: Does not consider ABUNDANCE of species, mostly NOT applicable for mobile organisms

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15
Q

advantages and disadvantages of berger-parker index

A

Advantage: extremely easy to calculate and to interpret, often works astonishingly well
Disadvantages: heavily influenced ONLY by the most dominant species, species number has no influence

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16
Q

advantages and disadvantages of simpson’s index

A

Advantage: Widely used
Disadvantage: Strongly influenced by distribution pattern

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17
Q

advantages and disadvantages of fisher’s alpha

A

Advantage: Very widespread, independent of sample size for larger N (and/or low overall diversity)
Disadvantages: Difficult to calculate (parametrical index, empirical approach), theoretical prerequisite: log-series distribution

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18
Q

advantages and disadvantages of shannon-wienert index

A

Advantage: Widely used (comparisons!)
Disadvantage: Generally considered as rather unsuitable!

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19
Q

what is the latitudinal gradient of species diversity

A

General tendency for diversity to increase towards the tropics

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20
Q

how does a site’s primary productivity effect it’s species diversity

A

more species at more productive sites

21
Q

How do species numbers develop on islands with former land-bridge connections?

A

On formerly connected islands, species diversity decreases over time, until an equilibrium is reached, as can be seen for the species diversity of lizards on former land-bridge islands in relation to time since isolation.

22
Q

what is the key factor determining number of species on an island

A

island area (size)

are - diversity pattern

23
Q

how can alpha and beta diversity be used to find gamma diversity

A

a*b=y or sometimes a+b=y

24
Q

advantages and disadvantages of using alpha diversity

A

ADV: easy to use and understand
DISADV: doesn’t account for abundance, not applicable to moving organisms

25
Q

how to calculate berger parker index

A

1/(number of individuals of most common species/total number of individuals)

26
Q

how to calculate simpsons index

A

1- (SUM all species ((no of individuals of a species/no of individuals)^2))

27
Q

how to calculate fishers alpha

A

species number = alpha term * log (1+ (total no of individuals/ alpha term))

28
Q

what are the flaws in species knowledge and sampling

A

very partial (most species have not been described), inaccurate (taxonomy errors), biased )v western)

29
Q

how many known species

A

1.9m

30
Q

describe the global gradient of species diversity

A

latitudinal, with more diversity near the tropics and less near the poles

31
Q

reference for latitudinal gradient of sp. Div.

A

cox and moore 2000

32
Q

which factor could be argued to explain the latitudinal gradient of species diversity

A

positive relationship between potential evapotranspiration and species

33
Q

how much variation is there to the number of birds on an island

A

v stable equilibrium

34
Q

what determines the number of species that can live on an island

A

the area of the island - amount of space available

35
Q

formula to express how many species can live on an island

A

“S=CA^Z
S = no of species
C = constant representing expected diversity
A = Island area
S= slope parameter when S and A are plotted logarythmically”

36
Q

which 2 population forces balance to create the equilibrium of species on an island

A

immigration of new species and extinction of old species. The point at which they intersect is the equilibrium

37
Q

which species can colonise remote islands

A

bats, landbirds, insects and molluscs can cross ocean gaps over 2000 miles, lizards can do 1000 miles, tortoises and rodents 500 etc

38
Q

why could species good at dispersing to different remote islands be bad colonizers

A

they could easily be blown away from the remote area e.g. birds

39
Q

why do flightless birds develop on islands

A

allows them to colonize the island and remain on it easier

40
Q

how does island size impact the number of species that can live there

A

more extinction on small islands

41
Q

which factors affect immigration/colonization rate

A

isolation of the island - bigger immigration pool if there are other islands/land nearby

42
Q

main 2 drivers of the species richness equilibrium

A

area and isolation

43
Q

how valid are observations on islands for closed off conservation areas (effectively enforced islands)

A

visible saturation ccurve, so to some degree terrestrial islands are have similar driving factors

44
Q

reading for island biogeography theory

A

gorman 1979

45
Q

how is diversity impacted if an island had a former land bridge connection to mainland

A

higher species diversity, but decreases over time in relation to time since isolation

46
Q

how fast do newly isolated islands take to reach species equilibrium

A

varies by size, but up to 20k yrs for birds, 30k yrs for lizards

47
Q

factors impacting time taken for newly isolated island to reach equilibrium

A

island size, taxonomic group in question, habitat requirements

48
Q

what can data about species richness loss in newly created islands tell us about nature reserve design

A

needs as large area as possible, one large habitat is better than many smaller habitats with same total area. If needed due to predators, keep them enar each other. keep source area nearby (not too isolated), try and create corridors to source area

49
Q

when may isolation be useful in nature reserves

A

protecting from predation e.g endangered european tree frog eats all endangered great crested newt tadpoles

GEOG0020: Ecological Patterns and Processes (9 decks)

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