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ecosystems Flashcards

1
Q

what is ecology

A

the study of interactions between organisms and their environment

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2
Q

list some physical factors that have an effect on ecology

A

temperature, water, sunlight, wind, soil chemistry, disturbance etc

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3
Q

list some biotic factors that have an effect on ecology

A

predator/prey, parasites, symbionts, competitors etc

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4
Q

what are the different levels of ecological organisation

A 
biosphere
biome
ecosystem 
community
population
individual
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5
Q

what is the biosphere

A

the parts of the earth inhabited by organisms

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6
Q

what is the biome

A

a climatic region e.g. tundra, deep sea, savannah, tropical rainforest

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7
Q

what is an ecosystem

A

the functional unit of ecology: the organisms in a habitat type that interact to create its structure e.g. rainforest in the amazon catchment

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8
Q

what is a community

A

a subset of the ecosystem that is found in one location e.g. amazon rainforest birds, their prey and predators

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9
Q

what is a population

A

the members of one species that interact together e.g. macaws

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10
Q

give some global patterns in biodiversity

A
  • species are not evenly distributed over the earth’s surface
  • different taxonomic groups often show parallel patterns of biodiversity e.g. rainforest is a favourable environment for amphibians, mammals and birds
  • distribution of threatened species is not similar for different taxonomic groups e.g. rare birds - Pakistan, rare mammals - south east Africa
  • there are more species near the equator than the poles
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11
Q

what are the most likely explanations for the greater number of species near the equators

A

there is greater climatic stability and productivity at the equator, leading to greater speciation/smaller niches.
at the equator there is the same amount of daylight all year round and the climate is warmer

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12
Q

what happens to the mammal biodiversity when forest size is increased and why

A

mammal biodiversity increases - some species need a larger range than others so the increase in range allows more species to inhabit the forest

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13
Q

what is an island

A

can be an island of one habitat e.g. woodland, water

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14
Q

what do immigration and extinction rates depend on

A

island size

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15
Q

what does the equilibrium number of species depend on

A

the equilibrium number of species depends on the size of the island and the rate of immigration and extinction

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16
Q

compare a small island to a large island in terms of their immigration and extinction rates

A

immigration rate is greater in large islands compared to small islands
extinction rate is greater in small islands compared to large islands

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17
Q

what does McArthur and Wilson’s model of habitat locations suggest about species diversity

A

greater barriers to colonisation will result in lower diversity
i.e. the further away an island the less species inhabit it

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18
Q

what are the global patterns in body size

A

Bergmann’s rule - find larger bodies at higher altitudes because temperature decreases at higher altitudes - larger mammals experience less heat loss
body size is larger in regions of low biodiversity
members of a tropical species of bird are more consistent in size than members of temperate species

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19
Q

do all organisms need energy

A

yes - either form the sun, chemicals or each other

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20
Q

in most ecosystems how is energy form the sun converted into organic molecules

A

by primary producers - by photosynthesis

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21
Q

what is gross primary production (GPP)

A

the total amount of energy generated by autotrophs in an ecosystem

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22
Q

what is an autotroph

A

an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

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23
Q

what is net primary productivity (NPP)

A

how much of the GPP is available to other organisms (autotrophs use some of the energy)
NPP = GPP - respiration by autotrophs

24
Q

what fraction of GPP is usually NPP

A

half

25
Q

in what regions of the earth is NPP greatest

A

equatorial regions, with high rainfall

26
Q

what factors can constrain NPP

A

energy (temperature, light penetration of aquatic ecosystems)
water (for terrestrial ecosystems)
limiting nutrients (nitrogen or phosphorus)

27
Q

what are the levels of the food chain

A

primary producers - plants
primary consumers - herbivores secondary consumers - carnivores
tertiary consumers - top carnivores - no predators

28
Q

give an example of a food chain

A

oak tree leaves eaten by caterpillars, which are eaten by robins, which are eaten by sparrow hawks

29
Q

what is the relationship between the levels of the food chain and their biomass

A

as you go up the levels of the food chain the biomass decreases

30
Q

what is the effect of losing energy from at each stage in the food chain

A

the number of links in the food chain becomes limited - this can be demonstrated by limiting the number of leaves in a tree hole

31
Q

in bottom up control what is the effect of increasing the energy or nutrient supply of the primary producers

A

energy or nutrient supply will increase at all levels of the food chain

32
Q

what does it mean if an ecosystem is under top-down control

A

herbivore numbers are limited by predators, not by primary production

33
Q

what is the effect of adding a top carnivore to a top down control system

A

it increases the number of herbivores

34
Q

food webs are usually more ………….. than a food chain

A

complicated

35
Q

what is a dominant species

A

are simply the most common/have biggest biomass

e.g. mussels are dominant species on a mussel bed

36
Q

what are keystone species

A

not necessarily numerous but have pivotal role because of their niche
e.g. sea star Pisaster feeds on mussels so creates gaps for other species

37
Q

how do red deer affect the hills in Scotland

A

they browse and prevent trees from growing, keeping the hills as moorland rather than woodland

38
Q

what is bioaccumulation

A

increasing concentrations of pollutants and other non-metabolised molecules up the food chain e.g. DDT, PCBs, methyl mercury

39
Q

what is the effect of DDT

A

cause egg-shell thinning in birds – but only at end of food chains, due to higher DDT concentrations - wiped out predator populations (birds of prey, pelicans, seabirds)

40
Q

what are detritivores and scavengers

A

they mop up dead bodies and toxins can also bioaccumulate in them because they have the same diet as predators but they don’t kill the animal

41
Q

many chemicals can act as ……… and enter rivers from sewage and feminise male fish

A

oestrogens

42
Q

what are the two types of competition

A
  • Intraspecific competition: between members of same species
  • Interspecific competition: between species
43
Q

why does competition arise

A

Arises because of resource limitations

44
Q

what does the competitive exclusion principle state

A

if two species compete for the same resource, one will drive other to (local) extinction

45
Q

what is an ecological niche

A

the position of a species within the ecosystem

46
Q

what is the niche of a sloth

A

tree-top large herbivore

47
Q

what is the fundamental niche

A

niche potentially occupied by a species – without any competition to affect the niche

48
Q

what is a realised niche

A

niche actually occupied by that species – due to competition

49
Q

what word describes coexisting

A

sympatry

50
Q

what word describes species living separately

A

allopatry

51
Q

what is character displacement

A

• A tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species - results in reduced competition

52
Q

the lynx and snowshoe hare show ………. 10 year cycles

A

parallel

53
Q

as well as influencing the numbers of prey, how else can predators affect their prey

A

they can influence their behaviour

e.g. zooplankton dive deeper during the day to avoid fish

54
Q

describe the arms race between bats and moths

A
  • Moths fly at night to avoid predatory birds
  • Bats evolve echolocation to fly at night and feed on moths
  • moths listen for bats’ echolocation clicks and either fly erratically, respond with own clicks or drop out of sky
  • Some bats produce only quiet clicks when approaching a moth
55
Q

what are the 2 ways that parasites can change the behaviour of their host

A

the host may change behaviour to avoid the parasite

parasites changes behaviour of host to increase transmission

56
Q

mutualism can either be facultative or obligate what does this mean

A

facultative - the relationship is optional nut not essential

obligate - the relationship is essential for survival

A (17 decks)

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