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Biology > G. Ecology > Flashcards

G. Ecology Flashcards

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1
Q

Factors affecting distribution of plant species

A

distribution closely linked to abiotic factors of the environment

  • temperature
  • water
  • soil pH
  • light
  • salinity
  • mineral nutrients
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2
Q

Factors affecting distribution of animal species

A

affected by both abiotic and biotic factors:

  • temperature - external temperatures affect all animals, especially those which don’t maintain constant body temperature (ectotherms); extreme temperatures require very special adaptations
  • water - animals vary in the amount of water they require to live; e.g. aquatic animals need water to live IN, while some animals (like desert rats) are adapted to live in arid areas
  • breeding sites - all animal species breed at some point in their life cycle; many species need a special type of site (mosquitoes in stagnant water) and can only live where these sites are available
  • food supply - many adapted to feed on specific foods and can only live where these foods are available (red pandas eat mostly the youngest and most tender bamboo shoots)
  • territory - some animal species establish and defend a territory, either for feeding or breeding –> result: clumped distribution (e.g. meerkat clans; Suricata suricata)
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3
Q

Random sampling using quadrats

A
  • random sample - every individual in a population has an equal chance of being selected
  • sample = part of population / area / whatever chosen to illustrate how a whole image looks like
  • random sampling - counting numbers in small randomly located parts of the total area, usually using square frames - quadrats
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4
Q

Random sampling using quadrats - procedure

A
  1. mark out grid lines along two edges of the area
  2. use a gdc or tables to generate 2 random numbers, use them as coordinates and place a quadrat
  3. count individuals inside the quadrat (usually of the PLANT population)
  4. repeat stages 2-3 as many times as possible
  5. measure the total size of the area studied (in m2)
  6. calculate the mean number of plants per quadrat
    population size = (mean no. per quadrat x total area) / area of each quadrat
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5
Q

Transect

A

an alternative to random sampling
investigation animal / plant species distribution along a line marked out across a site
particularly useful when there’s a gradient in an abiotic variable (e.g. seashores)

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6
Q

Ecological niche

A

the mode of existence of a species in an ecosystem

  • habitat - where the species live, including abiotic factors and the set of all ranges of limiting factors an organism can tolerate
  • nutrition - what the species eat & how does it obtain its food
  • interactions with other species
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7
Q

Fundamental niche

A

Potential mode of existence of a species, given its adaptations
Other species prevent a species from occupying its fundamental niche by out-competing or by excluding it in some way

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8
Q

Realized niche

A

the ACTUAL mode of existence of a species

results from its adaptations and competition from other species

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9
Q

Competitive exclusion principle

A

Only one species can occupy a niche in an ecosystem;

2 species have exactly the same niche? they will compete in ALL aspects of their life - one competitor will inevitably prove to be superior, causing disappearance of the other species from an ecosystem

similar niche? compete in overlapping parts of the niche (breeding sites, food, etc.) but not in the others - usually able to coexist

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10
Q

Herbivory

A

primary consumer feeds on a plant or other producer;
producer’s growth affects food availability for the herbivore

  1. Bison bonasus (European bison) - Hierochlore odorata (bison grass)
  2. Lupus europaeus (European Brown hare) - Beta vulgaris (sugar beet)
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11
Q

Predation

A

consumer feeds on another consumer

  1. Bison bonasus - Canis lupus (wolf)
  2. Lepus europaens (European Brown hare) - Vulpes Vulpes (red fox)
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12
Q

Parasitism

A

symbiotic relationship: one organism benefits (parasite), while the host is harmed;
parasite’s survival depends at least partially on the host

  1. tick Ixodes scapularis - deer in northeast USA (sucks blood from host, weakening them)
  2. tapeworm in the human intestine
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13
Q

Competition

A

two species striving for the same resource in the same place (their niches are overlapping)

  1. red foxes (vulpes vulpes) and wolfs (Canis lupus) compete for food (rabbits) in europeans grasslands
  2. lepus europaens vs. ocrytolagus cuniculus (European rabbit) in SW Europę
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14
Q

Mutualism

A

symbiotic relationship: both benefit

  1. Usnea subfloridiana and other lichens (= fungus + alga) grow mutualistically; alga supplies food made by photosynthesis, fungus absorbs mineral ions
  2. cleaner wrasse - small fish of warm tropical seas, cleans parasites from the body of larger fish, like reticulate damsel fish, obtaining food
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15
Q

Biomass

A

the total dry mass of organic matter in organisms in ecosystems

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16
Q

Measuring biomass

A
  • destructive technique - samples used are as small as possible
  • might be used to compare the amount of organisms at each trophic level in an ecosystem
  1. representative samples of all living organisms in the ecosystem are collected (e.g. from randomly positioned quadrats)
  2. organisms are sorted into trophic levels
  3. organisms are dried (placed in an oven at 60-80°C)
  4. mass of the organisms at each trophic level is measured using an electronic balance
  5. drying and measuring might be repeated to ensure all organisms are completely dry
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17
Q

Gross production

A

net production + respiration
total amount of organic matter produced by plants in an ecosystem
measured in kilo joules of energy per meter squared per year

18
Q

Net production

A

the amount of gross production of organic matter remaining after subtracting the amount used by plants in respiration

19
Q

Trophic levels - difficulties with classification

A
  • difficult to decide to which trophic level an organism should be classified
  • e.g. chimpanzees feed on fruit (primary consumers), but also termites and even larger animals (secondary, tertiary consumers)
  • solution: classifying an organism according to its main food source
20
Q

Biomass and energy in higher trophic levels

A
  • large loss of energy on each trophic level
  • RESPIRATION: both energy and biomass are lost, glucose is oxidized in respiration
  • -> energy released for use in the cell and lost as heat
  • -> mass (of glucose) converted into CO2 and water and then excreted (= lost form food chain)
  • FOOD - the energy content per gram doesn’t decrease along a food chain; on the contrary, it is richer in energy per gram on higher trophic levels BUT it’s total biomass is smaller on higher levels

higher trophic levels usually contain very small number of large organisms, with a low total biomass per unit area

21
Q

Ecological succession

A

series of changes to an ecosystem

caused by complex interaction between the community of living organisms and the abiotic environment

22
Q

Primary succession

A

starts in an environment where living organisms have not previously existed

23
Q

Example of primary and secondary succession

A

Slopes of Volcan Osorno in Southern Chile

  • large areas of bare volcanic ash (released during eruptions of the volcano)
  • mosses spread over the ash, eventually forming a complete cover
  • small herbs join the mosses
    • secondary succession –
  • shrubs entered the community, gradually replacing mosses and herbs
  • trees, including Nothofagus, gradually spread to replace the shrubs with a dense forest
24
Q

Secondary succession

A

occurs in areas where an ecosystem is present, but replaced by another ecosystem

25
Q

Biotic changes due to ecological succession

A
  • community causes abiotic environment to change
  • some species leave and other join the community
  • community may continue to change for thousands of years, but eventually a stable community develops - CLIMAX COMMUNITY
26
Q

Abiotic changes due to ecological succession

A
  • soil structure improves: organic matter content rises, amount of water that can be retained and the rate at which excess water drains through soil increases as well
  • soil erosion us reduced by binding action of the roots of larger plants
  • accumulation of minerals - soil can hold larger amounts, more minerals are held in the increasing biomass of the community
27
Q

Biome

A

a type of ecosystem characterized by a distinct vegetation and animal life
distribution of biomes depends on the amount of rainfall and the temperature in a area
changes in altitude produce effects similar to changes in latitude

28
Q

Desert

A
  • very low rainfall (100 mm per year)
  • most extreme temperature fluctuations of all biomes: daytime surface temp. 70°C, night - heat rapidly lost (cold nights)
  • very few plants
  • characteristic: drought-resistant plants that can store water (cacti), plants growing quickly after short, hard rains (germinate, send up shoots and flowers, and die all within a few weeks)
29
Q

Grassland

A
  • low rainfall or uneven/seasonal occurrence of small rainfall
  • warm, hot summers and cold winters
  • grasses and other herbs that can withstand grazing
30
Q

Shrubland

A
  • cold, wet winters
  • hot, dry summers, fires
  • drought-resistant shrubs, often with evergreen foliage
31
Q

Temperate deciduous forest

A
  • moderate rainfall
  • warm summers, cool winters
  • trees that shed leaves in winter
  • shrubs and herbs beneath trees - vertical stratification of plants and animals
32
Q

Tropical rainforest

A
  • very high rainfall
  • hot or very hot in all seasons
  • greatest plant species diversity of all biomes on Earth: tall evergreen trees, smaller trees, shrubs, herbs
33
Q

Tundra

A
  • very low temperatures
  • permafrost - permanently frozen subsoil in the farthest north
  • little precipitation, mostly as snow
  • very small trees, few herbs, mosses, and lichens
34
Q

Simpson Diversity Index

A

to calculate richness of species in an ecosystem
A high value of D suggests a stable and ancient ecosystem and a low D value could suggest pollution, recent succession or agricultural management

35
Q

Reasons for rainforest conservation

A

ECOLOGICAL:
rainforest fixes large amounts of CO2
damage to rainforest - widespread effects (soil erosion, river water salinization, floods)

ECONOMIC:
commodities (medicines)
income from ecotourism

ETHICAL:
every species has a right to live
cultural importance to indigenous tribes
future humans

AESTHETIC:
inspiration for artists
beautiful = bring us great joy

36
Q

ALIEN SPECIES:

The “killer” honeybees

A
  • 1956: African honeybee (very aggressive) brought to Brazil to breed a new variety of bee that would produce more honey than the Italian honeybee
  • escaped by accident
  • spread rapidly throughout the Americas
  • by 2000: killed 10 people
37
Q

ALIEN SPECIES:

The zebra mussel

A
  • finger-sized mollusk, native to Asia
  • 1998: discovered in a lake near Detroit
  • no one knows how exactly it was transported; probably carried accidentally by a ship
  • millions of dollars of damage: clogs the water intake pipes of cities whose water is supplied by affected lakes
  • threatens several native species with extinction by out-competing them
38
Q

ALIEN SPECIES:

The floating fern

A
  • Salvinia molesta
  • deliberately transported across the globe as an aquarium or pond plant
  • native to Brazil; transported to USA, UK, Australia; huge damage in Texas
  • damaged many lakes in tropics and sub-tropics
  • grows super duper rapidly - doubles the number of leaves in 2 weeks
  • spreads over water surface and eliminates water species by interspecific competition
  • controlled by introducing another alien species - salvinia weevil Cyrtobagus salviniae, which feeds of the fern - BIOLOGICAL CONTROL
39
Q

Biomagnification

A

the process by which chemical substances become more and more concentrated at each trophic level

cause: some pollutants are absorbed into living organisms and accumulate, because they’re not efficiently excreted

40
Q

Biomagnification of DDT

A
  • DDT (dichlorodiphenyltrichloroethane) = chemical pesticide that has been used to target insects
  • fat souluble
  • selectively retained within the tissues of an organism instead of being excreted
  • organisms at higher trophic levels consume more biomass to meet their energy requirements - eat more toxins

DDT sprayed on water to eliminate mosquito larvae —> taken up by algae –> passed on to primary consumers (small fish) and up

at each subsequent trophic level the concentration of DDT stored in the body will increase

birds that fed on fish:

  • very high levels of DDT discovered
  • chemical interferes with formation of egg shells
41
Q

Effect of UV light on living organisms

A

Animals:
penetrates tissues and damages DNA
gene mutation that can lead to uncontrollable cell division (skin cancer)

PLANTS:
damages the ability to carry out photosynthesis
can kill phytoplankton, reducing primary production and total productivity

42
Q

Effect of chlorofluorocarbons (CFCs) on ozone layer

A

Ozone layer:

  • stratospheric region composed of ozone
  • absorbs UV radiation, BUT there is a limit to how much can be absorbed

CFCs are broken down by ultraviolet radiation to release chloride ions which react with ozone, breaking it down into oxygen (O2)

One chlorine atom can destroy 100,000 ozone molecules – small amounts of CFC can break down large amounts of ozone

The thinning of the ozone layer by CFCs reduces the absorption of UV light in the stratosphere

Biology (9 decks)

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