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BIO120 > 13, 14, 15 > Flashcards

13, 14, 15 Flashcards

1
Q

what is ecology?

A

the science of biodiversity:
- how organisms interact with each other and with their environment
- distribution and abundance of species
- structure and function of ecosystems

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2
Q

how many species are there?

A

globally, too many to count. many (>85% are still unknown to science). one estimate, extrapolated from rates at which new taxa are described is 8.7 million (just eukaryotes)

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3
Q

is biodiversity equally distributed across the tree of life?

A

no, 70-90% of species are bacteria

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4
Q

define a populations

A

all the individuals of the same species in one place at one time

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5
Q

define an ecological community

A

all the species living together in one place at one time

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6
Q

define an ecosystem

A

all the species plus the non-living environment

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7
Q

why do we care about species range?

A
  • to understand where plants and animals can grow because they give us food, clothing, wood, medicine, etc
  • predict what will happen to biodiversity as the climate changes
  • predict how biodiversity will respond to habitat destruction, pollution, invasive species, etc
  • to understand disease risk of microbes
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8
Q

what determines where species live?

A
  • dispersal
  • abiotic conditions: climate, nutrients
  • species interactions: competition, predation, mutualism
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9
Q

what limits a species’ range?

A
  • dispersal
  • climactic or other inexhaustible conditions, eg temperature/salinity
  • food or other exhaustible resources, eg nutrients/space
  • species interactions eg competition/predation/mutualism
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10
Q

the sixth extinction

A
  • ongoing mass extinction, mainly as a result of human activities
  • 32% of known vertebrate species (8,851/27,600 species) are decreasing in population size or range
  • North American birds have declined in abundance by 29% since 1970
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11
Q

Margulis

A

Lynn Margulis was an American biologist whose serial endosymbiotic theory of eukaryotic cell development revolutionized the modern concept of how life arose on Earth.

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12
Q

Malthus

A

English economist and demographer who is best known for his theory that population growth will always tend to outrun the food supply.

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13
Q

Draw and describe a general graph for the performance of species against an environmental gradient
label:
- lethal zones
- where growth occurs
- where reproduction occurs
- where survival occurs

A

species have ranges of tolerance along environmental gradients

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14
Q

define the ecological niche

A
  • the combination of physiological tolerances and resource requirements of a species
  • more casually, a species’ place in the world - what climate it prefers what it eats, etc
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15
Q

draw a graph and describe the Hutchinsonian niche

A

the niche is an ‘n-dimensional hypervolume’ shaped by the environmental conditions under which a species can ‘exist indefinitely’. Each axis is an ecological factor important to the species being considered

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16
Q

factors determining biomes

A
  • temperature is mostly a function of latitude
  • higher latitudes colder; seasonality a function of temperature (summer-winter)
  • lower latitudes warmer; seasonality a function of rainfall (dry-wet season)
  • rainfall mostly depends on atmospheric circulation, offshore ocean currents, rain shadows
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17
Q

Intertropical convergence

A
  • shows a line of rain clouds across the pacific
  • ITCZ shifts seasonally, producing rainy and dry seasons in some parts of the tropics
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18
Q

how does the ITCZ form?

A

When the northeast trade winds from the Northern Hemisphere and the southeast winds from the Southern Hemisphere come together, it forces the air up into the atmosphere, forming the ITCZ.

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19
Q

Coriolis effect

A

the earth’s rotation deflects winds: objects (including hurricanes) appear to be deflected eastwards as they move away from the equator and deflected westwards as they move towards the equator

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20
Q

general trends of terrestrial vegetation with climatic variables

A
  • vegetation growth (primary productivity) increases with moisture and temperature
  • vegetation stature also increases so region with certain combinations of moisture and temperature develop predictable, characteristic types of vegetation (biomes)
  • seasonality is secondarily important
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21
Q

draw a Whittaker’s diagram

A
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22
Q

—– mostly determines terrestrial biomes

A

latitude

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23
Q

changes in temperature within basic latitudinal belts

A

land changes temperature more readily than water; maritime climates are moderate, continental climates are extreme; oceans provide thermal inertia

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24
Q

changes in precipitation within basic latitudinal belts

A
  • evaporation high from warm bodies of water, low from cold
  • prevailing winds
  • orographic precipitation (air forced up mountainsides undergoes cooling, precipitates on upper windward slopes)
  • rain shadows created on leeward slopes of mountain ranges
  • seasonality of moisture also important
25
Q

leeward slope

A

slopes that are oriented away from the wind

26
Q

draw diagram of orographic precipitation

A
27
Q

latitudinal patterns are complicated by

A

the distribution of landmasses

28
Q

how do ocean currents affect precipitation?

A

driest deserts occur inland of cold-water upwellings as cold water -> dry air

29
Q

when would animals’ geographical ranges not correspond to biomes (i.e. limited by climate or vegetation)

A
  • transcend biomes (ecological versatility, super generalists)
  • not at limits because of recent history (eg limited dispersal)
  • limited by other organisms
30
Q

describe ecological niche modelling

A
  • also called species distribution modelling
  • uses data from a species’ present distribution to predict where a species can live
  • usually relies on climate data; more rarely on other niche axes, such as resources
31
Q

what is ecological niche modelling useful for modelling for?

A
  • biological invasions
  • how species’ ranges may shift as climate changes
  • spread of vector-borne diseases
32
Q

describe Dengue

A

a virus vectored by Aedes mosquitoes

33
Q

observed range shifts

A
  • estimated that species are moving polewards
  • although many factors influence a species’ range, there is considerable evidence that numerous species are moving polewards to track recent changes in climate
34
Q

how are ranges of tolerance related to homeostasis?

A

reactions occur (enzymes function) best at optimum temperature and osmotic conditions where fitness is maximised.

35
Q

what does an animal’s physiology reflect?

A

the climate and other conditions to which the organism is adapted

36
Q

compare the tolerance of temperate animals to tropical animals?

A
  • temperate animals withstand colder temperatures than tropical animals
  • temperate animals also tolerate a wider range of temperatures than tropical animals
37
Q

trends in seasonal temperature variation

A

low near the equator and increases with latitude

38
Q

heat balance in poikilotherms

A

most reptiles, amphibians, fish, invertebrates
- lack physiological means to deviate from environmental temperature (although they use behavioural means): their temperatures fluctuate

39
Q

heat balance in homeotherms

A

must regulate heat balance to keep internal temperature within a narrow range: many traits contribute to this

40
Q

why do poikilotherms have lower energy requirements than similarly sized homeotherms?

A

maintaining a constant internal temperature requires energy

41
Q

list the 5 modes of heat gain or loss

A

radiation
conduction
convection
evaporation
redistribution

42
Q

radiation

A

heat transfer by electromagnetic radiation

43
Q

conduction

A

transfer by direct contact with substrate (eg feet lose heat to ground)

44
Q

convection

A

heat transfer mediated by moving fluid (usually air or water)

45
Q

evaporation

A

efficient cooling from wet surfaces

46
Q

redistribution

A

circulatory system redistributes heat among body parts, esp. core to appendages

47
Q

how does size matter to heat balance?

A
  • surface area determines equilibration rate
  • volume provides the inertia
48
Q

draw a diagram for radius vs SA:V and equilibrium

A
49
Q

Bergmann’s rule

A

homeotherms tend to be larger at higher latitudes (colder)

50
Q

if a sphere has the smallest SA:V, why aren’t homethoerms always spheres in cold climates?

A
  • sometimes SA is needed for function
  • sometimes particular shapes are needed for function
  • tradeoffs and adaptive compromises
51
Q

who has the maximum SA:V ratio?

A

Chrysopelea gliding snake, Borneo; restricted to warm tropics

52
Q

who has the minimum SA:V ratio?

A

American Pika, Ochotona princeps: alpine tundra rabbit; restricted to cold habitats; spherical shape, reduced ears for a rabbit

53
Q

Allen’s rule

A

homeotherms tend to have smaller appendages at higher, colder latitudes

54
Q

what other factors matter other than shape and size?

A
  • insulation
  • convective cooling enhanced by vascularisation
  • evaporative cooling
  • countercurrent circulation to limbs conserves heat
55
Q

describe how countercurrent circulation to limbs conserves heat

A
  • arteries and veins should be appressed in appendages to conserve heat; separated in appendages designed to shed heat
  • countercurrent flow maintains gradient, so heat is always flowing from outgoing blood to incoming blood
56
Q

draw a diagram for countercurrent circulation

A
57
Q

how is the skinny weasel in cold climates an example of a trade-off?

A
  • being long and thin makes weasels subjects to thermal stresses (costly) but allows them to be better predators (beneficial)
  • because they are long and thin, we infer that the fitness gains of being a good hunter offset the fitness costs of an expensive metabolism
  • if they can get enough prey they can stay warm despite their heat-wasting shape
58
Q

two reasons why natural selection produces deeply imperfect organisms

A
  • tradeoffs: being good at x may necessarily imply being bad at y
  • constraints: selection builds on what is already there, especially existing developmental programs.

BIO120 (61 decks)

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