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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
leeward slope
slopes that are oriented away from the wind
26
draw diagram of orographic precipitation
27
latitudinal patterns are complicated by
the distribution of landmasses
28
how do ocean currents affect precipitation?
driest deserts occur inland of cold-water upwellings as cold water -> dry air
29
when would animals' geographical ranges not correspond to biomes (i.e. limited by climate or vegetation)
- transcend biomes (ecological versatility, super generalists) - not at limits because of recent history (eg limited dispersal) - limited by other organisms
30
describe ecological niche modelling
- 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
what is ecological niche modelling useful for modelling for?
- biological invasions - how species' ranges may shift as climate changes - spread of vector-borne diseases
32
describe Dengue
a virus vectored by Aedes mosquitoes
33
observed range shifts
- 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
how are ranges of tolerance related to homeostasis?
reactions occur (enzymes function) best at optimum temperature and osmotic conditions where fitness is maximised.
35
what does an animal's physiology reflect?
the climate and other conditions to which the organism is adapted
36
compare the tolerance of temperate animals to tropical animals?
- temperate animals withstand colder temperatures than tropical animals - temperate animals also tolerate a wider range of temperatures than tropical animals
37
trends in seasonal temperature variation
low near the equator and increases with latitude
38
heat balance in poikilotherms
most reptiles, amphibians, fish, invertebrates - lack physiological means to deviate from environmental temperature (although they use behavioural means): their temperatures fluctuate
39
heat balance in homeotherms
must regulate heat balance to keep internal temperature within a narrow range: many traits contribute to this
40
why do poikilotherms have lower energy requirements than similarly sized homeotherms?
maintaining a constant internal temperature requires energy
41
list the 5 modes of heat gain or loss
radiation conduction convection evaporation redistribution
42
radiation
heat transfer by electromagnetic radiation
43
conduction
transfer by direct contact with substrate (eg feet lose heat to ground)
44
convection
heat transfer mediated by moving fluid (usually air or water)
45
evaporation
efficient cooling from wet surfaces
46
redistribution
circulatory system redistributes heat among body parts, esp. core to appendages
47
how does size matter to heat balance?
- surface area determines equilibration rate - volume provides the inertia
48
draw a diagram for radius vs SA:V and equilibrium
49
Bergmann's rule
homeotherms tend to be larger at higher latitudes (colder)
50
if a sphere has the smallest SA:V, why aren't homethoerms always spheres in cold climates?
- sometimes SA is needed for function - sometimes particular shapes are needed for function - tradeoffs and adaptive compromises
51
who has the maximum SA:V ratio?
Chrysopelea gliding snake, Borneo; restricted to warm tropics
52
who has the minimum SA:V ratio?
American Pika, Ochotona princeps: alpine tundra rabbit; restricted to cold habitats; spherical shape, reduced ears for a rabbit
53
Allen's rule
homeotherms tend to have smaller appendages at higher, colder latitudes
54
what other factors matter other than shape and size?
- insulation - convective cooling enhanced by vascularisation - evaporative cooling - countercurrent circulation to limbs conserves heat
55
describe how countercurrent circulation to limbs conserves heat
- 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
draw a diagram for countercurrent circulation
57
how is the skinny weasel in cold climates an example of a trade-off?
- 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
two reasons why natural selection produces deeply imperfect organisms
- 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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