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Principles Of Ecology > Midterm > Flashcards

Midterm Flashcards

1
Q

Ecology

A

Scientific study of interactions between organisms and their environment

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2
Q

Controlled experiment

A

Experimental groups are compared with a control group that lacks the factor being tested.
No control= no real experiment

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3
Q

Standard error

A

Graphs with smaller standard error are more accurate. You can make a standard error smaller by replicating.

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4
Q

Case study: factors affecting amphibian declines

A
  • habitat loss
  • pathogens
  • climate change
  • Ribeiroia trematoe flatworms
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5
Q

Scientific Method

A
  1. Make observations and ask questions (pattern)
  2. Use previous knowledge or intuition to develop hypothesis (process)
  3. Evaluate hypothesis by experimentation, observational studies, or quantitative models
  4. Use the results to modify the hypotheses, pose new questions, or draw conclusions about the natural world
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6
Q

Experimental design

A
  1. Replicate- perform each treatment more than once on independent units
  2. Assign treatments at random
  3. Analyze results using statistical methods
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7
Q

Observational field study

A

2 groups and you sample them

Ex) one’s healthy and one’s deformed

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8
Q

Controlled experiment

A

Able to control the variables

Ex) tadpoles and parasite Ribeiroia in the lab

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9
Q

Field experiment

A

Cages

Ex) ponds with pesticides vs. No pesticides; cages for pesticides

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10
Q

Spatial scales

A

Small: soil micrrorganisms
Large: atmospheric pollutants

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11
Q

Temporal scales

A

Short: leaf response to sunlight
Long: how species change over geologic time

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12
Q

Levels of Biological Organization

A 
Individual
Population
Community (diff species)
Ecosystem (abiotic and biotic)
Landscape
Biosphere
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13
Q

Population

A

Group of individuals of a species that are living and interacting in a particular area

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14
Q

Community

A

Association of populations of different species in the same area

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15
Q

Ecosystem

A

Community of organisms (biotic) plus the physical environment (abiotic)

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16
Q

Landscapes

A

Heterogenous areas, including multiple ecosystems that are connected

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17
Q

Biosphere

A

All living organisms on earth plus the environments in which they live

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18
Q

Evolution

A
  1. Change in genetic characteristics of a population over time
  2. Descent with modification- organisms gradually accumulate differences from their ancestors
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19
Q

Adaptation

A

A characteristic that improves survival or reproduction

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20
Q

Natural selection

A

Individuals with certain adaptations tend to survive and reproduce at a higher rate than other individuals

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21
Q

If the adaptation is heritable…

A

The frequency of the characteristic may increase in a population over time.
Ie) superbug evolution

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22
Q

Ecosystem processes

A
  • energy moves through ecosystems in a single direction only- it cannot be recycled
  • nutrients are continuously recycled from the physical environment to organisms and back again- that is the nutrient cycle.
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23
Q

Producers

A

Capture energy from an external source (eg. The sun) and use it to produce food

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24
Q

Net primary productivity (NPP)

A

(Accumulation of energy)

-energy captured by producers, minus the amount lost as heat in cellular respiration

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25
Q

Consumers

A

Get energy by eating other organisms or their remains

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26
Q

What is causing changes in salmon catch?

A
  • threats to streams

- changes in the oceans

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27
Q

Threats to streams

A

Damming, pollution, and overfishing

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28
Q

Changes in the ocean

A
  • climatic variation in the North Pacific
  • periods of high salmon production in Alaska= periods of low production in Oregon and Washington
  • correlation between salmon production shifts and sea surface temperatures
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29
Q

Pacific Decadal Oscillation (PDO)

A

Associated with 20 to 30 year cycles of warm and cool temperatures in the North Pacific

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30
Q

Weather

A

Current conditions- temperature, precipitation, humidity, cloud cover

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31
Q

Climate

A

Long-term description of weather, based on averages and variation measured over decades
-characterized by average conditions, but extreme conditions are also important

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32
Q

Mediterranean-type climate

A

Precipitation is concentrated in winter

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33
Q

Grassland precipitation

A

Spread evenly throughout the year

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34
Q

Conduction

A

Kinetic energy is transferred by molecules in direct contact with one another

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35
Q

Convection

A

Energy transfer by movements of air or water currents

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36
Q

Sensible heat flux

A

Energy transfer from warm air immediately above the surface to the cooler atmosphere by convection and conduction

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37
Q

Greenhouse gasses

A

Absorb and reradiate the infrared radiation emitted by Earth

  • water vapor (H2O)
  • carbon dioxide (CO2)
  • Methane (CH4)
  • Nitrous oxide (N2O)
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38
Q

Consequences of greenhouse gases

A

-without any greenhouse gasses in the atmosphere it would be 33 degrees colder. They have a pretty strong impact

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39
Q

Solar radiation

A
  • poles the sun’s rays are spread over a larger area and take a longer path through the atmosphere
  • near the equator, the sun’s rays strike earth’s surface perpendicularly
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40
Q

Surface heating and uplift

A
  • warm air is less dense than cool air, so the air above the warm surface rises
  • as the warm air rises, it expands and cools
  • eventually the air cools enough to form clouds
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41
Q

Where do clouds usually form?

A

Troposphere and stratosphere.

Also near the trophics leading to a low pressure zone

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42
Q

Where do deserts usually occur?

A

At areas of very low precipitation at high pressures

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43
Q

Atmospheric Circulation

A
  • warmee air moves from the equator north and south
  • air from the poles moves back down towards the surface
  • ferrell cell fluctuates the most. Is the temperate zone
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44
Q

Polar cell, Ferrell cell, and the Hadley cell result in which 3 major climatic zones?

A

Occurs in each hemisphere:

  1. Tropical
  2. Temperate
  3. Polar
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45
Q

Prevailing winds

A

Areas of high and low pressure created by the circulation cells resulting in air movements

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46
Q

The Coriolis Effect

A

Winds appear to be deflected due to the rotation of the Earth

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47
Q

Global Wind Patterns

A
  • prevailing winds change depending on the time of year

- wind tends to blow from areas of low pressure to areas of high pressure

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48
Q

Ocean Circulation

A
  • ocean currents are largely determined by prevailing winds

- wind produces drag on the surface of the water, and over time creates directions

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49
Q

Polar Downwelling

A
  • Where warm tropical surface currents reach polar areas: the water cools, ice forms, the water becomes more saline and more dense and sinks (downwelling).
  • The downwelling water mass moves back towards the equator, carrying cold polar water
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50
Q

Coastal upwelling

A
  • brings nutrients up into the zone with life feeding lots of small organisms
  • most zones of water remain pretty much unmixed
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51
Q

Coastal upwelling

A
  • where deep ocean water rises to the surface
  • occurs where prevailing winds blow parallel to a coastline
  • surface water flows away from the coast and deeper, colder ocean water rises up to replace it
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52
Q

Large-scale atmospheric and oceanic circulation patterns establish global patterns of temperature and precipitation

A
  • average annual temperatures become progressively cooler from the equator toward the poles
  • this pattern is altered by ocean currents, continental topography, and the distribution of land and water masses
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53
Q

Do temperatures fluctuate more over land or water?

A

More over land

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54
Q

Precipitation patterns associated with atmospheric circulation cells are modified by what?

A

Mountain ranges, semipermanent high- and low-pressure zones

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55
Q

Rain shadow effect

A

Moist on one mountain side. Arid on the other. Can also see major wind pattern differences on either side.

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56
Q

Evapotranspiration

A

Water loss through transpiration by plants, plus evaporation from the soil.
-transfers energy (as latent heat) and water into the atmosphere, thereby affecting air temperature and moisture

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57
Q

Albedo

A

Capacity of a land surface to reflect solar radiation- is influenced by vegetation type, soils, and topography
-rates of evapotransporation greatly decline in deforested areas. Causing the local climate to get dryer and hotter

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58
Q

Seasonality

A
  • temperate and polar zones have pronounced seasonal variation in solar radiation and temperature
  • difference in seasonal solar radiation increases from the tropics toward the poles, and results in varying day lengths
  • seasonality influences biological activity and distributions of organisms
  • aquatic environments also experience seasonal changes in temperature
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59
Q

Aquatic stratification

A
  • affects nutrients and oxygen
  • complete mixing (turnover) occurs in spring and fall
  • water, depending on its temperature, changes density
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60
Q

El Nino

A

Are longer-scale climate variations that occur every 3 to 8 years and last about 18 months

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61
Q

La Nina

A

Events are stronger phases of the normal pattern, with high pressure off the coast of South America and low pressures in the western Pacific

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62
Q

Long-term Considerations

A
  • earth’s climate alternates between warm and cool cycles
  • warmer periods are associated with higher concentrations of greenhouse gases
  • earth is currently in a cool phase characterized by formation of glaciers, followed by warm periods with glacial melting
  • these glacial-interglacial cycles occur at frequencies of about 100, 000 years
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63
Q

Milankovitch Cycles

A

The glacial-interglacial cycles have been explained by regular changes in the shape of Earth’s orbit and the tilt of its axis

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64
Q

The chemical environment

A

Key chemical determinants of biological function:

  • salinity
  • acidity
  • oxygen availability
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65
Q

Salnization

A

Soils in arid regions become saline when water is brought to the surface by plant roots or irrigation, and high rates of evapotranspiration result in salt build-up

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66
Q

Acidity

A

Ability of a solution to act as an acid: a compound that gives up protons (H+) to a solution

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67
Q

Alkalinity

A

Ability of a solution to act as a base: a compound that takes up H+ or gives up hydroxide ions (OH-)

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68
Q

What are biomes characterized by?

A

Leaf decidousness and succulence

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69
Q

Convergent evolution

A
  • plants don’t move around, so they’re forced to adapt and make it work where they are
  • so plants can be morphologically similar (function the same), but be taxinomically different
  • immobility of plants make them vulnerable to selective pressures
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70
Q

Terrestrail biomes

A
  • characterized by growth forms of the dominant plants, such as leaf decidousness or succulence
  • similar biotic assemblages indicate similar responses to climatic forces in different locations
  • plants are best for this classification
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71
Q

Tropical rainforest

A
  • high biomass, high diversity: about 50% of Earth’s species
  • 11% of Earth’s terrestrial vegetation cover
  • no seasonal changes
  • best tropical rainforests occur between 10 degrees N and S of the equator
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72
Q

Tropical deforestation

A
  • disappearing due to logging and conversion to pasture and croplands
  • about 50% of the tropical rainforest biome had been altered
  • soils are nutrient poor
  • nutirents are in the living material
  • when the huge massive vegetation is removed and converted to farmland it makes it hotter and dryer
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73
Q

Tropical Seasonal Forests and Savannas

A
  • wet and dry seasons
  • shorter trees, deciduous in dry seasons, more grasses and shrubs
  • less than 50% have been unaltered by human activity
  • threats: human population growth, converted to cropland and pasture
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74
Q

Hot Deserts

A
  • sparse vegetation and animal populations
  • abundance may be low but species diversity cam be high
  • 30 degrees N and S of the equator; exception being those formed by rain shadows
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75
Q

Temperate Grasslands

A
  • maintained by frequent fires and large herbivores such as bison
  • grasses grow more roots than stems and leaves, to cope with dry conditions
  • most human impacted biome on the planet due to high soil fertility
  • grasslands more continental
  • shrublands and woodlands more coastal
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76
Q

Temperature Shrublands and Woodlands

A
  • evergreen shrubs and trees
  • Mediterranean-type climates: wet winters and hot, dry summers
  • fire is common
  • converted to crops and vineyards, but the soils are nutrient-poor
  • shrublands in continental interiors occur in rain shadows and seasonally cold climates
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77
Q

Temperate Deciduous Forests

A
  • species diversity lower than tropical rainforests, but still high
  • more precipitation tends to occur when its warm
  • fertile soils and climate make this biome good for agriculture
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78
Q

Temperate evergreen forests

A
  • they receive high rainfall amounts and have mild winters
  • lower diversity than tropical and decidous forest
  • pine needles tend to be slightly acidic
  • high acidity tends to increase leaching
  • extensive clearing. Sometimes trees replaced with non-native species
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79
Q

Boreal Forest (Taiga)

A
  • permafrost (soil that remains frozen year round) prevents drainage and results in saturated soils
  • cold, wet conditions in boreal soils limit decomposition, so soils have high organic matter
  • lakes lost once permafrost is gone because nothing to support the lake
  • have not been as impacted by human activities though impacts are accelerating
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80
Q

Tundra

A
  • widespread permafrost
  • largest pristine areas on earth
  • increased exploration and development of energy resources
  • arctic warming at almost double the global average
  • further N and S most severe impacts of climate change
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81
Q

Mountains (Elevation)

A

On mountains, temperature and precipitation change with elevation, resulting in zones similar to biones

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82
Q

Marine Biological Zones

A
  • determined by ocean depth, light availability, and the stability of the bottom substrate
  • aphotic: where the light doesn’t penetrate
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83
Q

Coral reefs

A
  • restricted to warm, shallow water
  • complex habitat: a huge diversity of marine life
  • rates of biomass production are some of the highest in the world
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84
Q

Human impacts on marine biological zones

A
  • polluntants and nutrients via river
  • commercial fishing
  • greenhouse gas emissions
  • increase in UV radiation due to stratospheric ozone loss
  • excess nutrients algae growth
  • coral bleaching
  • acidification
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85
Q

Freshwater systems

A

Streams and rivers are lotic systems

  • smallest streams are first order streams
  • these converge to form second order streams
  • large streams are 6th order streams or greater
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86
Q

Spatial zonation in streams

A
  • distribuation of organisms reflect the energetic and environmental conditions experienced in progressively larger streams
  • vast majority of life occurs where the nutrients are
  • lakes are basically wide streams with less currents
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87
Q

Human impacts on freshwater habitats

A
  • sewage and industrial wastes
  • fertilizer runoff
  • non-native species
  • deforestation and erosion
  • dams
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88
Q

Cryonics

A

Preservation of bodies by freezing

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89
Q

Physiological ecology

A

Study of interactions between organisms and the physical environments that influence their survival and persistence

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90
Q

Two options with environmental change?

A

Tolerance and avoidance

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91
Q

Climate envelope

A

Range of condition over which a species occurs

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92
Q

Stress

A

Environmental change results in decreased rates of physiological processess, lowering the potential for survival, growth, or reproduction

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93
Q

Acclimatization

A

Adjusting to stress through behavior or physiology (individuals)

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94
Q

Ecotypes

A

Populations with adaptations to unique environments

-can eventually become separate species as populations diverge and become reproductively isolated

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95
Q

Latent heat transfer

A

Water absorbs heat as it changes from a liquid to a gas state

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96
Q

Stomata

A

Can control transpiration rates

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97
Q

Evaporative heat loss

A

Uncommon in animals

Ex) sweating in humans

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98
Q

Ectotherms

A

Regulate body temperature through energy exchange with the external environment

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99
Q

Endotherms

A

Rely primarily on internal heat generation- mostly birds and mammals

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100
Q

Surface are to volume ratio

A

Affects the exchange of energy with the environment

101
Q

Avoidance behavior

A

Includes seasonal migration

102
Q

Tolerance to freezing

A

Involves minimizing damage associated with ice formation in cells

103
Q

Thermoneutral zone

A

Range of environmental temperatures over which a constant basal metabolic rate can be maintained

104
Q

Lower critical temperature

A

When heat loss is greater than metabolic production; body temperature drops and metabolic heat generation increases

105
Q

Matric potential

A

energy associated with attractive forces on surfaces of large molecules inside cells or on surfaces of soil particles

106
Q

Osmotic potential

A

Water flows from an area of high concentration to a region of low concentration

107
Q

Hyperosmotic

A

More saline than environment

108
Q

Isoosmotic

A

Same salinity as environment

109
Q

Hypoosmotic

A

Less saline than environment

110
Q

Evaporative water loss

A

Minimized by skin resistance, or by living in moist environments

111
Q

Problems with freezing

A
  • water forms needle-like ice crystals that can pierce cell membranes
  • oxygen supply to tissues is restricted due to lack of breathing and circulation
  • when ice forms, it pulls water from cells
112
Q

Solutions to freezing

A
  • freezing water is limited to the space outside the cells
  • ice-nucleating proteins outside cells serve as sites of slow, controlled ice formation
  • glucose and glycerol are made inside the cella to lower the freezing point
113
Q

Holoparasites

A

Have no photosynthetic pigments and get energy from other plants

114
Q

Hemiparasite

A

Is photosynthetic, but obtains nutrients, water, and some of its energy from the host plant

115
Q

Photosynthesis (autotrophy)

A

Sunlight provides the energy to take up CO2 and synthesize organic compounds C-C bonds

116
Q

Chemosynthesis (chemolithotrophy)

A

Energy from inorganic compounds is used to produce carbohydrates

117
Q

Photosynthesis two major steps

A
  1. Light reaction: light is harvested and used to split water and provide electrons to make ATP and NADPH
  2. Dark reaction: CO2 is fixed in the Calvin cycle, and carbohydrates are synthesized
118
Q

Light compensation point

A

Where CO2 uptake is balanced by CO2 loss by respiration

119
Q

Saturation point

A

When photosynthesis no longer increases as light increases

120
Q

Photorespiration is not advantages if

A
  • low CO2

- high temperatures

121
Q

Crassulacean acid metabolism (CAM)

A

Minimizes water loss

122
Q

Optimal foraging theory

A

Animals will maximize the amount of energy gained per unti time, energy, risk involved in finding food.
-assumes that evolution acts on behavior of animals to maximize their energy gain

123
Q

Profitability of a food item (P)

A

Depends on how much energy (E) the animal gets from the food (net energy) relative to the amount of time (t) it spends finding and obtaining the food

124
Q

Marginal value theorem

A

An animal should stay in a patch until the rate of energy gain has declined to match the average rate for the whole habitat (giving up time)

125
Q

Critics to optimal foraging theory

A
  • does not apply well to animals that feed on mobile prey
  • for foragers, risk of exposure to their own predators is also important
  • defensive behaviours of prey also influence the costs and benefits to foragers
126
Q

Evolution

A

Change in allele frequencies (proportions) in a population overtime

127
Q

Genes

A

Made of DNA and specify encode proteins

-can have 2 or more forms called alleles

128
Q

Genotype

A

Genetic makeup of an individual

129
Q

Mutation

A
  • change in DNA

- produce new alleles

130
Q

Recombination

A
  • different combinations of alleles in offspring

- produces different genotypes within a population

131
Q

Phenotype

A

Observable characteristics of an individual

132
Q

Phenotypic plasticity

A

Range of phenotypes produced by a genotype

133
Q

Natural selection

A

Individuals with particular heritable traits survive and leave more offspring than others

134
Q

Directional

A

Individuals with one extreme of a heritable phenotypic trait are favoured

135
Q

Stabilizing

A

Individuals with an intermediate heritable phenotypic trait are favoured

136
Q

Disruptive

A

Individuals at either extreme of a heritable phenotypic trait are favoured

137
Q

Genetic drift

A

Low populations have chance events affecting which alleles passed to following generations

138
Q

Gene flow

A

Alleles move between populations via movement of individuals or gametes

139
Q

Adaptive evolution

A

Traits that confer advantages tend to increase in frequency over time

140
Q

Natural selection does not result in a perfect match between organisms and their environments

A
  1. Environments are constantly changing

2. Constraints on evolution

141
Q

Species

A

Groups of organisms whose members have similar characteristics and can interbreed

142
Q

Speciation

A

The process by which one species splits into two or more species

143
Q

“Arms race”

A

Predators evolve adaptations to capture prey, and prey evolve adaptations to avoid being eaten

144
Q

Coevolution

A

Reciprocal evolutionary change in interacting species

145
Q

Human impacts on evolution

A
  • extinction rate today is 100 to 1000 times higher than extinction rates seen in fossil records
  • habitat fragmentation leaves isolated patches, which can affect evolutionary processes
146
Q

life history

A

a record of events relating to its growth, development, reproduction, and survival.

  • age and size at sexual maturity
  • amount and timing of reproduction
  • survival and mortality rates
147
Q

Phenotypic plasticity

A

One genotype may produce different phenotypes under different environmental conditions

148
Q

Polyphenism

A

a single genotype produces several distinct morphs

149
Q

Isogamy

A

Gametes are equal in size ex) green alga)

150
Q

Anisogamy

A

Gametes of different sizes

151
Q

Complex life cycles

A

have at least two stages, with different body forms and that live in different habitats

152
Q

Metamorphosis

A

Abrupt transition in form between the larval and juvenile stages.

153
Q

Semelparous species

A

reproduce only once

154
Q

Iteroparous species

A

can reproduce multiple times.

155
Q

Competitive plants

A

with superior ability to acquire light, minerals, water, and space— have a selective advantage.

156
Q

Stress-tolerant plants

A

with phenotypic plasticity, slow rates of water and nutrient use - not palatable to herbivores.

157
Q

Ruderal plants

A

with short life span, rapid growth rates, heavy investment in seed production.

158
Q

Stress

A

any abiotic factor that limits growth

159
Q

disturbance

A

any process that destroys plant biomass

160
Q

trade-offs

A

Organisms allocate limited energy or resources to one function at the expense of another

161
Q

Provisioning eggs or embryos

A

yolk and protective coverings for eggs, nutrient-rich endosperm in plant seeds

162
Q

Parental care

A

invest time and energy to feed and protect offspring.

163
Q

Dormancy

A

State of suspended growth and development in which an organism can survive unfavorable conditions.

164
Q

Niche shifts

A

should occur when the organism reaches a size at which conditions are more favorable in the adult habitat than in the larval habitat.

165
Q

sequential hermaphroditism:

A

change in sex during the course of the life cycle
-Common in fish and invertebrates.
• The timing should take advantage of high reproductive potential of different sexes at different sizes.

166
Q

Behavioral ecology

A

is the study of the ecological and evolutionary basis of animal behavior.

167
Q

Proximate causes (immediate)

A

or how the behavior occurs.

168
Q

Ultimate causes

A

why the behavior occurs; the evolutionary and historical reasons

169
Q

Antipredator behaviors

A

include those that help prey avoid being seen, detect predators, prevent attack, or escape once attacked.

170
Q

Perceived risk of predation

A

• can alter foraging patterns

171
Q

Darwin proposed that the extravagant features of some males resulted from sexual selection

A

• Individuals with certain characteristics gain an advantage over others of the same sex solely with respect toto mating success.

172
Q

Direct benefits: in some species, males provide females with

A
  • gifts of food
  • help in rearing young
  • access to a territory with good nesting sites, food
173
Q

Indirect benefits: other species, males provide nothing

A

females may receive indirect genetic benefits

174
Q

The handicap hypothesis

A
  • males support costly and unwieldy ornaments

* Indication of vigorous individuals

175
Q

The sexy son hypothesis

A
  • female receives indirect genetic benefits through her sons
  • attractive sons to females produce many grandchildren.
176
Q

anisogamous species

A

females invest more to produce large eggs than male to produce sperm

177
Q

Dilution effect

A

as the number of individuals in a group increases, the chance of being the one attacked by a predator decreases.

178
Q

Flash effect

A

respond to a predator by scattering in different directions, making it difficult for the predator to select a target.

179
Q

Costs of group living

A
  • Food depletion
  • More time spent moving between feeding sites.
  • Subordinate members spend much time and energy on interacting with group members.
  • Closer contact: parasites and diseases often spread more easily.
180
Q

Population

A

Group of interacting individuals of the same species living in a particular area.

181
Q

Abundance:

A 
population size (# of individuals) 
population density (# of individuals per unit area).
182
Q

genet

A

single genetic individual. unique genetic makeup

183
Q

ramet

A

members of a genet are independent physiologically

184
Q

Dispersal limitation

A

can prevent species from reaching areas of suitable habitat

185
Q

Geographic range

A

the entire geographic region over which a species is found.

186
Q

Dispersion

A

Spatial arrangement of individuals within a population

187
Q

Regular

A

individuals are evenly spaced. variance/ mean <1

188
Q

Random

A

individuals scattered randomly. variance/mean ~1

189
Q

Clumped

A

the most common pattern. Variance/mean >1

190
Q

Relative population size

A

Number of individuals in one time period or place relative to the number in another.

191
Q

I - Area-based counts

A

Used most often to estimate abundance of immobile organisms.
Quadrats: Sampling areas of specific size, such as 1 m2.
• Individuals are counted in several quadrats; the counts are averaged to estimate population size

192
Q

II - Distance methods

A

Distances of individuals from a line or point are converted into estimates of abundance
Line transects:
Observer travels along line and counts individuals and their distance from the line.

193
Q

III - Mark–recapture studies

A

Used for mobile organisms. A subset of individuals is captured and marked or tagged, then released. At a later date, individuals are captured again, and the ratio of marked to unmarked individuals is used to estimate population size.

194
Q

ecological niche

A

physical and biological conditions that a species needs to grow, survive, and reproduce

195
Q

niche model

A

predicts a species’ distribution based on conditions at locations the species is known to occupy

196
Q

Habitat rules

A

for each species described environmental conditions where it was most likely to be found

197
Q

Sx = survival rate

A

Chance that an individual of age x will survive to age x + 1. Sx = Nx+1 / Nx

198
Q

lx = survivorship

A

Proportion of individuals that survive from birth to age x. lx = Nx / N0

199
Q

Fx = fecundity

A

Average number of offspring a female will have at age x.

200
Q

Cohort life table

A

follows the fate of a group of individuals all born at the same time (a cohort).

201
Q

Static life table

A

Survival and reproduction of individuals of different ages during a single time period (requires estimating age or some class interval).

202
Q

Survivorship curves can vary

A
  • Among populations of a species.
  • Between males and females.
  • Among cohorts that experience different environmental conditions
203
Q

A population can be characterized by its age structure

A

the proportion of the population in each age class.

204
Q

λ >1

A

population growth

205
Q

dN/dt = rN

A

equation for exponential growth

206
Q

λ = 1

A

population is stable

207
Q

λ < 1

A

population decline

208
Q

r=0

A

population stable

209
Q

r > 1

A

population growth

210
Q

r < 1

A

population decline

211
Q

Assumptions of exponential growth

A
  • no immigration or emigration
  • no resource limitation
  • no random mortality factors
  • no age or size structure or stable age structure
  • no genetic structure or constant genetic structure
  • continuous growth with no time lags
212
Q

Exponential growth

A

When individuals reproduce continuously, and generations can overlap.

213
Q

Geometric growth

A

If a population reproduces in synchrony at discrete time periods

214
Q

The population increases by a constant proportion

A

The number of individuals added is larger with each time period.

215
Q

λ

A

geometric growth rate or per capita finite rate of increase. /generational

216
Q

r

A

instant

217
Q

Doubling time (td)

A

Number of years it will take a population to double

218
Q

Net reproductive rate (R0)

A

Mean number of offspring produced by an individual during its lifetime

219
Q

How do populations increase?

A

multiplication, not addition

220
Q

Density-independent factors

A

Effects on birth and death rates are independent of the number of individuals in the population:
•Temperature and precipitation
•Catastrophes such as floods or hurricanes

221
Q

Density-dependent factors

A

Birth, death, and dispersal rates change as the density of the population changes.

222
Q

Population regulation

A

Density-dependent factors cause population to increase when density is low and decrease when density is high.

223
Q

Density-independent factors

A

can have large effects on population size, but do not regulate population size

224
Q

k

A

maximum carrying capacity

225
Q

anything that affects r can

A

change the predicted k

226
Q

logistic equation

A

incorporates limits to growth and shows how a population may stabilize at a maximum size, the carrying capacity.

227
Q

Logistic or sigmoidal growth

A

Population increases rapidly, then stabilizes at the carrying capacity (maximum population size that can be supported indefinitely by the environment)

228
Q

Ecological footprint

A

Total area of productive ecosystems required to support a population

229
Q

λ < 1

A

r < 0

230
Q

λ = 1

A

r = 0

231
Q

λ > 1

A

r > 0

232
Q

Population dynamics

A

The ways in which populations change in abundance over time.

233
Q

four main patterns of growth

A

exponential growth, logistic growth, fluctuations, and regular cycles.

234
Q

Exponential Growth

A
  • Population increases by a constant proportion at each point in time.
  • When conditions are favorable, a population can increase exponentially for a limited time.
235
Q

Logistic Growth

A

Some populations reach a stable size (equilibrium) that changes little over time.
These populations first increase, then fluctuate by a small amount around the carrying capacity(‘K’, birth = death rate

236
Q

Population Fluctuation

A

In all populations, numbers rise and fall over time.

For K to be constant, birth rates and death rates must be constant over time at any given density.

237
Q

Population Cycles

A

Some populations have alternating periods of high and low abundance at regular intervals.
Factors that drive population cycles may vary from place to place, and with different species.

238
Q

Delayed density dependence

A

Delays in the effect that density has on population size.

239
Q

Chance events

A

—genetic, demographic, and environmental events
—can play a role the extinction
Small populations, because of the “laws of probability”, are at greater risk.

240
Q

Genetic drift

A

-chance events influence which alleles are passed on to the next generation.
Allele frequencies can change at random from one generation to the next:
- reduced genetic variation
- increased frequency of harmful alleles

241
Q

Inbreeding

A

tends to increase the frequency of homozygotes:
•Individuals can have two copies of a harmful allele.
•Reproductive success is reduced.

242
Q

Demographic stochasticity

A

chance events affect survival and reproduction of individuals.

243
Q

Allee effects

A

At low densities, individuals have difficulty finding mates •growth rate decreases as population density decreases.
•Allee effects can reduce small population size even further

244
Q

Environmental stochasticity

A

—change in average birth or death rates from year to year because of random changes in environmental conditions.

245
Q

demographic stochasticity

A

—birth and death rates are constant, but the actual fates of individuals differ

246
Q

Isolation by distance

A

travel distance is long and risky

247
Q

patch size

A

small patches are hard to find and have high extinction rates

248
Q

metapopulation

A

sets of spatially isolate populations, linked by dispersal

Principles Of Ecology (2 decks)

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