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Biology 1B > Ecology > Flashcards

Ecology Flashcards

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1
Q

What is ecology?

A

It is the interactions between organism, biotic and abiotic environment and humans

Biotic factors: Living
Abiotic factors: Nonliving

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2
Q

What is traditional ecological knowledge?

A
  • its a western term used to summarize the understandings of nature and human relationships with nature, of different indigenous peoples
  • These systems of knowledge have been excluded from western dialogs about ecology or have been lost, but that is now changing
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3
Q

What are Biomes?

A
  • They are major terristrial ecosystems at a global scale
  • they have different combinations of climates and species within a similar range
  • Biomes are affected by climate (good predictor of biomes)
    • temperature and precipitation
  • Effects of elevation and latitude on biomes are similar

-The linkage between biomes and species isn’t perfect → Rough matches between biomes and species ranges

-Species distributions often overlap within biomes

-Geographical distributions (ranges) vary across species

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4
Q

How are biomes affected by climate?

A

Temperature: latitude dependent with some unique patches

Precipitation: Dry Vs. wet

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5
Q

What are some patterns of climate?

A
  • Temperature increases at lower latitudes because they receive more solar radiation
  • At the equator sunlight comes in from the sun making it warmer
  • As we get closer to the poles the angle that the sunlight comes in is lower meaning the light hitting is spread over a larger area (Lower intensity= less heat)
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6
Q

What are some patterns of precipitation? (increase and decrease)

A

-Increases at high elevations on windward side of mountains
* Cool air flows from the ocean on the windward side of a mountain range
* As the air cools, water vapor condenses → precipitation
* Descending air and reduced moisture left in the atmosphere → Rain Shadow on the leeward side of a mountain

  • DECREASES at mid latitude because of Hadley cell air circulation patterns
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7
Q

What is a rain shadow?

A

-Increases at high elevations on windward side of mountains
* Cool air flows from the ocean on the windward side of a mountain range
* As the air cools, water vapor condenses → precipitation
* Descending air and reduced moisture left in the atmosphere → Rain Shadow on the leeward side of a mountain

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8
Q

What are Hadley cells?

A
  • Hadley Cells: High precipitation in the tropics
    • Tropical air heats up → moisture rises and air cools
    • Cooler air precipitates moisture as rain in tropics
    • Rising air is displaced North or South → Creating winds and air transport
    • Transported air begins to cool down and sink
    • Dry air fall in mid latitudes
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9
Q

What are some characteristics/ pattern of temperate?

A

-Decreases at high elevations
* Every ~1000 m elevation increase causes a 5-10C temp. decrease (Lapse Time)

-Rising air expands (low density, lower pressure) and cools

-Falling air compresses (high density, high pressure) and warms

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10
Q

Why does the tilt of the earth cause seasons?

A
  • The earth is not perfectly aligned at the equator with the sun
  • During certain months different part of the earth have direct sunlight while others are further from the sun
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11
Q

How does the ocean affect the climate?

A

Oceans buffer climate, so climate extremes are stronger in the interior of continents

  • Water warms and cools slowly
  • Near the coast winters are milder and summers are cooler
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12
Q

Maritime climate

A

Lower amplitude of seasonal temperature fluctuations

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13
Q

Continetial climate

A

High amplitude of seasonal temperature fluctuations

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14
Q

Mediterranean climate

A

Characterized by hot, dry summers and cool, wet winters

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15
Q

What are indicator species?

A

-They are species that are tolerant to very specific/ healthy conditions

-They are used to make inferences on the conditions of the environment
* Presence of one or many bioindicators species at a site can tell us about environmental conditions

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16
Q

What are the types of abiotic and biotic gradients?How distribution limits be partially set by geographic distributions?

A

-Types of gradiants
* Temperature gradient
* Elevation gradient
* Storm risk gradient
* Predation risk gradient

  • Some gradients are physically continuous, other gradients are patchy and span a range of environmental conditions
  • Species occur where performance is highest along an environmental gradient

-Species distribution are often limited at one end of the range of abiotic environmental factors and at the other end by biotic factors

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17
Q

How can biotic factors influence abiotic limits?

A

EX: the food obtained through biotic interactions (predation) influences the temperature (abiotic) of the fish

	Limited food= less growth
	Excess food= higher growth
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18
Q

When two species have similar distributions, can we be sure that the same factors limit both of their ranges?

A

No, because one species may not always be limited by another
EX: While the white bark tree is limited to a specific range due to the Clark’s Nutcracker, the bird’s range isn’t limited by the trees but by another factor

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18
Q

When two species have similar distributions, can we be sure that the same factors limit both of their ranges?

A

No, because one species may not always be limited by another
EX: While the white bark tree is limited to a specific range due to the Clark’s Nutcracker, the bird’s range isn’t limited by the trees but by another factor

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19
Q

What is a performance curve?

A
  • A metric of organism performance
  • They measure how fitness varies with the abiotic factors
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20
Q

What sets limits to a species’ distribution?

A

-Multiple factors combine to determine where species can be present or absent
- dispersion
- abiotic environment
- Biotic environment
- Humans can influence or shift the limits
- organism behavior

  • They all occur simultaneously NOT in sequential
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21
Q

Key limits that influence species distribution - Is the biotic environment suitable for survival, growth and reproduction of the species?

A
  • Biotic factors: Living components of the environment
    • Species interactions
    • pollination
    • food
    • predators
    • successfully compete
      -Biotic Limits
    • Herbivory → cattle herbivores eat plant species and reduce the plants’ geographical distribution
    • Competition → Competition for similar resources, both species can NOT persist in areas that overlap as a result each species reduces its range to an area in which it can successfully persist
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22
Q

Key limits that influence species distribution - Is the abiotic environment suitable for survival, growth, and reproduction of the species?

A
  • Abiotic factors: Non living components
    * precipitation
    * sunlight
    * snowfall
  • Abiotic Limits
    * Temperature: species have a physiological tolerance to specific temperature→EX: Ocean Temperature
    * Climate: EX: Limits on land → drought tolerance
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23
Q

Key limits that influence species distribution - Can the species disperse to a locations?

A

-Dispersal: The movement of individuals or gametes away from (and potentially back to) their original location

-Dispersal occurs via several mechanisms
* Animal vector → ingestion/ excretion, exterior
* Mobility
* Wind
* Water

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24
Q

What is spacial scale?

A
  • The area
  • Spatial grain: The characteristic scale at which measurements are reported
  • Spatial extent: The overall region in which measurements are made at the selected spacial grain
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25
Q

What are the different diversity metrics?

A
  • abundance: Number of individuals (total or per species)
  • richness: The total number of species (#)
  • Evenness: Relative similarity in abundance of species
    * are the number of each species even/ close in #s
  • Composition: Identites of which species of present (describes)
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26
Q

What is the difference between richness and evenness?

A
  • richness: The total number of species (#)
  • Evenness: Relative similarity in abundance of species
    *are the number of each species / close in #s
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27
Q

What is the difference between richness and evenness?

A
  • richness: The total number of species (#)
  • Evenness: Relative similarity in abundance of species
    *are the number of each species / close in #s
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28
Q

Abundance

A

Number of individuals (total or per species)

29
Q

richness

A

The total number of species (#)

30
Q

Evenness

A

Relative similarity in abundance of species

31
Q

Composition

A

Identites of which species of present (describes)

32
Q

What is the species area relationship?

A
  • As the area increases the species richness also increases
  • The rate a which the area increase vs. species increase is 3/4 → as you look more specific this pattern may not continue
33
Q

What is the latitudinal diversity gradient?

A
  • it’s a pattern of changes in species richness with latitude
  • higher species richness near the equator, lower richness toward the north and south pole
34
Q

Why do some places have more diversity in the same area than others?

A

High biodiversity in the tropics

35
Q

Why does the LDG (latitude diversity gradient) occur?

A
  • Environment are less stressful in the tropics → more species can survive (Warmer/Wetter)
  • More energy available in the tropics → more ways to differentiate niches/support more species
  • High temp. in tropics biochemically drive higher mutation rate → thus speciation rates
  • More competition in the tropics drives more net speciation to get away from competition
  • More time to evolve new species in the tropics → conditions are consistently stable (no ice sheets)
    • Long time since disturbance = higher richness
  • More land area supports more species in tropics → Species area relationship
36
Q

Why does the LDG (latitude diversity gradient) occur?

A
  • Environment are less stressful in the tropics → more species can survive (Warmer/Wetter)
  • More energy available in the tropics → more ways to differentiate niches/support more species
  • High temp. in tropics biochemically drive higher mutation rate → thus speciation rates
  • More competition in the tropics drives more net speciation to get away from competition
  • More time to evolve new species in the tropics → conditions are consistently stable (no ice sheets)
    • Long time since disturbance = higher richness
  • More land area supports more species in tropics → Species area relationship
37
Q

What are some species patterns that are sub-global?

A

Species area relationship
* The rate is 3/4 as you increase the area

Island Biogeography theory

  • Island- places that are isolated (oceanic islands, mountaintops surrounded by desert, forest patched surrounded by fields, etc.)
  • As the area of the Island increase the richness also increase
    * Larger islands have lower extinction rates → there’s more ways for species to survive
  • As the distance between the Island and mainland increase the richness decreases
    * Islands closer to the mainland get more immigration of species than further islands
  • Equilibrium richness is determined by the balance between immigration and extinction → Island size and distance from mainland
38
Q

What is a population?

A
  • A group of individuals of a single species in a certain
  • Individuals may interact with each other
39
Q

What is a population?

A
  • A group of individuals of a single species in a certain
  • Individuals may interact with each other
40
Q

If dispersal isn’t limiting where is the range limit set?

A
  • It’s set where zero or negative population growth rates occur
41
Q

Why does the demography of a population change over time?

A
  • Births
  • deaths
  • Immigration
  • Emigration
42
Q

Why does the demography of a population change over time?

A
  • Births
  • deaths
  • Immigration
  • Emigration
43
Q

What is the BIDE model and what does each variable mean?

A

N(t+1)= N(t)+ B - D- E

  • N(t) is the number of individuals at time t
  • B is the number of births in the next time interval
  • I is the number immigrants in the next time interval
  • D is the number of deaths in the next time interval
  • E is the number of emigrants in the next time interval

→ The time intervals are usually one year for large plants and animals but it depends on the population being studied

44
Q

What is the BIDE model and what does each variable mean?

A

N(t+1)= N(t)+ B - D- E

  • N(t) is the number of individuals at time t
  • B is the number of births in the next time interval
  • I is the number immigrants in the next time interval
  • D is the number of deaths in the next time interval
  • E is the number of emigrants in the next time interval

→ The time intervals are usually one year for large plants and animals but it depends on the population being studied

45
Q

What is the simplified B-D model and what assumptions need to be made?

A

N(t+1)= N(t) + B-D

  • assume that no immigration/emigration → a closed population
  • N(t) the size of a population in a given year
46
Q

What is the exponential growth model?

A
  • N(t)= N(0) (e^rt)
    -N(t)-population size
    • N(0)- initial # of individuals @ t=0
    • r- rate of population growth per unit time (# time^-1) (inverse time)
47
Q

What is the difference between Geometric VS Exponential growth?

A

Geometric growth
* Discrete time (results in points on a curve graph graph)
* linear when the y-axis is log-scaled
* EX: A population of annual plants that reproduce once every winter

Exponential Growth
* Continuous time (results in a curved time)
* Can also be exponential decline
r >0 : Population growth
r =0 : Constant population
r <0 : Population decline
* linear when the y-axis is log-scaled
* EX: A population of bacteria that reproduce at any time

48
Q

Why do both exponential and geometric growth NOT continue forever?

A
  • The assumption that “each individual on average, has a rate of reproduction in the population equal to r regardless of the population size” breaks down
  • growth slows down as the population size becomes bigger
  • We need a more complex model to describe reality
49
Q

Why can populations not increase forever at exponential rate?

A

Carrying capacity is exceeded

50
Q

What is per capita population growth rate?

A
  • Rate of population divided by population size
  • A metric of the average rate of population change for an average individual in a population
51
Q

What is density dependence? How does per capita population growth rate change with population size?

A

The change in the per capita growth rate may be influenced by population size

- NO density dependence: Slope is constant
    - Exponential model
    - per capita rate doesn’t change with population
    - An individual has the same chance of reproducing or dying regardless of the population size

- Negative density dependence: Negative slope
    - The per capita growth rate decreases as the population is bigger

- Positive density dependence
    - The per capita growth rate increases as the population size increase
52
Q

What are examples of density-independent vs. density-dependent factors influencing a population?

A
53
Q

When does a population reach equilibrium?

A
  • A population comes to equilibrium when the per capita growth rate equals 0
  • If the population is neither growing or shrinking it is stabilized
  • Birth rate has negative density dependence → as the population increase birth rates decrease
  • Death rate as the population size increases also increase because of limited resources
  • Birth rate=death rate → Per capita = 0
54
Q

Why is negative density dependence more common?

A

Usually life becomes more challenging in denser population, reducing birth rates and increasing death rates
- Fewer resources per individual
- More competition among individuals
- fewer mates available
- more disease or parasites
- More predation risks (easier hunted when common)

55
Q

In the logistic model, what does the plot of per-capita population growth rate vs. N look like, and how does it compare to the plot of population growth rate vs. N? Biologically, how do you interpret these graphs?

A
56
Q

What is the logistic growth model?

A
  • Adds negative density to the exponential model
  • Exponential model multiplied by (1-N/K) which is a correction to make the model have a line that has a negative slope
57
Q

What are the properties of the logistic model?

A
  • when N=0 ,(is r) in small population, collapses to the exponential model
  • when N=K , The per capital growth rate =0 so the population is at equilibrium

1) Per capita growth rate is higher when the population is small and is identical to the exponential model

2) Population comes to equilibrium when N=K (the carrying capacity)

58
Q

What do r and k represent?

A

r is the intrinsic growth rate
- A constant number/ parameter, NOT a variable
- Describes how quickly a population size will increase starting at very low density
- “intrinsic” in relation to the species biology and the environmental context

K is the carrying capacity
- A constant number/ parameter NOT a variable
- The population size at which N comes to equilibrium

59
Q

According to the logistic growth equation…

A
  • the pre capita change in number of individuals per unit time is greater when N is close to zero (1/N* dN/dt= is bigger when N is close to zero)
  • The population growth rate (dN/dt) is zero when N=K
  • K is a fixed parameter
  • r is a constant
60
Q

According to the logistic growth equation…

A
  • the pre capita change in number of individuals per unit time is greater when N is close to zero (1/N* dN/dt= is bigger when N is close to zero)
  • The population growth rate (dN/dt) is zero when N=K
  • K is a fixed parameter
  • r is a constant
61
Q

What is a density independent factor?

A

→ dN/dt at any instant is limited by something unrelated to the size of the population

  • external environment aspects (cold winters, drought, storms, volcanic eruptions)
    • Population display erratic growth patterns because density independent factors change over time
  • Density independent factors can increase of decrease parameters like r and K over time (we often can NOT measure these effects directly)
62
Q

What are some density independent factor that may affect K and r?

A

Affecting K
- Change in temperature
- Change in moisture availability
- Change in land area

Affecting r
- Change in temperature
- Change in moisture availability
- Change in allele frequencies

63
Q

Are population fluctuations common? Why?

A

population fluctuations are common
- density independent factors that vary over time
- Variation in immigration and emigration

64
Q

What is a population collapse and why does it occur?

A
  • exponential growth (abundance of food in summer, growing population) → followed by very cold winter, deep snowpack (no lichen grazing possible) → high winter mortality, temporary collapse
  • Common misconception- collapse always occurs of a population temporarily exceeds carrying capacity
    • smaller fluctuations are more likely in this scenario
65
Q

Does the logistic model accurately model a population collapse?

A
66
Q

What is life history and how can it be linked to population growth?

A

life history: suite of traits related to species’ life cycle and the timing of major events
- Survival rates as juveniles
- avg lifespan
- age of first reproduction
- number and timing of reproductive episodes
- size and number of offspring in each episode
- duration and investment of parental care

→ Variable across species

67
Q

Why can organisms usually not simultaneously maximize performance of different functions?

A

principle of allocation

  • individual organisms have limited amount of resources to invest in different activities and functions.
    • Resources invested in one function are not available for another → trade off
  • In life cycles resources must be allocated among growth, survival and reproduction

→ Reproduction size-number tradeoffs

  • species can have smaller or fewer bigger offspring
  • Negative relationship → as the size of the offspring increase there is a decrease in the number of organisms produced

→ Cost of reproduction trade off

  • More reproduction in one year means less reproduction the next year
68
Q

What are examples of ‘slow’ life history traits, or organisms?

A
  • Slow species
    • Late reproductive age
    • Long life spans
    • Long maturation time

→ Only represents about 35% of the variation of life

69
Q

What are examples of ‘fast’ life history traits, or organisms?

A
  • Fast species
    • early reproductive age
    • Short life spans
    • Short maturation time
70
Q

What is a species interaction?

A

1) An individual of species A influences the behavior or life events of an individual of species B

2) An individual of species A influences the growth, survival or reproduction of an individual of species B

3) A population of species A influences the growth rate (dN/dt) of a population of species B

71
Q

What are some pairwise interactions?

A
  • Competition (asymmetric)
    * A and B both try to acquire the same limited resources
  • Predation (asymmetric)
    * A kills B
  • Herbivory (asymmetric)
    * A eats B, may or may not kill B
  • Parasitism (asymmetric)
    * A lives on/in B, may or may not kill B
  • Mutualism
    * A and B help each other
  • Commensalism
    * B helps A, no impact on B
  • Facilitation
    * General term for mutualism or commensalism

Biology 1B (3 decks)

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