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Biology - SBI4U1 > Unit 5 - Population Dynamics > Flashcards

Unit 5 - Population Dynamics Flashcards

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1
Q

crude density (D)

A

takes into account all the area

D = N ÷ S
crude density = # ÷ area

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2
Q

ecological density (D)

A

takes into account only the habitable area of the species

D = N ÷ S
ecological density = # ÷ habitable area

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3
Q

dispersion patterns of wild populations

A
  • clumped; most common (e.g. fish)
  • uniform (e.g. lions)
  • random (e.g. trees)
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4
Q

quadrat analysis

A

ideal for stationary and small organisms (e.g. plants)

average sample density = total number of individuals ÷ total sample area

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5
Q

mark-recapture sampling

A
  • ideal for mobile wildlife populations (e.g. fish, polar bears)
  • often demonstrate clumped dispersion

total # marked (M) ÷ total population (N) = # of recaptures (m) ÷ size of second sample (n)

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6
Q

technological tracking of populations

A
  • radio collars
  • sattelite-linked monitors decipher migration patterns
  • microcomputer tags; geographical information system (GIS) mapping is used to determine dispersion patterns and migration activities
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7
Q

ethics of technological tracking (the 3 R’s)

A

replacement (trapping with computer models), reduction (reducing the number of animals used), and refinement (adjust techniques to minimize pain/stress); suggested by the Canadian Council on Animal Care (CCAC)

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8
Q

factors affecting population growth

A
  • natality (birth rate)
  • mortality (death rate)
  • immigration and emigration
  • human actions and natural factors
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9
Q

formula for population size

A

(births + immigration) - (deaths + emigration)

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10
Q

formula for population change

A

([(births + immigration) - (deaths + emigration)] ÷ initial population size)) × 100

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11
Q

populations vs. communities

A
  • Populations are one species.
  • Communities are many species co-existing (e.g. the different organisms in a pond).
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12
Q

closed populations vs. open populations

A
  • Closed populations are stationary and are not affected by migration (e.g. fish in an aquarium).
  • Open populations are affected by migration (e.g. ants at a picnic).
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13
Q

fecundity vs. fertility

A
  • Fecundity is the theoretical maximum number of offspring that could be produced by a species in one lifetime.
  • Fertility is the actual number of offspring produced by an individual during its lifetime, and is affected by food supply, disease, and mating success.
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14
Q

patterns in survivorship of species

A

Type I

  • low mortality
  • high life expectancy
  • small number of offspring (e.g. mammals)

Type II

  • uniform risk of mortality
  • constant proportion of individuals dying at each age interval (e.g. songbirds)

Type III

  • high mortality
  • low life expectancy
  • large number of offspring (e.g. sea turtles)
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15
Q

carrying capacity (K)

A
  • the maximum number of organisms that can be sustained by available resources over a limited period of time
  • is dynamic; environmental conditions are always changing
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16
Q

biotic potential (r)

A

the maximum growth rate that a population exhibits under ideal environmental conditions

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17
Q

modelling population change

A
  • geometric growth (J-shaped)
  • exponential growth (J-shaped)
  • logistic growth (S-shaped; sigmoidal)
18
Q

geometric growth

A
  • organisms reproduce at a constant rate during fixed intervals
  • births take place at one time of the year (i.e. breeding season); population grows rapidly during breeding season, and declines throughout the year until the next breeding season
  • an annual growth rate can be determined
  • e.g. seals, deer, salmon
19
Q

formulas for geometric growth (λ)

A

λ = N(t+1) ÷ N(t)
rategeometric = population at interval ÷ initial population

N(t) = N(0)λt
rategeometric = (initial population)(geometric rate)time

20
Q

exponential growth

A
  • organisms reproduce at a constant rate continuously
  • slope of the tangent increases over time
  • reproduction is continuous throughout the year (i.e. no breeding season)
  • an instantaneous growth rate can be determined
  • e.g. yeast, bacteria, humans
21
Q

formulas for exponential growth (dN/dt)

A

dN/dt = rN
rateexponential = (intrinsic growth rate)(population)

td = 0.69 ÷ r
doubling time = 0.69 ÷ intrinsic growth rate

22
Q

logistic growth rate

A
  • population size grows until it levels off, as it approaches its carrying capacity
  • most common among wild populations
  • includes a lag phase (lowest growth; flattest slope), log phase (highest growth; steepest slope), and a stationary phase (zero growth; slope = 0)
  • e.g. sheep, harbor seals
23
Q

formula for logistic growth (dN/dt)

A

dN/dt = rmaxN × [(K - N) ÷ K]

rateinstantaneous = (maximum growth rate)(population) × [(carrying capacity - population) ÷ carrying capacity]

24
Q

density-dependent factors

A
  • intra-specific competition; within the same species (e.g. food, mating)
  • inter-specific competition; amongst different species (e.g. predation)
  • Allee effect; population is not viable due to a small size, because there’s a smaller chance of reproduction (e.g. passenger pigeon)
25
Q

density-independent factors

A

extreme weather, natural disasters, human impact, etc.

26
Q

r-selected strategies

A

life strategies used by populations that live close to their biotic potential

  • have a short life span
  • become sexually mature at a young age
  • produce large broods of offspring
  • provide little or no parental care to their offspring
  • e.g. insects, annual plants, algae
27
Q

K-selected strategies

A

life strategies used by populations that live close to their carrying capacity

  • have a relatively long life span
  • become sexually mature at a later age
  • produce few offspring per reproductive cycle
  • provide a high level of parental care to their offspring
  • e.g. mammals, birds, humans
28
Q

predator-prey interactions

A
  • predators limit the population of the prey by weeding out the weak (natural selection), and prey provide food for the predators
  • populations never reach 0; the relationship between predator and prey is sustainable
  • sinusoidal growth is a wave-like oscillating pattern that is typical of predator-prey interactions
    1. less predator = more prey
    2. more prey = more predator
    3. more predator = less prey
    4. less prey = less predator
29
Q

ecological niche

A
  • the role of an organism in a community
  • either fundamental (theoretical) or realized (realistic; with competition)
30
Q

inter-specific competition

A

interference

  • “default” competition; traditional
  • aggression between members of different species who fight over the same resource
  • e.g. tree swallows and bluebirds fight over birdhouses

exploitation

  • consumption of a shared resource by individuals of different species in which consumption of a resource limits the other species
  • e.g. arctic foxes and snowy owls prey on the same population of arctic hares
31
Q

passive defense mechanisms

A

protective structures

  • e.g. thorns

chemical

  • taste
  • toxins
  • smell

protective colouration

  • camouflage; involves the surrounding environment (e.g. chameleons)
  • mimicry; an organism imitates the physical appearance of a more dangerous organism (e.g. viceroy butterflies mimic monarch butterflies)
  • warning colouration; usually red and black (e.g. poison dart frogs)
32
Q

interspecific interactions

A

competition

  • competitive (-/-): both populations are negatively affected (e.g. cheetahs and lions)

predation

  • predator-prey or herbivore-plant (+/-): one population gains at the expense of the other (e.g. hawks and rabbits)
  • herbivore-plant (+/-): one population gains at the expense of the other (e.g. antelopes and grass)

symbiosis

  • parasitism (host-parasite) (-/+): one population gains at the expense of the other (e.g. deer and tapeworms)
  • mutualism (mutualistic) (-/-): both populations are positively affected (e.g. algae and coral)
  • commensalism (+/0): one population gains, while the other is unaffected (e.g. suckerfish and sharks)
33
Q

estimated human population on Earth

A

7.6 billion (2018) → 8.1 billion (2024)

  • doubling time of humans have changed drastically over time; 600 years (in antiquity) → 60 years (today)
  • carrying capacity of humans is currently unknown
  • dip in population in the 1300s, due to the bubonic plague
  • population skyrockets in the 1900s due to the discovery of antibiotics by Alexander Fleming (i.e. penicillin), and refrigeration increased sanitation techniques
34
Q

human population projections

A
  • positive growth (rapid growth or slow growth): more young people, less old people (higher natality, lower mortality)
  • zero growth: equal amount of young and old people (equal natality and mortality)
  • negative growth: less young people, more old people (lower natality, higher mortality)
35
Q

ecological footprint

A
  • the total amount of land needed to support one person
  • includes cropland, grazing land, fishing grounds, forest land, carbon absorption land, and building area
  • industrialized countries (e.g. U.S., Australia, Canada) have a greater footprint than developing countries (e.g. Egypt, China, India)
36
Q

biomagnification

A
  • the increasing concentration of toxic substances that enter the food chain or food web at low levels
  • e.g. methylmercury increases in concentration in organisms as the trophic level increases
37
Q

biomass

A

the renewable organic material from plants and animals

38
Q

energy transfer

A

as the trophic level increases, only 10% of energy is passed on

39
Q

bioremediation

A
  • the use of organisms, usually bacteria, to detoxify polluted environments such as oil spill sites or contaminated soils
  • e.g. chlorinated organic solvents like trichloroethene (TCE) and perchloroethylene (PCE or PERC) are commonly used in paint thinners, antifreeze, dry-cleaning, and industrial processes that involve grease removal
40
Q

limiting wastes

A
  • prevent, reduce, or eliminate the production of pollutants by use of such cleaner, nonpolluting technologies (e.g. wind power, solar photovoltaic systems, microturbines)
  • cleaning up the pollutants after they have been produced
  • the development of eco-cities: urban centres that are planned to minimize their impact on the local and regional environments and to foster sustainable lifestyles
41
Q

ecological effects caused by human activity

A

excessive use of fertilizers

  • inorganic fertilizers allow for the production of much more food on the same land base
  • excessive use may result in the release of nitrous oxide from soil, cause water pollution, and reduce soil fertility after extended
  • alternative cultivation practices can reduce fertilizer demand without reducing productivity.

deforestation

  • growing populations (especially equatorial regions) often cut down lots of trees for new farmland and housing
  • trees purify air, regulate water flow, influence climate, provide habitats, and support food webs and energy flow

loss of biodiversity

  • humans have degraded 40%-50% of Earth’s land surface via deforestation
  • many species become extinct or endangered due to displacement

ozone (O3) depletion

  • a layer of ozone in the lower stratosphere shields the Earth from 95% of the Sun’s radiation
  • ozone layer depletion is the result of many chlorofluorocarbons (CFCs) and other ozone-degrading chemicals being released in the air; the sources of these emissions is mostly from highly industrialized populations

pesticides

  • pesticides have increased harvests of crops, by kill many insects that compete with humans
  • pesticides pose a risk to territorial and aquatic ecosystems
  • the risk of long-term exposure to trace pesticide residues in food, water, and air is unknown

widespread pollution

  • air, water, and soil pollution are all the result of regular human activity (e.g. oil spills)
  • pollution is most severe in larger urban populations, where more waste is generated

Biology - SBI4U1 (5 decks)

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