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Life Sciences > Population Ecology (25 marks) > Flashcards

Population Ecology (25 marks) Flashcards

1
Q

Define the term Ecology.

A

The study of the mutual interaction among living organisms and between living organisms and the environment in which they live.

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2
Q

What is Population Ecology?

A

The part of ecology that focuses on the factors that influence the population size:

  • Growth rate
  • Growth forms
  • Distribution of individuals inside a population.
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3
Q

Define the term Species.

A

A group of living organisms with similar characteristics, which produce fertile offspring.

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4
Q

Define the term Population.

A

A group of organisms of the same species that are found in a particular area at the same time and can interbreed freely.

E.g. The population of giraffes in the Kruger National Park.

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5
Q

Define the term Community.

A

A group of different populations or species in a particular area.

E.g. The lion, rhino & zebra populations at KNP.

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6
Q

Define the term Ecosystem.

A

Units of biotic communities interacting with each other and the abiotic factors in a particular area.

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7
Q

Define the term Environment.

A

The external biotic and abiotic factors surrounding an organism and influencing its development and survival.

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8
Q

Define the term Habitat.

A

The specific environment in which a plant or animal species normally occurs.

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9
Q

Define the term Population Size.

A

The total number of individuals in a population.

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10
Q

Define the term Population Density.

A

The number of individuals of a population per unit area.

E.g. 10 sheep per hectare.

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11
Q

What are Population Parameters?

Name them. (4)

A

Population parameters are the factors that influence population size.

  • Natality
  • Mortality
  • Immigration
  • Emigration
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12
Q

Define the term Natality.

A

The birth rate of a population that is usually expressed as the number of live births per 1000 individuals per year.

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13
Q

Define the term Mortality.

A

The death rate of a population, usually expressed as the number of deaths per 1000 individuals per year.

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14
Q

Define the term Immigration.

A

The one-way movement of organisms INTO an area where they become established.

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15
Q

Define the term Emigration.

A

The one-way movement of organisms OUT OF an area

to become established.

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16
Q

Define the term Closed Population.

A

A population where immigration and Emigration do not occur.
Therefore Natality and Mortality are the only parameters that affect the population size.

E.g. Fish in a pond.

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17
Q

Define the term Meta Population.

A

Smaller populations spatially separated within an environment with SOME immigration and emigration taking place.

18
Q

What is the difference between DIRECT data collection techniques and INDIRECT data collection techniques?

A

Direct techniques involve the total count of all the individuals in a population, whilst
Indirect techniques only involve counting part of a population and using statistical calculations to estimate the total population size from the partial count.

19
Q

Name the DIRECT techniques for determining population size.

A
  • Census (in a human population)
  • Counting (e.g. animals in a nature reserve using a helicopter)
  • Aerial photographs of groups of animals (a penguin colony)
20
Q

Name the INDIRECT techniques for determining population size.

A
  • Mark-recapture method (also known as Petersen’s method).

- Quadrat method.

21
Q

How can you ensure VALIDITY of the Mark-Recapture method?

A
  • Marking methods should not HARM the organism.
  • Marks should be CLEARLY VISIBLE throughout the entire investigation.
  • Markings should NOT affect the organism’s BEHAVIOR or MOVEMENT.
  • SUFFICIENT TIME should be given FOR the MIXING of the 1st sample with the rest of the population BEFORE A 2ND SAMPLE IS CAPTURED.
  • CLOSED POPULATION
  • SHORT DURATION between 1st sampling and second sampling to ENSURE NO DEATHS OR BIRTHS occur.
22
Q

How can you ensure RELIABILITY of the Quadrat method?

A
  • The exact number of organisms in each quadrat sampling must be counted (including zeros).
  • The surface area of the quad must be known.
  • The surface area of the total demarcated area of the population must be known.
  • The quad needs to be placed randomly in the demarcated area.
  • Not reliable for clumped populations.
23
Q

How does Geometric/Exponential Growth occur?

A

When population figures increase rapidly due to ideal or optimal environmental conditions.

24
Q

What are Population Growth Forms?

Name the 2 basic ones.

A

Population growth forms are the distinctive growth patterns of a population.

  • Geometric/Exponential (J-shaped) growth form.
  • Logistic (S-shaped/sigmoid) growth form.
24
Q

How does Logistic Growth occur?

A

When a young population consisting of only a few individuals is locate on an area with sufficient resources and little predation.

The limiting factors transform or extend the J-shaped curve into an S-shape.

26
Q

Define the term Limiting Factors.

A

Factors that prevent the unlimited growth in a population that would exceed its maximum growth rate.

27
Q

List 7 limiting factors.

A
  • Shortage of food and water.
  • Shortage of living space.
  • Shortage of shelter.
  • Predation.
  • Diseases and Parasitism.
  • Accumulation of Toxins
  • Uninhabitable Temperatures.
28
Q

Define the term Environmental Resistance.

A

All the limiting factors of a particular population taking effect.

29
Q

Define the term Carrying Capacity.

A

The maximum number of individuals that an environment can sustain.

30
Q

Define the term Migration.

A

When a population moves from its original habitat and returns later, usually due to food availability.

31
Q

Density Dependent Factors VS Density Independent Factors.

A

Density Dependent: Factors that TAKE EFFECT when the population size or density increases. The LARGER the POPULATION, the GREATER the EFFECT of these factors.

  • Shortage of food & water (high competition reduces natality).
  • Shortage of living space (stress reduces natality rate).
  • Shortage of shelter (exposed adverse weather n predation).
  • Predation.
  • Accumulation of waste and toxins.
  • Disease and parasitism.

Density Independent: Factors that LIMIT the size of a population REGARDLESS of the population’s DENSITY.
- Extreme temperature changes.
- Natural disasters.
^ Usually cause a DRASTIC DECLINE in population

32
Q

Define the term Culling.

A

The selective killing of wild animals when their numbers exceed the carrying capacity of their habitat.

33
Q

What is SANParks?

A

South African National Parks.

35
Q

Name Human Intervention Methods for Regulating the Population Sizes of Animals

A
  • Culling
  • Relocation
  • Trans-frontier park creation
  • Birth control & Sterilization
36
Q

What is a Trans-frontier Park?

A

A national park connecting more than one country that was previously isolated by fences that opens up migration routes for animals.

37
Q

What is a Trophic Level.

A

The position that a living organism occupies in the food chain.

38
Q

Briefly describe each Trophic Level (Producer/Primary/Secondary/Tertiary/Decomposer)

A
  • Producers: •Green plants that are able to photosynthesise and produce their own food.
  • Primary Consumers: •Herbivores that rely fully on plant material.
    •Omnivores that rely partially on plant material.
  • Secondary Consumers: •Carnivores (feed on primary consumers).
    •Omnivores (feeding on animal material).
    •Scavengers (feeding on the remains of dead organisms)
  • Tertiary Consumers: •Carnivores that feed on secondary consumers.
  • Decomposers: •Bacteria and Fungi (saprophytes) that feed on dead organic material and break down organic compounds into simple, inorganic substances that are released into the soil.
39
Q

What are the 5 types of interaction that occur in communities?

A
  • Predation
  • Competition
  • Parasitism
  • Commensalism
  • Mutualism
40
Q

Define the term Predation.

A

Predation is a feeding interaction where one organism, the predator, hunts, kills and eats another organism, the prey.

41
Q

What qualities do PREDATORS have that make them well-adapted to hunt to catch their prey?

A 
\+ Speed
\+ Agility
\+ Camouflage 
\+ Sharp teeth and claws
\+ Intensified sense of smell and sight
42
Q

What qualities do PREY have that make them well-adapted to escape predators?

A
  • Herding
  • Ability to secrete poisonous substances
  • Warning colouration
  • Camouflage

Life Sciences (5 decks)

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