Ecology Flashcards

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1
Q

What is population size?

A

The total number of individuals in a population

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2
Q

How can the population size change?

A

It can increase, decrease or remain the same over time

It should generally go up

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3
Q

What factors affect population size?

A
  • Natality
  • Mortality
  • Immigration
  • Emigration
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4
Q

What factors increase population size?

A

Natality

Immigration

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5
Q

What factors decrease population size?

A

Mortality

Emigration

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6
Q

Show + population growth

A

(Natality + Immigration)>(Mortality + Emmigration)

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7
Q

Show - population growth

A

(Natality + Immigration)

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8
Q

Show no population growth

A

(Natality + Immigration)=(Mortality + Emmigration)

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9
Q

What does it mean when resources in an area are scarce?

A

There is a limited population that can be supported

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10
Q

What is carrying capacity?

A

The carrying capacity of an area is the total number of individuals that can be supported

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11
Q

Populations tend to grow until what? What happens if the population continues to grow after that?

A

Until the carrying capacity is reached. If the capacity is exceeded, the population will decrease.

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12
Q

What are the important characteristics of biological circles?

A
  • Frequency of reproduction, age of sexual maturity
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13
Q

What are the important characteristics of biological circles?

A
  • Frequency of reproduction
  • Age of sexual maturity
  • Reproductive maturity
  • Number of offspring
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14
Q

Characteristics of biological circles vary by what?

A

They vary by species

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15
Q

Usually, larger organisms have more or less offspring?

A

Less

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16
Q

Usually, smaller organisms have more or less offspring?

A

More

17
Q

What types of factors influence populations? (Abiotic or Biotic)

A

Both

18
Q

Describe biotic factors. Give examples

A

Living factors that can have an impact on a population

  • Food
  • Humans
  • Bacteria
  • Predation
19
Q

Describe abiotic factors. Give examples.

A

Non-living ecological factors of physical or chemical nature that can affect a population

  • Sun light
  • Atmospheric composition
  • pH
  • Temperature
  • Pheromones
20
Q

Define limiting factors (population growth)

A

Factors that limit the number and growth of a population

21
Q

Give examples of biotic limiting factors

A
  • Humans
  • Predation
  • Limited resources
  • Parasites
  • Bacteria
  • Food
22
Q

Give examples of abiotic limiting factors

A
  • Storms
  • Droughts
  • Floods
  • Volcanic activity
  • Deforestation
  • Temperature
  • Pheromones
23
Q

Name the different ways to estimate the size of a population

A
  • Count
  • Sample area
  • Mark and recapture
24
Q

Describe how to estimate population size using sample area

A
  1. Divide an area of land into equal plots and count the number of individuals in each plot
  2. Calculate the average number of individuals in the plots by choosing 3 plots
  3. Use proportion

Average # of individuals Total population
___________________= ______________
Area per plot Total area

25
Q

Describe how to estimate population size using mark and recapture

A
  1. Capture/Trap an animal
  2. Mark them with a tag, microchip or paint
  3. When the already marked individuals are recaptured use proportion:
number marked (1st) Number of recaptured with mark 
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_=\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 
size of whole population   Total caught in 2nd sample
26
Q

Why is mark and recapture used?

A

In the case that species move around a lot (migratory birds)

27
Q

A scientist captures 50 snakes and marks them. During recapture, 75 snakes are captures and 20 are marked. What is the total population?

A

187 snakes

28
Q

During mark and recapture, if you recapture less marked of the species then will you have a higher or lower population?

A

Higher

29
Q

What is population density/how do you find population density?

A

The number of individuals of a species divided by surface area or volume of water.

30
Q

What is the formula for population density?

A

PD= number of individuals
_______________________
Space (mL, L, cm) occupied

31
Q

Calculate population density of the fleas:

2400 fleas on an elephant with a total surface area of 100m2.

A

24 fleas/m2

32
Q

What is population distribution?

A

Population distribution refers to the way in which individuals are spread out over a territory

33
Q

What are the different types of population distribution?

A
  • Random
  • Uniform
  • Clumped
34
Q

Describe clumped population distribution.

A

The most common distribution in nature.

Individuals form clusters that improve chance of survival when you are also a prey for a predator

35
Q

Describe uniform population distribution.

A

Individuals maintain an equal-ish distance from each other; this indicates strong competition for space and resources

36
Q

Describe random population distribution.

A

It occurs when there are the same conditions over a territory and little competion between individuals. (or when the conditions are just random)

This is more likely for plants than animals