Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Ecology > Chapter 9: Population Growth > Flashcards

Chapter 9: Population Growth Flashcards

1
Q

Population dynamics?

A
  • how and why populations change in size through time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In a statistical study of a population what characteristics do we examine?

A
  • size, age, and sex structure (demography)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What can we do with the data we get in a statistical study examining population characteristics such as its demography?

A
  • predictions for future changes in populations or size..
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  1. 1 Population Growth:

- what is a central process in ecology?

A
  • population growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  1. 1 Population Growth:

- Numbers will increase due to ____ and decrease due to___.

A
  • births

- mortality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. 1 Population Growth:

- Can develop a simple model of population growth when population is?

A
  • closed or immigration and emigration are roughly equal or not happening at all
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  1. 1 Population Growth:
    - Explain a simple graph with x= time (t) and y= population size (N(t))
    * Growth of population with simple life history when resources are not limiting.
A
  • Change in the size of a hypothetical population of hydra through time. The change in population size (delta N), for a given interval, (delta t), differs as a function of time (t), as indicated by the slop of the line.
  • *slope of line = change in population size
  • organism has everything they need so it starts increasing so birth rat is higher than death rate…it will keep increasing since you have more adults you can reproduce more than there are deaths.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. 1 Population Growth:

- What is the equation for continuous population growth?

A 
dN/dt = rN 
N= population size
d= proportion dying 
r= instantaneous per capita rate of population growth
  • can tell you how fast a population is growing..aka decreasing or increasing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  1. 1 Population Growth:

- Exponential population growth equation?

A 
N(t) = N(0)e^rt
N(0)= initial population size at time 0 
-t= time 
-N = population size
- r = instantaneous per capita rate of population growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  1. 1 Population Growth:

- what does exponential population growth equation allow us to predict?

A
  • population growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. 1 Population Growth:
    - with exponential growth what does it mean when r= 0?
    - r>0?
    - r<0?
A
  • it means that the population size is not changing
  • you can have a population that is increasing..birth rate is higher than death rate
  • population that is decreasing..death rate is higher than birth rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

9.1 Population Growth:
-Exponential Growth
L> Characteristic of populations with ?

A
  • favourable enivonrmental conditions and low population density
  • rate of population increase or decrease continuously accelerating
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. 1 Population Growth:

- when is exponential growth usually seen?

A
  • when colonization is occurring …. lots of space and resources to grow..
    ex: mosquito population at the beginning of the summer.. a lot of populations start with exponential growth but nothing can continue with it forever….
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

9.1 Population Growth:
- Exponential growth
L> will it continue to grow forever?

A
  • no
  • the population will reach a point where it exceeds the resources available and there is a decline in the population size..
  • also if the population is very large the spread of diseases occurs more easily
  • after a period of exponential growth you usually get periods of drastic decline
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  1. 2 Life tables

- what are life tables?

A
  • a tool for describing age specific mortality (or survival) patterns
  • this is how ecologists estimate per capita growth rate, r
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  1. 2 Life tables

- when are life tables used?

A
  • when birth and death rates vary with age, can’t just use the proportions of individuals in the population giving birth and dying
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q
  1. 2 Life tables

- what were life tables first developed for?

A
  • human populations

- used by life insurance companies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q
  1. 2 Life tables

- begin with a ?

A

cohort

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q
  1. 2 Life tables

- what is a cohort?

A
  • group of individuals born in the same period of time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

9.2 Life tables
- cohort example?
L>use nx and lx

A
  • gray squirrels in 10 year study
  • nx= number of individuals from cohort alive at age x
  • lx= probability of survival at birth to any given age.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q
  1. 2 Life tables

- how do you get lx?

A

nx/n0
aka say n0= 530 and n1= 159
lx= 159/530 = 0.3….0.3 chance they will live another year

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q
  1. 2 Life tables

- what is dx?

A
  • number of individuals that have died during an interval

ex: n0-n1= 530-159= 371 died

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q
  1. 2 Life tables

- mortality and death rates are?

A

the inverse of each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q
  1. 2 Life tables

- what is qx?

A
  • age specific mortality rate-> proportion that died during interval x
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q
  1. 2 Life tables

- how do you calculate age specific mortality rate(qx)?

A

dx/nx

ex: d0/n0= 371/530

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q
  1. 2 Life tables

- does an organisms age specific mortality rate stay constant?

A
  • no
  • at a certain age your mortality rate is very low… until you get to another extreme where it is really high
  • *this only takes into account death rates not birth rates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q
  1. 3 Types of Life tables

- What are the two types of life tables you can have?

A
  1. Cohort or dynamic life table: following one group through time
  2. Time-specific life table
28
Q
  1. 3 Types of Life tables

- Time-specific life tables? Explain.

A
  • constructed by sampling the population to obtain a distribution of age classes during a single time period
  • easier to obtain data for this second type
29
Q
  1. 3 Types of Life tables

- What are the assumptions for the Time-specific life table?

A
  • constant mortality
  • no leaving/entering
  • must assume sampling is representative of their distribution
  • ex: used in fisheries a lot
  • spot sample ( not over time just in one instance)
30
Q
  1. 3 Types of Life tables

- Plant life tables are more or less complex than animal ones?

A
  • more complex
  • more difficult to study mortality and survivorship in plants because age and sometimes individuals can be difficult to determine
  • *how do you tell one individual from another …unless they are isolated or do they end up coming together?
31
Q

9.3 Types of Life tables
- Plant Life Tables are more Complex:
L> Can use life table to examine what?

A
  1. seedling mortality and survival
  2. Population dynamics of perennial plants marked as seedlings
  3. life cycles of annual plants
    * *estimations/predictions of population size in the future for practical or managing…so it doesn’t disappear…etc conservation
32
Q

Data from life tables can be used to plot what?

A
  • Mortality and Survivorship curves
33
Q
  1. 4 Mortality and Survivorship Curves:

- Mortality curve is based on?

A
  • the qx column

- with age(x axis)

34
Q
  1. 4 Mortality and Survivorship Curves:

- Survivorship curve is based on ?

A
  • the lx column

- with age(x axis)

35
Q
  1. 4 Mortality and Survivorship Curves:

- graphs can illustrate what?

A
  • the variation in mortality and survival patterns
36
Q
  1. 4 Mortality and Survivorship Curves:

- Types of Survivorship curves?

A

Type 1: Individuals live out physiological lifespan (humans and mammals)
- steady then it curves a bit and begins to decline with age
- good survivor ship with a steep drop off when they are older..happens in an instant
Type 2: survival does not vary with age (adult birds)
- straight line going down from the y axis to the x axis..
**constant throughout life at any age
Type 3: Mortality rate very high early in life (many invertebrates and plants)
- steady decline when younger then it in slows down
*seen in plants and inverts that produce a lot of offspring, also seen in turtles.

37
Q
  1. 4 Mortality and Survivorship Curves:

- In terms of survivorship curve types what was said to explain some of the variation in these?

A
  • life history
  • some put in their effort to making a lot of offspring without any effort elsewhere and other organisms are the opposite.
38
Q
  1. 5 Birthrate:

- what is birth rate?

A
  • number of births per female of age X per unit of time
39
Q
  1. 5 Birthrate:

- what do we need to calculate since birth rate varies with age?

A
  • age-specific schedule of births
40
Q
  1. 5 Birthrate:

- What is bx?

A
  • mean number of females born in each age group

* *x = age

41
Q
  1. 5 Birthrate:

- what is the gross reproductive rate?

A
  • sum of bx across age classes

* *how many offspring is a female likely to produce in their lifespan

42
Q
  1. 6 Fecundity Table:

- uses what column from the life table and?

A
  • uses survivorship column from life table along with age-specific birth rates. Can use this to find net reproductive rate.
43
Q
  1. 6 Fecundity Table:

- Net reproductive rate?

A

Ro= number of females left by a newborn female during its lifetime. Includes probability of survival to a particular age.

  • **how well will you survive and how many are they likely to produce….
  • net= value once you’ve correct for everything.
44
Q
  1. 6 Fecundity Table:

- Net reproductive rates = mean number of?

A
  • females born in each group adjusted for survivorship lxbx
    -table =
    x lx bx lxbx
    0 1 0 0
    1 0.3 2 0.60
  • 30% chance you will get to age 1
  • if you do = predicted to have two offspring
45
Q
  1. 7 What can Ecologists do with all this information?

- Age specific mortality and birth rates from life table and fecundity table can be used to project?

A
  • future changes in a population

- whether it is a healthy and growing population or if it is declining

46
Q
  1. 7 What can Ecologists do with all this information?

- Population projection table?

A
  • table of probabilities of surviving from one year to the next (sx=1-qx) and the number of offspring they are likely to produce
  • adds more complexity = closer to reality
47
Q

9.7 What can Ecologists do with all this information?
-What are the population projection calculations?
ex:
Year
0 1
20 27
10 6
5

A 
- Number of individuals in each age class (x) at year zero. 
L> 20 and 10 
- value 27 at year one?
L> (b1x6) + (b2x5)
=(2x6)+(3l5)
= 12 + 15=27

6–> 2-x S0= 20x0.4=6
5–? 10x S1= 10 x 0.5= 5

  • ** 5 alive each produce 3 off spring…15
  • 6 alive …2 produced each….12 total
48
Q
  1. 7 What can Ecologists do with all this information?
    - Population Projection Table:
    - Survival and fecundity rates are?Meaning what?
A
  • constant

- after a few years there is a stable age distribution and a constant rate of population increase.

49
Q
  1. 7 What can Ecologists do with all this information?
    - Population Projection Table:
    - -λ(lamnda)??
A
  • finite multiplication rate. When λ>1, population is growing and it is shrinking when λ<1
50
Q
  1. 7 What can Ecologists do with all this information?
    - Population Projection:
    - geometric population growth?
A
  • N(t)=N(0)λt
    • it is similar to equation for exponential growth but for discrete time intervals (ex one year)
  • λt=ert
  • λ=er
  • r=ln λ
51
Q
  1. 8 Stochasitic Processes

- These models use what?

A
  • unvarying birth and death rates
52
Q
  1. 8 Stochasitic Processes

- how many outcomes are predicted?

A
  • only one outcome predicted for given set of initial conditions
53
Q
  1. 8 Stochasitic Processes

- are the predictions from this realistic?

A
  • no

- in real life, birth and death rates vary among individuals

54
Q
  1. 8 Stochasitic Processes

- Population dynamics are the outcome of?

A

many individual probabilities

55
Q
  1. 8 Stochasitic Processes

- Models have been developed that vary?

A
  • the rates of brith and death around the mean estimate represented by the values of bx and sx
56
Q
  1. 8 Stochasitic Processes

- demographic stochasticity?

A
  • random ( stochastic) variations in birth and death rates from year to year can cause populations to deviate from predictions
57
Q
  1. 8 Stochasitic Processes

- Environmental stochasticity?

A
  • random variations in environment ( temperature, precipitation, natural disasters) that influence birth and death rates.
58
Q
  1. 9 Potential for Population Extinction:

- When is r negative?

A
  • when deaths are more frequent than births, population will decline
59
Q
  1. 9 Potential for Population Extinction:

- when r is negative what may it lead to?

A
  • extinction.
60
Q
  1. 9 Potential for Population Extinction:

- Possible causes of extinction and negative r values?

A
  • extreme environmental conditions, shortage of resources, habitat loss…diseases..etc
61
Q
  1. 9 Potential for Population Extinction:

- are all species equally susceptible ?

A
  • no some are more susceptible to extinction than others
62
Q
  1. 9 Potential for Population Extinction:

- ____ populations more vulnerable due to ___ and ____and loss of___.

A
  • small
  • demographic
  • environmental stochasticity
  • genetic variability
63
Q
  1. 9 Potential for Population Extinction:

- why are big mammals are often the ones that are at higher risk?

A
  • they produce fewer offspring..life history can make them more vulnerable.
64
Q
  1. 9 Potential for Population Extinction:

- what sized animals are at greatest risk on islands?

A
  • small animals…intolerant to environmental change s
65
Q
  1. 9 Potential for Population Extinction:
    - Explain the following study:
    - Demography of the endangered North Atlantic Right Whale.
A
  • population growth rate declined below replacement level because of increased mortality mothers.
  • population numbered only about 300 in 1990s; predicted to become extinct within 200 years if current conditions continued.
  • Female life expectancy declined from 52 to 15 years. Expected number of reproductive events during a female’s lifetime declined from 5 to 1.
66
Q
  1. 9 Potential for Population Extinction:

- Right whale recovery?

A
  • right whale population has increased to approx 450
  • more calves born in last decade.
  • shipping lanes in Bay of Fundy moved to reduce ship strikes. Shift of 4 nautical miles reduced risk by 80%.
  • Roseway basin off nS seasonally closed to ship traffic.

Ecology (24 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions