7. Part 2: Population Growth & Regulation

Model used to model populations with negative density dependence

Logistic growth model

The shape of the logistic growth curve is

Sigmoidal / S-Shaped

The logistic growth rate is ______ when population size is small, and _____ as population gets large

exponential
slows

The growth rate is zero when a population reaches ______ _____ (K)

carrying capacity

The midpoint of the logistic curve (K/2) is the

inflection point

The inflection point is where the

instantaneous growth rate is maximized

Does carrying capacity change as the population size changes?

No

When resources (ex. food) is doubled, what would you expect the carrying capacity value to do?

Double

What growth model is this the equation for?
dN/dt = rN(1-N/K)

Logistic

dN/dt is the expression for

instantaneous growth rate

Logistic growth is used when population is limited by density-_____ factors, and the geometric growth model is used when population is limited by density-_____ factors

dependent
independent

Proportion of individuals that occurs in different age classes

Age structure

Population growth will likely slow if much of the population is ___(2 reasons)___

Over the reproductive age
In an age class with a higher risk of death

Stage structure uses ___ ____ _____ rather than specific age

life stage categories
(e.g. hatchling, juvenile, adult)

Plot that displays the likelihood of an individual surviving across age classes

Survivorship curve

Type I/II/III survivorship curve?
Low mortality early in life, high mortality later in life (K-selected)

Type I

Type I/II/III survivorship curve?
Consistent mortality throughout life

Type II

Type I/II/III survivorship curve?
High mortality early in life, lower mortality later in life (r-selected)

Type III

Organizes data on the birth rates, death rates, and fecundity for each age class in a population; typically, only females are used

Life table

Life table made of data collected by following a group of individuals born at the same time throughout their life

Cohort life table

Life table made of data collected from individuals that vary in age classes during a single time period

Static life table

Would you use a cohort or static life table for species that have minimal movement and relatively short life spans?

Cohort
(Easy to track the same individuals over time)

Would you use a cohort or static life table for species that are highly mobile, have long life spans, and for which age can be easily determined?

Static

What life table variable?
Average # of female offspring produced per female per time period

fecundity rate (b_x)

What life table variable?
The probability of surviving from birth to any later age class

Survivorship (I_x)

Survivorship at any given age class is the product of _______ and _____

prior age’s survivorship
prior age’s survival rate

What life table variable?
Total number of female offspring that we expect an average female to produce over the course of her life

Net reproductive rate (R_o)

What is this the equation for?
SUM(I_x * b_x)

Ro (net reproductive rate)

Average time between the birth of an individual and the birth of its offspring

generation time

What is this the formula for?

Generation time

A population’s intrinsic growth rate can be calculated from the life table, depending upon _____ and _____

Net reproductive rate (Ro)
Generation time (T)

Population is growth when Ro >

1

The rate at which a population can change (increases/decreases) with shorter generation times

increases

What is this the equation for?

Exponential intrinsic growth rate

What is this the equation for?

Geometric intrinsic growth rate