Population Growth and Density Dependence Flashcards
Recognized that the tremendous capacity for
population increase could not be maintained in an
environment with limited resources
THOMAS MALTHUS
He argued that populations inevitably expand until they
outgrow their available food supply, causing the population growth to be reversed by disease, famine, war, or calamity.
THOMAS MALTHUS
He is also known for developing an exponential formula used to forecast population growth, which is currently known as the Malthusian growth model.
THOMAS MALTHUS
Malthus argued that populations inevitably expand until they
____________, causing the population
growth to be reversed by disease, famine, war, or calamity.
Outgrow their available food supply
He was
influenced by the English clergyman Thomas Malthus, who published his book in 1798 stating that populations with
abundant natural resources grow very rapidly. However, they limit further growth by depleting their resources.
CHARLES DARWIN
Developed the theory of natural selection.
Charles Darwin
It states that individuals will compete, with
members of their own or other species, for limited resources.
“Struggle for existence”
The successful ones are more likely to survive and pass on the
traits that made them successful to the next generation at a
greater rate.
Natural Selection
He said that “Population growth underlies most ecological problems of
interest, such as the dynamics of diseases, competition, and the
structure and dynamics of communities.”
WILLIAM MURDOCH
Is essential to long-term species persistence and is still the
central dynamical question in ecology.
Population regulation
This formula allows us to determine the rate of population change
with respect to certain variables - including population size, births, deaths, per
capita growth rate, and carrying capacity.
Population growth
Population Growth formula
dN/dt = B - D
Exponential Growth formula
dN/dt = rmax N
Logistic Growth
dN/dt = rmax N (K-N/K)
One way to determine how much a population size has
changed is to subtract the number of deaths from births if the data is given
POPULATION GROWTH
In this growth, the population grows as if there are unlimited
resources.
EXPONENTIAL POPULATION GROWTH
A population growth that levels off as population size
approaches carrying capacity, K.
LOGISTIC POPULATION GROWTH
Maximum population size that can be supported by the available resources in an
environment.
Carrying capacity (K)
A more realistic representation of how populations
grow.
Logistic growth model
Limiting factors that include temperature, sunlight, water and pH.
ABIOTIC
Limiting factors that include competition for resources,
predation, diseases
BIOTIC
Limiting factors that are not influenced by population size or density.
Density-independent factors
These factors can affect populations regardless of their size or density.
Density-independent factors
Limiting factors that are influenced by the size or density of a population.
Density-dependent factors
As the population size increases, these factors become more
important and can limit population growth.
Density-dependent factors
Happens when the rate of population growth
decreases as population density increases.
Negative density dependence
Occurs when the population growth rate increases as population density decreases.
Positive density dependence
Is the struggle between two organisms for the same
resources within an environment.
Ecological competition
is the competition for limited resources between
individuals of the same species.
Intraspecific competition
is the competition for limited resources between
individuals of different species
Interspecific competition
These are the Density-dependent factors:
*Competition
*Predation
* DISEASES
involves the threatening of a prey population by a predator, keeping
their numbers low
Predation
are considered density-dependent limiting factors
because as population density increases, they are able to spread more easily
within the population, eventually leading to a decrease in population growth.
Diseases and parasitism
a highly
contagious viral disease that affects both
domestic pigs and wild boars.
African Swine Fever (ASF)
Similarities of exponential growth and logistic growth
*Both describe the growth of a population.
*Both depend on the size of the population.
Differences of exponential growth and logistic growth
*EG refers to a growth whose rate is proportional to the size of the population over a specific period of time.
*LG refers to a population growth whose rate
decreases with the increasing number of individuals and it becomes zero when the
population becomes its maximum
refers to a growth whose rate is proportional to the size of the population over a specific period of time.
Exponential growth of a population
Refers to a population growth whose rate
decreases with the increasing number of individuals and it becomes zero when the
population becomes its maximum.
Logistic growth
The growth curve of the exponential growth
J-shaped
The growth curve of the logistic growth
Sigmoid
In population status, The population crash occurs due to the mass mortality
Exponential Growth
In population status, The population crash occurs very rarely during the logistic growth.
Logistic Growth
It lacks any upper limit
Exponential Growth
consists of an upper limit called the carrying capacity
Logistic Growth
does not frequently reach a stationary
phase
Exponential Growth
It reaches a stationary phase
Logistic Growth
occurs when the resources are plentiful
Exponential Growth
occurs when the resources are limited.
Logistic Growth
depends on the size of the population
Exponential Growth
depends on the size of the population, competition
and the amount of resources
Logistic Growth
