Chapter 6 Flashcards
Individuals of the same species residing
in a particular area are referred to as a
__________.
population
________ of the ecosystem is directly
impacted by population dynamics
Sustainability
A ________ consists of a group of
interacting individuals of the same
species that occupy a specific area
at the same time. In most natural
populations, individuals vary slightly
in their genetic makeup; which is
why they do not all look or behave
exactly like a phenomenon called
____________.
population, genetic diversity
Speaks of a population’s birth
rate, or the quantity of new
members brought about via
reproduction.
Typically expressed as the
number of live births per 1,000
individuals per yea
NATALITY
Describes the death rate,
or the total number of
people who pass away
within a population within
a given time frame
MORTALITY
The ratio of men to women in
a population is known as the
“sex ratio.” It is frequently
stated as the ratio of males
to girls, or 100 to 1.
SEX RATIO
The proportion of individuals
in each age group in a
population
AGE STRUCTURE
Common Age Group
pre-reproductive
post-reproductive
The number of individuals present in a
subjectively designated geographic
range
POPULATION
SIZE
Population size is influenced by four
factors:
births, deaths, immigration,
and emigration.
If the number of individuals added from
births and immigration equals the
number lost to deaths and immigration,
then there is__________
zero population growth
The number of individuals of a
population in a certain space at a given
time
POPULATION
DENSITY
For __________, it is usually
expressed as the number of individuals
per unit area while for aquatic
ecosystems, it is usually expressed as
the number of individuals per unit
volume
terrestrial ecosystems
The spatial pattern in which the
members of a population are found in
their habitat
POPULATION
DISPERSION
Individuals within populations are
distributed in patterns that may be
________, _________, or _________
random, uniform, or clumped
__________ can be produced
by the social interactions within
populations, by the structure of the
physical environment, or by a
combination of the two
Patterns of dispersion
__________- in population
ecology is a change in the number of
members of a certain species in a
particular location during a particular
time period
Population growth
Populations vary in their capacity for growth, also
known as the ___________ of the population
biotic potential
The rate at which a population could
grow if it had unlimited resources is
the ___________, r.
intrinsic rate of increase
It is expressed as the number of new
individuals per existing individual per
unit of time, such as the number of
piglets per existing sow per year.
intrinsic rate of increase, r.
_______________ consists of
all the factors acting jointly to limit
the growth of a population. The
__________ of a species in a given
place and time is determined by the
interplay between its biotic potential
and environmental resistance.
Environmental resistance, population size
The population size of a species in a given place and time is determined by
the interplay between its _________ and ___________
biotic potential, environmental resistance.
Growth factor of Abiotic
Favorable light
Favorable temperature
Favorable chemical
environment
Decrease factor of abiotic
Too much or too little light
Temperature too high or too low
Unfavorable chemical
environment
FACTORS THAT TEND TO INCREASE
OR DECREASE THE POPULATION
Abiotic and biotic
growth factor of biotic
High reproductive rate
Generalized niche
Adequate food supply
Suitable Habitat
Ability to compete for resources
Ability to defend against predators
Resist parasites and diseases or parasites
Migrate
Adapt to environmental change
decrease factor of biotic
Low reproductive rate
Specialized niche
Inadequate food supply
Unsuitable or destroyed habitat
Too many competitors
Can’t defend against predators
Inability to fight diseases or parasites
Inability to migrate
Inability to adapt to environmental change
the number of
individuals of a given species
that can be sustained
indefinitely in a given space
(area or volume)
carrying
capacity, K
TYPES OF POPULATION GROWTH CURVE
EXPONENTIAL GROWTH
LOGISTIC GROWTH
SURVIVOR-SHIP CURVES
shows the population grows faster
with time
starts out slowly and then proceeds
faster and faster as the population
increases.
If the number of individuals is
plotted against time, this sequence
yields a_____________
Exponential growth, J-shaped exponential
growth curve
It involves exponential population
growth when the population is small
and a steady decrease in population
growth with time as the population
approaches the carrying capacity.
A plot of the number of individuals
against time yields a ____________ logistic growth curve.
logistic growth. sigmoid or S-shaped
_______ plot the numbers in a cohort still alive at each age.
Survivor curves
A _______ refers to a group of individuals that share common characteristics or
experiences within a defined time period or population (Setia, 2015).
cohort
________ is flat during early and
middle life and drops suddenly
as death rate increases among
the elderly
Type I
Associated with species such as
humans and other large
mammals that produce few
offspring that are well cared
for
type 1
________ is intermediate, with
mortality more constant over
life spans. This type is seen in
Hydra, gray squirrels, and birds
Type II
________ shows very high death
rates for the young, followed
by lower death rates.
Type III
This type is often associated
with organisms, such as
oysters, that produce very
many offspring but provide
little or no care. More
examples are trees, marine
invertebrates, and most fishes
Type III
Species use different reproductive strategies to survive and adapt
to their environments. These strategies fall into two main
categories: Reproductive Strategies
r-strategists and K-strategists
These species thrive in unstable,
unpredictable environments by
focusing on rapid reproduction.
R-Strategists
Characteristics of r-strategists
Rapid reproduction
Minimal Parental Care
High reproductive rates
Early maturity, short lifespan
Rapid Reproduction
Offspring are independent from
birth
Minimal Parental Care
Large number of offspring, few
survive
High Reproductive Rates
These species are adapted to more
stable environments, emphasizing
survival over reproduction.
K-strategists
Characteristics of k-strategists
late maturity
longer lifespan
significant parental care
stable populations
Reproduce later, fewer
offspring
Late Maturation
Focus on survival and care for
offspring
Longer Lifespans
High investment in each
offspring’s success
Significant Parental Care
Populations remain near the
environment’s carrying capacity (K)
Stable Populations
n population ecology, two key categories of factors influence
population size (POPULATION FLUCTUATIONS)
density-dependent and density-independent factors
These factors become more pronounced as a population grows larger and denser.
They are intrinsic to the interactions within the population and ecosystem
Density-Dependent Factors
characteristics of density dependent factors
Competition for Resources
predation
disease
Limited food, water, and shelter
lead to greater competition
Competition for Resources
Larger populations make prey
more visible to predators
Predation
Higher density increases the
spread of diseases
Disease
these influences impact populations regardless
of their size and tend to be abiotic (non-living) in nature:
Density-Independent Factors
Characteristics of density-independent factors
Natural Disasters
Environmental Changes
Climate Extremes
Hurricanes, wildfires, droughts,
floods
Natural Disasters
Pollution, habitat destruction,
temperature shifts
Environmental Changes
Unseasonable heat or cold
impacting survival
Climate Extremes
