chapter 5 Flashcards
id: a group of individuals belonging to the same species living together in a particular place at a particular time
Population
why are populations studied in ecology?
1) because the individuals making them up use the same resources in a certain area;
2) affected by the same conditions in the area;
3) interact with other organisms in the same way
4) population studies hold the key to saving endangered species and controlling pest populations and disease epidemics
id: (a characteristic of populations)
these are not present in the lower level of organization, individuals and may change from time to time
emergent properties
enum: (6)
emergent properties
1) population size
2) population density
3) age distribution
4) natality rate
5) mortality rate
6) population growth rate
enum: (4)
variables that affect population size
1) number of births
2) number of deaths
3) number of immigrants (joining the population)
4) number of emigrants (leaving the population)
id: refers to the numbers of individuals of the same species occupying a unit of area at a particular time
population density
Population density tends to be (lower, higher) in areas with plentiful resources than in areas with scarce resources.
higher
which is more useful, population size or population density? why?
population density - because it relates the number of individuals and the wastes they produce with the amount of resources available in a unit of area
id: the ability of a population to increase in size through reproduction whether by giving birth, budding or fission
natality
id: refers to the greatest number of new individuals that can be produced under ideal environmental conditions
maximum natality
id: refers to the number of new individuals produced under actual environmental conditions
realized natality
id: refers to the number of deaths in a population
mortality
id: it occurs when environmental conditions are ideal
minimum mortality
id: environmental conditions cause organisms to die earlier than their physiological longevity would allow
realized mortality
mortality varies with (health, age)
age
id: the survivorship data of a group of individuals in a population that were born more or less together
a cohort
how is a survivorship curve produced?
when the survivorship data of a group of individuals in a population that were born more or less together is plotted, with number surviving at the start of each age interval in the vertical axis and age on the horizontal axis
enum: (3)
kinds of survivorship curves
Type I (convex curve)
- survivorship is high (mortality rate is low)
- individuals are young, MR increases as they grow older
(mammals with few offsprings that are large
Type II
- MR is more or less the same regardless of age
(some lizards, hydras, mice and rabbits)
Type III (concave curve)
- individuals of the population die a the free-swimming larval stage due to predation
- once the larvae have attached to a substratum and secrete the shell, more individuals survive (MR decreases)
- type of curve is shown by species that do not provide parental care to their offspring
enum: (3)
age distribution pyramids
1) Expanding
- greater no. of young indivs
- expected to show rapid growth in the future
- undeveloped countries
2) Stable
- greater number of young indivs, but not much difference
- slow growth (40% of growth is due to immigration)
- developed countries
3) Collapsing
- greater number of older people than the young
- population size is declining (not enough replacement for the dead)
ToF: Population size influences natality and mortality rates of a population and, thus, also affects population growth rate.
No, age distribution does
A population with many young people entering the (reproductive, pre-reproductive) age is expected to increase in size in the future.
reproductive
enum: (3)
division of age distribution
1) pre-reproductive stage
2) reproductive stage
3) post-reproductive stage
ToF: The duration of these three stages varies with different organisms and with different cultures of peoples
true
____________ have a long pre-reproductive stage during metamorphosis, followed by a brief reproductive period, after which they die. Similarly, the _______________ lays eggs only once in its lifetime and immediately dies soon after, its energy having been spent in swimming upstream from the ocean and in releasing its eggs
insects; pink salmon
Population Growth Rate is Determined by an Organism’s Innate ________ to ____________ and by __________ Factors that __________ Population Growth
Capacity; Reproduce; Environmental; Prevent
how can number of births and deaths in a population be expressed?
as the average number of births and deaths per individual (per capita) during the time period
id: the number of offspring produced per unit time by an average member of the population
per capita birth rate (b)
id: per capita birth rate (by convention)
the number of births per 1000 individuals (by convention)
id: the number of deaths per 1000 individuals
per capita death rate (d)
id: the difference between the per capita birth rate and per capita death rate
per capita rate of increase
_____________ is also the population growth rate, expressed on a per capita basis
Per capita rate of increase
when the per capita rate of increase of a population is maximum (under favorable conditions, abundant resources and low population density, it is called _____________
biotic potential: intrinsic rate of increase (r) of the population
enum: (5)
factors influencing the intrinsic rate of increase (also called biotic potential) of a population
- these factors are innate to the species
1) Age at first reproductive episode
2) Frequency of reproduction
3) Number of individuals produced at each reproductive episode
4) Length of reproductive period
5) Survival up to and through reproductive age
The smaller the organism, the (lower, greater) is the per capita birth rate
greater
(Elephants, for example, reproduce once every 4 years and have only 1 offspring. Dogs have puppies yearly with a litter of 4-6 and chickens lay eggs several times a year. Bacteria have the highest biotic potential. E. coli, for example, divides into two every 20 minutes)
In the field where resources are limiting and conditions not always favorable due to disease and competition, e.g., the actual per capita rate of increase or realized r is (greater, lower) than rmax
lower
what causes the difference between r and rmax?
environmental resistance, the sum total of the conditions and resources that prevent rmax from being realized
id: the sum total of the conditions and resources that prevent rmax from being realized
environmental resistance
When environmental conditions are favorable, resources unlimited and the population density is low, populations tend to __________
increase rapidly
exponential growth produce a ____________ curve
j-shaped
Exponential population growth is characterized by an accelerating population growth that occurs when optimal conditions allow a constant ____________ growth rate
per capita
The unrestricted growth of populations in unlimited environments often lasts briefly only. It ends when the resources become ____________ to support the population, when an environmental condition _____________, like the coming of rain or snow, or when the ______________ season ends.
inadequate; changes; reproductive
The lack of resources or environmental change that occurs would (decrease, increase) per capita death rate and (decrease, increase) per capita birth rate of a population, thus, affecting r.
increase; decrease
what causes population to not increase exponentially indefinitely in nature? due to what?
the increase per capita death rate and decrease per capita birth rate of a population; lack of resources and environmental change
what is a boom and bust pattern of population change?
when a population size declines, then increases again from year to year
what kinds of plants and insects show a boom and bust population oscillation?
annual plants and insects
Exponential population growth may be very important to populations during the process of ______________ themselves and during the process of __________ from some sort of exploitation
- give an example
establishing; recovery;
explosive algal growth in an enriched body of water and rapid increase of whale populations once whaling was stopped
what happens when the number of organisms reached the population size that the resources in the environment can support for an indefinite period of time
population growth slows down
what is the other term for the slowing down of population growth? how does its growth curve look like when graphed?
logistic population growth; sigmoidal (S-shaped growth curve)
when the population approached the carrying capacity of the island, N/t becomes (smaller, bigger) and the line of the graph actually becomes __________ or (stable, fluctuates) near the carrying capacity
smaller; flat; fluctuates
id: the population size when the population becomes stable
carrying capacity
id: the population size that can be supported by the resources present in the environment growth is computed by taking into consideration K
carrying capacity
id: the ratio N/K
environmental resistance
environmental resistance (decreases, increases) as N increases
increases
In logistic population growth, increase in population size is (slow, fast) at first (_________ phase), gradually becomes faster, then becomes rapid. As resources become (diminished, adequate) population increase slows down until ______________ is reached.
slow; lag; diminished; carrying capacity
Theoretically, there is (no, more) further change in population size once N has reached K or the carrying capacity
no
why do some species not make a smooth transition from exponential growth to logistic population growth?
because such populations use up their resources and temporarily overshoot or exceed the carrying capacity of their environment
why do some species temporarily overshoot or exceed the carrying capacity of their environment?
because of a reproductive time lag
what is a reproductive time lag?
the period needed for the birth rate to fall and the death rate to rise in response to resource overconsumption
despite a reproductive time lag, population size still increase, why is this?
due to a population growth momentum
Density-Dependent and Density-Independent Factors Limit Population Growth by Acting on __________________ and ___________________ rates
birth and death rates
Some environmental factors may affect a bigger proportion of the population more when the population density is (low, high)
high
enum: (3)
factors that may affect population density
disease
competition
predation
Competition becomes more intense when population density is (low, high), resulting in a (lowering, increasing) of population density. In like manner, an infection will affect a (lower, greater) number of individuals of the population when population density is high.
high; lowering; greater
id: factors that regulate population size
density-dependent factors
Density-dependent factors tend to regulate a population at a relatively constant size that is near the carrying capacity and this is a very good example of a _______________ system in nature
negative feedback system
id: factors that affect population density whether population density is high or low
density-independent factors
Density-independent factors are generally (biotic, abiotic)
abiotic
id: factors that act separately or together, affecting the carrying capacity of an environment for a species
limiting factors
The Human Population Continues to (Decrease, Increase) but World Per Capita Growth Rate has Declined over the Past Several Years
Increase
After agriculture developed around 8000 BC, the human world population increased gradually for about (1,000 / 10,000) years before it reached 1 billion (around 1800).
But after only (130, 150) years (in 1930), it reached 2 billion, and then 3 billion after (30, 130) years (in 1960) and 4 billion after 15 years (1975) In 2012, world population reached (7 billion, 10 billion), just as predicted by the United Nations
World population has been, therefore, growing exponentially and if plotted, a (J, S) shaped curve is produced.
10,000; 130; 30; 7 billion; J-shaped
id: a British clergyman and economist, was one of the first to recognize that the human population cannot continue increasing at a fast rate because it might outstrip the rate of food production. He pointed out that population growth could lead to famine, disease and war,
Thomas Malthus
The world population is currently increasing by about ___ million people per year. This rate of increase of the world population was not due to an increase in birth rate, but due to a dramatic decrease in death rate.
83
the world birth rate has (declined, inclined) since the early 1800s
declined
Most published estimates place Earth’s carrying capacity from _________ to ________ billion.
4 to 16 billion
Earth’s carrying capacity for humans is decided simply by natural environmental constraints.
no, also by peoples’ choices
enum: (3)
Countries can be classified into two groups, highly developed and developing, based on their rates of ________
population growth
degree of industrialization
relative prosperity
enum: (5)
characteristics of highly developed countries
low population growth rates due to low birth rates
low infant mortality rates
longer life expectancies
highly industrialized
have higher average GNI PPP per capita
id: the amount of time it would take for its population to double its size, assuming its current growth rate did not change
doubling time
Doubling time identifies whether a country is highly, moderately or less developed. The shorter the doubling time of a country, the (less, more) developed the country.
less
id: the number of children a couple must produce to “replace” themselves
replacement-level fertility
The total fertility rate is _____ worldwide which is higher than replacement levels. It is _____ in highly developed countries, except the ______
2.6; 1.7; US
id: the average number of children born to a woman in her lifetime
total fertility rate
The Life Histories of Organisms may be __________, and Have a (Low, High) Intrinsic Rate of (Decrease, Increase) or Equilibrial, where the Populations of the Species are Near Carrying Capacity Much of the Time
opportunistic; high; increase
id: the series of events from birth through reproduction and death, varies among species
life histories
life history is the result of ________
natural selection
Populations that exhibit a big-bang reproductive strategy, called semelparity, typically live in an unpredictable environment controlled by density- (dependent, independent) factors, such as climate.
independent
id: populations that exhibit a big-bang reproductive strategy
semelparity
Semelparous species are also called (r-selected, k-selected) species because they have a (low, high) intrinsic rate of increase or r.
r-selected species; high
id: the type of life history shown by larger-bodied and longer- living species, they often mature late, produce few offspring several times in their lifetime and care for their young, a kind of reproductive strategy called iteroparity
equilibrial life history
the population size of organisms with equilibrial life history is held near the carrying capacity by density- (dependent, independent) factors
density-dependent
id: a reproductive strategy where species often mature late, produce few offspring several times in their lifetime and care for their young
iteroparity
Iteroparous species are also called (r-selected, k-selected) species because they tend to do well, being (small, big) -bodied, in competition when their population size is near the carrying capacity
k-selected; big
id: amount of energy, time and other resources allocated to the production and care of offspring
reproductive effort
id: (2) before these vertebrates reach sexual maturity, they spend their energy and other resources for maintenance and growth. However, after they have become sexually mature, they have to allocate their limited energy into _______________ (3)
fish and reptiles
growth, maintenance, and reproduction
Organisms that delay reproduction will tend to grow (slower, faster) and reach a (smaller, larger) size, which is associated with a (lower, higher) reproductive rate. But delaying reproduction to a later age also (decreases, increases) the chance the individual will die before reproducing.
faster; larger; higher; increases
where adult survival is higher, organisms delay reproduction and allocate (less, more) energy to reproduction
less
In other words, during the course of evolution a ____________ between survival traits and traits that enhance reproduction have occurred, so as to increase the _______ of organisms
trade-off; fitness
id: a population that is divided into several local populations in distinct habitat patches among which individuals occasionally migrate
metapopulation
Population ecologists have discovered that many populations are not distributed as one large population across a landscape but as a ______________ or subpopulations in distinct habitat patches
series of local populations
The patches of habitat vary in their ability to provide the _______________ of a species.
requirements
id: areas where reproductive success is greater than local mortality and population densities are higher than those at less suitable sites.
good habitats; source habitats
id: patches where local reproductive success is lower than local mortality
sink habitats
a sink population will (decrease, increase) in size until extinction occurs
decrease
ToF: Metapopulations are also created when humans alter the landscape, such as a forest, by fragmenting existing habitats of other organisms to make way for houses, cities, farms, etc.
True
As a result, the concept of metapopulation has become an important area of study in conservation biology in relation particularly to ___________ and _____________ species.
endangered and threatened
id: exist between two or more populations that allow individuals from source habitats to reach sink habitats to increase population size and improve the genetic diversity of populations in sink habitats
Habitat corridors
Habitat corridors made by man (can, cant) help the animals
can
enum: (3)
Factors that allow Populations to be Distributed Uniformly, Randomly or Clumped Together in Space
Physical Conditions
Chemical Conditions
Biological Factors
ToF: some organisms can tolerate the full range of conditions existing on earth
false
enum: (3)
types of spatial distribution of plants a
clumped
random
uniform
enum: (4)
resources influencing the spatial distribution of plants and animals
water
light
mates
underground nutrients
ToF: in some cases, population distribution may vary as the plants age
true
enum: (3)
what influences the Commonness and Rarity of Species
Local Population Size
Geographic Range
Habitat Tolerance
why is it that some populations tend to be more vulnerable to extinction than others?
abundance of the species
- rare species are in greater danger of extinction while abundant ones are not
who devised a classification system to determine the commonness or rarity of species based on a combination of three factors?
Deborah Rabinowitz
organisms which have a large population size, extensive range of distribution and broad range of tolerance for conditions are the most (rare, common) organisms
common
organisms with small population size, (narrow, broaden) geographical range and low tolerance for environmental conditions show extreme rarity and are, therefore, very prone to extinction
narrow
ToF: If a species suffers in only one aspect, such as small local populations but has extensive range and broad tolerance for habitat, its chances for extinction is still less
false: Even if a species suffers in only one aspect, such as small local populations but has extensive range and broad tolerance for habitat, its chances for extinction is also great.
Ecologists have discovered that (there is, there is no) strong positive correlation between size of geographic range and population size
there is
Species that have large local populations have (narrow, extensive) geographic range, while species with small local populations generally have a (narrow, extensive) range of distribution also
extensive; narrow
