Chapter 23 Flashcards
A _________ is a group of individuals of a single species that occupy the same general area.
Population
Individuals in a population (3)
- rely on the same resources
- are influenced by the same environmental
- are likely to interact and breed with one another
_____________ is the study of factors that affect a population
Population ecology
Populations can be influenced by the interactions between _______________, resulting in variations in population size.
Biotic and abiotic factors
Population ecology is used to study(3)
- How to develop sustainable fisheries
- how to control pest and pathogen
- human population growth
In population ecology, factors that influence a population include: (4)
- density
- structures
- size
- growth rate
__________: the number of individuals of a certain species in a given area
Population density
To determine population density, it would be necessary to census the ____________.
entire population
population densities are estimated by indirect indicators, such as number of _________________.
birds nest or rodent burrows
Another estimation technique is the _______________.
mark-recapture method
Mark-recapture method
animals are trapped, marked and then recaptured after a period of time
If individuals aggregate in patches, their dispersion is ______. This is often due to nutrients distributed _____.
Clumped
unevenly
In some cases, behavioral interactions between individuals ensures a nearly _________.
equal spacing
equal spacing this type of dispersion pattern is called __________.
uniform
This is the ________ dispersion pattern
random
If there is no biotic or abiotic interaction to determine the dispersion, individuals may be spaced unpredictably, this is the random dispersion pattern, commonly occurs in _______
rainforest
The age ______________ is the distribution of individuals among age groups
structure of a population
The age structure of a populations provides insight into: (3)
the history of a populations survival
- reproductive success
- how the population relates to environmental factor
Type I,
Flat at start, reflect low death rates, and death rates increase in older groups
Type II
mortality is constant over time
Type III
high death rates at 1st, and few survive to older age
Two types of life history strategies are _________ and_________.
opportunistic
equilibrial
Opportunistic (2)
- mature quickly and reproduce young
- produce many offspring
Opportunistic growing populations tend to follow the exponential growth model as indicated by a _______________.
Type III survivorship curve
Equilibrists(4)
- Mature and reproduce older
- have a more elaborate social context to their lives
- produce fewer offsprings than opportunists
- exhibit parental care
Populations following an equilibrial strategy exhibit a _______________________.
type I survivorship curve
The ____________ describes the rate of expansion of a population of a population under optimal growth condtions, with no biotic or abiotic limitation
Exponential growth model
In nature, a population may grow exponentially for a while, but eventually one or more environmental factors will limit its _________.
growth
The _____________ is therefore a more realistic model for wild populations
logistic growth model
The logistic growth model describes
the growth of an idealized population that is slowed when it encounters limiting factors
The _________ of an environment is the number of individuals that can be maintained by that environment
carrying capacity
What factors contribute to the slowing of the growth rate in the logistic growth curve?
Intraspeific competition
density-dependent
The addition of individuals to a population leads to competition of resources, thus is referred to as ________________ (competition of the same species)
Intraspecific competition
This means the population growth is largely __________, a biotic factor
density-dependent
___________ first slow the population growth rate, then limit its size.
Density-dependent factor
Density-dependent factor(2)
- Their effects intensify as the population grows
- They result in a increase of a population’s death rate and a decrease in its birth rate
__________ are unrelated to the number of individuals in the population.
Density-independent factor
Density-independent factor include
Abiotic event
in nature, many populations never reach carrying capacity before some_____________?
density-independent factors limit their growth rate
In tight predator-prey relationship, as in the cycle of the snowshoe hare and the lynx,________________.
both prey and predator cycle together
Population ecology can help guide us toward resource management goals for example (3)
- Increase populations of organisms we wish to harvest
- Decrease populations of pests
- Save populations of organisms threatened with extinction
The U.S. endangered species act defines(2)
- endangered species
- Threatened species
An __________ as one that is in danger of extinction throughout all or a significant portion of its range
Endangered species
A _____________ as one that is likely to become endangered in the foreseeable future
Threatened species
According to the logistic growth model, the fastest growth rate occurs when a population size is at roughly___________________________.
Half the carrying capacity
Theoretically, populations should be harvested down to this level, assuming that growth rate and carrying capacity are stable over time
half the carrying capacity
In northern Atlantic cod fishery
- estimates of cod stocks were to high
- the practice of discarding young cod(not of legal size) at sea caused a high mortality rate than was predicted
- the fishery collapsed in 1992 and had not recovered.
The human population can be described using the ___________________.
exponential growth model
To calculate the growth of the human population we use the same parameters as with other populations: ________________________________________
Birth rates and death rates
__________: Birth rates were once higher than death rates, however both birth rates and death rates are near equilibrium showing no growth
Demographic transition
Another important parameter fro describing the human population is its __________.
age structure
An ____________ shows the proportion of individuals in different age group.
age structure diagram
show what percentage of people in a population is young, of reproductive age, part of the work force, or retired.
age structure diagram
it can help us predict population growth in the immediate future and what to do about it,
age structure diagram
The wider the base of the age structure diagram, the faster the population growth because the next generation will soon enter their reproductive years. this is a ___________________________.
population momentum
As the human population grows, density-dependent factors, such as resource ________ and _______, increase significantly
Consumption and pollution
Current estimates
- ______people within the next 20 years and
- _______ by mid-21st century
8 billion
9.5 billion
Do we have sufficient resources to sustain 8 or 9 billion people?
To accommodate all the people expected to live on out planet by 2025, the world will have to nearly double food production
An ecological footprint is an estimate of the amount of land required to provide the raw materials an individual or a population consumes, including (5)
- food
- fuel
- water
- housing
- waste disposal
-the worlds richest countries have 20% of the global population
use 86% of the worlds resources
The rest of the world has 80% of the population
uses just 14% of global resources
some researches estimate that if everyone on earth had the same standard of living as people living in the united states,
we would need the resources of 4.5 planted earth
