Biology [Final Exam Prep]
Populations
A group of organisms of the same species that occupy a particular area and breed with one another
Replacement Fertility Rate
Fertility rate at which each woman has, on average, one daughter who survives to reproductive age.
Which cannot be a symbiosis? a) mutualism b) parasitism c) commensalism d) interspecific competition
d) interspecific competition
Survivorship Curves
A survivorship curve is an age-specific plot that shows how many members of a cohort remain alive over time Three types are common in nature Type I: Survivorship is HIGH until late in life Type II: Death rate VARIES little with age Type III: Death rate PEAKS early in life
Limiting Factors and Population Growth
Density-dependent and density-independent factors can interact to determine the fate of a population Example: A population of reindeer introduced to St. Matthew island in 1944 peaked, then collapsed by 1966 Food became scarce, then thousands of reindeer starved to death during an unusually harsh winter
How Population Size Changes
Immigration Emigration Migration › Daily › Seasonal Births Deaths
Life History Strategies
Shows how an organism allocates its resources between growth, maintenance, and reproduction over the course of its lifetime
Zero population growth › Number of births balances number of ___________ › Population size remains __________
* deaths * stable 2,000 mice living in a corn field 200 of the 2,000 mice die per month Females give birth to 1,000 babies per month Birth rate = 1,000 / 2,000 = 0.5 Death rate = 200 / 2,000 = 0.1 r = b-d r = 0.5 - 0.1 = 0.4
Clumped Dispersion
*Suitable physical, chemical, & biological conditions are patchy, not UNIFORM. * Many animals form SOCIAL GROUPS. * Many offspring are NOT highly mobile & are forced to live "where they landed."
Population
A group of organisms of the same species that live in a specific location and breed with one another more often than they breed with members of other populations.
Limiting Factor
A necessary resource, the depletion of which halts population growth.
Exponential Growth
A population grows by a fixed percentage in successive time intervals; so the size of each increase is determined by the current population size.
Life History Pattern
A set of traits related to growth, survival, and reproduction such as age-specific mortality, life span, age at first reproduction, and number of breeding events.
Population density refers to the number of individuals in an _______, not how they are _________.
AREA DISPERSED
Ecological Footprint
Area of Earth's surface required to sustainably support a particular level of development and consumption.
Total Fertility Rate
Average number of children the women of a population bear over the course of a lifetime.
Eventually, _______________-dependent controls will slow human population growth
DENSITY
Logistic Growth
Density-dependent limiting factors cause population growth to slow as population size increases.
Population Distribution
Describes whether individuals are clumped, uniformly dispersed, or randomly dispersed in an area.
From the Industrial Revolution Onward
Energy of fossil fuels led to mechanized agriculture and to improved food distribution systems Invention of chemical fertilizers and synthetic pesticides increased agricultural productivity Improvements in food safety, sanitation, and medicine lowered death rates and shifted the survivor-ship curve The population is currently 7 billion and the United Nations estimates that it will reach 9 billion by 2050
Density-Independent Factor
Factor that limits population growth and arises regardless of population density.
Density-Dependent Factor
Factor that limits population growth and has a greater effect in dense populations than less dense ones.
Density-DEPENDENT
Factors such as disease are related to crowding and competition › Control population size through negative feedback, resulting in logistic growth patterns
Per Capita Growth Rate
For some interval, the added number of individuals divided by the initial population size.
Survivor ship Curve
Graph showing the decline in numbers of a cohort over time.
Cohort
Group of individuals born during the same time interval
Human Population Growth The size of the human population is at its ___________________ level ever and is expected to __________________.
HIGHEST INCREASE
Exponential growth › Population size ___________ G = r N
INCREASES by the same proportion in every successive time interval as long as r remains constant and greater than zero › Though r is constant, the population grows faster and faster, with a characteristic doubling time › The plot of population size against time results in a characteristic J-SHAPED curve G = r N
Zero Population Growth
Interval in which births equal deaths.
Nearly Uniform Dispersion
Is a rare event in nature; when it does occur, it is usually the result of FIERCE COMPETITION for limited resources.
Age structure
Is the number of individuals in each of several AGE CATEGORIES
Plot sampling
It estimates the total number of individuals based on direct counts in a small area › used for organisms that are not very mobile, in a uniform area
Carrying capacity
Maximum number of individuals of a species that an environment can sustain.
Biotic Potential
Maximum possible rate of population growth under optimal conditions.
Mark-Recapture Sampling
Method of estimating population size of mobile animals by marking individuals, releasing them, then checking the proportion of marks among individuals recaptured later.
Plot Sampling
Method of estimating population size of organisms that do not move much by making counts in small plots, and extrapolating from this to the number in the larger area.
Demographic Transition Model
Model describing changes in birth and death rates that occur as a region becomes industrialized.
Immigration
Movement of individuals into a population.
K-selected Species
Movement of individuals into a population.
Emigration
Movement of individuals out of a population.
Human Population Growth Humans have temporarily evaded environmental resistance to growth through expansion into ____________________, cultural interventions, and technology
NEW HABITATS
Population Density
Number of individuals per unit area.
Random dispersion
Occurs in nature if environmental conditions are rather UNIFORM in the habitat & members are neither attracting nor repelling each other.
Reproductive Base
Of a population, all individuals who are of reproductive age or younger
Age structure
Of a population, the distribution of individuals among different age categories.
An R-SELECTED species is adapted to conditions that change __________ and unpredictably - favors traits that maximize number of offspring
RAPIDLY SHORTER DEVELOPMENT, EARLY REPRODUCTION, FEWER BREEDING EPISODES, MANY YOUNG PER EPISODE, LESS PARENTAL INVESTMENT PER YOUNG, HIGH MORTALITY RATE, SHORTER LIFE SPAN
Pre-reproductive and reproductive groups make up the population's _______________________.
REPRODUCTIVE BASE
A K-SELECTED SPECIES is adapted to life in a __________ environment - favors traits that improve offspring quality
STABLE LONGER DEVELOPMENT, LATER REPRODUCTION, MORE BREEDING EPISODES, FEW YOUNG PER EPISODE, MORE PARENTAL INVESTMENT PER YOUNG, LOWER MORTALITY RATE, LONGER LIFE SPAN
R-Selected Species
Species adapted to an environment that changes rapidly and unpredictably, so population size is often far below carrying capacity.
Demographics
Statistics that describe a population.
Population size
The number of individuals in a population
Population density
The number of individuals in a specified portion of a habitat
Population Size
Total number of individuals in a population.
For a given species, the maximum rate of increase per individual under ideal conditions is its ______. a) biotic potential b) carrying capacity c) environmental resistance d) density control
a) biotic potential
Maximum number of individuals sustainable by the resources in a given environment a) carrying capacity: b) exponential growth: c) biotic potential: d) limiting factor: e) logistic growth:
a) carrying capacity
Most commonly, individuals of a population show a _____distribution within their habitat. a) clumped b) random c) nearly uniform none of the above
a) clumped
Species richness is greatest in communities ________. a) near the equator b) in temperate regions c) near the poles d) that recently formed
a) near the equator
Species that live in unpredictable habitats are more likely to show traits that are favored by__________ . a) r-selection b) K-selection
a) r-selection
A population of worms is growing exponentially in a compost heap. Thirty days ago there were 400 worms and now there are 800. How many worms will there be thirty days from now, assuming conditions remain constant? a) 1,200 b) 1,600 c) 3,200 d) 6,400
b) 1,600
The human population is now about 7 billion. It reached 6 billion in ________. a) 2007 b) 1999 c) 1802 d) 1350
b) 1999
If you remove a species from a community, the population size of its main______ is likely to increase. a) parasite b) competitor c) predator
b) competitor
A tick is a(n)______. a) parasitoid b) ectoparasite c) endoparasite
b) ectoparasite
population growth plots out as a J-shaped curve a) carrying capacity: b) exponential growth: c) biotic potential: d) limiting factor: e) logistic growth:
b) exponential growth:
The type of physical environment in which a species typically lives is its _____. a) niche b) habitat c) community d) population
b) habitat
By a currently favored hypothesis, species richness of a community is greatest between physical disturbances of _______intensity or frequency. a) low b) intermediate c) high d) variable
b) intermediate
Suppose 200 fish are marked and released in a pond. The following week, 200 fish are caught and 100 of them have marks. There are about _____fish in this pond. a) 200 b) 300 c) 400 d) 2,000
c) 400
_______steal parental care. a) Mutualists b) Commensalists c) Brood parasites d) Predators
c) Brood parasites
All members of a cohort are the same _________. a) sex b) size c) age d) weight
c) age
maximum rate of increase per individual under ideal conditions a) carrying capacity: b) exponential growth: c) biotic potential: d) limiting factor: e) logistic growth:
c) biotic potential:
The oldest established land communities are_______ . a) in the Arctic b) in temperate zones c) in the tropics d) on volcanic islands
c) in the tropics
Growth of a forest in an abandoned corn field is an example of ______. a) primary succession b) resource partitioning c) secondary succession d) competitive exclusion
c) secondary succession
Biological control of pest species. a) has no side effects b) involves mutualists c) uses natural enemies d) requires use of chemicals
c) uses natural enemies
________is a density-independent factor that influences population growth. a) Resource competition b) Infectious disease c) Predation d) Harsh weather
d) Harsh weather
_______can lead to resource partitioning. a) Mutualism b) Parasitism c) Commensalism d) Interspecific competition
d) Interspecific competition
A life history pattern is a set of adaptations that influence the individual's __________ . a) longevity b) fertility c) age at reproductive maturity d) all of the above
d) all of the above
Essential resource that restricts population growth when scarce a) carrying capacity: b) exponential growth: c) biotic potential: d) limiting factor: e) logistic growth:
d) limiting factor:
With _______, one species evolves to look like another. a) camouflage b) competition c) predation d) mimicry
d) mimicry
The ecological footprint of a person in the United States is about ________that of a person in India. a) half b) twice c) one-ninth d) nine times
d) nine times
Compared to the less developed countries, the highly developed ones have a higher _________. a) death rate b) birth rate c) total fertility rate d) resource consumption rate
d) resource consumption rate
Wildlife managers use ___________________ to decide how to manage populations
demographic information
Match each term with its most suitable description. a) carrying capacity: b) exponential growth: c) biotic potential: d) limiting factor: e) logistic growth: "population growth plots out as an S-shaped curve"
e) logistic growth:
Lizards that eat flies they catch on the ground and birds that catch and eat flies in the air are engaged in ______competition. a. exploitative b. interference c. intraspecific d. interspecific e. both exploitative and interspecific f. both interference and intraspecific
e. both exploitative and interspecific
The rate at which population size grows or declines depends on the rate of ________. a) births b) deaths c) immigration d) emigration e) a and b f) all of the above
f) all of the above
Density-INDEPENDENT
factors such as fire, storms, and other natural disasters are unrelated to crowding - no logistic growth pattern
Mark-Recapture sampling
is used to estimate population size of mobile animals › - the proportion of marked animals in a recaptured sample represents the proportion in the population
Each species has a life history pattern
life history pattern Life span, age at maturity, and number of offspring produced vary widely among organisms › Individuals at different stages of life require different resources › NATURAL influences life history traits
The scale of the area sampled and the timing of a study can influence the ________________________.
observed demographics Example: Seabirds crowd together during the breeding season, but disperse when breeding is over
Predation
one free-living species feeds on another and usually kills it
Population growth (G) for a given interval is calculated based on ________________ (r) and the ____________ of individuals (N)
per capita growth rate number G = r x N
The demographic transition model describes
population growth rate changes over time as a country becomes economically developed
Individuals are often categorized as
pre-reproductive reproductive post-reproductive
Defining r = rate of increase
r = Birth rate per individual per unit time Death rate per individual per unit time (r = b-d)
Biotic Potential The maximum _________
rate of increase (r) under ideal--nonlimiting—conditions It varies from species to species because of three parameters › at what age each generation starts REPRODUCING › how OFTEN reproduction occurs › how many offspring are born each time HIGH r, microorganisms LOW r, large mammals
Interspecific Competition:
two species access a resource
Mutualism
two species interact and both benefit by the interaction
Commensalism
two species interact and one competition benefits while the other is neither helped nor harmed
Four stages based on Industrialization:
• PREINDUSTRIAL: Birth and death rates are both high • TRANSITIONAL: Death rate declines; birth rate remains high • INDUSTRIAL: Birth rate declines • POSTINDUSTRIAL: Negative growth rate
Logistic growth
› A small population starts growing slowly in size, then it grows rapidly, then its size levels off as CAPACITY is reached › Graph of logistic growth yields an S-SHAPED curve › When a change in environment lowers carrying capacity, population size declines
COHORT
› Group of individuals born IN THE SAME TIME interval › Tracking a cohort from A COHORT FROM BIRTH until the last one DIES reveals patterns of reproduction, death, migration › Data about cohorts are summarized in LIFE TABLES › Help determine how harvesting or environmental changes may affect population numbers › Insurance companies use human life tables
Characteristic DEMOGRAPHIC - statistics that describe population's
› Size › Density › Distribution › Age structure