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