Population Ecology Worksheet

1. Characteristics of PopulationsA. Each __________—a group of individuals of the same

species living in the same area (habitat)—has certain characteristics.

1. The ________ is the number of individuals making up its gene pool.2. ___________ defines the relative proportions of individuals of each age—especially with respect to reproductive years.3. _________ is the number of individuals per unit of area or volume—the habitat.4. ___________________ refers to the general pattern in which the population members are dispersed through its habitat.

B. Populations can be dispersed in three patterns.1. Members of a population living in ________ is very common for these reasons.

a. Suitable physical, chemical, and biological conditions are patchy, not uniform.b. Many animals form social groups.c. Many offspring are not highly mobile and are forced to live “where they landed.”

2. Uniform_______________ is rare in nature; when it does occur, it is usually the result of fierce competition for limited resources.3. _______________ dispersion occurs in nature if environmental conditions are rather uniform in the habitat and members are neither attracting nor repelling each other.

2. Elusive Heads to CountA. To determine the number of animals in a particular area,

you could try a full count to measure _____________; this may be difficult especially with elusive animals such as deer.

B. You could divide up the area into smaller __________; count the number of deer in one quadrat and ________ the number for the whole area.

C. Because many animals _________a lot, it may be better to use the capture–recapture method.

3. Population Size and Exponential GrowthA. Gains and Losses in Population Size

1. ___________ is dependent on births, immigration, deaths, and emigration.2. Population size may also change on a predictable basis as a result of daily or __________ called migrations.

B. From Zero to Exponential Growth1. ____________ designates a near balance of births and deaths.2. Rate of increase: r = net reproduction per individual per unit time.3. The growth rate formula is: G = ________.

a. A graphic plot of exponential growth results in a ___________ curve that becomes steeper with advancing time.

b. As long as r is ________, the population will continue to increase at ever-increasing rates—easily measured by noting the “doubling time.”

C. What Is Biotic Potential?1. The ____________ of a population is its maximum rate of increase under ideal—nonlimiting—conditions.2. The biotic potential varies from species to species because of three parameters: a.

b.

c. 4. Limits on the Growth of Populations

A. What Are the Limiting Factors?1. The actual rate of increase of a population is influenced by ______________________.

2. Limiting factors (nutrient supply, predation, competition for space, pollution, and metabolic wastes) ______________ to population growth.

B. Carrying Capacity and Logistic Growth1. The ________________ of resources defines the carrying capacity for a particular population in a given environment.

a. The carrying capacity can vary over time and is expressed graphically in the S-shaped curve pattern called _____________.b. The formula for logistic growth is: G = ______________

2. Logistic growth deals with _____________ controls.a. The main density-dependent factors are competition for resources, predation, parasitism, and disease.b. These factors exert their effects in ________________ to the number of individuals present.

C. Density-Independent Factors1 Some events, such as weather, tend to increase the death rate without respect to the number of ______________.2. Lightning, floods, snowstorms, and the like affect large populations as well as ________ groups.

5. Life History PatternsA. Each species has a life history pattern that influences

survival, fertility, and the age of first reproduction.B. Life Tables

1. Life tables follow the fate of a group of newborn individuals (_______) through their lives to calculate the survivorship schedule.2. The number of _________ born to individuals in each age interval is also recorded.

C. Patterns of Survival and Reproduction

1. Survivorship curves are plots of the __________________________ of death for a given population in a given environment.2. Most animals are characterized by one of these types of curves.

a. A ________ curve is typical of large mammals where few offspring are produced and cared for so that infant mortality is low; death usually comes after an extended life.b. A Type II curve is typical of many animals where the chances of survival or death are about the _________ at any age.c. A Type III curve indicates low survivorship, or conversely, ____________ in early life.

6. Natural Selection and Life Histories A. David Reznick and John Endler studied the differences in

size and survival of guppies in Trinidad. 1. They were interested in the effects of predation on

guppy populations in two streams with different predators.

2. Their hypothesis was that predation by killifish and pike-cichlids is a selective agent that acted to shape guppy life history patterns.

B. They discovered that differences in growth rate and reproductive maturity have a genetic basis because the effects were the same in lab-reared guppies and the natural populations.

C. The experimenters performed other field experiments that stretched over eleven years.

1. Guppies that had been exposed to one predator, and then moved to another, displayed changes.

2. Reznick and Endler showed that life history traits can be inherited, but these traits can also evolve.

7. Human Population GrowthA. Notice these startling statistics:

1. The world population reached _________ in 1999.2. The annual rate of increase averaged _____ percent.

B. How did the human population grow to such large numbers?

1. Humans expanded into new_________ and climatic zones.2. ___________ increased the carrying capacity of the land to support humans and their animals.3. Medical practice and improved sanitation conditions removed many _____________ factors.4. New forms of _________ from fossil fuels ushered in the industrial revolution.

C. Consider this: It took 2.5 million years for the world’s human population to reach 1 billion; it took only_________ years to reach the sixth billion.

8. Fertility Rates and Age StructureA. At the present rate of increase, the world human

population may reach __________ by 2050.1. The total fertility rate (TFR) is the average number of children born to _______ during their reproductive years, and is currently ______ children per female.2. Even if the replacement level of fertility is achieved (about two children per woman), the human population will continue to grow for another _______ years.

B. Any population with a broadly based age structure (many women in reproductive years) will continue _________ population growth.

1. Effective family ________ programs can achieve a faster decline in birth rate than economic development alone.2. ________ has the most far-reaching family planning program.

a. Couples are limited to having one, maybe two, children.b. There are many incentives, and the program has lowered the TFR from 5.7 to 1.8.

9. Population Growth and Economic EffectsA. Demographic Transitions

1. In the _____________ model, changes in population growth are linked to four stages of economic development.

a. In the _______stage, living conditions are harsh; birth and death rates are high; and there is little increase in population size.b. In the __________ stage, living conditions improve; death rate drops; and birth rate remains high.c. In the __________stage, growth slows.d. In the _________ stage, zero population growth is reached; birth rate falls below death rate.

2. Some _______ countries are in the industrial stage (for example, the United States, Canada, and Japan); some countries (for example, Mexico) are in the ________transitional stage.

B. A Question of Immigration Policies1. The greatest increase in _________came in 1986 when legislation gave legal status to undocumented immigrants who proved they had lived in the country for years.2. Economic __________ in the past twenty years have fanned resentment against newcomers and increased calls for limits on new immigrants.

C. A Question of Resource Consumption1. The United States uses about a________ of the world’s goods, services, and natural resources but constitutes only _____percent of the world’s population.2. Other countries such as ______and_________ are asking for a greater share of the economic pie.

D. Impacts of No Growth1. It takes a large __________of younger individuals to support individuals in the higher age brackets.2. Can humans defy the laws of nature that dictate the number of individuals, which can be supported per unit of space, or are we just postponing the _________?