SBI4U1 Chapter 14 Population Ecology Worksheets

Name: ______Date: ______

14.1 – Characteristics of Populations After reading section 14.1 complete the questions below.

To study populations, scientists measure such characteristics as population size.

The ______is the number of individuals of the same species that occur per unit area or volume.

D = N D=______, N= ______, S= ______S

1. Find the population density if there are 650 geese living in a 500 hectare region.

Some populations live in habitats where certain areas of the region are not used.

Example: Moose in ponds.

______is the population density calculated using the total area of the entire habitat.

______is the population density calculated using the area actually used by the individuals.

1. 540 moose occupy 90 ha of total habitat that includes 26 ha of pond. Calculate the crude and ecological densities.

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Population Dispersion Label each type of dispersion and briefly describe and provide an example for each.

Name the types of dispersion that wild species rarely show:

Measuring Population Characteristics Rarely, scientists can make an exact count of the total number of individuals in a population. This is possible in situations such as isolated laboratories. However, most of the time, populations are not isolated and are dynamic. This can make finding population size difficult. Therefore, different techniques are used to calculate estimates of population size and density.

Techniques used to estimate population size: 1. quadrat sampling 2. mark-recapture sampling

Define “Quadrat”:

Quadrat sampling is most effective for: ______

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Average sample density = total # of individuals total sample area Estimated population size = average sample density X total size of study area

1. To estimate the size of the slug population on a golf course, biology students randomly selected five 1.0-m2 quadrats in a 10 m X 10 m site. The numbers of slugs in each quadrat were 4,8,9,5, and 1. Estimate the population density and size of slugs in this study site.

2. A forester runs several 10 m2 quadrats through a 100 ha woodlot. Five of the quadrats produced the following results: 15, 17, 25, 16, and 20. Find the density of oaks in the woodlot and estimate the size of the oak population in this woodlot.

Mark-recapture sampling: compares the proportion of marked and unmarked animals captured in a given area.

M = m M = ______, m = ______N n N = ______, n = ______

1. Suppose that in a study of a particular species of rodent, a sample of 200 was trapped, marked, and released. Later, a second sample of 200 was obtained and it was discovered that 20% of these animals were recaptured. Based on these data, estimate the size of the total population.

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2. In a river in British Columbia, 430 sockeye were captured and marked on the fin with a uniquely numbered T-bar anchor tag. Two weeks later, a total of 154 sockeye salmon were recaptured and 15 bore the tags on their fin. Estimate the sockeye salmon population in this river during this study.

3. A researcher caught and tagged a sample of 50 deer mice in an isolated field. She waited two weeks and then captured a second sample, consisting of 63 mice. Of these 63 mice, 10 were tagged. How big was the population of mice in the field?

Read Pages 648-659, Complete questions #1-4 on pg. 659

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14.2 – Measuring and Modelling Population Change

______: the maximum # or organisms that can be sustained by available resources over a given period of time.

4 main determinants affect population dynamics:

1. ______3. ______2. ______4. ______

Label the different types of survivorship curves. Give characteristics of each.

Calculating Changes in Population Size

Population change = (give equation)

Differentiate between open and closed populations.

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Population Growth Models Match the following:

Geometric growth  Growth that levels off as the size approaches its carrying capacity Exponential growth  Growth where organisms reproduce continuously at a constant rate Logistic growth  Growth where organisms reproduce at fixed intervals at a constant rate

Geometric Growth = N(t+1) = ______, N=______, t=______N(t)

1. A nesting colony of gannets on Isle Bonaventure exhibits geometric growth. During the year, an initial population of 50 000 birds had 32 000 births and 29 000 deaths. Calculate the geometric growth rate and estimate the population sizes after 2 and 10 years.

2. A population of deer contains 10 000 individuals. During a year, 5000 individuals are born and 4500 die. What will be the size of the population 10 years from now?

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Exponential Growth dN = rN dN = ______, N = ______, r = ______dt dt td = 0.69 r

1. After the rainy season begins in the tropics, a small population of mosquitoes exhibits exponential growth. The initial population size 980 and their intrinsic growth rate r is 0.345 per day.

Calculate: a) the populations initial instantaneous growth rate.

b) the doubling time for the population.

c) How many doubling times will have to pass in order for the population to exceed 2 000 000? How many days is this?

2. Calculate the size of a population in 10 years, given a current population size of 5000 individuals and a growth rate of 0.04 individuals per capita per year.

Logistic Growth dN = rmaxN (K-N) dN = ______, rmax = ______, dt K dt N = ______, K = ______

1. A population is growing continuously. The carrying capacity of the environment is 1000 individuals and its maximum growth rate, rmax, is 1.00. Determine the population growth rates based on a population size of 20, 200, 500, 900, 990, and 1000.

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Label the type of growth each of the graphs below represents.

Read pg. 660 -669 and complete Q’s # 1-6 on pg. 669.

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14.3 Factors Affecting Population Change

Density-Dependent Factors Density-dependent factors influence population regulation, having a greater impact as population density increases or decreases.

Example: Food supply

Factors related to high population densities:

Fill in the blanks:

1. When many individuals of a population rely on the same resources, such as food supply for survival, ______occurs. As the competition increases, the amount of food per individual often decreases, which can lead to a decrease in reproductive success.

2. ______is the interaction in which a predator catches, kills, and consumes prey. Some predators prefer one type of prey over another if that prey has a larger population and is easier to catch. This may result in density-dependent regulation of the preferred species of prey.

3. Disease can also limit population size. Pathogens are able to be passed on easily if there are ______available.

Factors related to low population densities:

Define and give an example of each:

a) Allee effect

b) Minimum viable population size

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Density-Independent Factors Density-independent factors influence population regulation regardless of population density.

Examples: floods, pesticides

Read Pg. 671 – 675 and complete Q’s #1-5 on pg. 675

14.4 Interactions Within Communities Match the following:

___Ecological niche a) Traits tend to be more divergent in two species occupying the same geographical range over those that are geographically isolated ___Interspecific competition b) Competitions that involves consumption of shared resources ___Realized niche c) An organism’s biological characteristics ___Resource partitioning d) Competition between different species who fight over the same resources ___Fundamental niche e) Avoidance or reduction in competition by occupying nonoverlapping ecological niches ___Exploitative competition f) The biological characteristics that an organism actually uses ___Character displacement g) Interactions between individuals for an essential common resource ___Interference competition h) Biological characteristics that an organism is theoretically capable of using under ideal conditions

Defence Mechanisms Fill in the blanks:

Predator-prey relationships have resulted in diverse defence mechanisms. Plants use

______---such as thorns, hooks, spines, and needles----and chemical defences against herbivores. Animals can display passive defence mechanisms such as ______, active defences such as______, or behavioural defences such as ______.

Define two types of mimcry.

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Symbiosis Define symbiosis:

Match the following:

___Mutualism a) One organism benefits at the expense of another organism. ___Commensalism b) Both organisms benefit from each other. ___Parasitism c) One organism benefits and the other is unaffected

Read pg. 676 – 688 and complete Q’s # 1 – 7 on pg. 688.