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Populations (Ecology)

•What’s the difference between a cohort and static life table and what are the difficulties with each? Be able to interpret data in a life table.

• Be able to draw or interpret survivorship curves for different populations. What are the differences between the three types?

• Why does population age structure matter?

• What happened to Pablo Escobar’s hippos? What are some possible consequences? What might happen in the future?

• What are exponential and geometric growth?

• Be able to graph population size over time for a given growth rate (like figure 10.11).

• What’s the difference between density dependent and density independent factors to limit growth? Give examples. Which one regulates population size? Why?

• What is logistic growth? Explain how the growth rate changes at different population sizes. Be able to compare logistic and exponential growth.

• What are the four factors that affect population size over time?

• What are population cycles? What are some of the factors that drive them?

• What is delayed density dependence and why does delayed density dependence cause populations to fluctuate? What factors affect these fluctuations? Be able to draw typical population fluctuation figures like fig. 11.10.

• What’s the difference between stabilizing and destabilizing feedbacks? How do delayed feedbacks affect a stabilizing feedback?

• How does population size affect the likelihood of extinction?

• What is the Allee effect? How does it affect growth rate at different population densities? Draw a figure illustrating this.

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Related questions

Question :Mutations that cause sickness and/or death after reproduction has occurred:

Question 1

options: can be passed on to future generations.

will not be passed on to future generations. are unlikely to occur.

are only passed on to future generations in species that have short life spans.

Question 2

In a population exhibiting logistic growth, what happens when the carrying capacity is exceeded?

Question 2 options:

The growth rate becomes zero until the population is back within the carrying capacity.

The growth rate becomes negative until the population is back within the carrying capacity.

The population crashes and becomes extinct.

The population's fertility drops to zero.

Question 3 How does exponential growth differ from logistic growth?

Question 3 options:

Logistic growth models take the population's age structure into account.

Long-term exponential growth is more commonly observed than long-term logistic growth in nature.

The logistic model of growth incorporates environmental limitations on population size.

Logistic growth generally comes with infinite expansion.

Question 4 Density-dependent and density-independent growth factors influence the size of a population by causing changes in the:

Question 4 options:

death rate and pattern of dispersion.

birth rate and death rate.

age structure and birth rate.

carrying capacity and age structure.

Question 5 The life history of an organism does not include the organism's

Question 5 options:

reproduction

All of these are included in an organism's life history.

death

birth

  1. Rank the following terms from largestto smallest: ecosystem, population, biosphere, community.

    1. biosphere (largest)
      ecosystem
      community
      population (smallest)
    2. ecosystem (largest)
      biosphere
      community
      population (smallest)
    3. biosphere (largest)
      ecosystem
      population
      community (smallest)
    4. ecosystem (largest)
      community
      biosphere
      population (smallest)

  2. Which of the following includes theother three: ecosystem, population, biosphere, community.

    1. The ecosystem contains all the communities on the earth, allthe biospheres on the earth, and all of the populations on theearth.
    2. The community contains all the ecosystems on the earth, all thebiospheres on the earth, and all of the populations on theearth.
    3. The population contains all the ecosystems on the earth, allthe communities on the earth, and all of the biospheres on theearth.
    4. The biosphere contains all the ecosystems on the earth, all thecommunities on the earth, and all of the populations on theearth.

For questions 3–7, consider the following things in your frontyard: cardinals, robins, rocks, raccoons, bees, decaying leaves,mosquitos, humans, beetles, water, blue grass, sunlight, moss,soil, worms, pine trees, and the air (containing oxygen, nitrogen,and carbon dioxide).

  1. What are the biotic components ofyour front yard?

    1. The biotic components are the blue grass, moss, and pinetrees.
    2. The biotic components are the cardinals, raccoons, bees,mosquitoes, beetles, blue grass, moss, worms, and pine trees.
    3. The biotic components are the cardinals, robins, raccoons,bees, mosquitoes, humans, beetles, blue grass, moss, worms, andpine trees.
    4. The biotic components are the cardinals, robins, raccoons,bees, mosquitoes, humans, beetles, blue grass, moss, worms, andpine trees, rocks, decaying leaves.

  2. What are the abiotic components ofyour front yard?

    1. The abiotic components are the rocks, water, and soil.
    2. The abiotic components are the air containing oxygen, nitrogen,and carbon dioxide.
    3. The abiotic components are the decaying leaves, water, andsunlight.
    4. The abiotic components are the rocks, decaying leaves, water,sunlight, soil, and the air containing oxygen, nitrogen, and carbondioxide.

  3. How many different populations arethere in your front yard?

    1. There are 7 different populations.
    2. There are 9 different populations.
    3. There are 11 different populations.
    4. There are 13 different populations.

  4. Identify the components of thecommunity in your front yard.

    The front-yard community consists ofthe following populations:

    1. cardinal, robin, raccoon, bee, mosquito, human, beetle, bluegrass, moss, worm, pine tree.
    2. cardinal, robin, raccoon, bee, mosquito, beetle, worm.
    3. blue grass, moss, pine tree.
    4. cardinal, robin, raccoon, bee, mosquito, beetle, blue grass,moss, worm, pine tree.

  5. Identify the components of theecosystem in your front yard.

    The front-yard ecosystem consists ofthe following populations:

    1. robin, bee, mosquito, beetle, worm, raccoon.
    2. robin, raccoon, bee, mosquito, human, beetle, blue grass, moss,worm, pine tree, rocks, decaying leaves, water, sunlight, soil, aircontaining oxygen, nitrogen, carbon dioxide.
    3. decaying leaves, water, sunlight, soil, air containing oxygen,nitrogen, carbon dioxide.
    4. robin, raccoon, bee, mosquito, beetle, moss, worm, water,sunlight, soil, air containing oxygen, nitrogen, carbondioxide.

  6. Think about the term biodiversity. Towhat does it refer and what does the biodiversity level of acommunity or ecosystem indicate? Which answer below is notcorrect.

    1. Biodiversity is the measure of the different types of organismsin a population.
    2. Biodiversity is the measure of the different types of organismsin an ecosystem.
    3. Biodiversity is the measure of the different types of organismsin a biosphere.
    4. Biodiversity is the measure of the different types of organismsin a community.

  7. Why are population studies importantin ecology?

    Population studies help scientiststo:

    1. gauge the overall health and vitality of populations andecosystems
    2. understand and predict how populations and ecosystems willrespond to various diseases and environmental conditions
    3. predict the future of populations and ecosystems
    4. all of the above

  8. The features of populations thatscientists study to determine the overall health of populationsare:

    1. growth pattern, growth rate, density, size
    2. size, distribution, growth rate, and growth pattern
    3. distribution, size, density, growth rate
    4. size, density, distribution, growth rate, and growthpattern

  9. What factors play a role indetermining the size and growth of populations?

    The size and growth of a populationis influenced by the following:

    1. the gene pool of a population
    2. the amount and availability of useable resources andnutrients
    3. the birth rate and death rate of the population
    4. all of the above

  10. Consider a population composed of 25blue jays. What is a quantitative feature of this population?

    1. blue is the color of the birds
    2. the type of bird is a blue jay
    3. the population size of 25
    4. all of the above

  11. Consider a population composed of 25blue jays. What is a qualitative feature of this population?

    1. the type of bird is a blue jay
    2. blue is the color of the birds
    3. the population size of 25
    4. all of the above

For questions 14-17, consider the following description of awooded area near your home: The wooded area is 100 feet wide and 10feet long. In the year 1999 there were 1,700 crickets in the woodedarea, and in the year 2001 there were 3,000 crickets in the woodedarea.

  1. What was the size of the cricketpopulation in the year 1999?

    1. In the year 1999, the size of the cricket population was 1,700crickets per square foot.
    2. In the year 1999, the size of the cricket population was 1,700crickets.
    3. In the year 1999, the size of the cricket population was 3,000crickets.
    4. In the year 1999, the size of the cricket population was 3,000crickets per square foot.

  2. What was the density of the cricketpopulation in the year 2001?

    1. In the year 2001, the density of the cricket population was3,000 crickets.
    2. In the year 2001, the density of the cricket population was1,700 crickets.
    3. In the year 2001, the density of the cricket population was 3crickets per square foot.
    4. In the year 2001, the density of the cricket population was 1.7crickets per square foot.

  3. What was the net growth of thiscricket population between the years 1999 and 2001?

    1. The net growth of this cricket population between the years1999 and 2001 was 650 crickets.
    2. The net growth of this cricket population between the years1999 and 2001 was 1,300 crickets.
    3. The net growth of this cricket population between the years1999 and 2001 was 1,700 crickets.
    4. The net growth of this cricket population between the years1999 and 2001 was 3,000 crickets.

  4. What was the growth rate of thecricket population between the years 1999 and 2001?

    1. The growth rate of the cricket population between the years1999 and 2001 was 650 crickets per year.
    2. The growth rate of the cricket population between the years1999 and 2001 was 1,300 crickets per year.
    3. The growth rate of the cricket population between the years1999 and 2001 was 1,700 crickets.
    4. The growth rate of the cricket population between the years1999 and 2001 was 3,000 crickets.

For questions 18-22, use the following set of observations onthe size of the dandelion population in your backyard:

Time Population Size (Number of Dandelions) 1970 111971 121972 141973 271974 661975 911976 1001977 1001978 1001979 100

  1. How many data points are there in thetable above?

    1. There are 5 data points
    2. There are 10 data points
    3. There are 15 data points
    4. There are 20 data points

  2. What are the variables in this dataset?

    1. time
    2. population size
    3. all of the above
    4. none of the above

  3. What type of growth pattern does thisdandelion population exhibit?

    1. This dandelion population exhibits an S-shaped growthpattern.
    2. This dandelion population exhibits an exponential growthpattern.
    3. This dandelion population exhibits an exponential, J-shapedgrowth pattern.
    4. This dandelion population exhibits a linear growthpattern.

  4. What does the graph indicate aboutthe dandelion population in your backyard during the period of 1971to 1974?

    1. During the period of 1971 to 1974 the dandelion populationexhibited a phase of linear growth.
    2. During the period of 1971 to 1974 the dandelion populationexhibited a phase of S-shaped growth.
    3. During the period of 1971 to 1974 the dandelion populationexhibited a phase of exponential growth.
    4. None of the above.

  5. The graph indicates that the size ofthe dandelion population remained relatively stable from 1975 to1979.

    1. true
    2. false

  6. What factors play a role indetermining the overall health of a community?

    The overall health of a community is influenced by the followingfactors:

    1. the level of biodiversity in the community and the overallhealth and vitality of each of the populations in thecommunity
    2. the geographic location and size of the community
    3. the amount of useable resources in the area in which thecommunity lives and the types of adaptive traits in the variouspopulations of the community
    4. all of the above

  7. What are the general pathways throughwhich resources cycle in ecosystems?

    1. Resources cycle in an ecosystem through two general mechanisms:biotic cycling and abiotic cycling.
    2. Resources cycle in an ecosystem through two general mechanisms:biotic cycling and biotic-abiotic cycling.
    3. a and b
    4. none of the above

  8. Explain the flow of resources andnutrients through the trophic levels of a feeding chain.

    1. Organisms in level 4 are eaten by organisms in level 3;
      organisms in level 3 are eaten by organisms in level 2;
      organisms in level 2 are eaten by organisms in level 1; and soforth.

      The living organisms in level 1 are called producers becausethey convert light energy from the sun to make glucose moleculesfor use by all other living organisms. Organisms in levels 2 andhigher are called consumers because they eat other living organismsand gain from them at least some of the nutrients they require tosustain life.

    2. Organisms in level 1 are eaten by organisms in level 4;
      organisms in level 2 are eaten by organisms in level 3;
      organisms in level 4 are eaten by organisms in level 2; and soforth.

      The living organisms in level 4 are called producers becausethey convert light energy from the sun to make glucose moleculesfor use by all other living organisms. Organisms in levels 3 andlower are called consumers because they eat other living organismsand gain from them at least some of the nutrients they require tosustain life.

    3. Organisms in level 1 are eaten by organisms in level 2;
      organisms in level 2 are eaten by organisms in level 3;
      organisms in level 3 are eaten by organisms in level 4; and soforth.

      The living organisms in level 1 are called producers becausethey convert light energy from the sun to make glucose moleculesfor use by all other living organisms. Organisms in levels 2 andhigher are called consumers because they eat other living organismsand gain from them at least some of the nutrients they require tosustain life.

    4. none of the above

  9. Distinguish between a food chain anda food web.

    1. A food chain is a set of overlapping and interconnected foodchains.

      A food web is a linear series of feeding steps by which energyand nutrients are transferred from one organism to the next.

    2. A food chain is a linear series of feeding steps by whichenergy is transferred from one organism to the next.

      A food web is a set of overlapping food chains.

    3. A food chain is a linear series of feeding steps by whichenergy and nutrients are transferred from one organism to the next.A food web is a set of overlapping and interconnected foodchains.
    4. A food chain is a linear series of feeding steps by whichnutrients are transferred from one organism to the next.

      A food web is a set of interconnected food chains.

  10. What are the major biogeochemicalcycles in ecosystems, and which resources are transferred andtransformed in each cycle?

    1. Carbon cycle – carbon
      Hydrologic cycle – water
      Nitrogen cycle – nitrogen
      Phosphorus cycle – phosphorus
    2. Carbon cycle – carbon
      Nitrogen cycle – nitrogen
      Phosphorus cycle – phosphorus
    3. Carbon cycle – carbon
      Nitrogen cycle – nitrogen
    4. Hydrologic cycle – water
      Phosphorus cycle – phosphorus

  11. How are the production of ATP,proteins, DNA, RNA, and membranes in cells impacted by thebiogeochemical cycles of an ecosystem?

      • The production of ATP (energy-storage molecules) in cells isimpacted by the phosphorus cycle because phosphorus is a criticalbuilding block of ATP molecules.
      • The production of DNA and RNA are impacted by both the nitrogenand phosphorus cycles because both nitrogen and phosphorus areintegral parts of the nucleotide subunits used to build nucleicacids (DNA and RNA).
      • The production of new proteins in cells is impacted by thenitrogen cycle because nitrogen is an integral part of the aminoacid subunits used to build proteins.
      • The production of membranes in cells is impacted by thephosphorus cycle because phosphorus is a critical component of thephospholipid molecules used to build both cell membranes andorganelle membranes.
      • The production of ATP (energy-storage molecules) in cells isimpacted by the phosphorus cycle because phosphorus is a criticalbuilding block of ATP molecules.
      • The production of new proteins in cells is impacted by thenitrogen cycle because nitrogen is an integral part of the aminoacid subunits used to build proteins.
      • The production of DNA and RNA are impacted by both the nitrogenand phosphorus cycles because both nitrogen and phosphorus areintegral parts of the nucleotide subunits used to build nucleicacids (DNA and RNA).
      • The production of membranes in cells is impacted by thephosphorus cycle because phosphorus is a critical component of thephospholipid molecules used to build both cell membranes andorganelle membranes.
      • The production of ATP (energy-storage molecules) in cells isimpacted by the phosphorus cycle because phosphorus is a criticalbuilding block of ATP molecules.
      • The production of new proteins in cells is impacted by thenitrogen cycle because nitrogen is an integral part of the aminoacid subunits used to build proteins.
      • The production of DNA and RNA are impacted by both the nitrogenand phosphorus cycles because both nitrogen and phosphorus areintegral parts of the nucleotide subunits used to build nucleicacids (DNA and RNA).

  12. Under what conditions is the overallhealth of the biosphere threatened by the activities of livingorganisms?

    1. irreversibly deplete the earth's useable and renewableresources and degrade the quality of vital and useableresources
    2. release molecules into the environment that are toxic to livingorganisms and disrupt the natural biogeochemical cycles of anecosystem
    3. both a and b
    4. none of the above

  13. What general factors have contributedto many of the environmental problems facing our globalsociety?

    1. Industrial activities are largely to blame for the majorenvironmental problems facing our global society today
    2. Humankind's rapid population growth is to blame for the majorenvironmental problems facing our global society today
    3. Modern technological and industrial activities are to blame forthe major environmental problems facing our global societytoday
    4. Humankind's rapid population growth and modern technologicaland industrial activities are largely to blame for the majorenvironmental problems facing our global society today

  14. List the major environmental problemsfacing the world today as a result of humankind's rapid populationgrowth and modern technological and industrial activities.

    1. pollution (of air, water, and land), acid rain, smog, globalwarming, ozone thinning
    2. decreased water quality, decreased amount of suitable land forfarming, grazing, and human habitation, deforestation, decreasedsoil fertility, water shortages, decreased fossil-fuelreserves
    3. global warming and the greenhouse effect
    4. a and b

Read the following news report and then answer the questionsbelow. In answering these questions be sure to consider everythingyou have learned in this course.

The China Connection

By all rights the lush rain forest on Kauai shouldn't exist. TheHawaiian island's soil is nutrient-poor, yet somehow sustainsplants. Oliver Chadwick, a soil scientist at the University ofCalifornia at Santa Barbara has discovered Kauai's secret:phosphorus blown to the island on dust from central Asia, more than3,700 miles away.

Chadwick, who has tramped through Kauai's forests for more thana decade, long suspected that prevailing westerly winds rainedenriching dust on the island. But only recently, after carefulcomparison of soil samples from Asia with Kauai's soil, was he ableto pinpoint the origin of an airborne fertilizer: a huge desert inwestern China called Takla Makan. "It's an enormous basin that's atremendous source of dust," he says.

Other rain forests probably depend on long-distance transport,too. Dust from the Sahara Desert, for example, may support theAmazon. Says Chadwick: "Every part of the planet is interconnectedthrough the atmosphere." (Discover, May 1999, p. 19)

  1. What is the movement of dust fromcentral Asia to Kauai via wind an example of?

    1. The movement of dust from central Asia to Kauai via wind is anexample of a biogeochemical pathway, specifically the hydrologiccycle.
    2. The movement of dust from central Asia to Kauai via wind is anexample of a biogeochemical pathway, specifically the phosphoruscycle.
    3. The movement of dust from central Asia to Kauai via wind is anexample of a biogeochemical pathway, specifically the nitrogencycle.
    4. The movement of dust from central Asia to Kauai via wind is anexample of a biogeochemical pathway, specifically the carboncycle.

  2. What are the biotic and abioticportions of the Kauai rainforest ecosystem mentioned above?

    1. The biotic portion of the Kauai rainforest consists of all ofthe living organisms found in the rainforest. The abiotic portionof the Kauai rainforest consists of the soil and water found onthis island.
    2. The biotic portion of the Kauai rainforest consists of all ofthe living organisms found in the rainforest. The abiotic portionof the Kauai rainforest consists of the soil, wind, and water foundon this island, as well as the dust and phosphorus that has blownthere from China.
    3. The biotic portion of the Kauai rainforest consists of thesoil, wind and water found in the rainforest. The abiotic portionof the Kauai rainforest consists of all the living organisms foundon this island.
    4. The biotic portion of the Kauai rainforest consists of thesoil, wind, water, and living organisms found in the rainforest.The abiotic portion of the Kauai rainforest consists of the dustand phosphorus that has blown there from China.

  3. Of what use is the phosphorus dustfrom China to the living organisms in the Kauai rainforest?

    1. The cells of the living organisms in the Kauai rainforest usethe phosphorus to make the phospholipid subunits of membranes, usedto protect cells and to partition cells into functionalcompartments (organelles).
    2. The cells of the living organisms in the Kauai rainforest usethe phosphorus to make ATP energy-storage molecules, which are usedto power the many chemical (photosynthesis, glycolysis, the Krebscycle) and genetic (mitosis, meiosis) processes of living things,as well as their physical movements.
    3. The cells of the living organisms in the Kauai rainforest usethe phosphorus to make the nucleotide (A, C, G, T, U) subunits ofDNA and RNA, which are required by cells and living organisms forthe storage and transmission of genetic information from onegeneration to the next, and provide cells with the instructions tomake the proteins they need to function appropriately.
    4. all of the above

  4. What might be a possible consequenceof permanent shifts in the prevailing winds that would no longerbring dust from China's Takla Makan desert to the Kauairainforest?

    1. If phosphorus-rich dust from the Takla Makan desert is nolonger transported to the Kauai rainforest, then the amount ofphosphorus present in the Kauai rainforest may be insufficient tosupport the current amount and types of the living organisms livingthere. Under these conditions, phosphorus would become a limitingfactor to population growth in the Kauai rainforest. The variousliving organisms in the rainforest would then begin competing forthe limited amount of phosphorus.
    2. The living organisms that are able to most efficiently uptakephosphorus from the soil are those that are most likely to survive,while organisms that are unable to efficiently uptake phosphorusfrom the soil are most likely to die off. The varying ability ofliving organisms to acquire and use phosphorus is determined by thegenes of each species, which have been selected over long periodsof time as a result of evolution. As some living organisms andspecies die off, the biodiversity of the rainforest decreases.
    3. both a and b
    4. none of the above

The following paragraph is an abstract from the article tittled:Ecology of the Lesser Siren, Siren intermedia, in anIsolated Eastern Texas Pond

The Lesser Siren (Siren intermedia) is a fully aquaticsalamander with functionally limited overland dispersal. Details ofthe ecology of this species throughout its geographic range anddiversity of habitats are limited. In this study, I investigatedthe ecology of a presumably isolated population of S.intermedia in eastern Texas. The conservative estimatedpopulation density was 0.33 sirens/m2 with a standingcrop biomass of 9.66 g/m2. Growth rates averaged 0.022mm/day in total length, slightly slower than other populations.Growth rate was not significantly different between males andfemales, nor was it correlated with size. The diet of the studypopulation included at least 10 different taxa, of which tadpolesand snails (Order Basommatophora) were the most important prey.Like other populations, activity was highest during late winter andearly spring, which coincides with the breeding season. Theabundance of siren captures was weakly influenced by watertemperature but not correlated with precipitation. Bite marks arehypothesized to be a result of siren courtship behavior. Theabundance of males and females captured with fresh bite marks wassignificantly correlated with the number of gravid females. Becausesirens are predatory generalists and represent a significantproportion of biomass in many aquatic environments, it is importantto understand siren ecology throughout its geographic range andbroad use of habitat types.

The following questions are in regards to the study above:

1.How does this article demonstrate scientific research?

2.What was the question posed by the researcher? (either statedor implied)

3.Did the researcher(s) answer the question? What is theevidence from the article?

4.Is this research a piece of a larger research project? How doyou know?

5. Which type of research method and this the projects becategorized under? choose from the following.
Testing ahypothesis, Measuring afunction or relationship, Measuring a value, Constructing a model, Observational/exploratory research,Industrial or appliedresearch

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