Learning Guide Unit 2
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ENGL 1405 UNIT 2
February 8-14
Unit 2: Ecology and Sustainability
Topics
Ecosystems and the Biosphere
Community and Population Ecology
Learning Objectives
Examine a biodiversity hotspot and choose an endangered species listing possible solution(s) to sustain its existence. (DF)
Research the benefits of reduce, reuse, recycle and how they apply to your community.
Tasks
Read the Learning Guide and the Reading Assignment
Participate in the Discussion Assignment (post, comment, and rate in the Discussion Forum)
Make entries to the Learning Journal
Take the Self-Quiz
Introduction
Energy Flow through Ecosystems
Ecosystems exist underground, on land, at sea, and in the air
Organisms in an ecosystem acquire energy in a variety of ways, which is transferred between trophic levels as the energy flows from the base to the top of the food web, with energy being lost at each transfer. There is energy lost at each trophic level, so the lengths
of food chains are limited because there is a point where not enough energy remains to support a population of consumers.
Fat soluble compounds biomagnify up a food chain causing damage to top consumers even when environmental concentrations of a toxin are low.
Biogeochemical Cycles
Mineral nutrients are cycled through ecosystems and their environment. Of particular importance are water, carbon, nitrogen, phosphorus, and sulfur. All of these cycles have major impacts on ecosystem structure and function.
As human activities have caused major disturbances to these cycles, their study and modeling is especially important. Ecosystems have been damaged by a variety of human activities that alter the natural biogeochemical cycles due to pollution, oil spills, and events causing global climate change.
The health of the biosphere depends on understanding these cycles and how to protect the
environment from irreversible damage.
Terrestrial Biomes
Earth has terrestrial and aquatic biomes. Aquatic biomes include both freshwater and marine environments.
There are eight major terrestrial biomes: tropical rainforests, savannas, subtropical deserts, chaparral, temperate grasslands, temperate forests, boreal forests, and Arctic tundra. The same biome can occur in different geographic locations with similar climates.
Temperature and precipitation, and variations in both, are key abiotic factors that shape the composition of animal and plant communities in terrestrial biomes.
Some biomes, such as temperate grasslands and temperate forests, have distinct seasons with cold and hot weather alternating throughout the year.
In warm, moist biomes, such as the tropical rainforest, net primary productivity is high as
warm temperatures, abundant water, and a year-round growing season fuel plant growth.
Other biomes, such as deserts and tundra, have low primary productivity due to extreme temperatures and a shortage of water.
Aquatic and Marine Biomes
Aquatic biomes include both saltwater and freshwater biomes.
The abiotic factors important for the structuring of aquatic biomes can be different than those seen in terrestrial biomes. Sunlight is an important factor in bodies of water, especially those that are very deep, because of the role of photosynthesis in sustaining certain organisms.
Other important factors include temperature, water movement, and salt content.
Oceans may be thought of as consisting of different zones based on water depth, distance from the shoreline, and light penetrance.
Different kinds of organisms are adapted to the conditions found in each zone. Coral reefs
are unique marine ecosystems that are home to a wide variety of species. Estuaries are found where rivers meet the ocean; their shallow waters provide nourishment and shelter for young crustaceans, mollusks, fishes, and many other species.
Freshwater biomes include lakes, ponds, rivers, streams, and wetlands.
Bogs are an interesting type of wetland characterized by standing water, a lower pH, and a lack of nitrogen.
Population Demographics and Dynamics
Populations are individuals of a species that live in a particular habitat.
Ecologists measure characteristics of populations: size, density, and distribution pattern.
Life tables are useful to calculate life expectancies of individual population members. Survivorship curves show the number of individuals surviving at each age interval plotted
versus time.
Population Growth and Regulation
Populations with unlimited resources grow exponentially—with an accelerating growth rate. When resources become limiting, populations follow a logistic growth curve in which population size will level off at the carrying capacity.
Populations are regulated by a variety of density-dependent and density-independent factors.
Life history characteristics, such as age at first reproduction or numbers of offspring, are characteristics that evolve in populations just as anatomy or behavior can evolve over time. The model of r- and K selection suggests that characters, and possibly suites of
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characters, may evolve adaptations to population stability near the carrying capacity (K-
selection) or rapid population growth and collapse (r-selection).
Species will exhibit adaptations somewhere on a continuum between these two extremes.
The Human Population
Earth’s human population is growing exponentially.
Humans have increased their carrying capacity through technology, urbanization, and harnessing the energy of fossil fuels. The age structure of a population allows us to predict population growth. Unchecked human population growth could have dire long-
term effects on human welfare and Earth’s ecosystems.
Community Ecology
Communities include all the different species living in a given area.
The variety of these species is referred to as biodiversity. Many organisms have developed defenses against predation and herbivory, including mechanical defenses, warning coloration, and mimicry. Two species cannot exist indefinitely in the same habitat competing directly for the same resources. Species may form symbiotic relationships such as commensalism, mutualism, or parasitism.
Community structure is described by its foundation and keystone species. Communities respond to environmental disturbances by succession: the predictable appearance of different types of plant species, until a stable community structure is established.
Reading Assignment
Doršner, K. (2020). Essentials of environmental science (2nd edition)
. Read chapters 6 and 7 in the textbook and answer the 'End of Chapter Review Questions' in each chapter.
Discussion Assignment
Your posts should cover the questions below in full, and be at least 300 words long.
Go to the following links below. Choose one hotspot that is near the place where you currently live or have lived.
Some links to help you:
Map: Biodiversity Hotspots
Hotspots: Conservation International
The Biodiversity Hotspots
The IUCN List of Threatened Species
Study the information about that biodiversity hotspot that you have chosen.
Then answer the following questions:
1. Which biodiversity hotspot did you choose to write about? (Give the name)
2. Where is it located? (Give the world, region and country)
3. What are two important species (give common and scientific names) that live there? Why are they important?
4. What is one endangered species (give common and scientific name) that lives there? Why is it endangered?
5. List thre other interesting facts that you have learned about this place.
6. List one thing you feel could be done to help save it.
Any materials cited should be referenced using the style guidelines established by the American Psychological Association (APA).
Learning Journal
Go to the EPA website and learn about <Reduce, Reuse, Recycle=
1. Are any of these options and/or types of programs available in YOUR local community/village/town? Which ones? Explain.
2. What about in your home? Explain.
3. If none are used in your local town or home, which could be? Explain.
4. Please outline in your own words, one new thing you learned this week in the course. How does it apply to your life?
5. Tell me, the professor, how this course is going for you so far? How do you find the material?
The Learning Journal entry should be a minimum of 400 words and not more than 750 words. Use APA citations and references if youuse ideas from the readings or other sources.
Self-Quiz
The Self-Quiz gives you an opportunity to self-assess your knowledge of what you have learned so far.
The results of the Self-Quiz do not count towards your final grade, but the quiz is an important part of the University’s learning process, and it is expected that you will take it to ensure understanding of the materials presented. Reviewing and analyzing your results will help you perform better on future Graded Quizzes and the Final Exam.
Please access the Self-Quiz on the main course homepage; it will be listed inside the Unit.
Checklist
Read the Learning Guide and the Reading Assignment
Participate in the Discussion Assignment (post, comment, and rate in the Discussion Forum)
Make entries to the Learning Journal
Take the Self-Quiz
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