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BIO 240 - Chapter 4 (EXAM 2)

by: Jenna Larson

BIO 240 - Chapter 4 (EXAM 2) BIO 240

Marketplace > Central Michigan University > Biology > BIO 240 > BIO 240 Chapter 4 EXAM 2
Jenna Larson
GPA 3.51

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Complete Notes for Chapter 2 9/30/16 - 10/7/16
Conservation of Natural Resources
Dr. Deric Learman
Class Notes
Biology, conservation, Natural Resources
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This 11 page Class Notes was uploaded by Jenna Larson on Saturday October 8, 2016. The Class Notes belongs to BIO 240 at Central Michigan University taught by Dr. Deric Learman in Fall 2016. Since its upload, it has received 2 views. For similar materials see Conservation of Natural Resources in Biology at Central Michigan University.


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Date Created: 10/08/16
9/19/16 Chapter 4 Species Interactions and Community Ecology Lecture Presentations prepared by Reggie Cobb Nash Community College © 2015 Pearson Education, Inc. This lecture will help you understand: • • Feeding relationships, energy flow, trophic levels, and food webs • • The process of succession • Potential impacts of invasive species • Restoration ecology © 2015 Pearson Education, Inc. Central Case Study: Black and White and Spread All Over • In 1988, ballast water discharged from a ship accidentally released zebra mussels into Lake St. Clair • By 2010, they had spread to 30 states • • They cause millions of dollars of property damage each year © 2015 Pearson Education, Inc. 1 9/19/16 Species interactions • Species interactions are the backbone of communities • © 2015 Pearson Education, Inc. Competition occurs with limited resources • Competition • • Food, water, space, shelter, mates, sunlight, etc. • • Competition between members of the same species • High population density: increased competition • • Competition between members of different species • • Leads to competitive exclusion or species coexistence © 2015 Pearson Education, Inc. Results of interspecific competition • • One species may exclude another from using the resource • Zebra mussels displaced native mussels in the Great Lakes • • • Natural selection favors individuals that use different resources or shared resources in different ways © 2015 Pearson Education, Inc. 2 9/19/16 Resource partitioning • • Competing species coexist by specializing • • Or share resources (one species may be active during the day and the other at night) © 2015 Pearson Education, Inc. An exploitative interaction: predation • • One member benefits while the other is harmed (+/- interactions) • • • Process by which individuals of one species (predators) capture, kill, and consume individuals of another species (prey) © 2015 Pearson Education, Inc. Predation affects the community • • The number of predators and prey influences community composition • Predators can, themselves, become prey • • Zebra mussels are prey for North American predators (fish, ducks, muskrats, crayfish) © 2015 Pearson Education, Inc. 3 9/19/16 Predation can drive population dynamics • Increased prey populations increase food for predators • • Decreased predator populations increase prey populations © 2015 Pearson Education, Inc. Predation has evolutionary ramifications • Natural selection leads to evolution of adaptations that make predators better hunters • Individuals who are better at catching prey • • Take better care of offspring • • • They develop elaborate defenses against being eaten © 2015 Pearson Education, Inc. Prey develop defenses against being eaten © 2015 Pearson Education, Inc. 4 9/19/16 Parasites exploit living hosts • • A relationship in which one organism (parasite) depends on another (host) for nourishment or some other benefit • • Some live within the host • • Some contact hosts infrequently • • Some live on exterior of host • Fleas, ticks, and sea lampreys © 2015 Pearson Education, Inc. Mutualists help one another • • Each partner provides a service the other needs (food, protection, housing, etc.) • • A relationship in which the organisms live in close physical contact (mutualism and parasitism) • • Mycorrhizae: plant roots andfungi • • Bees, bats, birds, and others transfer pollen from one flower to another, fertilizing its eggs © 2015 Pearson Education, Inc. Ecological communities • • An assemblage of populations of organisms living in the same area at the same time interacting with each other • Interactions determine the structure, function, and species composition of the community • • Species coexist and interact with one another • Communities change, and why these patterns exist © 2015 Pearson Education, Inc. 5 9/19/16 Energy passes among trophic levels • Some of the most important community interactions involves who eats whom • • Trophiclevels • • • Detritivores and decomposers © 2015 Pearson Education, Inc. Producers: the first trophic level • • Organisms that capture solar energy for photosynthesis to produce sugars • Green plants • • Algae © 2015 Pearson Education, Inc. Consumers: consume producers • Primary consumers • Organisms that consume producers • Herbivores: • Secondary consumers • Organisms that prey on primary consumers • wolves, • Tertiaryconsumers • Predators: © 2015 Pearson Education, Inc. 6 9/19/16 Detritivores and decomposers • Organisms that consume nonliving organic matter • • Scavenge waste products or dead bodies • • • Break down leaf litter and other nonliving material • • Enhance topsoil and recycle nutrients © 2015 Pearson Education, Inc. Data Question: Trophic Level Pyramid • Using the ratios shown in this example, let’s suppose that a system has 3000 grasshoppers. • How many rodents would you expect? © 2015 Pearson Education, Inc. Food webs show feeding relationships and energy flow • • • • A visual map of feeding relationships and energy flow among organisms • They are greatly simplified and leave out most species © 2015 Pearson Education, Inc. 7 9/19/16 Some organisms play outsized roles in communities • • Has a strong or wide-reaching impact far out of proportion to its abundance • Removing a keystone species has substantial ripple effects • © 2015 Pearson Education, Inc. Species can change communities • • Predators at high trophic levels indirectly promote populations at low trophic levels by keeping species at intermediate trophic levels in check • Extermination of wolves led to increased deer populations … • • © 2015 Pearson Education, Inc. Communities respond to disturbance in various ways • • An event that has rapid/dramatic impacts on environmental conditions • Removal of keystone species, natural disturbances (fires, floods, etc.) • • • A community resists change and remains stable despite the disturbance • • A community changes in response to a disturbance, but later returns to its original state © 2015 Pearson Education, Inc. 8 9/19/16 Succession follows severe disturbance • • The predictable series of changes in a community after a severe disturbance • • Disturbance removes all vegetation and/or soil life • Glaciers, drying lakes, volcanic lava covering the land • • The first species to arrive in a primary succession area • Lichens: fungi + algae © 2015 Pearson Education, Inc. Succession follows severe disturbance (cont’d) • • A disturbance has removed much, but not all, of the biotic community • • • • Remains in place with few changes until another disturbance restarts succession © 2015 Pearson Education, Inc. Frequently Asked Question • Once we disturb a community, won’t it return to its original state if we just leave the area alone? © 2015 Pearson Education, Inc. 9 9/19/16 Invasive species pose threats to community stability • • A species introduced by to community by people • • Non-native species that spreads widely and becomes dominant in a community • • Growth-limiting factors (predators, disease, competitors, etc.) are absent • Major ecological effects • • Some invasive species (e.g., honeybees) help people © 2015 Pearson Education, Inc. Data Question: Invasive Mussels Modify Communities • What differences do you see between the distribution of quagga mussels and the distribution of zebra mussels? • Suggest two hypotheses for one of these differences © 2015 Pearson Education, Inc. We can respond to invasive species with control, eradication, or prevention • • Total elimination of a population • • • Limit growth, spread, and impact of a population • • Removing them manually • Applying toxic chemicals • • Introducing predators ordiseases © 2015 Pearson Education, Inc. 10 9/19/16 We can respond to invasive species with control, eradication, or prevention (cont’d) • • Prevention, rather than control, is the best policy • • Analyzing the biology of the organism allows scientists to model the environmental conditions they might thrive in. • Example: • In 2007, researchers applied knowledge of how zebra and quagga mussels use calcium from water to create their shells • They mapped high and low-risk and high-risk regions across North America. © 2015 Pearson Education, Inc. Altered communities can be restored • Humans have dramatically changed ecological systems • • The science of restoring an area to an earlier (pre-settlement) condition • Tries to restore the system’s functionality (Example: filtering of water by a wetland) • • The on-the-ground efforts to restore an area • Difficult, time-consuming, and expensive © 2015 Pearson Education, Inc. Conclusion • Species interactions affect communities • • Cause weak and strong, direct and indirect effects • Feeding relationships are represented by trophic levels and food webs • Humans have altered many communities • • Ecological restoration attempts to undo the changes we have caused © 2015 Pearson Education, Inc. 11


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