BIO 240 - Chapter 3 (EXAM 1)
BIO 240 - Chapter 3 (EXAM 1) BIO 240
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This 12 page Class Notes was uploaded by Jenna Larson on Monday September 19, 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 25 views. For similar materials see Conservation of Natural Resources in Biology at Central Michigan University.
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Date Created: 09/19/16
9/8/16 Chapter 3 Evolution, Biodiversity, and Population Ecology Lecture Presentations prepared by Reggie Cobb © 2015 Pearson Education, Inc. Nash Community College This lecture will help you understand: • How evolution influences biodiversity • Ecological organization • Population characteristics • Population ecology © 2015 Pearson Education, Inc. Central Case Study: Saving Hawaii’s Native Forest Birds • 'akiapōlā'au (“aki” for short) • Sparrow-sized honeycreeper birds that exist only on the Hawaiian Islands • Human actions now threaten native species of flora and fauna • Cutting down trees • Introducing non-native animals • Foreign disease spread to the islands • Refuge managers and conservation biologists • Work hard to protect the Hakalau’s forests. © 2015 Pearson Education, Inc. 1 9/8/16 Evolution: the source of Earth’s biodiversity • • A population or group of populations whose members share characteristics and can breed with each other to produce fertile offspring • • A group of individuals of a species that live in the same area at the same time • • • Biological evolution • Genetic change in populations over time • Genetic changes often lead to modifications in appearance or behavior © 2015 Pearson Education, Inc. Natural selection shapes organisms and diversity • • The process whereby inherited characteristics that enhance survival and reproduction are passed on more frequently to future generations than those that do not • • Example: Hawaii hosts a treasure of biological diversity © 2015 Pearson Education, Inc. Evolution by natural selection • • One of the best-supported and most illuminating concepts in science • • It is vital for a full appreciation of environmental science • • Evolutionary processes influence agriculture, pesticide resistance, medicine, health, etc. © 2015 Pearson Education, Inc. 2 9/8/16 Selection acts on genetic variation • Genes in DNA are passed along to future generations • • Accidental changes in DNA that may be passed to the next generation • Nonlethal mutations provide genetic variation on which natural selection acts • Sexual reproduction also leads to genetic variation • © 2015 Pearson Education, Inc. Natural selection shapes organisms • Premises of natural selection: • • They produce more offspring than can survive • Individuals of a species vary in their characteristics because of genes and the environment • • • Characteristics that promote reproductive success © 2015 Pearson Education, Inc. Selection acts on genetic variation • • Selective pressures among closely related species cause them to acquire different traits • • Occurs when very unrelated species living in similar environments in separate locations independently acquire similar traits © 2015 Pearson Education, Inc. 3 9/8/16 Evidence of selection is all around us • Natural selection is evident in every adaptation of every organism • • The process of selection conducted under human direction • © 2015 Pearson Education, Inc. Understanding evolution is vital for modern society • Understanding and application of evolutionary processes play a key role in our everyday lives • • Clothes we wear • • Preventing antibiotic resistance in feedlots • • Even technology and engineering solutions have developed as a result of our understanding of evolution © 2015 Pearson Education, Inc. Evolution generates diversity • • The variety of life across all levels of biological organization • Genes • • • Communities • Scientists have described about 1.8 million species • • Tropical rainforests are rich in biodiversity © 2015 Pearson Education, Inc. 4 9/8/16 We study ecology at several levels • • Study of interactions among organisms and their environment • © 2015 Pearson Education, Inc. Levels of ecological studies • • Relationships between individuals and their environment • • • The distribution and abundance of individuals • • Focuses on patterns of species diversity and interactions © 2015 Pearson Education, Inc. Levels of ecological studies (cont’d) • • Studies living and nonliving components of systems to reveal patterns • • Explains how and why ecosystems, communities, and populations are distributed across geographic regions © 2015 Pearson Education, Inc. 5 9/8/16 Habitats, niche, and specialization are key concepts in ecology • Habitat • • • An organism’s survival depends on having suitable habitats © 2015 Pearson Education, Inc. Habitats, niche, and specialization are key concepts in ecology (cont’d) • • An organism’s functional role in a community • • Organism that have specific niche • Example: the 'akiapōlā'au • • Organisms with a broad niche • Example: common myna © 2015 Pearson Education, Inc. For ecologist, populations show features that help predict their dynamics • Predicting a population’s growth or decline is useful for managing wildlife and fisheries and for monitoring threatened and endangered species © 2015 Pearson Education, Inc. 6 9/8/16 For ecologist, populations show features that help predict their dynamics © 2015 Pearson Education, Inc. Population size • • The number of individuals present at a given time • May increase, decrease, cycle, or remain the same • • Passenger pigeons were once the most abundant bird in North America; now they are extinct as a result of human actions © 2015 Pearson Education, Inc. Population density • • The number of individuals in a population per unit area • • But increase competition and vulnerability to predation • Also increase transmission of diseases • • But individuals enjoy more space and resources • • They need many resources and a large area to survive © 2015 Pearson Education, Inc. 7 9/8/16 Population distribution can also inform ecologist about population dynamics • • Spatial arrangement of organisms • • Haphazardly located individuals, with no pattern • Resources are widespread • • Evenly spaced individuals • Territoriality, competition • • Most common in nature • Arranged according to resources © 2015 Pearson Education, Inc. Population distribution © 2015 Pearson Education, Inc. We can measure population growth • Four factors of population change • Natality: • Mortality: • Immigration: arrival of individuals from outside the population • • Emigration: departure of individuals from the population • © 2015 Pearson Education, Inc. 8 9/8/16 Population growth calculations • Population growth rate • Rate of change in a population’s size per unit time • Equals (birth rate + immigration rate) - (death rate + emigration rate) • Tells us the net changes in a population’s size per 1000 individuals per year • Growth rate is expressed as a percent: • Population growth rate × 100% • Allows comparison of populations of different sizes © 2015 Pearson Education, Inc. Unregulated populations increase by exponential growth • • A population increases by a fixed percent • Graphed as a J-shaped curve • It occurs in nature with: • • Low competition • © 2015 Pearson Education, Inc. Limiting factors restrain population growth • • Physical, chemical, and biological attributes of the environment limiting population growth • • the maximum population size of a species that a specific environment can sustain © 2015 Pearson Education, Inc. 9 9/8/16 Limiting factors restrain population growth • • S-shaped curve the shows how limiting factors slow and stop exponential growth © 2015 Pearson Education, Inc. Data Question: Predicting Growth Rates • Looking ahead several decades into the future, what do you predict the population growth graph for the Eurasian collared-dove in the western United States will look like? © 2015 Pearson Education, Inc. Carrying capacities can change • • The carrying capacity can change • Humans lower environmental resistance for ourselves • • Technologies have overcome limiting factors • • • We have reduced the carrying capacity for countless other organisms • Calling into question our own long-term survival © 2015 Pearson Education, Inc. 10 9/8/16 Weighing the Issues • Carrying Capacity and Human Population Growth • Name some specific means by which we have apparently raised Earth’s carrying capacity for our species. • Do you think we can continue to raise our carrying capacity? How might we do so? • Are the ways in which we might accommodate more people in the future the same as the ways in which we have expanded our population so far? • What limiting factors exist for our population today? • Might the Earth’s carrying capacity decrease? Why or why not? © 2015 Pearson Education, Inc. Conservation biodiversity • • Committed people are taking action to: • Safeguard biodiversity • Restore Earth’s ecological and evolutionary processes © 2015 Pearson Education, Inc. Innovative solutions are working • At Hakalau • Ranchland is being restored to forests • Invasive plants are being removed and native ones planted • Animals are being protected while new populations are being established • Across Hawaii • People are protecting land • Restoring native habitats • Protecting areas offshore © 2015 Pearson Education, Inc. 11 9/8/16 Innovative solutions are working (Cont’d) • Ecotourism • Tourists visit protected areas • Hawaii’s residents are benefiting from their conservation efforts. © 2015 Pearson Education, Inc. Climate change poses an extra challenge • Global climate change now threatens conservation biology efforts • Change in temperatures alters many aspects of the environment • The protected areas may become unsuitable for the species being protected • Scientists and managers need to come up with new ways to help save declining populations © 2015 Pearson Education, Inc. Conclusion • The fundamentals of evolution and population ecology are integral to environmental science • Natural selection, speciation, and extinction help determine Earth’s biodiversity • Understanding how ecological processes function at the population level is crucial to protecting biodiversity © 2015 Pearson Education, Inc. 12
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