BISC 100 - Lecture 35: Biodiversity


Flashcards on BISC 100 - Lecture 35: Biodiversity, created by Chelsi Souch on 10/08/2016.
Chelsi Souch
Flashcards by Chelsi Souch, updated more than 1 year ago
Chelsi Souch
Created by Chelsi Souch over 7 years ago

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Why Biodiversity Matters • The expanding human population threatens • biodiversity and • the disappearance of natural ecosystems. • Only about a quarter of Earth’s land surfaces remain untouched by human alterations
• Healthy ecosystems provide resources, such as water, wood, and fish, and services such as recycling nutrients, • preventing erosion and mudslides, • controlling agricultural pests, and • pollinating crops.
Coastal wetlands... act as a buffer against hurricanes, • reduce the impact of flooding, • filter pollutants, and • furnish nesting sites and breeding areas for birds and marine turtles and nurseries for a wide variety of fish and shellfish.
• Biological diversity, or biodiversity, includes • genetic diversity, • species diversity, and • ecosystem diversity. • Thus, the loss of biodiversity encompasses more than just the fate of individual species.
Genetic Diversity raw material that makes microevolution and adaptation to the environment possible. • If local populations are lost, then • the number of individuals in the species declines, and • the genetic resources for that species decline.
Species Diversity Ecologists believe that we are pushing species toward extinction at an alarming rate. • The present rate of species loss may be 100 times higher than at any time in the past 100,000 years. • Some researchers estimate that at the current rate of destruction, over half of all currently living plant and animal species will be gone by the end of this century
Two recent victims of human-caused extinctions are the • Chinese river dolphins and • Formosan clouded leopard
Ecosystem Diversity An ecosystem includes the organisms and the abiotic factors in a particular area. • Because of the network of interactions among populations of different species within an ecosystem, the loss of one species can have a negative effect on the entire ecosystem. • The disappearance of natural ecosystems results in the loss of ecosystem services, functions performed by an ecosystem that directly or indirectly benefit people, including • air and water purification, • climate regulation, and • erosion control.
Causes of Declining Biodiversity Ecologists have identified four main factors responsible for the loss of biodiversity: 1. habitat destruction and fragmentation, 2. invasive species, 3. overexploitation, and 4. pollution. • The ever-expanding size and dominance of the human population are at the root of all four factors.
Habitat Destruction • Biodiversity is threatened by the massive destruction and fragmentation of habitats by • agriculture, • urban development, • forestry, and • mining. • According to the IUCN, habitat destruction affects more than 85% of all birds, mammals, and amphibians that are threatened with extinction.
Invasive Species • Invasive species have • competed with native species, • preyed upon native species, and • parasitized native species.
Overexploitation People can overexploit wildlife by harvesting at rates that exceed the ability of populations to rebound. • Excessive commercial harvesting, poaching, and sport hunting have greatly affected populations of • tigers, • the American bison, and • Galápagos tortoises. • Overharvesting also threatens rare trees such as mahogany and rosewood that produce valuable wood.
Pollution Air and water pollution is a contributing factor in declining populations of hundreds of species. • The global water cycle can transport pollutants from terrestrial to aquatic ecosystems hundreds of miles away. • Pollutants that are emitted into the atmosphere may be carried aloft for thousands of miles before falling to earth in the form of acid precipitation.
The Carbon Cycle
The Phosphorus Cycle Organisms require phosphorus as an ingredient of nucleic acids, phospholipids, and ATP and as a mineral component of vertebrate bones and teeth. • The phosphorus cycle does not have an atmospheric component. • Rocks are the only source of phosphorus for terrestrial ecosystems • Phosphates move from land to aquatic ecosystems much more rapidly than they are replaced. • Soil characteristics may also decrease the amount of phosphate available to plants. As a result, • phosphate is a limiting factor in many terrestrial ecosystems and • farmers and gardeners often use phosphate fertilizer, such as crushed phosphate rock or bone meal, to boost plant growth.
The Nitrogen Cycle Nitrogen is • an ingredient of proteins and nucleic acids and • essential to the structure and functioning of all organisms. • The atmospheric reservoir is huge; almost 80% of the atmosphere is nitrogen gas (N2 ). • However, plants cannot use nitrogen gas. • The process of nitrogen fixation converts gaseous N2 to ammonia (NH3 ). • Ammonia then picks up another H+ to become ammonium (NH4 + ), which plants can assimilate.
Nitrogen has two abiotic reservoirs: 1. the atmosphere and 2. the soil
• Two major sources of nitrogen are 1. combustion of fossil fuels and 2. modern agricultural practices. • Some nitrogen escapes to the atmosphere, where it forms nitrous oxide (N2O), a gas that contributes to global warming. Human activities are disrupting the nitrogen cycle by adding more nitrogen to the biosphere each year than natural processes do.
Nutrient Pollution The growth of algae and cyanobacteria in aquatic ecosystems is often limited by low nutrient levels, especially • phosphorus and • nitrogen. • Nutrient pollution occurs when human activities add excess amounts of these chemicals to aquatic ecosystems
Conservation and Restoration Biology Many of the environmental problems facing us today have been caused by human enterprises. • Ecological research is the foundation for • finding solutions to these problems and • reversing the negative consequences of ecosystem alteration.
Conservation biology goal-oriented science that seeks to understand and counter the loss of biodiversity
Restoration ecology uses ecological principles to develop methods of returning degraded areas to their natural state.
Biodiversity “Hot Spots” Conservation efforts are often focused on biodiversity hot spots, relatively small areas that have • a large number of endangered and threatened species and • an exceptional concentration of endemic species, those that are found nowhere else. • The “hottest” of Earth’s biodiversity hot spots are shown in Figure 20.37
Conservation at the Ecosystem Level Conservation biology increasingly aims at sustaining the biodiversity of entire • communities, • ecosystems, and • landscapes, regional assemblages of interacting ecosystems, such as an area with forest, adjacent fields, wetlands, streams, and streamside habitats
Landscape ecology is the application of ecological principles to the study of land-use patterns. • Its goal is to make ecosystem conservation a functional part of the planning for land use.
Edges between ecosystems
movement corridor a narrow strip or series of small clumps of suitable habitat connecting otherwise isolated patches. can promote dispersal, • help sustain populations, and • are especially important to species that migrate between different habitats seasonally. • But a corridor can also spread disease, especially among small subpopulations in closely situated habitat patches.
Restoring Ecosystems Bioremediation uses living organisms to detoxify polluted ecosystems. Some restoration projects have the broader goal of returning ecosystems to their natural state.
The Goal of Sustainable Development As the world population grows and becomes more affluent, the demand increases for the provisioning services of ecosystems, such as • food, • wood, and • water. The goal of sustainable development is to meet the needs of people today without limiting the ability of future generations to meet their needs. • Sustainable development depends on • continued research, • the application of ecological knowledge, and • the connection of the life sciences with • social sciences, • economics, and • humanities.
Evolution Connection: Can Biophilia Save Biodiversity? Edward O. Wilson uses the term biophilia to describe the human desire to affiliate with other life in its many forms. • Many biologists have embraced the concept of biophilia and turned their passion for nature into careers. • If biophilia is evolutionarily embedded in our genomes, then there is hope that we can become better custodians of the biosphere.
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