6011206
Descripción
Fichas por Chelsi Souch, actualizado hace más de 1 año
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Creado por Chelsi Souch
hace más de 8 años
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| Pregunta | Respuesta |
| ECOLOGY | Scientific studies of the interactions that determine the distribution and abundance of organisms |
| 3 WAYS TO LOOK AT ECOLOGY | 1.Levels and principles 2. Population Ecology 3. Conservation Biology |
| ECOLOGICAL LEVELS | Biosphere Biome Ecosystem Community Population Individual |
| BIOSPHERE | Definition: That portion of the earth where all living organisms reside - Total of all of Earth’s ecosystems |
| Abiotic factors of the biosphere | Patterns in the distribution of life mainly reflect differences in the abiotic environmental factors - Usable energy source, temperature, water, inorganic nutrients - Some additional factors - aquatic ecosystems: dissolved oxygen levels, salinity, currents, tides - Terrestrial ecosystems: elevation, wind, storms, fire |
| Biomes | A biome is a major terrestrial or aquatic life zone, characterized by –vegetation type in terrestrial biomes or –the salinity and physical environment in aquatic biomes. |
| Freshwater biomes | (cover <1% of Earth) have <1% salt concentration, ~6% known species include lakes, streams, rivers, and wetlands used for drinking water, crop irrigation, sanitation, industry. |
| Marine biomes | typically have ~3% salt concentration include oceans, intertidal zones, coral reefs, and estuaries. |
| How climate affects terrestrial biome distribution | – Terrestrial biomes are primarily determined by climate, especially temperature and rainfall. – Earth’ s global climate patterns are largely the result of (i) radiant energy from the sun, and (ii) Earth’s movement in space. The descending dry air masses head into latitudes above 30°, and initially pick up moisture but later drop it as they cool at higher latitudes. This creates the relatively wet northern and southern temperate zones. • Temperate zones generally have milder climates than the tropics or the polar regions. They occur in latitudes between the tropics and the Arctic Circle (north) and the Antarctic Circle (south). |
| Uneven heating of Earth | |
| How climate affects terrestrial biome distribution | Heated by the direct rays of the sun, air at the equator rises, then cools (forming clouds), and drops rain. – This largely explains why rain forests are concentrated in the tropics, the region from the Tropic of Cancer to the Tropic of Capricorn. |
| How uneven heating of Earth produces various climates | |
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| ECOSYSTEM | Unique communities of organisms that interact with one another and their surrounding environments in a given area |
| ECOSYSTEM COMPONENTS | Abiotic resources Abiotic conditions Primary producers Consumers Decomposers |
| COMMUNITY | Unique assemblage of populations all the populations that inhabit a specified area collections of populations that have the ability to interact with one another key information: 1) number of species present 2) relative abundance of species 3) how different species contribute to community |
| DESCRIPTIVE PARAMETERS FOR COMMUNITIES | Diversity Stability Trophic Structure |
| BIODIVERSITY: THREE TYPES | |
| ECOLOGICAL COMMUNITY | |
| STABILITY | Ability to return to original composition following perturbation |
| TROPHIC STRUCTURE | Feeding relationships across the different trophic levels |
| What is a population? | An interacting group of individuals of a particular species that use common resources and are regulated by the same natural phenomena. Ecologists describe the number of individuals in a population by the population size or by the population density |
| Population Structure and Dynamics | Density and Dispersion Density Dispersion patterns |
| Density and Dispersion | patterns are important population variables |
| Density | The number of individuals per unit area |
| Dispersion patterns | How individuals in a population are spaced within their areas |
| How to quantify a population? | Mark and recapture: Used to quantify mobile organisms. ex. animals Quadrat analysis: Used for immobile organisms. plants or sedentary animals |
| Mark and Recapture (formula) | |
| Dispersion patterns: CLUMPED | Local aggregation in patches |
| Clumped patterns usually result from | a) an unequal distribution of resources for plants and animals b) Associations with mating and social behavior of animals |
| Dispersion patterns: UNIFORM | Even distribution over an area |
| Dispersion patterns: RANDOM | Pattern less, unpredictable distribution. Rare, ex. clams distributed across a sandy ocean bottom Where the factors affecting them are numerous and complexly interrelated |
| GROWTH OF A POPULATION Exponential increase: | proportional to the number of individuals that already exist |
| The Exponential Growth Model | |
| The Logistic Growth Model | This model takes limits to population growth to consideration The rate of growth is exponential in the beginning, but is limited by how close it is to the, Carrying capacity (K): maximum population size that an environment can support. |
| POPULATION GROWTH CURVES | Exponential Logistic Complex |
| POPULATION GROWTH IS LIMITED BY ENVIRONMENTAL RESISTANCE Density Dependent Factors | FOOD SHORTAGE AVAILABILITY OF SUNLIGHT TEMPERATURE CHANGES INVASION BY PREDATORS OR PATHOGENS WASTES BUILD UP TO TOXIC LEVELS BREEDING SPACE PHYSIOLOGICAL FACTORS BOOM AND BUST Complex pattern Snowshoe hare and lynx: Effects of biotic factors predator-prey relationship keeps growth of population under check |
| POPULATION GROWTH IS LIMITED BY Density Independent Factors | Effects of abiotic factors Climate, weather, floods, fires, storms Human activity earth quakes Tsunamis Volcanic eruptions |
| SURVIVORSHIP CURVES | |
| GROWTH AND REPRODUCTIVE STRATEGIES | |
| Principles of population ecology have practical applications – Principles of population ecology are useful in managing natural resources Three such principles in practice are | 1. Harvesting crops without damaging the resource. 2. Maximum sustained yield: Harvesting is done at a level that produces a consistent yield without forcing population to decline. 3. Integrated pest management: Use a combination of Biological, chemical and cultural methods in agriculture to control pests |
| 3 DETERMINANTS OF COMMUNITY STRUCTURE | Historical processes • Resource utilization and tolerance • Interspecific Interactions: 1. Competition 2. Predation 3. Symbiosis PARASITISM (+, -) MUTUALISM (+,+) COMMENSALISM (+,0) |
| ECOLOGICAL NICHE | Is the sum total of an organism’s use of biotic and abiotic resources in its environment or in other words how it “fits in to” an ecosystem • A fundamental niche is the resources a population is theoretically capable of using under IDEAL circumstances. • Biological constraints (competition, predation, resource limitations) restrict organisms to their realized niche |
| RESOURCE UTILIZATION AND TOLERANCE | Niche: ex. A barnacle’s niche: Attachment sites on the intertidal rocks Amount of exposure to air and sea water Food it consumes Only rarely does the realized niche of an organism approximate its fundamental niche: realized niche is always smaller |
| Opportunistic Populations | rapid sexual maturity, produce many offspring (quantity vs quality), little or no parental care, short life span, high death rate, unpredictable climates, usually one time reproduction, smaller off spring (or eggs) |
| Equilibrial populations | Opposite of all these traits: rapid sexual maturity, produce many offspring (quantity vs quality), little or no parental care, short life span, high death rate, unpredictable climates, usually one time reproduction, smaller off spring (or eggs) |
| APPLICATION OF POPULATION OF ECOLOGY | 1. Conservation of endangered species 2. Sustainable resource management 3. Studies on invasive species 4. Biological control of pests 5. Integrated pest management |
| Human Population Dynamics | Human population growth has started to slow after centuries of exponential increase • The human population –Has been growing almost exponentially for centuries, standing now at about 7.4 billion |
| Most Populous Cities of the World 2015 | |
| What is demographic transition? | • Is the shift from high birth rates and death rates to low birth rates and death rates |
| What is the age structure of a population? | It is the proportion of individuals in different age-groups • Affects its future growth |
| What is “Ecological Footprint” (EFP)? | • An ecological footprint is the amount of land and water area a person or a human population would need to provide the resources required to sustainably support itself and to absorb its wastes, given prevailing technology. • The term was first introduced in 1996 by Canadian ecologists William Rees and Mathis Wackernagel (a graduate student working with Rees at the University of British Columbia at the time). • Footprinting is now widely used around the globe as an indicator of environmental sustainability. • It can be used to measure and manage the use of resources throughout the economy. It is commonly used to explore the sustainability of individual lifestyles, goods and services, organisations, industry sectors, regions and nations. |
| The ecological capacity of the world may already be smaller than | the population’s ecological footprint |
| COMMUNITY INTERACTIONS 1. Competition | 1A. Competitive Exclusion Two species of barnacles on intertidal rocKs Interspecific competition prevents species from occupying the same niche 1B: Resource Partioning Habitat partitioning reduces competition: Sympatric species show this type. ex: Darwin’s finches: those who have different sizes of beaks use same habitats. It is also called Character Displacement Allopartric species can not live in the same habitats (requirements are mostly the same) |
| COMMUNITY INTERACTIONS 2. PREDATION | DYNAMICS OF PREDATOR (wolf) AND PREY (moose) POPULATIONS |
| Keystone Species | Many species in a community depend on ONE type of organism, called Keystone species. • Not the dominant producers • These organism make up a small portion of the community by weight, yet exerts a disproportionate influence on community diversity. • Many KS are versatile predators, that maintain competition. Ex. Seastars prey on diverse tide pool invertebrates Birds eat herbivore insects Mycorrhizal fungi influence composition of plant communities |
| Effects of predation on communities | Keystone predators help maintain diversity by consuming, and reducing the density of prey that are very strong competitors. Ex: If sea star, Pisaster is removed, Mussels (Mytilus) out competes many other shoreline organisms. Sea otters are keystone predators |
| DEFENSE MECHANISMS AGAINST PREDATORS PREY’S ADAPTATIONS TO AVOID PREDATION | 1. Size 2. Avoidance: Fleeing, Hiding (camouflage) 3. Mimicry (Batesian and Mullarian) 4. Defensive structures (Spines and armor) 5. Chemicals (in plants Strychnine, nicotine) 6. Chemicals in animals (poisonarrow frog) |
| Adaptation to avoid predation Camouflage | |
| Adaptation to avoid predation CHEMICAL DEFENSES: Poison arrow frog | |
| Mimicry | • Is a “copycat” adaptation in which one species mimics the appearance of another. • Is used by some species to gain protection – In Batesian mimicry (advertising mimicry), • A palatable or harmless species mimics an unpalatable or harmful model. Ex. Viceroy butterfly & Monarch butterfly Adaptation to avoid predation Advertising mimicry : Batesian Mimicry 35 Hawk moth larva (successful when in lower # s) Looks like the distasteful and noxious Snake |
| Adaptation to avoid predation Deceptive mimicry: Mullarian mimicry | Cuckoo bee Yellow jacket |
| Coevolution of Predator and Prey | Coevolution: is a term that describes longterm evolutionary adjustments of species to one another. Passiflora makes toxic substances to protect its leaves from herbivores. Heliconius catapillars can breakdown the toxins therefore can eat these leaves. Plant also excrete yellow sugar droplets which almost looks like the eggs of the insect. What evolutionary adaptive mechanism works to prevent this herbivory? |
| 1. COMMENSALISM | CATTLE EGRETS CATCH MORE INSECTS WHEN THEY FORAGE ALONGSIDE BUFFALOS BUFFALOS ARE NOT HELPED OR HARMED Other examples for commmensalism Epiphytic plants: Orchids, Bromeliads Barnacles attached to large fish Tropical fish and sea anemone |
| 2. MUTUALISM | Ants and Bull’s horn Acacias 5 Ants of the species Pseudomyrmex nests ONLY in the hollowed thorns of an Acasia species. They feed on the protein bodies (Beltian bodies) and sugar droplets. Ants provide protection to the plant preventing herbivory. Ants not only attacks the herbivores but also use them as additional food. Ants also help the plant compete with other plants. |
| 3. PARASITISM | EXTERNAL PARASITISM: ECTOPARASITES A SPECIAL CASE OF PREDATION |
| 3B. INTERNAL PARASITISM: ENDOPARASITE 7 Extremely Specialized: | Many protists and invertebrates that affect humans. (Malaria parasite: Plasmodium) The more closely the life of parasite is linked with that of its host, the more morphology and behavior are likely to have modified during the course of its evolution. |
| 3C: Brood Parasitism | Cuckoos lay their eggs in nests of other species of birds. The host parent raise the brood parasite as if they were one of their own clutch. In some species evolution has fostered the hosts’ ability to detect parasite eggs and reject them. |
| SUMMARY OF COMMUNITY INTERACTIONS | |
| In short: Ecological succession | is a transition in species composition of a community following a disturbance |
| Disturbance is a prominent feature of most communities – Disturbances are events thaT | Damage biological communities, remove organisms from them, and alter the availability of resources • Are characteristic of most communities |
| Primary succession | Primary succession occurs in an area where no community previously existed. Is the gradual colonization of barren rocks |
| Secondary succession | • Occurs after a disturbance has destroyed a community but left the soil intact • Replacing a disturbed community Communities can recover from some forms of natural and human caused disturbances. Depending on the community, the time required for recovery varies from decades to centuries. |
| – Energy flow and chemical cycling | Depend on the transfer of substances in the feeding relationships, or trophic structure, of an ecosystem. |
| Trophic relationships | Determine an ecosystem’s routes of energy flow and chemical cycling. |
| Trophic levels | Divide the species of an ecosystem based on their main sources of nutrition. |
| Energy flow | • Is the passage of energy through the components of the ecosystem. • Flows through an ecosystem when consumers feed on producers. • Cannot be recycled within an ecosystem, but must flow through continuously. |
| –Chemical cycling | • Is the use and reuse of chemical elements within the ecosystem |
| Trophic structure is a key factor in community dynamics | Every community has a trophic structure • A pattern of feeding relationships consisting of several different levels – Trophic structures can be represented by food chains • The stepwise flow of energy and nutrients from plants (producers), to herbivores (primary consumers), to carnivores (secondary and higherlevel consumers) |
| Herbivores, which eat plants, algae, or autotrophic bacteria, are the | primary consumers of an ecosystem |
| Secondary consumers | include many small mammals, such as rodents, and small fishes that eat zooplankton. |
| Tertiary consumers | such as snakes, eat mice and other. secondary consumers |
| Quaternary consumers | include hawks and killer whales |
| Detritivores, or decomposers | • Derive their energy from the dead material left by all trophic levels. • Are often left off of most food chain diagrams. Ex. animal scavengers, fungi, and prokaryotes |
| Food chains interconnect, forming food webs | A food web is a key biotic factor in many ecosystems – The feeding relationships in an ecosystem • Are typically not as simple as in an unbranched food chain. • Are usually woven into elaborate webs. |
| Productivity and the Energy Budgets of Ecosystems | Biomass • Is the amount of organic material in an ecosystem. – An ecosystem’s primary productivity • Is the rate at which plants and other producers build biomass. |
| An energy pyramid | Only about 10% of the energy stored at each trophic level • is available to the next level |
| Ecosystem alteration can upset chemical cycling | Ecosystem studies show that drastic alterations, such as the total removal of vegetation • can increase the runoff and loss of soil nutrients |
| Environmental changes caused by humans, such as | acid precipitation • can unbalance nutrient cycling over the long term |
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