Ecology - Ecology Ecology All things on Earth All BIOTIC =...

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Unformatted text preview: Ecology Ecology All things on Earth All BIOTIC = living BIOTIC living insects fungi plants mammals amphibians fish birds substrate reptiles sunlight temperature disturbances (fire, hurricanes) nutrients ABIOTIC = nonliving ABIOTIC nonliving wind precipitation precipitation bacteria ECOLOGY ECOLOGY Ecosystem Community Population Organism Hierarchy of Life Earth biosphere ecosystems communities populations organisms organ systems organs tissues cells molecules atoms subatomic particles a community of species combined with their abiotic (nonliving) environment populations of all the different species occupying a particular place at the same time ecosystem community population organism a group of interacting organisms of the same species that occupy a specific area at the same time any single life form Ecology and Environmentalism Ecology 1950’s – chemical 1950’s fertilizers and pesticides fertilizers DDT = “miracle weapon” 1960’s – predatory birds and human milk Biomagnification Ecology and Environmentalism Rachel Carson Rachel Silent Spring 1962 Ecology Ecology Environmentalism Organismal Ecology Organismal Ability to adapt to environment Abiotic factors • • • • • • Sunlight Water Temperature Wind Rock, soil Periodic disturbances Organismal Ecology Organismal Ability to adapt to environment Abiotic factors Physiological responses Organismal Ecology Organismal Ability to adapt to environment Abiotic factors Physiological responses Anatomical responses Organismal Ecology Organismal Ability to adapt to environment Abiotic factors Physiological responses Anatomical responses Behavioral responses Population Ecology Population Factors that effect a population’s: Size Size Density Density Growth rate Population structure Population Density Population = # individuals / unit area How do you measure population density? 1. Count all individuals 2. Estimate density • Count individuals in sample plots Count •e.g. Alligators in km2 • Indirect indicators Indirect •e.g. Rodent burrows, bird nests Population Density 3. Mark-recapture method Mark-recapture • Place traps w/in population boundary Place • Mark captured animals Mark • Release marked animals Release • Wait Wait • 2nd capture • Estimate population density! Estimate Mark – Recapture A population biologist traps 50 carp in a pond. She tags them and releases them. She returns the following week and traps again, this time catching 100 (10 of which are tagged) What is the total population density? What if she trapped 100 carp? She tags them and releases them. She returns the following week and traps again, This time catching 80 (40 of which are tagged) What is the total population density now? Patterns of Dispersion Patterns Clumped Uniform Random Random Population Growth Models Population a single bacterium…. After 20 minutes… After 40 minutes… After 60 minutes… After 36 hrs… 1 becomes 2 2 becomes 4 4 becomes 8 Enough bacteria to form a layer 1ft. deep over the entire Earth! 1ft. Exponential Growth! The Exponential Growth Model The LOGISTIC GROWTH MODEL LOGISTIC Before 1915…uncontrolled hunting Before H Hunting controlled 1935: Population leveled off Carrying Capacity Carrying Regulation of Population Growth Regulation Density-Dependent Factors •limited food supply •buildup of poisonous wastes •limited # of nesting sites Regulation of Population Growth Regulation Density-independent Factors Abiotic factors •sudden temperature change •environmental trauma Regulation of Population Growth Regulation Population Cycles Biotic Potential Low Biotic potential Low High Biotic potential -Large size -Small size -Slow development -Long-lived -Reproduction later in life -Few large offspring -Parental care -Fast development -Short-lived -Reproduction early in life -Many small offspring -No parental care Survivorship Curve Survivorship Human population growth Human Birth Rate vs. Death Rate Birth Birth Rate vs. Death Rate Birth ECOLOGY ECOLOGY Ecosystem Community Population Organism Communities Communities Key Properties: Diversity Communities Communities Key Properties: Diversity Prevalent form of vegetation Communities Communities Key Properties: Diversity Prevalent form of vegetation Stability Communities Communities Key Properties: Diversity Prevalent form of vegetation Stability Trophic structure Interactions among organisms Interactions Intraspecific: interactions within a species within Interspecific: interactions between different species between Interspecific Interactions Interspecific Competition Interspecific Interactions Interspecific Competition Interspecific Interactions Interspecific Competition Competitive Exclusion Principle The sum total of a species’ use of the biotic and abiotic resources in its environment The Ecological Niche an organism’s ecological role How it “fits into” an ecosystem 2 species with species identical niches Local extinction of less competitive species OR One species evolves to use a different set of resources Resource Partitioning Resource Partitioning Resource iin Anolis lizards n Anolis Interspecific Interactions Interspecific Competition Predation Predator adaptations Predator Acute senses Fangs, speed, agility Poison Plant defenses Plant against herbivores Chemical defenses Physical defenses Animal defenses Animal against predators Passive Animal defenses Animal against predators Active Mimicry Mimicry King snake Coral snake Mimicry Mimicry Batesian Mullerian Predation and species diversity “Keystone species” Sea otters 1700 - 1800’s – Sea otter population declined 1700 Sea otters eat sea urchins Sea Sea urchins eat kelp Sea Kelp kelp forests food and shelter Kelp for hundreds of marine species for all species all dependent on kelp forest on Sea Otter Sea Urchins Kelp forest 1911 – 1,000 – 2,000 left International treaty to protect Trend has been reversed Interspecific Interactions Interspecific Competition Predation Symbiosis Parasitism Parasitism Mutualism Mutualism Leafcutter Ants Leafcutter Living in a Living Community Community Indicator Species Indicator A species whose presence is an indicator of ecosystem health Umbrella Species A species whose protection species also protects many other species species Secondary consumers Primary consumers Producers Producers The sun = E source tertiary consumer secondary consumer secondary primary consumer primary producer FOOD PYRAMID tertiary consumer secondary consumer primary consumer primary producer DECOMPOSERS… turning a food chain into a food cycle tertiary consumer secondary consumer primary consumer primary producer tertiary consumer 10% secondary consumer 10% primary consumer 10% primary producer 10 lbs 100 lbs 1,000 lbs 10,000 lbs Low efficiency of E transfer: Low • there are many fewer top carnivores than plants and herbivores • top carnivores are usually the first to suffer when the ecosystem is disrupted • top carnivores are often the species most vulnerable to extinction Global biodiversity Global Question: How many species are there? Answer: No one knows! 1.8 million species described Estimate between 5- 50 million species • • • 56% of these are insects 56% 14% are plants 14% only 3% are vertebrates (birds, mammals, and fishes) only Why such a range?? Why 5 million - - - 50 million million Undescribed, unknown species Source: Precious Heritage: The Status of Biodiversity in the United States © The Nature Conservancy and NatureServe Why Biodiversity Matters Why We depend on other species! • Food, clothing, oxygen, shelter….. • 25% of all pharmaceutical prescriptions = plant substances Drugs for: Hodgkin disease & other cancers Madagascar’s rosy periwinkle Medicines Medicines Derived From Plants ...
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This note was uploaded on 11/17/2010 for the course BIO bio 101 taught by Professor C during the Spring '05 term at Diablo Valley College.

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