CHAPTER 14 Interactions in Ecosystems: Day One
Habitat versus Niche Review! What is a habitat? All of the biotic and abiotic factors in the area where an organism lives. Examples: grass, trees, and watering holes! Where it lives!
Habitat versus Niche What is a niche? Review! Composed of all of the physical, chemical, and biological factors that a species needs to survive Niche includes: type of food a species eats, tolerating certain types of abiotic conditions, and a species behavior. How it lives! Habitat is like an address in an ecosystem and a niche is like the job in an ecosystem.
Resource availability Provides structure to communities What is a community? Different groups of species Many species share similar habitats and use some of the same resources Florida Everglades
Competitive Exclusion Can present a problem if two species use the same resource in the same way One species will always be better adapted to the environment.
Competitive Exclusion States that when two species are competing for the same resources, one species will be better suited to the niche, and the other species will be pushed into another niche or become extinct. Example: In Great Britain, North American gray squirrel (better suited) introduced and pushed out the native European red squirrel. Caused red squirrel population to decline rapidly.
Other outcomes from competitive exclusion Niche partitioning: Divide resources based on competitive advantages Evolutionary response: Different sizes of teeth could affect the way they eat
Competitive Exclusion Principle http://nicolellawhhs.weebly.com/unit-5-chapter-14- interactions-in-ecosystems.html
Ecological equivalents Are species that occupy similar niches but live in different geographical regions. Examples: Mantella frog of Madagascar and poison dart frog of South America Both have the same niche in similar habitats, but will never compete for the same resources because they live in different geographical regions.
Community Interactions Competition and predation are two important ways in which organisms interact. Competition occurs when two organisms fight for the same limited resource.
Competition Two types of competition: Interspecific competition: Competition between two different species (competing for space) Examples: cats and dogs
Competition Two types of competition: Intraspecific competition: Competition between members of the same species Examples: male birds, lions
Predation Process by which one organism captures and feeds upon another organism. Timber Rattlesnake
More Community Interactions Symbiosis: Any relationship where two species live closely together and interact. 3 types: Mutualism Commensalism Parasitism
Relationships Between Organisms http://nicolellawhhs.weebly.com/unit-5-chapter-14- interactions-in-ecosystems.html
Ticket Out the Door 1. Complete the table about factors that influence ecosystems. Type of Factor Definition Examples Biotic Factors Abiotic Factors 2. When does competition occur? 3. What is a resource? 4. What is the competitive exclusion principle? 5. What is predation? 6. When predation occurs, what is the organism called that does the killing AND eating, and what is the food organism called?
CHAPTER 14 Interactions in Ecosystems: Day One Continued
Mutualism Both species benefit from the relationship. Example: Ants and aphids: Ants get a sugary substance from the plants while the plant receives protection from the ants
Commensalism One organism benefits while the other is unaffected. Example: Barnacles on whales: Barnacles hitch a ride on the whale gathering food during transport; the whales receives nothing out of the relationship
Parasitism One organism benefits while the other is harmed. Examples: Flea and dog: Flea gets home/food while the dog is harmed because the flea feeds on its blood!
Parasites Two types of parasites: Ectoparasite: lives on the outside of an organism, attaching itself to the outside of the host Examples: fleas, ticks, and leeches Endoparasite: found on the inside of living organisms, feed on nutrients ingested by their host Examples: tapeworms and hookworms
Symbiotic Relationships Untamed Science http://nicolellawhhs.weebly.com/unit-5-chapter-14- interactions-in-ecosystems.html
Ticket out the Door 1. Determine which ecological factors are a part of a lion s niche and which are a part of a lion s habitat by placing the above items in the correct column. a. Items: food, hunting behavior, other lions, trees, watering hole, wildebeast, zebra, sand, temperature, grass, savanna Habitat Niche 2. What are the three possible outcomes of competitive exclusion? 3. What are ecological equivalents? 4. Complete the table about main classes of symbiotic relationships. Class Description of Relationship mutualism commensalism parasitism 5. The organism from which a parasite obtains nutritional needs is called a(an).
CHAPTER 14 Interactions in Ecosystem: Day Two
Populations What is a population? A group of the same species of organism living in the same place.
Characteristics of Populations How do populations grow? Four important characteristics of a population are: Geographic distribution Population density Growth rate Age structure
Geographic Distribution May also be called it s range Describes the area inhabited by a population Varies in size depending upon the type of organism
Geographic dispersion Shows how individuals in a population are spaced Allows ecologists to study population dispersion Way in which individuals of a population are spread in an area or a volume Three types of population dispersion: Clumped dispersion Uniform dispersion Random Dispersion
Clumped dispersion Individuals live close together in groups in order to facilitate mating, gain protection, or access food
Uniform dispersion Individuals living at specific distances from one another Caused by territoriality and intraspecific competition
Random dispersion Individuals are spread randomly within an area or volume
Population Dispersion http://nicolellawhhs.weebly.com/unit-5-chapter-14- interactions-in-ecosystems.html
Population density Number of individuals per unit area (defined space) Varies greatly depending on the species and ecosystem Measures the crowdedness of an area Population density = # of individuals area (units 2 )
Population growth Affected by three factors Number of births Number of deaths Number individuals that enter and leave the population Immigration movement INTO an area Emigration movement OUT of an area
Ticket Out the Door 1. What are four main characteristics of a population? 2. What is a population s geographic distribution? 3. Another term for geographic distribution is. 4. What is population density? 5. What three factors affect population size? 6. If more individuals are born than die in any period of time, how will the population change? 7. Complete the table about changes in population size. Type of Change Definition Resulting Change in Size Immigration Emigration
CHAPTER 14 Interactions in Ecosystem: Day Two Continued
Population growth based on available resources Growth is a function of the environment Directly determined by the amount of resources available Two distinct types of population growth Exponential Logistic
Exponential growth Population has abundant space and food Occurs when the individuals in a population reproduce at a constant rate Lack of limiting factors (causes population growth to decrease) Shown as a J-shaped curve in a graph Examples: bacteria!
More on exponential growth When a population has unlimited resources and continues to grow to its full living potential, it is called its biotic potential. A population that has reached biotic potential has reached its maximum reproductive capacity. That means it has reproduced as much as it can!
Logistic Growth Occurs when the population s growth slows or stops following a period of exponential growth Most realistic Caused by resources becoming less available Influenced by limiting factors Can slow down when birthrate decreases or death rate increases Represented as an S-shaped curve
Carrying Capacity Represented as K Largest number of individuals that a given environment can support Can change when the environment changes Region A= very close to exponential growth Region B= declining birthrate; inc. death rate Region C= pop. reaches K; usually fluctuates around Carrying Capacity
Limiting factors Is a factor that causes population growth to decrease Two types of limiting factors: Density-dependent Density-independent
Density-Dependent Factors Depends on population size Becomes limiting only when the population density reaches a certain level Density is the number of organisms per unit area Best seen when population is large and dense Do not affect small, scattered populations Examples: competition, predation, parasitism, and disease
Competition Occurs if crowded organisms compete for food, water, space, sunlight, and other essentials Can occurs between members of the same species Can also occur between members of different species remember no two species can occupy the same niche in the same place at the same time
Effect of Predation Population size often controlled by predation Takes place in the predator-prey relationship Best mechanism of population control
Parasitism and Disease Limit growth of population Take nourishment at the expense of their hosts often weakening them and causing disease and death
Density-Independent Factors Affect all populations regardless of size Examples: unusual weather, natural disasters, seasonal cycles, and human activities Can see a population crash Dramatic decline in the population size over time
Age Structure Population growth depends on how many people of different ages make up a given population. Populations with large numbers of young offspring have greater potential for rapid growth Population Pyramids or Age-Structure Diagrams show age structure in a population.
Patterns of Population Growth The scientific study of human populations is called demography Examines the characteristics of human populations and attempts to explain how those populations will change over time Birthrates, death rates, and the age structure of a population help predict why some countries have high growth rates while other countries grow more slowly
Human Population Growth It took from the beginning of mankind to around 1800 for the human population to reach 1 billion. In the last 200 years, the human population has reached just over 6 billion. The U.N. estimates the world s population to be 12.5 Billion by 2050. What effects will these numbers have on the Earth? Other forms of life?
The Demographic Transition Over the past century, population growth in the US, Japan, and much of Europe has slowed dramatically. One hypothesis as to why these countries have slowed in their growth is the demographic transition (a dramatic change in birth and death rates). As countries modernize, there are advances in nutrition, medicine, and sanitation. These result in more children surviving into adulthood and more adults living to old age. These changes lower the death rate and begin the demographic transition.
Population Biotic Potential http://nicolellawhhs.weebly.com/unit-5-chapter-14- interactions-in-ecosystems.html
Ticket out the Door 1. How will a population change if there is abundant space and food and if the population is protected from predators or disease? 2. When does exponential growth occur? 3. When does logistic growth occur? Word Bank: Births Emigration Deaths Immigration 4. When resources are abundant in a particular area, individuals may move into the population of this area. This movement of individuals into a population from a different population is called. 5. A very cold winter has left many deer in a population hungry and sick. By the end of the winter, this population will likely decrease because of. 6. A deer population experiences growth when the rate of reproduction increases. This change in population size is due to. 7. As humans move into their territory, many members of a deer population move away and join other herds. This movement of individuals out of a population into a new population is called.
CHAPTER 14 Interactions in Ecosystems: Day Three
Ecological succession Succession means the sequence of biotic changes that regenerate a damaged community in a previously uninhabited area Ecosystems are constantly changing in response to natural and human disturbances. When an ecosystem changes, older organisms gradually die out and new organisms move in.
Ecological succession Can result from slow changes in the physical environment Sudden natural disasters or human activities also play a role in ecological succession Ecological succession can be Primary Secondary
Primary succession Establishment and development of an ecosystem in an area that was previously uninhabited Occurs on land where no soil exists Occurs on surfaces formed as volcanic eruptions build new islands or cover the land with lava rock or volcanic ash Can also occur on bare rock
Primary succession First, lichens that do not need soil to survive grow on rocks Lichens are made up of fungus and algae; helps break up rocks Next, mosses grow to hold the newly made soil Each of these are known as a pioneer species Meaning these are the first species to populate an area
Primary succession Soil starts to form as lichens, weather, and erosion help break down rocks into smaller pieces When lichens die they decompose, adding organic matter to the rock to make soil
Primary succession Simple plants like mosses and ferns can grow in the new soil
Primary succession Simple plants die, adding more nutrients to the soil Soil layer thickens Grasses and wildflowers begin to take over
Primary succession Grasses and wildflowers will die, adding nutrients to the soil Shrubs and trees can survive now
Primary succession Insects, small birds, and mammals begin to move into the area What was once bare rock, can now support an area of life
Secondary succession Begins in a place that already has soil and was once the home of living organisms Occurs faster and has different pioneer species than primary succession Often see this after a natural disaster such as a forest fire or volcano
Climax community A stable group of plants and animals that is the end result of the succession process Final and stable community Does not always mean big trees Grasses in prairies Cacti in deserts
Climax Communities Climax Communities
Ecological Succession
Ticket Out the Door 1. What is ecological succession? 2. What is primary succession? 3. The first species to populate an area when primary succession begins are called. 4. When a disturbance changes a community without removing the soil, what follows? 5. An area that was once referred to as a climax community without removing the soil, what follows?