ecosystem interactions
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Ecosystem Interactions. Honors Biology Chapter 14. Where & how organisms live. Range- geographical reach. Habitat- where. Ecological Niche- how. Niche includes food, abiotic conditions, behavior. Competition results when species, in the same community, overlap in use of resources - PowerPoint PPT PresentationTRANSCRIPT
Ecosystem Interactions
Honors Biology Chapter 14
Where & how organisms liveRange- geographical reach
Habitat- where
Ecological Niche- how
Niche includes food, abiotic conditions, behavior
• Competition results when species, in the same community, overlap in use of resources– Strong selective force– Competitive exclusion
• Banishment/extinction
• Evolution• Niche partitioning
Niche (resource) partitioning
Ecological Equivalents – same niche…different communities
Convergent evolution’s fingerprint
Predation – Another interaction with highly selective outcomes
Symbiosis – a kinder interaction, tho’ not without an evolutionary punch
Mutualism – both benefit
Parasitism – parasite benefits, host harmed
Commensalism – one benefits, the other unaffected
Population Dynamics• Population: all the individuals of a
species that live together in an area
• Demography: the statistical study of populations, make predictions about how a population will change
Population Dynamics
• Three Key Features of Populations• Size • Density • Dispersion
• (spatial distribution)
Three Key Features of Populations
1. Size: number of individuals in an area
Influences on Population SizeSurvivorship Reproductive Strategies
1. R Strategists short life span, small
body, reproduce quickly, many young, little parental care
2. K Strategists long life span, large
body, reproduce slowly, few young, parental care,
Three Key Features of Populations
2. Density: measurement of population per unit area or unit volume
Formula: Dp= N/S
Pop. Density = # of individuals ÷ unit of space
Human Population Density
Three Key Features of Populations
3. Dispersion: describes their spacing relative to each other• clumped• uniform• random
Clumped for protection, resources,mating or social interaction
Uniform dispersion due to intraspecies competition / territoriality
3. Dispersion: describes their spacing relative to each otherThree Key Features of Populations
Random dispersion implies absence of interaction - rare. Mature communities.
Patterns of Dispersion
Population Growth Patterns• Growth Rate: Birth Rate (natality) -
Death Rate (mortality)• How many individuals are born vs. how
many die• Birth rate (b) + Immigration rate (i) −
death rate (d) = rate of natural increase (r).
• Total Growth must add immigration & subtract emigration statistics
Population Growth Patterns
Exponential – J shaped curve Logistic – S curve
Population Growth PatternsThe “Boom Bust” Curve
World Human Population Growth
Other Factors Affecting Population Growth
• Age Structure
POST-REPRODUCTIVE
REPRODUCTIVE PRE-REPRODUCTIVE
Age Demographics for Three Countries
Immigration and Emigration Can Strongly Effect Population Dynamics
Estimated rates of US population growth with or without immigration.
Immigration & Emigration Influences on Total Rate of Growth
Demographic TransitionThe move from “Developing” to “Developed”
Country
Other Factors Affecting Population Growth
• Carrying Capacity- the maximum population size that can be supported by the available resources– There can only be as many organisms
as the environmental resources can support
Carrying Capacity
Carrying Capacity (k)
Time
J-shaped curve (exponential growth)
S-shaped curve (logistic growth)
#
Other Factors Affecting Population Growth
• Limiting Factors - any biotic or abiotic factor that restricts the existence of organisms in a specific environment.
Two Types of limiting Factors1. Density-dependent
factors- increase effect as population size increases. (disease, competition, parasites)
4. Density-independent factors- affecting populations regardless of
their density (temperature, storms, habitat destruction, drought)
Gradual, sequential change in an area that regenerates or creates a community an area
Succession at Mt. St. Helens.
Ecological Succession
Succession after the Yellowstone fires.
Primary succession: occurs where life has not previouslyexisted
Retreating Glaciers at Glacier Bay Alaska
Primary Succesion – Very Slow
Secondary Succession – Faster (soil already present)
Mount St. Helens
Succession• Climax Community theoretical end-point of
succession. Stable community.