Download Ecology Population

Ecology Population
LO’s
- the meaning of ecology, population symbiotic
relationships
- can explain population demographics and
ways in which population sizes are regulated.
- can explain various types of symbiotic relationships.
Ecology
• Study of the interactions between organisms and the
environment
• Study of the physical and biological variables
governing the distribution & growth of living things
Population
• Individuals of a given species occurring at one
place at one time
• Population ecology
– Study of population growth & interactions
Population
Is a groups of individual of the same species that
live in the same area
Population Characteristics
1.
Population Density:
• Number of organisms per unit area
• Density influences survival
2.
Spatial Distribution:
• Dispersion: The pattern of spacing a population within
an area (Way that individuals are arranged
• 3 main types of dispersion
• Clumped
• Uniform
• Random
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Individuals form clusters
Clumping due to interaction of
individuals
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Individuals evenly spaced
Often results from territoriality
Also plants with allelopathy
Lacking definite order
Individuals do not influence
others growth
Population
Limiting Factors
3.
Population growth rate
– How fast a given population
grows
– Factors that influence this
are:
• Natality
• Mortality
• Emigration - movement
out of a population
• Immigration - movement
into a population
Population Size
• (births + immigrants) – (deaths + emmigrants) =
Population change
• Immigration – movement into a population
• Emigration – movement out of a population
Carrying Capacity
• Indefinite exponential growth is limited
• Shortages of growth factors will limit population
growth
• Carrying capacity = maximum number that can be
supported in a particular environment
Population size
(births + immigrants) – (deaths + emigrants) = Population change
Boom & Bust Cycle
• Sometimes populations do not level off
• Exponential growth with a sudden die-off
Interactions Within Communities
Community
• Grouping of populations living together in a
particular area at a particular time
Abiotic Factors
• Nonliving factors
within the
environment
– Air
– Water
– Rocks
• Abiotic factors affect
living (biotic) factors
Biotic components are the living things that shape an ecosystem.
Biotic factor - any living component that affects another organism
- needs energy to do work and food for proper growth
- Plants, animals, fungi, protiste and bacteria
Ecosystem
• Biotic & abiotic factors in a certain area
• Biotic and abiotic factors combine to create a system
(ecosystem)
Habitat
• Space within an area
where an organism lives
• Each organism plays a
certain role
Niche
• Two ways of defining
– An organism’s role in the environment
– Organism’s use of biotic & abiotic resources
Density Dependent Factors
• Factors that affect a population only if its density changes
• Types of density dependent factors
– Competition
– Predation
– Parasitism
Competition
• Interaction among organisms for the same
resources
– Food
– Living space
• Regulates population size & is a driving force
of evolutionary change
Competition Types
• Intraspecific – among the same species
• Interspecific – between species
Predation
• One species will kill & eat another
• Interactions maintain natural populations
• More prey results in more predators
• Less prey reduces predator numbers
Parasitism
• One species living at the expense of another
• Regulates populations by weakening or killing
Symbiosis is a close relationship between two or
more different species.
There are 3 types of symbiosis we will discover:
Commensalism—A relationship where one species
obtains food or shelter from the other species. Does
not harm or help the other species.
Mutualism—A relationship where both species
benefit from the relationship
Parasitism-- A relationship between two species in
which one species (the parasite) nourishes itself to the
disadvantage of the other species (the host).
Demography
• Statistical study of human population
• Human population is in exponential growth
Human Population Growth has Different
Patterns
• Stable population
– Remains the same
– Same number entering reproductive age as at
end of reproductive age
• Population pyramid
– Graphic representation of population age
– Shows patterns in population change
Biotic and abiotic factors are interrelated. If one
factor is changed or removed, it impacts the
availability of other resources within the system