1 Populations and Communities Chapter 1 Section 1: Living Things and the Environment Ecology The study of the interactions between organisms and the living and non-living components of their environment. Things to know: An organism obtains the things it needs to live from its environment (habitat) One area may contain many habitats A species is a group of organisms that can mate and produce offspring that can reproduce Factors in the Environment Biotic factors- all the living things in an ecosystem Abiotic factors- all the non-living things in an ecosystem Water Sunlight Oxygen Temperature Soil Levels of Organization The smallest level of organization is a single organism, which belongs to a population that includes all other members of its species in the area
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Populations and Communities
Chapter 1
Section 1: Living Things and the Environment
Ecology
� The study of the interactions between organisms and the living and non-living components of their environment.
Things to know:
� An organism obtains the things it needs to live from its environment (habitat)
� One area may contain many habitats
� A species is a group of organisms that can mate and produce offspring that can reproduce
Factors in the Environment
� Biotic factors- all the living things in an ecosystem
� Abiotic factors- all the non-living things in an ecosystem
� Water
� Sunlight
� Oxygen
� Temperature
� Soil
Levels of Organization
� The smallest level of organization is a single organism, which belongs to a population that includes all other members of its species in the area
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Levels of Organization
� The population belongs to a community of different species.
Living Thingsand the Environment
Levels of Organization
� The community and abiotic factors together form an ecosystem.
Living Thingsand the Environment
Levels of Organization in Ecology
Ecosystem
Community
Population
Organism
Section 2: Studying Populations
Main Idea
Detail Detail Detail Detail
Graphic Organizer
Direct observation
Indirect observation
Sampling Mark-and-recapture studies
There are four main ways to determine the size of a population.
How do you determine population size?
� Direct observation- count all
� Indirect observation- count signs of organisms (nests)
� Sampling –an estimate; count organisms in a small area and multiply to find the number in a large area
� Mark & Recapture – mark so many then recapture and use a formula to estimate
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Factors that determine population growth rate
� Death rate
� Birth rate
� Immigration (movement in)
� Emigration (movement out)
Changes in Population Size
� Populations change in size if new members join the population or if members leave the population.
� If BR > DR then population increases
� If BR < DR then population decreases
Population density
� The size of a population that occupies a limited area
� Measures how crowded a population is
Formula:
D = number of individuals
unit of area
Limitations of Growth
� Only occurs for a short period of time
� Due to environmental limitations
� Limiting factor – a factor that restrains the growth of a population
EX: resources (food and water), habitat size (space), competition, weather
An important limiting factor:
� Carrying capacity (K) – the number of individuals the environment can support over a long period of time
� Capacity is greater when prey is abundant and smaller when prey is scarce