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4 Population EcologyPopulation EcologyC
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Levels of Ecological OrganizationLevels of Ecological Organization
• Everything on Earth is connected, so how do ecologists study anything?
• Ecology is the study of how organisms interact with each other and with their environments
• Scientists study ecology at various levels of organization.
• Everything on Earth is connected, so how do ecologists study anything?
• Ecology is the study of how organisms interact with each other and with their environments
• Scientists study ecology at various levels of organization.
Lesson 4.1 Studying Ecology
Levels of Ecological OrganizationLevels of Ecological Organization• Individual•Ecology involves describing relationships between individual organisms and their environment.
•Populations• Individual organisms are classified - species•Species = group of individuals that interbreed and produce fertile offspring
•Members of a species that live in the same area at the same time = a population.
• Individual•Ecology involves describing relationships between individual organisms and their environment.
•Populations• Individual organisms are classified - species•Species = group of individuals that interbreed and produce fertile offspring
•Members of a species that live in the same area at the same time = a population.
Levels of Ecological OrganizationLevels of Ecological Organization
•Communities• All of the populations in a particular area.• Ecology involves interactions among species.
• Ecosystems• Include all the livings things and their physical
environments within a particular area• Living and nonliving things.• Ecology involves studying the living and nonliving
components of a system together.
•Communities• All of the populations in a particular area.• Ecology involves interactions among species.
• Ecosystems• Include all the livings things and their physical
environments within a particular area• Living and nonliving things.• Ecology involves studying the living and nonliving
components of a system together.
Levels of Ecological OrganizationLevels of Ecological Organization
•Biosphere•Includes all parts of Earth that host life, with all of its organisms and environments.•Ecology involves how matter and energy cycle through the biosphere and influence organisms worldwide.
•Biosphere•Includes all parts of Earth that host life, with all of its organisms and environments.•Ecology involves how matter and energy cycle through the biosphere and influence organisms worldwide.
Biotic and Abiotic FactorsBiotic and Abiotic Factors• Biotic factors: Parts of
an ecosystem that are living or used to be living
• Ex: living tree, dead tree
• Abiotic factors: Parts of an ecosystem that have never been living
• Ex: oxygen, sunlight
Lesson 4.1 Studying Ecology
HabitatHabitat
•The specific environment in which an organism lives
•Habitats consist of biotic and abiotic elements.
•Habitats provide an organism with resources—anything an organism needs to survive and reproduce, including food, shelter, and mates.
•The specific environment in which an organism lives
•Habitats consist of biotic and abiotic elements.
•Habitats provide an organism with resources—anything an organism needs to survive and reproduce, including food, shelter, and mates.
Lesson 4.1 Studying Ecology
Lesson 4.2 Describing PopulationsLesson 4.2 Describing Populations
From 1900 to 2000, the white-tailed deer population of New York state grew from about 20,000 to more than 1 million. Densities of more than 100 deer per sq mi occur in some metropolitan areas.
From 1900 to 2000, the white-tailed deer population of New York state grew from about 20,000 to more than 1 million. Densities of more than 100 deer per sq mi occur in some metropolitan areas.
Population SizePopulation Size
Lesson 4.2 Describing Populations
• The number of individuals in a population at a given time
• Sudden and dramatic decreases in population size can indicate an unhealthy population headed toward extinction.
• When population size increases or remains steady, it is often a sign of a healthy population.
Determining Population SizeDetermining Population Size
Counting Laysan Albatross Nests
• It is nearly impossible to count each individual in a population
• Population is estimated using sampling techniques.• Count individuals in
small sample area• Use that to estimate
number of individuals in large overall area
Population DensityPopulation Density
Lesson 4.2 Describing Populations
• Measure of how crowded a population is
• Larger organisms generally have lower population densities.
• Low population density: More space, resources; finding mates can be difficult
• High population density: Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators
Northern pintail ducks
Population DistributionPopulation Distribution
Lesson 4.2 Describing Populations
• How organisms are arranged within an area:
• Random distribution: Organisms arranged in no particular pattern, resource are spread out
• Uniform distribution: Organisms evenly spaced; individuals hold territories/compete for space
• Clumped distribution: Organisms grouped near resources; most common distribution in nature
Population DistributionPopulation Distribution
Age StructureAge Structure
Lesson 4.2 Describing Populations
• Age structure describe the relative number of organisms of each age group within population
• Can be used to predict future population growth of a population
• Young individuals who have not yet reached the age where they can reproduce are called pre-reproductive
• Older individuals past the age of having offspring are called post-reproductive
Age StructureAge Structure
•Population with even age distribution will likely remain stable (births = deaths).•Population made up of mostly post-reproductive individuals will likely decline over time.•Population made up of mostly pre-reproductive individuals will likely increase over time.
•Population with even age distribution will likely remain stable (births = deaths).•Population made up of mostly post-reproductive individuals will likely decline over time.•Population made up of mostly pre-reproductive individuals will likely increase over time.
Age Structure DiagramAge Structure DiagramA
ge
How will each population change over time?
Lesson 4.3 Population GrowthLesson 4.3 Population Growth
From 1800 to today, the human population has grown from about 1 billion to more than 6.8 billion—an exponential rate of increase.
From 1800 to today, the human population has grown from about 1 billion to more than 6.8 billion—an exponential rate of increase.
Biotic PotentialBiotic Potential
Lesson 4.3 Population Growth
• An organism’s maximum ability to produce offspring in ideal conditions
• Many factors influence biotic potential, including gestation time (time to “be born”) and generation time (span from time of organism’s birth until time it has its own offspring).
• Organisms with high biotic potential can recover more quickly from population declines than organisms with low biotic potential.
