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3.1 POPULATIONDonna.Roldan.Penton
biosphere
ecosystem
community
population
organism
What is population?
POPULATION
-- group of similar species/organism living in a certain place at the same time.
3.2 Characteristics of Population
Population Dynamics
Three Key Features of Populations
1. Size2. Density3. Distribution
SIZE-- pertains to the number of individuals in a population.
Example: The recorded population of people in the Philippines on July 2000 is 72, 000, 000.
KIND PLACE TIME NUMBER
Homo Sapiens
Philippines July 2000 72, 000, 000
FACTORS THAT AFFECTS THE SIZE OF A POPULATION
1. Natality -- numbers of species that are born
2. Mortality-- number of species that die
3. Immigration- numbers of species that entered
the land
4. Emigration- numbers of species that leave the land
Immigration
Emigration
Births DeathsPopulation
Change
++
-
-
Factors That Affect Population Growth
DENSITY
-- number of individuals or species living in a particular area of that population.
EXAMPLE:100 cows/hectare
DISTRIBUTION
-- describes the spacing of organisms relative to each other.
Patterns of Distribution:
1. Clumped Distribution2. Uniform Distribution3. Random Distribution
CLUMPED DISTRIBUTION
The organism are concentrated in an area. It may offer the population protection from enemies.
UNIFORM DISTRIBUTION
The organisms are evenly distributed over an area.
RANDOM DISTRIBUTION
There is no specific order in random distribution, the organism is spread throughout the area with-out an over-all pattern.
3.3 POPULATION GROWTH
SURVIVORSHIP and MORTALITY
The growth of a population depends upon the balance of mortality and natality.
BIOTIC POTENTIAL
It is the number of offspring that could exist if all offspring survived and produced young.
The life history of a housefly.
A female can lay 120 eggs and hatch them in one day. Within the sixth day, the pupa forms. In a week, adults emerge from the pupa. In the span of two weeks, single pair of flies produce 120 offsprings.
ENVIRONMENTAL RESISTANCE
Factors that reduces the growth rate of population. It is when a population does not reach its biotic potential because there are factors that affect its growth.
- resource shortage (water/food)- disease, competition of organisms, predation
Carrying Capacity- the maximum number of individuals in a particular population that the environment can support over an indefinite period of time in terms of food, space and shelter.
CARRYING CAPACITY
3.4 Limiting Factors of Population
1. Density-dependent factors
Biotic factors in the environment that have a greater limiting effect as population size increases.
Examples:
disease competition parasites
2. Density-independent factors
Abiotic factors in the environment that affect populations regardless of their density.
Examples:
temperature storms
habitat destruction drought
4.1 COMMUNITY
COMMUNITY
It is the place where populations interact.
Can considered from two viewpoints:
- Autecology – each organism is a member of a community
- Synecology – group of organisms in a particular area
4.2 SPECIAL RELATIONSHIP AMONG ORGANISMS
Biotic communities live and interact together. Interaction
between different trophic levels of organisms involves predation
and competition.
PREDATION
Predator:
consumer that captures and eats other consumers.
Prey: the organism that is eaten by a predator.
COMPETETITION
Competition doesn’t involve always the same species, but it is more severe among the same numbers of species because they have common needs.
4.3 SYMBIOTIC RELATIONSHIP
SYMBIOSIS
It means living together of two or more organisms of different species.
1. Parasitism: one organism benefits (the mosquito) while the other (the host) is harmed.
2. Mutualism: both species benefit.
3. Commensalism: one species benefits while the other remains unaffected.
4.4 COMMUNITY ROLES
Producers:
Organisms that make their own energy (food).
a. Use the process of photosynthesis.b. Oxygen is a by-product (waste material).
Consumers:
Organisms that can’t make their own food.Must eat producers or other consumers for energy.
Decomposers:
Organisms that feed on dead plants and animals.
4.5 ECOLOGICAL HABITATS AND NICHES
Habitat:
The place where an organism lives and that provides food, shelter, moisture, and temperature needed for survival.
Examples:a. Swampb. Field c. Laked. Tree
Where an organism lives.
Niche:
Role of an organism in the ecosystem, including unique ways an organism survives, such as: how it interacts with other organisms, how it obtains food and shelter, and avoids danger.
Examples:
a. Anteaters keep the ant population.b. Bacteria eats dead animals assisting in
decomposition. And keeping them from piling up, while adding nitrogen to the soil
Role an organism plays
4.5 ENERGY FLOWS/ENERGY TRANSFER/FOOD
CHAIN/FOOD WEB
TROPHIC PATTERN
Three Classifications of Consumers:
a. Herbivores: plant-eaters
b. Carnivores: animal-eaters
c. Omnivores: plant and animal eaters
Food Chains are basic representation of energy transfer from producers to consumers.
Food Webs demonstrate how the organisms are interconnected in a
more complex, realistic way.
Food Web