Lesson # 27. Populations in Ecology. ECOLOGY. It is the study of the interaction that living things have with each other and with their environment. Importance of Ecology. It provides the information base that society can use to make decisions about the environment . E C O L O G Y .
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Populations in Ecology
It is the study of the interaction that living things have with each other and with their environment
Importance of Ecology
It provides the information base that society can use to make decisions about the environment
All the members of a single species that live together in a specific geographic region.
The population of all species living in a single region.
It is the community plus all the non-living elements that interact with it (rainfall, chemicals nutrients, soil).
4- The Biosphere
It is the interactive collections of all the Earth’s ecosystems.
Populations: Size and Dynamics
Water flea Daphnia
Populations growth exponentially because each living thing is capable of playing part in giving rise to more units.
CharlesDarwin: “There is not exception to the rule that every organic being naturally increase at so high a rate, that, if not destroyed, the Earth would soon be covered by the progeny of a single pair”.
Logistic growth: Population starts growing exponentially, but eventually the rate of growth slows and finally ceases altogether, stabilizing at a certain level (K).
1- Water supply
2- Food supply
All the forces of the environment that act to limit population growth.
3- Living space
6- Wastes produced by the organisms
Carrying capacity (K)
It is the maximum population density of a given species that a defined geographical area can sustain over time.
When species stabilize their rate of growth to a certain level they are known as “equilibrium species”
The growth of the population of equilibrium species is limited by carrying capacity (K)
Fly population increases enormously
Abundant food supply
Change in temperature
Fly population decreases enormously
Food is gone
In contrast to equilibrium species, other species like houseflies tends to fluctuate greatly in reactions to variations in its environment
When population size tends to fluctuate greatly in reactions to variations in its environment they are known as “opportunistic species”
The population sizes of these species tend to be only limited by their reproductive rate ( r ).
r-selected species: Species whose population sizes tend to be limited by reproductive rate.
Limited by carrying capacity (K)
Limited by reproductive rate ( r )
Produce fewer offspring
Produce many offspring
Provide greater care for offspring
Provide no care for offspring