Population and Relationships

1. Population and Relationships • Population and growth • Limiting factors • Population growth curves • Exponential • Logistics • Symbiotic relationships

2. Population and Growth • Population- consists of all individuals of the same species that live together in one place at one time.

3. Population and Growth • Biodiversity- the number and variety of organisms in a given area during a specific period of time

4. Population and Growth In order to predict population growth the following must be considered: • Population Size • Population Growth Rate • Carrying Capacity • Limiting Factors

5. Population and Growth • Population size- the number of individuals in a population • Population growth rate- the rate at which the birthrate is greater than the death rate. (Growth occurs when more individuals are being born than dying in a population)

6. Population and Growth • Carrying Capacity- the population size that an environment can sustain • Limiting Factors- Factors That Control Population Growth • Competition • Predation • Parasitism • Crowding • Stress • Disease

7. Population and GrowthLimiting Factors Competition- Situation in which two or more organisms attempt to use the same scarce resource • Primary sources of Competition: • Food • Water • Space • Mates

8. Population and GrowthLimiting Factors Predation- A relationship between two organisms in which one organism kills (predator) and devours another organism (prey). - Affects population size of both predator (increases) and the prey (decreases). - Often cyclical.

9. Population and GrowthLimiting Factors • Parasitism- The relationship between two organisms where one organism benefits (parasite) and the other is harmed (host). • Example: Tapeworm • You are harmed because it lives off your intestinal fluids • Segments break off to form a new worm!

10. Population and GrowthLimiting Factors • Crowding- exceeding the carrying capacity of a habitat which can result in stress and disease. • Stress and disease can lead to poor reproductive success and can cause damage to the habitat.

11. Population Growth CurvesExponential Exponential growth: • Population increases by a constant proportion per unit of time • At this growth rate the population exhibits a J-shaped curve

12. Population Growth CurvesLogistic Logistic growth: • Population increases rapidly for a period of time, its growth begins to slow, and ultimately, growth stops (the birthrate and death rate become equal). • At this growth rate the population exhibits an S-shaped curve. • K (carrying capacity) = maximum population size that an environment can support K

13. Symbiotic Relationships • Symbiosis- a close long term relationship between two or more species that can be beneficial or harmful • Beneficial: • Mutualism= • Both benefit • Commensalism= • Only one benefits & other is not harmed or helped • Harmful: • Parasitism= • One benefits & Host slowly harmed

14. Symbiotic Relationships Mutualism- Both Benefit Example- Lichen (fungus and algae together) • Fungi provides- • carbon dioxide • moisture • Algae provides- • food • oxygen

15. Symbiotic Relationships • Commensalism- one benefits, the other is neither harmed or helped • Example- whale and a barnacle • Whale • unharmed • Barnacles • Protection from predators • Transportation to new food sources

16. Symbiotic Relationships • Parasitism- one benefits (parasite), other harmed (host) • Example- flea and a dog • Flea • Food • Shelter • Dog • Itches • Can become infected with diseases

17. Fill out the chart: + = benefits, - = harmed, 0 = neutral (neither harmed nor helped) + + + 0 - +