Presentation on theme: "Populations! definition= a group of organisms of the same species that live in a particular area *Evolve over generations when frequency of alleles change."— Presentation transcript:
1 Populations!definition= a group of organisms of the same species that live in a particular area*Evolve over generations when frequency of alleles change from one generation to the next
2 Population Growth Rate at which a population grows depends on: 1. Birth rate2. Death rate3. Immigration (moving into a population)4. Emigration (moving out of a population)
3 Carrying capacitythe number of organisms that can be supported by the environmental resources in a given ecosystemprevents populations from growing out of control!controlled by limiting factorsany condition of the environment that limits the size of a populationregulates population growth!
4 Humans & Carrying Capacity How humans increase our carrying capacity?Agriculture (Green Revolution)Industry/technology-improved sanitation systemsMedicine (example: Penicillin, antibiotics)Determined by:Biotic (living) factors- any organismAbiotic (non-living) factors- rocks, weather, temperature
5 Types of Limiting factors 1. Density-dependent factor- limit population size when the population reaches a certain size- usually biotic factorsExamples: predation, competition, parasitism, disease
6 Predation All consumers are predators! Inverse relationships with prey & predatorsGreatest effect on large populations
7 CompetitionOccurs when organisms try to make use of the same resourcesCompete for food, water, mates, spaceCan be between same or different species
8 ParasitismRelationship where one organism feeds on the tissues/body fluids of another organismMember benefits: ParasiteMember harmed: Host
9 Types of Limiting factors cont. 2. Density-independent factor - limit population size regardless of overall size - usually abiotic factors Examples: natural disasters, weather - cause Boom-and-bust curves = exponential growth followed by a sudden collapse
10 Growth models J-shaped curve = exponential growth - high birth rate, low death rate-ideal conditionsExample: Algae blooms- indicate excess of fertilizers (lots of nutrients available)
11 Growth models cont. S-shaped curve - birth rate = death rate - occurs when density- dependent factors become limited- carrying capacity is reached!- usually observed in larger organisms
12 Communitiesgroup of interacting populations of different species that occupy the same area at the same timeExample: your backyard (grass, trees, flowering plants, insects, rabbits, squirrels, etc.
13 Ecosystems Includes both biotic & abiotic factors Biodiversity! terrestrial or aquaticBiomes are more defined, based on temperature, precipitation differences, and specific plant and animal life