Populations A particular species living in a particular place at the same time

Population Growth Biotic Potential: The highest rate of reproduction a population can reach. Biotic Potential: The highest rate of reproduction a population can reach. Sentence: Sentence:

Population Growth Biotic Potential: The highest rate of reproduction a population can reach. Biotic Potential: The highest rate of reproduction a population can reach. Sentence: The biotic potential of fruit flies is reached when 120 eggs laid by the female hatch into successful offspring. Sentence: The biotic potential of fruit flies is reached when 120 eggs laid by the female hatch into successful offspring.

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring120

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring1207,200

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring1207,200432,000

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring1207,200432,00025,920,000

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring1207,200432,00025,920,0001,555,200,000

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring1207,200432,00025,920,0001,555,200,00093,312,000,000

Fruit Fly Population Growth Generation Generation # of Offspring # of Offspring1207,200432,00025,920,0001,555,200,00093,312,000,0005,598,720,000,000

Fly generations Number of Flies

Fly generations Number of Flies The graph looks like the shape of what letter?

Population Growth We call this type of curve a J – shaped We call this type of curve a J – shaped curve and the population growth it represents exponential growth

Population Growth (cont.) Population may be limited by factors called Limiting Factors. Population may be limited by factors called Limiting Factors. Examples: Examples:

Population Growth (cont.) Population may be limited by factors called Limiting Factors. Population may be limited by factors called Limiting Factors. Examples: Examples: –Water –Shelter –Nutrients –Mates –Nesting Sites

Population Growth Carrying Capacity: The maximum population of a particular species that a given habitat can support over a given period of time. Carrying Capacity: The maximum population of a particular species that a given habitat can support over a given period of time.

S - shaped Growth Curve Time Number of Individuals in the population K = Carrying Capacity

Growth = Births exceed Deaths Growth = Births exceed Deaths Decline = Deaths exceed Births Decline = Deaths exceed Births Natality: birthrate; the production of new individuals by birth, hatching, germination, or cloning. Natality: birthrate; the production of new individuals by birth, hatching, germination, or cloning. Mortality: deathrate; the ratio of deaths in an area to the population of that area. Mortality: deathrate; the ratio of deaths in an area to the population of that area. Immigration: migration into a place Immigration: migration into a place Emigration: migration out of a place Emigration: migration out of a place

Number of Individuals in the population K = Carrying Capacity Time The number of organisms in a population tends to rise above and fall below the carrying capacity.

Limiting Factors Limiting Factor: an environmental factor that limits the growth, abundance, or distribution of a population of organisms in an ecosystem (e.g. water, nutrients, sunlight, prey, etc.). Limiting Factor: an environmental factor that limits the growth, abundance, or distribution of a population of organisms in an ecosystem (e.g. water, nutrients, sunlight, prey, etc.). 1. Density Dependent 2. Density Independent

Density Dependent Examples: Examples:

Density Dependent Examples: Examples: –Food –Water –Living Space –Predation –Disease: –Disease: High densities makes it easier for parasites to find hosts and spread the disease – –Stress: usually has a negative effect on populations. Stress can make organisms weak and more prone to disease.

Density Independent Examples: Examples:

Density Independent Examples: Examples: –Natural Disasters/Weather (e.g. drought, hurricane, flood, fire) (e.g. drought, hurricane, flood, fire) –Sunlight –Temperature –Human Activities

Population Growth Practice: Bacteria reproduce by splitting (binary fission). A certain species reproduces every 20 minutes. If we start with one bacterial cell, how many cells will there be at the end of 3hrs? Bacteria reproduce by splitting (binary fission). A certain species reproduces every 20 minutes. If we start with one bacterial cell, how many cells will there be at the end of 3hrs? Show your work in the form of a population GRAPH. The independent variable is TIME and the dependent variable is the GROWTH/NUMBER of bacteria. Show your work in the form of a population GRAPH. The independent variable is TIME and the dependent variable is the GROWTH/NUMBER of bacteria.

Data: Time Number of (in minutes) Bacteria 0 min1 20 min 40 min 60min (1hr) 80 min 100 min 120 min (2hrs) 140 min 160 min 180 min (3hrs) Note: Graph the time in minutes