Unit 2 Communities Populations Change in the community

Change in the community… n Part of ecology is studying the constant cycles of

Changes in the community… Succession: a series of predictable changes that occur in a

Succession (cont. ) Primary succession: form of succession where growth begins in an area

Succession (cont. ) Secondary succession: when a disturbance changes a community and the community

Population Dynamics Characteristics of Populations - Geographic Distribution (where people live) - Density -

Population Dynamics Factors that affect population growth: 1) Number of births 2) Number of

Population Growth Exponential Growth - Reproduction occurs at a constant rate - Growth is

Population Growth Number of Yeast Cells Logistic Growth - Growth slows as less resources

Population Growth Limiting Factors: factors that cause population growth to decrease Limiting Growth Factors

Population Growth Density Dependent Factors: factors that depend on the number of organisms in

Population Growth Density Independent Factors: factors that affect a population in the same way

Human Population Growth n The human population remained relatively stable until approximately 500 years

Human Population Growth Industrial Revolution begins Bubonic plague Agriculture begins Plowing and irrigation

Human Population Growth n Distribution of population by age for industrialized and developing countries

Math Connections n The human population increases on average 1. 4% every year. If

Reflection What affect might the increase in human population have on the environment and

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Unit 2: Communities & Populations

Change in the community… n Part of ecology is studying the constant cycles of change that occur within an ecosystem Factors affecting change Loss of Habitat Shortage of Resources Population Growth Disease

Changes in the community… Succession: a series of predictable changes that occur in a community over time -can be a drastic change or just a change of seasons.

Succession (cont. ) Primary succession: form of succession where growth begins in an area that had no living organisms Example: Growth beginning on new land formed by cooling lava. Pioneer species: 1 st species to populate the area in primary succession

Succession (cont. ) Secondary succession: when a disturbance changes a community and the community must grow back again Ex: when land is cleared for farming and then trees are allowed to grow back

Primary Succession Secondary Succession

Population Dynamics Characteristics of Populations - Geographic Distribution (where people live) - Density - Growth rate

Population Dynamics Factors that affect population growth: 1) Number of births 2) Number of deaths 3) Number of organisms entering or leaving the ecosystem

Population Growth Exponential Growth - Reproduction occurs at a constant rate - Growth is unlimited - Forms a J-shaped curve

Population Growth Number of Yeast Cells Logistic Growth - Growth slows as less resources become available - Carrying capacity: maximum number of organisms the ecosystem can hold - Forms a S-shaped Carrying capacity curve Time (hours)

Population Growth Limiting Factors: factors that cause population growth to decrease Limiting Growth Factors - Amount of nutrients (food, water, etc. ) - Competition - Predation - Disease (Parasitism)

Population Growth Density Dependent Factors: factors that depend on the number of organisms in a population Examples: competition, predation, parasitism, resource availability

Population Growth Density Independent Factors: factors that affect a population in the same way no matter what size the population is Examples: Weather, Natural disasters, Human activities

Human Population Growth n The human population remained relatively stable until approximately 500 years ago n Advances in medicine, agriculture and technology have increased humans rate of survival n Today the human population is above 6 billion and still growing

Human Population Growth Industrial Revolution begins Bubonic plague Agriculture begins Plowing and irrigation

Human Population Growth n Distribution of population by age for industrialized and developing countries U. S. Population Males Females Rwandan Population Males Females

Math Connections n The human population increases on average 1. 4% every year. If the population is 6 billion now what would the population be next year? 6, 000, 000 x 0. 014 = 84, 000 people Next years’ population would be 6, 084, 000 n If the human population continues this growth the size would double in the next 50 years!

Reflection What affect might the increase in human population have on the environment and other people? What will happen when humans reach their carrying capacity? What do you think is the human carrying capacity on Earth?