Ecology Biology

What happens to a community when a lot of people move in at one time? Populations What happens to a community when a lot of people move in at one time?

What happens to a community when a lot of people move out at one time? Populations What happens to a community when a lot of people move out at one time?

Community Interactions Interactions between organisms in a community have a huge impact on ecosystems.

https://www.census.gov/popclock/

Symbiosis —a relationship in which two species live closely together. More interactions Symbiosis —a relationship in which two species live closely together. Usually one species lives on or inside of another. One species always benefits and other can be harmed, helped, or have no effect.

Mutualism —a symbiotic relationship in which both species benefit. Types of Symbiosis Mutualism —a symbiotic relationship in which both species benefit. Ex: Flowers and the insects that pollinate them.

Ex: barnacles on a whale Types of Symbiosis Commensalism —a symbiotic relationship in which one species benefits and the other is unaffected. Ex: barnacles on a whale

Ex: Fleas, ticks, tapeworms and their hosts. Types of Symbiosis Parasitism —a symbiotic relationship where one species benefits and the other is harmed. Ex: Fleas, ticks, tapeworms and their hosts.

Ecological Succession Ecological Succession —The series of predictable changes that occurs in a community over time. As an ecosystem changes, older species gradually die out and new species move in.

Types of Succession Primary Succession —When succession occurs on surfaces where no soil exists. Ex: after a volcanic eruption builds a new island or covers land with lava rock.

Types of Succession Image of Primary Succession

Ex: a forest after a fire. Types of Succession Secondary Succession —When a disturbance changes an ecosystem without removing the soil. Ex: a forest after a fire.

Types of Succession Image of Secondary Succession

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Population Growth Several factors affect population size: Births — # of organisms born Deaths — # of organisms that die

Population Growth Immigration—The movement of organisms into a population Emigration—The movement of organisms out of a population

Population Growth

Exponential Growth Populations with unlimited resources will continue to multiply rapidly. J curve on graph

Exponential Growth Graph

Logistic growth Logistic growth - occurs when a population’s growth slows and then stops following a period of exponential growth. S curve on graph

Logistic growth graph

Carrying Capacity Carrying capacity—The maximum number of organisms that the environment can support

Carrying Capacity

Density Dependent Factors Density-dependent factors need large populations , or dense populations, not scattered or small ones. Competition Predation Disease Stress from overcrowding Parasitism

Density Independent Factors Density-Independent Factors affect all populations regardless of their size or density Drought Hurricanes Tornadoes Floods Forest fires Other natural disasters

Biodiversity Biodiversity—the total variety of organisms in the biosphere.

Maintaining biodiversity Humans can help maintain biodiversity by: Enforcing the Endangered Species Act Making laws protecting the wilderness (including rainforests)

Destroying Biodiversity Humans can destroy biodiversity by: Habitat destruction Introducing invasive species (ex: Zebra mussels in Great Lakes, rabbits in Australia, etc.)

Human activities causing global warming Burning fossil fuels and cutting down the rainforests are increasing greenhouse gases (especially CO2), which is most likely causing global warming.