THINK-PAIR-SHARE Until the middle of the 20th century, the US government paid bounties on wolves. For many years, people thought that predators were dangerous animals that should be killed. Because of this practice, most of our large predators are now endangered. What would most likely happen in an ecosystem if all of the predators were removed? Explain why this might happen.

SC.912.L.17.5 POPULATION DYNAMICS

WHAT ARE WE LEARNING? Standard 17: Interdependence Benchmark SC.912.L.17.5: Analyze how population size is determined by births, deaths, immigration, emigration, and limiting factors (biotic and abiotic) that determine carrying capacity. SC.912.L.17.2 Explain the general distribution of life in aquatic systems as a function of chemistry, geography, light, depth, salinity, and temperature. SC.912.L.17.4 Describe changes in ecosystems resulting from seasonal variations, climate change, and succession. SC.912.L.17.8 Recognize the consequences of the losses of biodiversity due to catastrophic events, climate changes, human activity, and the introduction of invasive, non-native species. SC.912.N.1.4 Identify sources of information and assess their reliability according to the strict standards of scientific investigation.

 An ecosystem consists of all plants, animals and micro- organisms (biotic factors) in an area functioning together with all of the non-living physical parts (abiotic factors) of the environment.  Abiotic → Non-living  light, temperature, soil, pH, water, pollutants.  Biotic → Living  parasitism, disease, predation WHAT IS AN ECOSYSTEM?

CHECK ME OUT!!! Corals live near the surface of the ocean water in some warm regions of the world. The corals provide a home for algae. The algae, in turn, produce food that is used by the corals. Which is a biotic factor in this ecosystem? A.The temperature of the water B.The salt content of the water C.The size of the algae population D.The amount of sunlight that reaches the coral

 Interaction of living and nonliving things means that the natural world always is changing  A population is all organisms of the same species living in the ecosystem at the same time.  Four factors affect population size.  Number of births  Number of deaths  Immigration  Emigration  Most populations are stable rather than growing endlessly ARE ECOSYSTEMS CONSTANT OR DYNAMIC?

 A limiting factor is anything that tends to make it more difficult for a species to live and grow, or reproduce in its environment.  Food  Habitat  Predators WHAT ARE LIMITING FACTORS? Abiotic FactorsBiotic Factors SunlightPathogens Soil (Type, pH) Predators and Prey WaterCompetition Natural disasterSymbiosis

 There are two types of limiting factors:  Density-dependent (depend on size of population)  Competition and predation  Density-independent (doesn’t depend on population size)  Drought, flood  Climate change  Natural disasters WHAT ARE LIMITING FACTORS?

 The maximum number of organisms the resources of an ecosystem can support is determined by its carrying capacity. WHAT IS CARRYING CAPACITY?

CHECK ME OUT!!! A disease kills most members of a predator population. Which is the most likely effect on the prey population? A.It too will be killed by the disease B.It will decrease in size C.It will increase in size D.There will be no effect on the prey

 What does the bucket represent?  What does the hose filling the bucket represent?  What does the runoff represent?  What does the holes in the sides of it represent?  Is this environment stable? Explain. CARRYING CAPACITY ANALOGY

 A change in any part of an ecosystem can affect other parts of the ecosystem  Seasonal changes  Climate change  Natural disasters  Human activity  Pollution  Habitat destruction  Invasive species WHAT FACTORS AFFECT ECOSYSTEMS?

 Ecosystems are always changing due to natural or humans causes.  Sometimes it results in ecological successions.  A succession is a natural process in which one organism replaces another.  Begins with a pioneer species able to live on limited resources.  Ends with a climax community, with fairly stable organisms adapted to the conditions WHAT FACTORS AFFECT ECOSYSTEMS?

 No Soil - Growth starts on bare rock.  Ex: volcanic eruptions, new volcanic islands, or glacier retreat.  Pioneer Plants - Lichens and Moss WHAT IS PRIMARY SUCCESSION?

WHAT IS SECONDARY SUCCESSION?  It occurs in an area where life once existed but has then been destroyed  Ex. wild fire, plant removal, hurricane  Soil is present  Secondary succession is far more common.

CHECK ME OUT!!! Which event will MOST LIKELY cause secondary succession? A.fire B.volcano erupting C.predator moving in D.seasons changing

A glacier melts and, as it retreats, it reveals a layer of bedrock. What process will occur slowly to establish a community on the bedrock? A.economic recession B.ecological succession C.primary succession D.secondary succession CHECK ME OUT!!!

ATTACKING THE EOC

CHECK ME OUT!!! When brown tree snakes were first introduced to the island of Guam, they had no natural predators. These snakes sought out and ate many of the eggs of insect-eating birds. What probably occurred after the introduction of the brown tree snakes? A.The bird population increased. B.The insect population increased. C.The bird population began to seek a new food source. D.The insect population began to seek a new food source.

CHECK ME OUT!!! If the number of herbivores in the Everglades increased, what would most likely happen to the size of the area over which a Florida panther traveled? A.It would decrease since the panthers would need to guard their prey. B.It would increase as the panthers searched more widely for the best food. C.It would increase since the panthers would have more energy to walk farther. D.It would decrease because the panthers could find enough food in a smaller area.

CHECK ME OUT!!! A population of organisms grows briefly and then stabilizes. What does the leveling off of the population size indicates? A.The population has reached the carrying capacity of the ecosystem B.The population has exceeded the carrying capacity of the ecosystem C.The population is affected by a density-independent limiting factor D.The population is no longer able to adapt to environmental changes

CHECK ME OUT!!! The number of pythons found throughout Everglades National Park has increased in recent years. These huge snakes are not native to Florida and are believed to have been released into the wild by pet owners. Wildlife biologists have initiated attempts to capture and remove these pythons. Which statement best explains the biologists’ reason for removing these pythons from the Everglades? A.The pythons could upset the territorial boundaries of native organisms. B.The pythons could adapt to overcome diseases common to native snakes. C.The pythons could prey on native organisms and cause native populations to decline. D.The pythons could begin to interbreed with native snakes and produce a more successful species.

CHECK ME OUT!!! Which of the following is an example of primary succession? A.lichens growing on rocks following a volcanic eruption B.grasses growing after a forest fire C.oak trees replacing pine trees in a forest D.non-native species introduced into a climax community

CHECK ME OUT!!! The graph of a fly population illustrates which characteristic of an ecosystem? A.carrying capacity B.limiting factors C.exponential growth D.density-independent limiting factor

CHECK ME OUT!!! Many bird species in the forests of eastern North America have very large geographic ranges. Bird species in tropical forests have very small geographic ranges. Many forest areas within the ranges of these birds are being destroyed. Scientists believe that the destruction of forests affects birds with small ranges more than birds with large ranges. As a result of the destruction of forests, birds with a small geographic range are most likely to A.lose their specific niche B.adapt to a new environment C.lose their ability to navigate D.become less susceptible to disease

Cod is a popular fish in the human diet. If too many cod were removed due to overfishing, which of these would most likely occur? A.The penguins would become extinct. B.The phytoplankton population would decrease. C.The leopard seals would eat more squid. D.The killer whale population would increase. CHECK ME OUT!!!

Horseshoe crabs are used by fisherman for bait. If the horseshoe crab population were reduced by overfishing, which of these groups of organisms would most likely decrease in number? A.plankton, razor clams, and loggerhead turtles B.sanderlings, loggerhead turtles, and striped bass C.grackles, plankton, and diamondback terrapin D.striped bass, sanderlings, and razor clams CHECK ME OUT!!!

Scientists estimate that more than 200 non-native organisms have been introduced into Everglades National Park. Which of these statements is not true about non-native organisms? A.They often form mutualistic relationships with native organisms. B.They can deplete the food sources of native organisms. C.They are often aggressive at acquiring and maintaining territory. D.They can prey on native organisms causing them to go extinct.

CHECK ME OUT!!! The use of certain chemicals by humans has caused holes to form in the Earth’s ozone layer. This allows more ultraviolet (UV) light to reach the oceans. Scientists are concerned that an increase in UV light will start killing microscopic marine algae. Which of these statements describes how the ocean food web would be affected by a large decrease in microscopic marine algae? A.There will be fewer marine animals because there will be fewer producers. B.There will be no change because the algae are very small. C.There will be more consumers because the UV light kills producers. D.There will be fewer consumers because the UV light kills decomposers.

The pesticide DDT was used to kill mosquitoes for many years. DDT entered bodies of water, moved up the food chain, and built up in the tissues of fish. When female bald eagles ate these fish, they produced eggs with very thin shells. The eggs broke when the eagles sat on their nests. The U.S. government banned the use of DDT in A B C D CHECK ME OUT!!!