Ecosystems and Evolution


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Ecosystems and Evolution

  1. 1. Chapter 4, Section 1
  2. 2.  An ecosystem is all of the organisms living in an area together with their physical environment.  Oak Forest  Coral Reef  Park  Vacant Lot  Ecosystems do not have clear boundaries.  Things move from one ecosystem to another. Pollen can blow from a forest into a field, soil can wash from a mountain into a lake, and birds migrate from state to state.
  3. 3.  Biotic factors are environmental factors that are associated with or results from the activities of living organisms .  Plants (living or dead)  Animals (living or dead)  Waste Products  Abiotic factors are environmental factors that are not associated with the activities of living organisms .  Air  Water  Rocks  Light  Temperature.
  4. 4.  In order to survive, ecosystems need five basic components:  Energy  Mineral nutrients  Water  Oxygen  Living organisms.  Ecosystems contain biotic and abiotic factors.  If one part of the ecosystem is destroyed or changes, the entire system will be affected.
  5. 5.  Organisms – Any form of life.  Species – Groups of organisms that resemble one another in appearance, behavior, chemistry, and genetic makeup  Every organism is a member of a species.  Species are groups of organisms that are closely related can can mate to produce fertile offspring.
  6. 6. Other animals Known species 281,000 1,412,000 Insects 751,000 Fungi 69,000 Prokaryotes 4,800 Plants 248,400 Protists 57,700
  7. 7.  Members of a species interact in groups called populations.  Populations of different species living and interacting in an area form a community.  Populations are groups of organisms of the same species that live in a specific geographical area and interbreed.  All the members of the same species that live in the same place at the same time.  A community interacting with its physical environment of matter and energy is an ecosystem.
  8. 8. Universe Galaxies Solar systems Biosphere Planets Earth Biosphere Ecosystems Ecosystems Communities Populations Organisms Realm of ecology Communities Organ systems Organs Tissues Cells Populations Protoplasm Molecules Atoms Organisms Subatomic Particles Fig. 3-2, p. 51
  9. 9.  Habitats are places where an organism usually lives.  Every habitat has specific characteristics that the organisms that live there need to survive. If any of these factors change, the habitat changes.  Organisms tend to be very well suited to their natural habitats.  Animals and plants usually cannot survive for long periods of time away from their natural habitat.
  10. 10. 1. List the abiotic and biotic factors you see in the northern ecosystem in Figure 3 (page 100). 2. Describe a population not already mentioned. 3. Describe which factors of an ecosystem are not part of a community. 4. Why might a scientist say that an animal is becoming rare because of habitat destruction?
  11. 11. Chapter 4, Section 2
  12. 12.  Look at Figure 7 (page 103)  Discuss the characteristics that you think help the chameleon when it hunts.
  13. 13.  1809, France, Jean Baptiste Lamarck  Proposed a hypothesis for how organisms change over generations.  Over the lifetime of an individual, physical features increase in size because of use or reduce in size because of disuse.  Changes are passed on to offspring.  Lamarck was correct in thinking that the change in species is linked to the “physical conditions of life.”  Lamarck was incorrect in thinking that changes that occur during the lifetime of an individual organism are passed on directly to their offspring.
  14. 14.  1859, England, Charles Darwin  While on a voyage (HMS Beagle) noticed:  Organisms in one population differ slightly from each other in form, function and behavior.  Some of the differences are hereditary.  Proposed a hypothesis for how species change over time  The environment exerts a strong influence over which individuals survive to produce more offspring.  Some individuals, because of certain traits, are more likely to survive and reproduce than other individuals.
  15. 15. “Can we doubt…that individuals having any advantage, however slight, over others would have the best chance of surviving and of procreating their kind? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favorable variations, I call Natural Selection.” --- Charles Darwin
  16. 16.  Natural selection is the process by which individuals that have favorable variations and are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do.  Darwin proposed that over many generations, natural selection causes the characteristics of populations to change.  Evolution is a change in the characteristics of a population from one generation to the next.
  17. 17.  Darwin thought that nature selects for certain traits, such as sharper claws, because organisms with these traits are more likely to survive.  Over time, the population includes a greater and greater proportion of organisms with the beneficial trait.  As the populations of a given species change, so does the species.  Adaptation – an inherited trait that increases an organism’s chance of survival.
  18. 18.  All populations have genetic variation.  The environment presents challenges to successful reproduction.  Individuals tend to produce more offspring than the environment can support.  Individuals are better able to cope with the challenges presented by their environment tend to leave more offspring than those individuals less suited to the environment.
  19. 19.  13 or 14 separate species of finches collected from the Galapagos Islands  All birds are about the same size and color.  Most important differences between species are in the size and shape of their beaks.  Each beak is highly adapted to different food sources.
  20. 20.  Large beaks – Crush seeds in beaks  Narrow beaks – Eat insects  Short, stubby beak – Eats seeds and few insects  Sharp beaks – Poke holes in food or pick insects out of cactus
  21. 21.  Coevolution - The process of two species evolving in response to long-term interactions with each other is called.  An example is the Hawaiian honeycreeper (page 106), which has a long, curved beak to reach nectar at the base of a flower. The flower has structures that ensure that the bird gets some pollen on its head.  When the bird moves the next flower, some of the pollen will be transferred, helping it to reproduce.
  22. 22.  The honeycreeper’s adaptation is along, curved beak.  The plant has two adaptations:  The first is the sweet nectar, which attracts the birds.  The second is the flower structure that forces pollen onto the bird’s head when the bird sips nectar.
  23. 23.  Artificial selection - the selective breeding of organisms, by humans, for specific desirable characteristics.  Examples:  Dogs have been bred for certain characteristics.  Fruits, grains, and vegetables are also produced by artificial selection. Humans save seeds from the largest, and sweetest fruits. By selecting for these traits, farmers direct the evolution of crop plants to produce larger, sweeter fruit.
  24. 24.  Resistance - the ability of an organism to tolerate a chemical or disease-causing agent.  An organism may be resistant to a chemical when it contains a gene that allows it to break down a chemical into harmless substances.  Humans promote the evolution of resistant populations by trying to control pests and bacteria with chemicals.
  25. 25.  A pesticide is sprayed on corn.  It kills most of the grasshoppers.  The grasshoppers that survive have a gene that protects them from the pesticide.  The surviving insects pass on the resistance gene to their offspring.  Each time the corn is sprayed, more resistant grasshoppers enter the population.  Eventually the entire population will be resistant, making the pesticide useless.
  26. 26. 1. Describe several ways in which artificial selection can benefit humans. 2. Explain how a population of insects becomes resistant to a pesticide. 3. Describe the role of the environment in the theory of natural selection. 4. A population of rabbits evolves thicker fur in response to a colder climate. Is this an example of coevolution? Explain your answer.