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Do Now:

Do Now:. Identify each animal & identify each as either a primary consumer or secondary consumer. Identify the relationship between them. Explain how these organisms are important to each other. Do Now:. primary consumer & secondary consumer Predator/Prey relationship.

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Do Now:

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  1. Do Now: • Identify each animal & identify each as either a primary consumer or secondary consumer. • Identify the relationship between them. • Explain how these organisms are important to each other.

  2. Do Now: • primary consumer & secondary consumer • Predator/Prey relationship. • Importance in terms of population control/balance/health/evolution.

  3. Chapter 5: Ecosystems & living organisms

  4. Evolution • A process of change through time

  5. Theory of Evolution • Suggests that existing forms of life on earth have evolved from earlier forms over long periods of time • Evolution accounts for the differences in structures, function, and behavior among life forms as well as changes that occur in populations over many generations

  6. (C) Charles Darwin

  7. 1. Overproduction • Within a population, there are more offspring produced in each generation than can possibly survive.

  8. 2. Competition • Natural resources; like food, water, and space available to a population is limited • Because there are many organisms with similar nutritional requirements, there must be competition between them for the resources needed to survive

  9. (C) Darwin • Charles Darwin devised a theory of evolution based on variation and natural selection as seen in the Galapagos islands. • Included in his theory were six main ideas: 1. Overproduction 2. Competition 3. Survival of the Fittest 4. Natural Selection 5. Reproduction 6. Speciation

  10. Do Now: • List the six main ideas of Darwin’s Theory of Evolution: 1. 2. 3. 4. 5. 6.

  11. Competition • Different species living in the same environment, or habitat, may require the same resources. When the resources are limited, competition occurs among the species. Intraspecific: competition within a population

  12. Competition 2.Competition- is the struggle between different species for the same limited resources. The more similar the needs of the species, the more intense the competition. Interspecific: competition between different species.

  13. Competition 3.Each species occupies a niche in the community. A niche is the role the species plays, and includes the type of food it eats, where it lives, where it reproduces, and its relationships with other species.

  14. Competition 4.When two different species compete for the same niche in a community, the weaker species is usually eliminated establishing one species per niche in a community.

  15. Do now: • How do the processes of _______ contribute to natural selection? • overproduction of offspring • individual variation among individuals in a population • environmental limits on population growth (natural selection) • differential reproductive success • HINT: Do not simply describe these four observations; connect them into an integrated response.

  16. Do Now: Sample Answer • Because more offspring are produced in a population than survive to reproduce and because individuals vary within the population, some individuals will be better adapted (more fit) for the current environmental conditions. These individuals have a greater likelihood of reproducing and passing their fitness to their offspring. As a population approaches the carrying capacity of its environment, the individuals with the greatest fitness are most likely to survive and reproduce. • This is an ongoing process as organisms respond to changes, however minute, in their environment.

  17. Do Now: • Define ecological niche and explain the role of limiting resources in the determination of an organism's ecological niche.

  18. Do Now: Answer • Every organism is thought to have its own role, or ecological niche, within the structure and function of an ecosystem. An ecological niche is basically determined by all of a species’ structural, physiological, and behavioral adaptations. Any resource at a suboptimal level relative to an organism’s need for it or at a level in excess of an organism’s tolerance for it is a limiting resource. • The resources can include mineral content of soil, extremes of temperature, and amount of precipitation. The limiting resources can affect part of an organism’s life cycle. For example, the ring-necked pheasant was introduced in North American but didn’t survive in the southern United States because the eggs can’t develop properly in the warm southern temperatures.

  19. Limiting Factors Gause’s Experiments

  20. Limiting Factors Gause’s Experiments

  21. Which type of Competition?

  22. Interspecific Competition!

  23. Competitive Exclusion: one species is excluded from a portion of a niche by another as a result of interspecific competition. (2 species with identical niches can’t coexist.)

  24. Do Now: • The Norway rat and the black rat were both introduced to this country from Europe. The Norway rat is found only in cities and inhabits most cities in the U.S. The black rat can live in cities and rural areas but in New Jersey is ONLY found in rural areas. Some cities in New Jersey, which previously had only black rats, now have only Norway rats. Discuss this phenomenon in terms of competitive exclusion, resource partitioning and limiting resources.

  25. Do Now Answers: • No two species can indefinitely occupy the same niche in the same community because competitive exclusion eventually occurs. • Interspecific competition for limiting resources will result in the competitive exclusion of one of the species. In this particular case, the black rat was driven from the cities through competition of resources with the Norway rat. • The two species of rats do not show evidence of resource partitioning that would allow the rats to coexist in the same habitat. Instead the black rat has confined its habitat to the rural areas while the Norway rat has taken over city existence.

  26. Limiting Factors Gause’s Experiments

  27. Variations among members of a population make some of them better adapted to the environment than others • It is generally the best-adapted individuals that will survive. • The environment is the agent of natural selection determining which species will survive. 3. Survival of the Fittest

  28. Survival of the Fittest

  29. Survival of the Fittest

  30. (4) Natural Selection Traits which are beneficial to the survival of an organism in a particular environment tend to be retained andpassed on, and therefore, increase in frequency within a population. (variation)

  31. (4) Natural Selection Traits which have low survival value to an organism tend to diminish in frequency from generation to generation.

  32. (4) Natural Selection If environmental conditions change, traits that have low survival value may now have a greater survival value. Therefore, traits that prove to be favorable under new environmental conditions will increase in frequency. (differential reproductive success) Industrial Melanism

  33. Do Now: • Charles Darwin concluded that inherited traits favorable to survival would be preserved over time. • Look at this graph of a DDT spray program aimed at eliminating a mosquito species. Explain the data contained in the graph at point I –VI and relate the graph’s data to Darwin’s conclusion.

  34. Answer • The mosquito population is at a sustainable level (I). When DDT is initially introduced into the population, the population of mosquitoes declines (II) as most of the mosquitoes have no resistance to the DDT chemical. • However due to natural variations within the mosquito population, a few mosquitoes do have a trait (resistance to DDT) that improves their chances of survival and reproductive success (III). • Those individuals that possess the most favorable combination of characteristics (better adapted for the DDT environment) are more likely to survive, reproduce, and pass their traits to the next generation – differential reproductive success (IV). • As the spray program ends, the mosquito population grows (V) until it reaches a size where the limiting resources of the environment would keep the extent of the population level (I and VI).

  35. Do Now: How did an Insects resistant to insecticides occur?

  36. Ex: Insects resistant to insecticides • Genetic make-up of some insects make them resistant to the effects of insecticides • Before the widespread use of insecticides, this trait was of no particular survival value • With the increased use of insecticides, this trait developed a very high survival value • Therefore, insects with resistance to insecticides survived and reproduced much more successfully than those lacking the trait • As a result, the frequency of insecticide resistance has increased greatly in insect populations Important! The trait already exists within the genetic make-up of the organism.

  37. Ex: Rats resistant to rodenticidesNot Immune!

  38. 5. Reproduction • Individuals that survive and then reproduce transmit these variations to their offspring

  39. Do Now: • The diagram represents a tree containing three different species of warbler, A, B, and C. Each species occupies a different niche. A fourth species, D, which has the same environmental requirements as species B, enters the tree at point X. Members of species B will most likely  (1.) live in harmony with species D  (2.) move to a different level and live with species A or species C  (3.) stay at that level but change their diet  (4.) compete with species D

  40. Natural selection can favor Resource Partitioning: differences in resource use among species.

  41. Resource Partitioning

  42. Effect of community complexity on Species richness

  43. 6. Speciation • The development of a new species occurs as variations or adaptations accumulate in a population over many generations. • Ex: primitive human  present man? • Canis lupus Canis familiaris?

  44. Speciation? “El Chupacabra”

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