Chapter 5: Evolution and Community Ecology

1. Chapter 5: Evolution and Community Ecology

2. Section 1: Evolution Describe the four primary mechanisms of biological evolution Describe how speciation and extinction affect the diversity of life on Earth. TERMS: evolution, gene mutation, genetic drift, natural selection, fitness, adaptation, artificial selection, speciation, extinction.

3. Incredible Diversity of Life • 1.5 to 1.8 million known species • Possibly 13-20 million • Tropical Rain Forests, Coral Reefs and everywhere else

4. Evolution • What makes you, YOU? What makes each species unique and different?

5. Genes • Sequences of DNA codes for each particular trait • Tall, small, blue eyes, human, goldfish, pine tree • Evolution is a change of genes over time

6. Evolution • “Change over time” • Change of Gene Pool over time • Why would genes change over time?

7. 4 Ways Evolution Occurs • Mutation • Migration • Genetic Drift • Natural Selection

8. Mutation Accidental change in DNA that can give rise to variation among individuals

9. Migration: GENE FLOW Movement of individuals into (immigration) or out of (emigration) a population Sometimes called “Gene Flow”

10. Gene Flow (Migration)

11. Genetic Drift • Evolution that occurs by chance • Natural Disasters • Run in with human nets, etc.

12. Natural Selection Process by which traits useful for survival and reproduction are passed on more frequently than those that are not

13. 3 Conditions for Natural Selection • Organisms produce more offspring than can survive. • Nature has limitations (limiting factors) • Struggle for survival

14. 3 Conditions for Natural Selection (2) Individuals vary in characteristics, some of which are heritable Not every species is same Some fish are faster, darker, smaller Genes different Heritable Differences

15. 3 Conditions for Natural Selection (3) Individuals vary in fitness, or reproductive success Survival of Fittest Fittest for its environment Adaptation: an inherited trait that increases an organisms chance of survival and reproduction.

16. Adaptations Desert plants have small or no leaves at all The insect that blends in and is able to survive may be more likely to reproduce.

17. Adaptations White coat of polar bear helps in hunting Results of natural selection all around us NATURE SELECTS Big ears of desert jack rabbit allow it to cool off quickly Long neck of giraffe allow it to reach food

18. Resistance Resistance: the ability of one or more organisms to tolerate a chemical designed to kill it • Able to survive and reproduce • Pesticide resistance • Antibiotic resistance

19. Impacts of Natural Selection: Resistance

20. Why is this a problem?

21. Artificial Selection: How Humans Use Evolution Artificial Selection: selective breeding of organisms by humans • Selecting certain desirable traits • Size, sweetness, color, shape, • Very common

22. Artificial Selection Selecting desirable traits and breeding only those with those traits.

23. Speciation • Process by which new species are generated • Can occur in a number of different ways; the most important way is called allopatric speciation– Geographic Isolation • Has resulted in every form of life on Earth— today and in the past

24. Sympatric Speciation Sympatric speciation is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region. Sympatric refers to organisms whose ranges overlap or are even identical, so that they occur together at least in some places, such a distribution may be the result of sympatric speciation.

25. The canyon is a barrier to dispersal by small mammals, and as a consequence the isolated populations can diverge.

26. Speciation: How did we get millions of species?

27. Extinction • The disappearance of species from Earth • Generally occurs gradually, one species at a time, (BACKGROUND RATE of EXTINCTION). When environmental conditions change more rapidly than the species can adapt • There are five known mass extinction events, each of which wiped out a large proportion of Earth’s species.

28. Extinction

29. Biodiversity has increased over time, but mass extinctions are also natural events (5 major events) How do we get this data? Did You Know?During the Permo-Triassic extinction 250 million years ago, 70% of all land species and 90% of all marine species went extinct.

30. Extinctions • Species gone forever • NORMAL • Mass Extinction: short period of time when large number of species go extinct (65 MYA) • Currently in mass extinction…caused by humans • Rapid climate change

31. www.lamer.lsu.edu/invasivespecies/zebramussel/problem.com Louisiana Marine Education Resources: Special Topics Invasive Species Page 125: read the article, go to the website and THEN answer the question…Why is the Zebra Mussel a lesser problem in Louisiana than the rest of the country?

32. www.lamer.lsu.edu/invasivespecies/zebramussel/problem.com The zebra mussel has completely displaced 20 native mussel species in Lake St. Clair.

33. Why is the Zebra Mussel a lesser problem in Louisiana than the rest of the country?

34. Section 1: Evolution Review Describe the four primary mechanisms of biological evolution Describe how speciation and extinction affect the diversity of life on Earth. TERMS: evolution, gene mutation, genetic drift, natural selection, fitness, adaptation, artificial selection, speciation, extinction

35. Section 1 Quiz C. A successful individual is well adapted to its environment and produces offspring that survive to pass on genes. 1) Which of the following best describes a successful individual in evolutionary terms? A. A successful individual possesses traits that are different from the traits of the rest of the population. B. A successful individual produces many offspring that possess unique traits. C. A successful individual is well adapted to its environment and produces offspring that survive to pass on genes. D. A successful individual will be well adapted to its environment and produce a few high quality offspring.

36. 2) In the history of the world, how many mass extinctions have occurred?A. 5B. 7C. 10D. 13 A. 5

37. 3) In a mass extinction, the rate of extinction exceedsA. 99 percent.B. 85 percent.C. the rate of environmental change.D. the rate of background extinction. D. the rate of background extinction

38. 4) A reintroduced population of wolves in a national park is 90% grey and 10% black, consistent with the wolf population in other regions. After several generations in isolation, the national park’s wolf population is 60% grey and 40% black. The wolf population has likely experiencedA. natural selection.B. genetic drift.C. mutations.D. migration. • genetic drift • Evolution that occurs by chance

39. 5) When the environment changes too quickly for an organism to adapt, what will occur?A) EvolutionB) SpeciationC) Genetic DriftD) Extinction D. Extinction

40. True or False 6) Two populations of a deer species are separated when a glacier forms. After the glacier melts, the two populations have become different species. This is an example of allopatric speciation. TRUE

41. Short Answer 7) A disaster wipes out 50 percent of a small population of birds. Prior to the disaster, about half the birds had a green wing patch and half had a blue wing patch. Several generations after the disaster, only 10% have a blue wing patch, and 90% have a green wing patch. What do you infer happened, and why? The bird population experienced genetic drift as the result of a sudden catastrophe. The disaster reduced genetic diversity in the population and changed the proportion of birds with a green wing patch vs. a blue wing patch.

42. Short Answer 8) Pronghorn are a species of extremely fast hooved mammal that live on the plains of western North America. They are so fast that NOcurrent North American predator can catch them. During the ice age, cheetahs occupied North America. Speculate about how pronghorn became so fast. Pronghorn probably evolved in an evolutionary “arms race” with the cheetah population. They became faster and faster to escape from cheetahs, which were probably fast enough to catch them.

44. Section 2: Species Interaction Discuss the factors that influence an organisms niche Compare and contrast predation, parasitism, herbivory Describe mutualism and commensalism TERMS: niche, tolerance, resource partitioning, predation, coevolution, parasitism, symbiosis, herbivory, mutualism, commensalism.

45. Species Interaction What resources are the plants in this picture competing for? Competition for resources all around us

46. Niche • Describes an organism’s use of resources and functional role in a community • Habitat • Food It Eats • When, How Reproduces • What organisms does it interact with

47. Niche Impacted By Tolerance and Competition • Affected by an organism’s tolerance—its ability to survive and reproduce under changing environmental conditions • Often restricted by competition

48. Tolerance Limits

49. A species with a restricted tolerance for environmental conditions is a specialist • A species with a Wide tolerance is called a generalist

50. Fundamental vs. Realized Niche Fundamental = Without competition Realized = With competition (restricted niche)