1. Ecosystems and Evolutionary Change Environmental Sciences: Towards a Sustainable Future Chapter 5

2. This Lesson Discusses Those Factors That Contribute to Ecosystem Change Change is inevitable. Adaptations, natural selection and sexual reproduction are the tools of change. Differential vulnerability of each species to environmental change. Change on a geological time scale.

3. Selection of Traits and Genes: Definitions DNA: molecule that carries the genetic code of an organism Chromosome: structure on which DNA of an organism is arranged

4. Selection of Traits and Genes: Definitions Gene: segment of DNA that codes for a particular protein Allele: form of a gene. Each person carries 2 alleles for each gene Trait: certain characteristic of an organism; e.g., hair color, disease resistance, intelligence

5. The Link Between DNA and Traits

6. Selection by the Environment Genetic variation: genetic differences that exist among individuals Gene pool: sum total of all the genes that exist among individuals of a species

7. Selection by the Environment Differential reproduction: some individuals in the population reproduce more than others

8. Change Through Selected Breeding Selected breeding: artificial selection e.g., selection for dogs with shorter legs Process is repeated in subsequent generations

9. Change Through Natural Selection Factors of environmental resistance act as selective pressures Natural selection: the process by which evolution occurs Individuals which possess certain traits produce more viable offspring than individuals lacking those traits

10. Recipe for Change GENES ENVIRONMENT ADAPTATIONS NATURAL SELECTION: For? or Against?

11. Adaptations

13. Selective Pressure

14. Genetic Variation Generated by sexual reproduction Each gamete (sperm and egg) carries one set of alleles Fertilization or the union of sperm and egg results in the combination of both sets of alleles = unique individual

15. Genetic Variation in Eye Color

17. Genetic Variation Mutation: any inheritable change in the DNA molecule. Lethal mutation: results in death of organism.

18. Genetic Variation Neutral mutation: neither harms nor benefits organism. Mutations are rare and random events. Spontaneous Induced

19. Speciation Process by which separate populations of a single species develop into distinct species. Selective pressures on each population are different.

20. Speciation Populations of a given species become isolated from each other. No interbreeding between populations occurs.

21. Speciation: Foxes

22. Speciation: Galapagos Finches

23. Developing Ecosystems All ecosystems have the same functional “parts”. Only the “actors” who play these parts are different across ecosystems. Example: Buffalo vs. Kangaroo

24. Developing Ecosystems Why have species evolved so differently across ecosystems with similar environmental conditions? (Hint: remember the recipe for change.)

25. The Limits of Change New selective pressures require species to: adapt, migrate, or go extinct.

26. The Limits of Change Factors affecting species’ adaptation to environmental change: Geographical distribution. Habitat specialization. Genetic variation. Size of individual. Reproductive rate.

27. Will The Panda Survive In A Changing Environment?

28. Evolution Natural selection occurs slowly. Punctuated equilibrium theory: model of evolution in which there is little change in a balanced ecosystem. A shift in the environmental conditions will alter selective pressures, thereby causing rapid changes in the species until balance is restored.

29. Geological Time Scale

30. Drifting Continents 250 million years ago Today

31. Plate Tectonics

32. Tectonic plates: slabs of rock that make up the earth’s surface; 14 major plates Tectonic plates move approximately 6cm per year 4 basic tectonic plate interactions

33. Divergent Boundaries Rising convection currents force apart plates Result: mid-ocean ridges, rift valleys

34. Transform Boundaries Two plates slide past each other Result: fault lines marking major earthquake activity; San Andreas fault

35. Convergent Boundaries Plates moving toward each other Result: oceanic plate moves under a continental plate; Cascade mountains

36. Continental Plate Collision Formation of mountain ranges http://www.hcrhs.hunterdon.k12.nj.us/science/helen.html What happened when Mount St.Helens erupted?

37. Tectonic Movement: Climatic Effects Changing position on earth’s surface Movements alter ocean currents Mountain formation alters air currents

38. Evidence Of Evolution Fossil record Species evolution DNA nucleotide similarities and differences

39. Stewardship of Life: A Question Revisited Why is the fifth principle of sustainability important in understanding the following issues? Endangered species Agriculture Biotechnology Medicine