Ever-changing Populations

1. What is this Evolution stuff? Ever-changing Populations

2. Evolution: Change in allele frequencies in a population’s gene pool over time. Evolution does not occur in individuals… but in populations.

3. Population: Interbreeding group of individuals (onespecies) in a given geographic area

4. Gene pool: The collection of genes (alleles) of a population

5. Change in base sequence…Heritable (receivable) change in a gene… →Gives rise to new genes → Can be harmful → May be beneficial Mutation:

6. Gene flow: Genes being added (immigration) or taken away (emigration) from a gene pool

7. The Voyages of Charles Darwin

8. The Galapagos Islands are about 525 miles from South America, at the equator.

9. Natural selection: How an env. favors or disfavors certain phenotypes: The fittest survive and reproduce. Genes of less fit individuals are lost.

10. Natural Selection: 4 Principles • 1. Overproduction of offspring • Most “fit” will survive • Inc. competition for resources

11. Natural Selection: 4 Principles • 2. Variation • Traits (phenotypes) differ • Can affect ability to find / utilize food, H2O, shelter, O2, to reproduce, etc.

12. Natural Selection: 4 Principles • 3. Adaptation • Leads to h in freq. of particular structure, physiological process, or behavior – allowing org. to survive /reproduce better. • Fitnessused to describe reproductive success

15. Natural Selection: 4 Principles • 4. Descent with Modification • Environment Changes – Nat. Sel. yields pops. w/new phenotypes to adapt • New pops. live differently from ancestors

16. Better adapted than it’s ancestors? With its sheer strength and deadly, bacteria-ridden saliva, the Komodo dragon is the top predator in its range.

17. More about the Komodo… • Komodo dragons have thrived in the harsh climate of Indonesia's Lesser Sunda Islands for millions of years, although amazingly, their existence was unknown to humans until about 100 years ago. • Reaching 10 feet (3 meters) in length and more than 300 pounds (136 kilograms), Komodo dragons are the heaviest lizards on Earth. They have long, flat heads with rounded snouts, scaly skin, bowed legs, and huge, muscular tails. • As the dominant predators on the handful of islands they inhabit, they will eat almost anything, including carrion, deer, pigs, smaller dragons, and even large water buffalo and humans. When hunting, Komodo dragons rely on camouflage and patience, lying in wait for passing prey. When a victim ambles by, the dragon springs, using its powerful legs, sharp claws and serrated, shark-like teeth to eviscerate its prey. • Animals that escape the jaws of a Komodo will only feel lucky briefly. Dragon saliva teems with over 50 strains of bacteria, and within 24 hours, the stricken creature usually dies of blood poisoning. Dragons calmly follow an escapee for miles as the bacteria takes effect, using their keen sense of smell to hone in on the corpse. A dragon can eat a whopping 80 percent of its body weight in a single feeding.

18. Natural Selection: 4 Principles (review) • Overproduction of offspring • Variation • Adaptation • Descent with modification

19. Types of Natural Selection Stabilizing Selection • Env. will eliminate individuals at extremes of population. • Example: • small babies-less healthy • large babies-trouble being born • avg. babies – more fitness • Giraffes: Long necks are better for getting a mate, short necks are better for drinking water. Medium-sized necks have been selected for.

20. Stabilizing Selection:

21. Types of Natural Selection Stabilizing Selection Disruptive Selection • Environment favors individuals at extremes – not intermediates • Can split population into subgroups • Example: • birds live in area where medium-size seeds are less common – birds with large/small beaks eating large/small seeds are more fit

22. Disruptive Selection:

24. Types of Natural Selection Stabilizing Selection Disruptive Selection Directional Selection • environment favors individuals at oneextreme • Example • Lighter colored moths more easily seen, birds eat them more freq.

25. Directional Selection:

26. Types of Natural Selection (review) Stabilizing Directional Disruptive

27. Species: group of individuals that share some features and caninterbreed

28. Speciation: Change in a species > Can be very slow, or relatively rapid.

29. What causes Speciation? Geographic barriers like rivers and mountains

30. What causes Speciation? Reproductive barriers – like different anatomy or incompatible gametes

31. What causes Speciation? Temporal barriers – reproduce at different times

32. What causes Speciation? Behavioral barriers: blocked by courtship rituals & other habits • Three male king penguins follow a female in a courtship ritual.

33. What causes Speciation? (review) Reproductive Barriers Geographic Barriers Temporal Barriers Behavioral Barriers

34. Evolution ENSI Lesson on Human Evolution- Hominoid Chromosomes

36. Patterns of Evolution • Macroevolution • large scale changes over long periods of time. • Some important patterns …

37. Mass extinctions Large numbers of species died out Typically due to habitat change that was too rapid to adapt to.

38. Mass extinctions Large numbers of species died out

39. Website

40. Gradual extinction • Cause: other organisms, climate change, disasters • Gradual ext. and speciation occur at approx. same slow rate Thylacine (Tasmanian Wolf) A carnivorous marsupial. The last one died in a zoo in 1933.

41. Adaptive radiation (divergent ev.) A species changes into many different forms

42. Convergent evolution Unrelated organisms evolve similarities (analogous structures) when adapting to similar environments; ex: shark, seal, dolphin, fish = streamlined bodies, fins for movement

43. Coevolution Two species evolve in response to changes in each other ex: certain flowers attract certain insects to pollinate • Tangle-veined fly (Prosoeca ganglbaueri) visits a small flowering herb called the mountain drumstick (Zaluzianskya microsiphon) in the Drakensberg Mountains of southern Africa.

44. Coevolution • Island of Mauritius • Humans & their livestock inhabited island in 1581 • Last Dodo seen in 1681

45. Coevolution Calvaria Tree Only about 15 trees left on island, each just over 300 years old. Dodo would eat seeds. Only partially digested seeds would ever germinate…

46. Homologous Structures Similar body structures inherited from common ancestry Examples…

47. Homologous Structures

48. Homologous Structures

49. Gradualism Evolution proceeding in small, gradual but continuous steps

50. Punctuated equilibrium Long periods of stable evolution suddenly have periods of rapid change show in fossil record