Evolutionary Forces and Speciation: Understanding Cheetah Speed & Owl Evolution

1. Problem Solving • Cheetahs are the world’s fastest land mammal. They have the ability to run almost 70 mph in pursuit of prey. All other big cats can only run about 35 mph over very short distances • Do you think the cheetah’s speed is important to its survival? Why or why not? • How do you think a biologist would explain the cheetah’s speed, based on the fact that their ancestors (and all other cats) only run 35 mph • Remember, you are trying to think of a way that all cheetahs got faster over time

2. Evolution

3. Microevolution • Microevolution is the occurrence of small-scale changes in allele frequencies in a population, over a few generations. Therefore, species can still breed. • These changes may be due to several processes: • Mutation: structural changes • natural selection/artificial selection: selection of certain allele for favorable characteristics • gene flow: transfer of genes from one generation to next • genetic drift: random accumulation of genes in a population; some genes may be removed. • http://www.wadsworthmedia.com/biology/0495119814_starr/big_picture/ch16_bp.swf

4. Genetic Drift

5. Population Selection • Directional selection: • Stabilizing selection: • Disruptive selection: • http://bcs.whfreeman.com/thelifewire/content/chp23/2302001.html

6. Gradualism vs punctuated equilibrium • Gradualism - evolution proceeds at a steady pace, without the sudden development of new species or biological features

7. Punctuated equilibrium • species will experience little evolutionary change for most of their geological history • evolution occurs in localized rare, rapid events of branching speciation (called cladogenesis) • Cladogenesis - the process by which species split into two distinct species, rather than one species gradually transforming into another

9. What caused these ancestral related owls to evolve? • What is the process called?

10. Speciation • Making of a new species over time • Sexual dimorphism • http://www.pbs.org/wgbh/evolution/library/05/2/l_052_04.html • Example:Geographic isolation

11. Jean-Baptiste Lamark • 3 basic ideas: • A change in the environment causes a resulting change in the org. behavior • The behavior change causes the org. to use or not use various organs • The added use of an organ will cause it to grow & become more complex, the disuse of an organ will cause it to atrophy or waste away For Example, Lamarck thought that giraffes got longer necks by stretching to reach food. By using all of the muscles in the neck, their necks got longer. The giraffes would then pass on the extra height to their offspring, who would be born just as tall as their parents. “Use it or lose it”

12. Charles Darwin • A religious, naturalist who put together evidence from his voyage to theorize “decent with modification”. (common ancestor) • He reluctantly published On the Origin of Species in 1859 after pressure from A. Wallace. • Macroevolution

13. Darwin’s idea 4 Basic Ideas: • There are variations w/in populations of organisms and these variations can be passed to offspring • Each generation produces more offspring than survive to adulthood = Overproduction • The organism must struggle to exist. • The organism with the favorable characteristics survive better and reproduce more often, thus transmitting their traits to the next generation “Survival of the fittest” = adaptation Evolution by Natural Selection http://www.teachersdomain.org/resource/tdc02.sci.life.evo.howreally/

14. Artificial Selection: Nature provides variation, and humans selected useful variations. Example: dog breeding G. Mendel's work on genetics supported Darwin’s ideas. Natural Selection: In nature variations are selected for to change the species “fitness”. Example: giraffe neck Selection

15. Antibiotic resistance http://nortonbooks.com/college/biology/animations/ch17a04.htm Does nature always select best?

16. Evidence supporting Evolution • Fossil • Biogeography • Anatomy • Developmental • Biochemical

18. Time scale • http://www.johnkyrk.com/evolution.html

19. Nature of Fossils • A fossil is a trace of long-dead organisms. • Fossils are often found in layers of sedimentary rock, which is formed when sediment, such as dust, sand, or mud is deposited by wind and water. • Usually develop from the hard body parts which are replaced by minerals over time

20. Distribution of Fossils • The lowest stratum, or layer, in a cross section of Earth is oldest, while the top stratum is the most recent. • Fossils found within a single stratum are of the same approximate age. • Relative age of a fossil says that a given fossil is younger or older than another based on what stratum it is found • Fossil Activity • Absolute age could be estimated from radioactive dating

22. Radioactive dating • http://www.teachersdomain.org/resource/tdc02.sci.life.evo.radiodating/

23. The Fossil Record • Fossil evidence shows a long history of life on Earth. • The history of life is one of constant change and a tremendous diversity of life-forms • We can trace how organisms have changed over time by comparing fossil remains from different eras • Lyell: “Principals of geology”; explained that the geological features of the earth occurred over long periods of time.

24. Transitional fossils:

25. How did all these flightless birds, who are related, end up on different contents?

26. Biogeography Evidence • Biogeographical: is the study of the geological distribution of fossils and of living organisms. • A comparison of recently formed fossil types with types of living organisms in the same geographic area shows that new organisms arise in areas where similar forms already lived. • http://www.exploratorium.edu/origins/antarctica/ideas/gondwana2.html • How does Biogeography support evolution?

27. Anatomical Evidence • Homologous Structures – similar features originated in shared ancestor. • i.e. beaks of birds, forelimbs • Analogous Structures – same function & look alike, but developed independently • Vestigial Structures – Useful to ancestors but not to modern organism. • i.e. Whales evolved from land animals (hind legs

28. Homologous Structures

29. Analogous Structures

30. Analogous Structures

31. Vestigial Structures

32. Developmental Biology • Embryology: in early stages of life embryos are all similar, suggesting common ancestry. • What do evolutionary scientist think when the embryos all appear similar in early development?

34. Biochemical Evidence • Molecular: DNA is more similar than different among most species. • Human DNA is 99.9% alike • What does that suggest about Humans?

36. Patterns of Evolution • Convergent Evolution – Look similar, but not related at all. • i.e. Shark & porpoise

37. Divergent Evolution – 2 or more related populations or species become more & more dissimilar (Can result in new species) • i.e. Galapagos Finches, dogs

38. Coevolution – change of 2 or more species in close association w/ each other. • Newts produce a potent nerve toxin that concentrates in their skin. • Garter snakes have evolved resistance to this toxin. • The relationship between these animals has resulted in an evolutionary arms race that has driven toxin levels in the newt to extreme levels.

39. Human Evolution

40. Human Evolution

41. What is a Primate? • A primate is a member of the biological order Primates, the group that contains lemurs, lorisids, galagos, tarsiers, monkeys, and apes (including great apes and humans).

42. Primate classification

43. Mountain gorilla • Spends more time on the ground more than any other non-human primate • Feet most resemble those of humans • Found in Uganda and Rwanda

44. Australopithecus afarensis

45. Australopithecus afarensis • Lived between 3.9 and 2.9 million years ago • “Lucy” was discovered in 1974 • Bipedal = walks on 2 legs • Before the discoveries of A. afarensis in the 1970s, it was widely thought that an increase in brain size preceded the shift to bipedal locomotion. • “Selam” • 3 year old female A.afarensis discovered in Ethiopia 2006

46. Comparingskulls LUCY