Evolution

1. Evolution Year 10 Science

2. Evolution • Life appeared on earth over 3000 million years ago. • As time passed life forms changed and developed into the organisms of today. • This change is known as evolution.

3. Evolution definition • Evolution is the change in organisms over time.

4. Variation • Of all the variations that exist in animals some will help them to survive in their environment.

5. Adaptations • Nature ‘selects’ the variations with survival value. • These variations with survival value are called adaptations

6. Adaptations “Any specific inherited structural or behavioural characteristics that enhance an organisms ability to survive and reproduce in a particular environment”

7. Adaptations • Adaptations can be classified as; • structural - where the adaptation is physical • Behavioural - where the adaptation controls the way they act

8. Adaptations

9. List all the adaptations of a; • Polar bear • Lion • Camel • Rabbit

10. Variation • Variations are the result of the random assortment of chromosomes during meiosis, and the combination of gametes (sex cells) during fertilisation. • Further genetic variation occurs as a result of mutations.

11. Survival • The organisms best adapted to their environment are the most likely to produce offspring and pass on these favourable characteristics.

12. The theory of evolution • This gradual development of different species from a common ancestor is called evolution. • The word ‘evolution’ is derived from the Latin evolutus, meaning unrolled.

13. Alternatives to evolution

14. Early theories of evolution • George Buffon (1707-88) suggested that species could change. • Erasmus Darwin (1731-1802) suggested one species could change into another. • Jean Baptiste Lamarck (1744-1829) thought that characteristics acquired during a creatures lifetime then could be passed on.

15. Early theories of evolution • Charles Darwin (1809-82) was convinced that species developed from a common ancestor. • Darwin was prompted into publishing his work after Alfred Russel Wallace (1823-1913) developed an identical theory.

16. Darwin’s theories Darwin and Wallace were the co-developers of the theory of evolution by natural selection. Darwin’s theory • A species produces more offspring than can survive. • There is variations among the offspring. • Those best suited to their environment will survive and reproduce. • Favourable variations are passed down to the offspring increasing their chances of survival.

17. Natural Selection • Natural selection is sometimes called survival of the fittest. • The best adapted individuals will survive long enough to reproduce and pass on their successful characteristics to the next generation. • Those individuals that do not adapt to their environment usually die out.

18. Artificial Selection • This is the process by which humans select those characteristics that are valued. • Only the individuals with the favourable characteristics are allowed to reproduce.

19. Selection of peppered moths http://www.nhm.ac.uk/nature-online/evolution/what-is-evolution/natural-selection-game/the-evolution-experience.html

20. Peppered Mothshttp://www.techapps.net/interactives/pepperMoths.swf • 1. Draw a data table similar to the one shown below where data is recorded for moths after 5 minutes of running the simulation. • 2. Explain how the color of the moths increases or decreases their chances of survival. • 3. Explain the concept of "natural selection" using your moths as an example. • 4. What would happen if there were no predators in the forest. Would the colors of the moths change over time? Defend your answer.

21. Speciation • A species is defined as a group of organisms that normally interbreed in nature to produce fertile offspring. • The formation of a new species is called speciation

22. The evolution experience • http://www.nhm.ac.uk/nature-online/evolution/what-is-evolution/natural-selection-game/the-evolution-experience.html

23. Geographic isolation • The first step in speciation is geographic isolation. • Different populations change through natural selection and mutations. • Subspecies appear different but are still capable of interbreeding.

24. Reproductive isolation • Reproductive factors that may cause speciation are: • Mates are not recognised • Differences in mating seasons • Chromosomal changes

25. Types of evolution Divergent evolution • the idea that many new forms can evolve from a single ancestor. • The idea is that new environments are inhabited, causing the evolution of new species.

26. Types of evolution Divergent evolution - Marsupials

27. Types of evolution Convergent evolution • Occurs when organisms evolve and end up having similar adaptations. This is due to: • living in similar environments • having similar habitats and lifestyles.

28. Types of evolution Convergent evolution

29. Types of evolution Parallel evolution, • Occurs where related species evolve similar features while separated from each other. • The result is organisms that look alike and have common ancestry, but are found in different locations.

30. Types of evolution Parallel evolution - Monkeys

31. Evidence for evolution • Evidence for evolution comes from palaeontology, the study of fossils • Fossils are the preserved evidence of past life usually found in sedimentary rocks. • The fossil record allows us to trace major events in the history of life on Earth.

32. Fossils Fossils may be the: • actual remains of organisms (e.g. mammoths frozen in ice, insects trapped in a type of sap called amber) • hard parts of organisms (e.g. shells, teeth and bones) • impressions of organisms (e.g. hollowed casts, moulds where substances have replaced the organism) or • evidence of the presence of organisms (e.g. footprints).

33. The appearance of life • In 1953, S. Miller and H. Urey passed electric sparks into a gas mixture that was thought to be similar to the early atmosphere of the Earth. Organic molecules were produced.

34. The history of the world

35. Transitional forms • For major groups of organisms, transitional forms have been found in their evolutionary pathway. • Modern vertebrates appear to have evolved first as jawless fish, then bony fish, then amphibians, reptiles, birds and finally mammals. • Transitional forms provide the links between them all, including the air-breathing crossopterygian fish, and the bird-like reptile, Archaeopteryx.

36. Other evidence for evolution Anatomical studies • Comparisons of the anatomy of various organisms provide indirect evidence of their evolution from common ancestors. • These fundamentally similar structures are called homologous structures. • The basic pentadactyl limb (a limb with five digits)

37. Other evidence for evolution Embryonic development • Embryos of different life forms are very similar in the early stages of development.

38. Other evidence for evolution Body chemistry • Certain proteins are commonly in a large number of organisms. • Large differences in amino acids correspond to large differences in appearance and smaller differences are found in animals that look similar. Therefore proteins can be used to predict evolutionary relationships.

39. Other evidence for evolution The distribution of plants and animals • Biogeography is the study of the distribution of plants and animals.

40. Genetic evidence • The basic genetic code is the same in all living organisms. • Eg – the genetic make-up of the chimpanzee is 98.5% identical to a human. • This supports the idea that all living things evolved from common ancestors.

41. Human Evolution KINGDOM - Animal PHYLUM - Chordata SUB PHYLUM - Vertebrata CLASS - Mammalia ORDER - Primate FAMILY - Hominidae GENUS - Homo SPECIES - sapiens

42. Human evolution Primates Humans belong to the order Primates and have many of the features of the primate group. Primates (including us) have: • forward-facing eyes that allow binocular vision • pentadactyl digits (five fingers/toes on each limb) • four upper and four lower incisor teeth • opposable thumbs (for grasping things) • nails (not claws) on the fingers and toes • large brains for their body size • a flexible skeleton, with arms that rotate in the shoulder socket to allow them to reach behind their body (great for swinging in trees!).

43. Human evolution Humans are unusual, as we also: • walk upright (are bipedal) • have fewer and smaller teeth than the apes • have a flattened face • have a very large skull capacity, and large brain, about three times larger than that of apes • make and use tools • use various verbal and visual languages to communicate • are self-aware.

44. Possible evolutionary tree for primates

45. Hominoids • The hominoids include the lesser apes (gibbons), great apes (gorillas, chimpanzees and orang-utans) and humans. • The earliest humans almost certainly arose from the same common ancestor that produced the other hominoids. • Although they have similar ancestors, apes and humans are very distantly related, taking different evolutionary pathways millions of years ago.

46. Human family tree

47. Australopithecus (southern ape) • Lived in Africa 4-2 MYA • Fruit eating beings who developed co-operative behaviour and family structures. • There were several species • A. afarences • A. africanus • A. boisei • A. robustus

48. Homo habilis (handy man) • Lived in the African savannas 2-1.5 MYA. • Made the first stone tools. • Were scavengers not hunters. • Worked together in groups.

49. Homo erectus (upright man) • Lived 1.8 MYA and spread from Africa to Eurasia. • Developed a complex social structure and wore clothes. • Harnessed fire and communicated through sign language.

50. Homo neanderthalensis (Neanderthal man) • Appeared 35,000-100,000 years ago. • These cave dwellers used tools and buried their dead. • Subsided on meat and could speak