Evolutionary Evidence of Evolution

Transcription

1 Evolutionary Evidence of Evolution

2 Evolution - the process in which relative changes in the genetic makeup (characteristics) of a species occurs over time

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4 Sometimes changes in populations are environmental - NOT changes in genetic make up. Country Soldier s Height (1850 s) Soldier s Height (2005) U.S. 171 cm cm France 165 cm cm Netherlands 164 cm cm Germany 164 cm cm Japan 155 cm cm

5 1. Flying fish (Exocoetus volitans) use large pectoral fins to glide in air to escape predators. Contrast how Lamarck and Darwin might account for the origin of these large pectoral fins & ability to glide. 2. A farmer spends much of her time outdoors. As a result, her skins become very tanned. What would Lamarck predict about her children? What would Darwin predict about her children? How does this reflect the key difference in their theories?

6 Radiometric Dating Atoms that are unstable (radioactive isotopes) will decay over time into different atoms. This decay occurs at a constant rate. Different atoms have different rates of decay. By looking at the ratio of atoms approximate age can be determined Different ages will require different types of isotopes (eg 14 C, 235 U, 40 K)

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9 A fossil human bone is found and was measured to contain approximately 6.25% of its original carbon-14. Carbon-14 decays to nitrogen-14 with a half life of 5.7 thousand years. How old is the bone? C-14 decays to N Half life =5700yrs 100% ---> 50% ---> 25% ---> 12.5% ---> 6.25% 1 half life 2 half lives 3 half lives 4 half lives Therefore the C-14 decayed 4 half lives 4 x 5700 yr = 22,800 yrs old

10 A scientist is radiometrically dating 3 different fossils. Fossil A is dated using element A (half-life = 50 yrs), fossil B is dated using element B (half-life = 100 yrs), fossil C is dated using element C (half-life = 1000 yrs). If each fossil contains 50% of the radioactive element, and 50% of the daughter element, which one is oldest? 10

11 Questions A sample of igneous rock is found to contain the radioactive parent and daughter isotope uranium-235 and lead-207 in the ratio of 12.5% : 87.5% respectively. Assuming that no lead was present when the rock first formed, estimate the age of this sample. Parent isotope Daughter isotope Half Life (years) 235 U 207 Pb 713 million

12 Parent isotope Daughter isotope Half Life (years) 14 C 14 N 5730 A fossil skull of Homo neanderthalensis is discovered in northern Europe and is tested using Carbon-14 dating. Palaeontologists are curious about whether the Neanderthal was living at the same time as members of H. sapiens, also thought to have been living in the same area of Europe 45,000 years ago. Measurements suggest that, of the original amount of carbon-14 isotope present in the skull when the Neanderthal died, only 1.56% remains in the fossil fragment. a) How old is the fossil? b) Could the Neanderthal have coexisted with Homo sapiens? Explain?

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14 Evidence of Evolution 1. Work as a group to go through the activities/ questions. 2. At the end, develop a summary of the information. SUMMARY STATEMENTS: - What can scientists learn about evolution from fossils? - How can scientists use fossils? - What examples do you have? 14

15 EVIDENCE - 1 provide evidence for the history of life glyptodont fossil vs modern day armadillo

16 Fossils include: hard body parts (shells, teeth, bones), impressions of burrows, footprints, scats, chemical remains

17 bodies trapped in sediments ---> layers of sediment deposit on top ---> harden into sedimentary rock ideal: oceans, volcanic ash, peat bogs, frozen ground, amber

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19 Transitional fossils show intermediate links between groups of organisms, and share characteristics to two separate groups eg. Archeopteryx is the link between ancient reptiles and modern birds

20 Ida - "The Day After" 20

21 Evidence 2 Geographical Distribution of Species

22 Evidence 3 Geographical Distribution of Species

23 Geographical Distribution of Species places that have separated in more recent evolutionary time show a similarity in their species. eg Tasmania vs Australia places that have been isolated for long periods of time show unique species diversity. eg. Madagascar vs Africa

24 Evidence 3 Embryology related organisms have embryos that show similar stages of development (i.e., common ancestor)

25 Evidence 4 Anatomy species that have a close relationship show similar structure structures of the same origin may be used for different purposes eg bat wing and human arm (called homologous structures)

26 Evidence 4 Anatomy Some structures may appear similar but have a different evolutionary origin eg. Moth wing and Bird wing (called Analogous Structures)

27 Evidence 4 Anatomy Some structures may appear similar but have a different evolutionary origin eg. Moth wing and Bird wing (called Analogous Structures)

28 Evidence 5 DNA

29 Evidence 5 DNA Closer Species show similar DNA structure

30 Homework 1. Ensure that you have completed the activity cards & summaries (to be posted). 2. Pg 340 # 3, 5, 7, 8, 10-12,16 30