Lab 2A--Life on Earth

Transcription

1 Lab 2A--Life on Earth Geology 1402 Chapters 3 & 7 in the textbook 1

2 A comment Many people including professional scientist are skeptical of evolution or outright reject it. I am not attempting to change your mind if you are in that group. I am attempting to explain an idea that is widely accepted by the scientific community and is supported by extensive evidence. 2

3 Evolution Broad definition: Change Organic evolution: Change in life forms 3

4 Organic Evolution How life has changed through time. How all life is interrelated through ancestry. Fossils: tangible record of changes in species 4

5 Linnaean Classification Scheme System for classifying (grouping) organisms---usually by form Grouped by shared similar characteristics, that is to say, they have the same forms and look very similar. 5

6 Why classify organisms? Avoid complete chaos Determine which have a common ancestor -or- Who is related to whom 6

7 Caution Not all similarities mean a close ancestral relationship Often similarities come from adapting to a similar environment 7

8 Linnaean Classification Scheme DNA confirms relationships has changed some old ideas We find relationships with ancestors by looking at the number of differences in amino acid sequences which make up DNA 8

9 Classification of Life (Fossils & Living Groups) Kingdom Protista Kingdom Fungi Kingdom Animalia Kingdom Plantae Singlecelled organisms Source: 9

10 Classification of Life (Fossils & Living Groups) Domain: Archaea prokaryotes (bacteria) Domain: Eubacteria prokaryotes (bacteria) Domain: Eukaryota--eukaryotes Kingdom Protista Kingdom Fungi Kingdom Animalia Kingdom Plantae Lab book page 25 is out of date. Monera was split into Archaea and Eubacteria. 10

11 Linnaean Classification Kingdom Phylum Subphylum Class Order Family Genus Species 11

12 Lamarck An Idea Rejected Inheritance of acquired characteristics Organisms adapt a giraffe stretches neck to reach high leaves Giraffe can pass the longer neck to young No It doesn t happen this way. 12

13 Evolution 13

14 Evolution Idea evolved slowly Many people before Darwin suggested evolution 14

15 Darwin had read Thomas Malthus Malthus published: Essay on the Principle of Population (1798) A key idea: favourable variations would tend to be preserved, and unfavourable ones to be destroyed. Survival of the fittest. 15

16 Evolution Darwin on the H.M.S. Beagle ( ) Observed bird populations on isolated islands Recognized different species but closely related species (finches) Recognized the influence of environment on differing species. Published On the Origin of Species (1859) 16

17 Evolution Basic idea: Species descended from prior species Debated and accepted within a decade. Very remarkable accomplishment. Controversy came when humans were included in the theory 17

18 Note: Darwin never said: Humans descended from monkeys. Darwin said: Apes and humans have a common ancestor. 18

19 Natural Selection survival of the fittest the most suitable for the environment (not the strongest!) This applies to individuals and to species Variations Some individuals able to survive better and reproduce more abundantly Traits (forms) dominated 19

20 Keys to Natural Selection Variation within a population among individuals. The variation must be inheritable. Differences in reproductive success based upon those differences. 20

21 Artificial Selection Humans decide which individual will breed with which. Examples: Dog breeding Race horse breeding Cattle breeding Turkey breeding 21

22 What are the two things that every living thing does? Eat Reproduce 22

23 What are the two things that every living thing does? Eat & reproduce Pass on your traits: Eat better than your competition (survive) Reproduce more 23

24 Changes Changes in organisms or populations are often due to changes in the environment. The ones that survive are those that can adapt and tolerate the environmental changes. The successful trait must already be available in the gene pool. (Discuss) 24

25 Genes, DNA & RNA 25

26 Genetics Austria-Hungary Gregor Mendel Published in 1865 Unknown to Darwin Experimented with peas Demonstrated that traits from each parent were inherited by offspring Traits passed by genes 26

27 Genes Genes are paired one set from each parent Note: Sexual reproduction produces more variation than asexual reproduction. Genes do not mix (Key point!) Some are dominant and obvious Others are recessive and hidden Passing of genes produces variation in a population 27

28 DNA: deoxyribonucleic acid Genes are sections on the DNA. Allele: part of the gene that passes on the trait to offspring. DNA molecules: basic hereditary units DNA: information for making proteins out of amino acids Proteins make cells 28

29 DNA Each nucleotide contains one of the following: Adenine A Thymine T Cytosine C Guanine G These nucleotides determine the characteristics of an organism 29

30 Mutations How Change Happens Alterations in DNA Genes can move from one part of the DNA to another Amino acids are substituted for others: the code changes 30

31 What can cause mutations? Radiation (even ultraviolet radiation) Cosmic rays and gamma rays Chemicals Random changes in the genetic code 31

32 Are mutations good or bad? Comments from class. Discussion What do we call bad mutations in humans? Bad birth defects Good helpful traits Neutral makes no difference The call How well does the organism adapt to the environment? 32

33 RNA Two Types DNA inside the cell RNA Passes through the cell wall mrna Messenger RNA: Carries message from DNA to site where proteins are formed (outside the cell) 33

34 RNA Two Types DNA inside the cell RNA outside the cell trna Transfer RNA: Ferries amino acids to sites where they are assembled into proteins (outside the cell) 34

35 Speciation The development of new species A change in the gene pool Isolated populations diverge, that is, change and eventually cannot interbreed Now have a new species 35

36 What is a species? Species Group of organisms Similar structure, function and development Able to produce fertile offspring (in nature) Examples of non-species: Mule (female horse and male donkey) Liger (tiger and lion only happens in zoos) 36

37 Patterns of Evolution 37

38 Patterns of Evolution Divergent evolution A single species evolves into two distinct species, each with distinctive traits Adaptive radiation Many new species evolving different traits to live in different environments Convergent evolution Unrelated species exhibit similar adaptations when they inhabit similar environments (wings: birds and bats) 38

39 Divergent Evolution in Plants All had a common ancestor 39

40 Adaptive Radiation Bills Adapt 40

41 Convergent Evolution 41

42 Vestigial Structures (Remaining structures) 42

43 How fast is evolutionary change? Phyletic gradualism Small changes over a long period of time Punctuated equilibrium Very distinct changes over a very short period of time with little change in between these bursts (draw diagram) 43

44 Comparison How quickly does change happen? 44

45 Organization of Life Old way: Based upon observable traits that arise from genetic processes. Now: A clade a group of organisms that share a common ancestor based upon DNA analysis, not just observable forms. 45

46 Clade A clade a group of organisms that share a common ancestor based upon DNA analysis, not just observable forms. 46

47 Clade Based upon DNA similarity 47

48 Clade Different species within a category must have a common ancestor 48

49 Clade A clade a group of organisms that share a common ancestor based upon DNA analysis, not just observable forms. 49

50 Clade 50

51 Review of Classification of Life (Fossils & Living Groups) Domain: Archaea Domain: Eubacteria Domain: Eukaryota Kingdom Protista Kingdom Fungi Kingdom Animalia Kingdom Plantae 51

52 Any questions? Please do lab two & the supplement. Omit all questions in the lab book that have a table to fill in. 52