Vocab Darwin & Evolution (Chap 15)

Transcription

1 Vocab Darwin & Evolution (Chap 15) 1. Evolution 2. Theory 3. Charles Darwin 4. Fossil 5. Species 6. Natural variation 7. Artificial selection 8. Struggle for existence 9. Fitness 10.Adaptation 11.Survival of the fittest 12.Natural selection 13.Descent with modification 14.Common descent 15.Homologous structure 16.Vestigial organ Answer the following questions from chapter 15 in your notes label them clearly Book questions: p , p , p

2 Evolution Intro Essential Questions 1. Describe an environmental factor and how it has shaped a species. 2. Describe important events in the development of the Theory of Evolution. 3. How does selective breeding compare to natural selection? 4. What are three sources of evidence that support biological evolution?

3 Development of a Theory A theory is well supported by empirical evidence It can change as technology changes as our knowledge or information changes as we find new evidence.

4 Introduction to Darwin & Evolution Charles Darwin is known for developing a revolutionary hypothesis. Origin of a species by natural selection. Important part of today s Theory of Evolution. Useful natural variation is preserved by means of natural selection. The way life changes over time

5 Natural variation Naturally occurring differences among organisms of the same species and or same families. Caused by natural variation in genetics as a result of: Gene recombination mutation

6 In 1831 Darwin took a job on the HMS Beagle. Numerous observations Collected evidence and specimens Developed, Origin of the species by natural selection

7 From the voyage, Darwin noted the huge amounts of Biodiversity. More than what he orginally knew The characteristics varied noticeably (natural variation). Biodiversity The Galapagos islands. Every species seemed remarkably well suited to the life that it led.

8 For a species to survive Its members must stay alive They must be able to reproduce. Darwin and fitness The ability of an individual to survive and reproduce. Adaptations are behaviors and characteristics that enabled organisms to be more fit.

9 Darwin and the Finches He concluded: the different species of finches were the result of a common ancestor adapted to the environment. Applicable to other species

10 Each organism had behaviors and characteristics that help it catch food, withstand harsh conditions reproduce

11 Common descent Different species of similar organism derived from a common ancestor Descent with modification Species today look different from their ancestors because of changes in response to the environment.

12 Pinta Island Intermediate shell Pinta Tower Some factors that may influence shell type: food availability, climate, predators. Marchena James Fernandina Santa Cruz Isabela Santa Fe Floreana Hood Hood Island Saddle-backed shell Isabela Island Dome-shaped shell

13 Describe an environmental factor and how it has shaped a species. The amount of water an ecosystem gets, influences the amount of photosynthesis, which determines the amount of primary productivity, which leads to the amount of consumer diversity and biomass. 13

14 Beetles on a diet: Influence of the environment The environment drought leads to few plants that these beetles can eat. All the beetles have the same chances of survival and reproduction However food restrictions cause beetles in the population to be a little smaller than the preceding generation of beetles.

15 Beetles of a different color: influence of the environment Most of the beetles in the population (say 90%) have the genes for bright green coloration and a few of them (10%) have a gene that makes them more brown. Over time, things have changed: brown beetles are more common than they used to be and make up 70% of the population.

16 Darwin and other Scientist Some of the ideas that helped Darwin came from other scientist. Hutton and Lyell The Earth was much older than originally expected. The processes that have shaped the Earth in the past are the same 17 million years old processes that operate in the present

17 Lyell proposed his principles of Uniformitarianism Natural laws must be constant Must explain past events in terms of observable events Geological change occurs slowly and gradually Because of these geological ideas Darwin concluded that if the earth can change so can life. If the earth were millions of years old this would enable Evolution, (gradual genetic change)

18 Lamarck was a scientist who had proposed a mechanism for biological change (evolution). Based on selective use or disuse of organs. Evolution toward complexity & perfection. However his concepts lacked real evidence. Aquired traits aren t always passed to offspring Lamark s ideas identified the importance of adaptations.

19 Malthus: if the Human population continued to grow unchecked, we would run out of living space and food for everyone. War, famine, and disease help to keep the population in check. Malthus: applicable to all organisms not just humans Darwin: high birth rates and a shortage of life s basic needs caused organisms into a struggle for existence. What factors determine who dies who survives?

20 To summarize Darwin: Organisms will change over time (evolve). Because of natural variation Because of the struggle for existence Because of competion and the survival of the fittest (Natural Selection) Living species have descended, with changes from previous or different species by natural selection. (common ancestor & descent with modification)

21 Darwin s Theory 1. Natural Inherited Variation: No two members of a species are exactly a like. 2. Competition: Organisms compete with each other and their environment to survive. 3. Struggle for Existence: More organisms are born than can reach adulthood.

22 Darwin s Theory con t. 4. Survival of the fittest: The organism best fitted to their environment will survive as a result of natural selection. 5. Common Descent & Descent with Modification: All species are descended from species that lived before them.

23 Artificial Selection vs Natural Selection Both process rely on natural variation A slightly different advantage and/or disadvantage in the struggle to survive. Those well-suited to their environment will have better odds. The selection, ones that leave offspring. Both lead to changes in a population

24 Natural Selection Defined Natural selection / survival of the fittest The struggle for existence naturally selects from natural variation those traits that are most useful in the survival of the fittest.

25 Natural selection (con t.) How it works. Species that acquire or have adaptations that are favorable for their environment will pass down those adaptations to their offspring. Eventually, only individuals with those favorable adaptations will survive that is how the species changes over time, or evolves

26 Natural Selection Controlled by natural events. Changes the inherited characteristics of a population. Changes increase a species fitness in its environment.

27 Natural selection rate is influenced by Changes in the environment Abiotic or biotic: food source, predator, climate Genetic variation of population

28 Artificial Selection Humans select those traits that they find useful This is selective breeding Changes occur in the inherited characteristics of a population

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30 Artificial selection / selective breeding has influenced all domesticated animals and agricultural plants and animals.

31 Darwin s Evidence of Evolution includes The fossil record Geographic distribution of living species Homologous body structures Similarities in early development which is composed of which indicates which implies which implies Physical remains of organisms Common ancestral species Similar genes Similar genes

32 Evidence of Evolution Evidence for evolution can be found in: I. the fossil record II. III. the geographical distribution of living species homologous structures IV. Embryology V. Biochemistry

33 The fossil record shows the history of life. Life on the earth has experienced many changes Climates have changed

34 Great biodiversity

35 Shows sequences of possible life forms.

36 Transitional life forms (missing link). Prehistoric archaeopteryx Modern bird

37 Geographical distribution Organisms exposed to similar pressures can have similar characteristics but not be related. Natural selection Beaver NORTH AMERICA Capybara Muskrat SOUTH AMERICA Beaver Muskrat Beaver and Muskrat Coypu Capybara Coypu and Capybara Coypu

38 Geographical distribution (Con.t) Related organisms can be very dissimilar in characteristics Common descent and Descent with modification Natural variation

39 Hydrochoerus hydrochaeris Capybara Myocastor coypus Coypu Ondatra zibethicus Castor canadensis Muskrat Beaver

40 Homologous structures features that are similar in arrangement & in function. Have similar embryonic tissue origin DNA analysis for these organisms show many similarities in genes

41 Turtle Alligator Bird Mammal Ancient lobe-finned fish

42 The frequency of homologous structures suggest Common ancestor, unlikely that each species arose separately. Common evolutionary origin

43 Structures of organisms that do not have a common evolutionary origin, but similar function are called analogous structures. (Wings of birds and wings of dragon fly)

44 Another structure used to show an evolutionary trend is called a vestigial organ. Vestigial organs or structures have no apparent function in an organism. Neither an advantage nor a disadvantage It is thought that a structure becomes vestigial when, there is no longer pressure for that trait

45 Comparing Embryos Used to show evolutionary relationships and trends. An embryo is the earliest stage of growth and development of both plants and animals. The presence of gill slits and tails in vertebrate embryos shows that they may share a common ancestor.

46 Modern Evidence Biochemistry also provides evidence for evolution. Comparisons of DNA and RNA of different species can show how closely related organisms are genetically. Many organisms share many of the same genes Scientist have found similar genes in yeast, plants, and humans. Like all scientific theories Evolution changes with new evidence and improved technology.