IBDP>CORE TOPICS> TOPIC 5 ECOLOGY AND EVOLUTION>TOPIC 5.4 EVOLUTION
Assessment statements
5.4.1 Define evolution.
5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
5.4.3 State that populations tend to produce more offspring than the environment can support.
5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival.
5.4.5 State that the members of a species show variation.
5.4.6 Explain how sexual reproduction promotes variation in a species.
5.4.7 Explain how natural selection leads to evolution.
5.4.8 Explain two examples of evolution in response to environmental change; one must be antibiotic resistance in bacteria.
5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
5.4.3 State that populations tend to produce more offspring than the environment can support.
5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival.
5.4.5 State that the members of a species show variation.
5.4.6 Explain how sexual reproduction promotes variation in a species.
5.4.7 Explain how natural selection leads to evolution.
5.4.8 Explain two examples of evolution in response to environmental change; one must be antibiotic resistance in bacteria.
Something interesting……future humans
Based on the video….
1. What is evolution?
2. Why do changes happen in organisms?
1. What is evolution?
2. Why do changes happen in organisms?
Watch the videos and answer the questions-
5.4.1 Define evolution. 5.4.2 Outline the evidences of evolution
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3. What do you understand by the term "common descent"?
4. When changes occurs in a species it is called ____________ and when species come and go it is ___________ (macroevolution/microevolution) 5. How can you say that every organism is related to the other? 6. Why is the sentence "humans evolved from chimps" a common misconception? 7. What can be considered "evidences" to prove common ancestry? 8. What are transitional fossils? 9. FIND OUT: Humans have been interfering with nature for long (e.g. domestication and breeding of animals and plants). Does this have an effect on evolution? Questions 1 to 9 to be submitted by 16th Sept 2014…7 am. (Please submit a pdf version) |
Evolution is the cumulative changes taking place in the heritable characteristics of a population.
Watch the videos and answer questions 10 to 16. submission 17th Sept 2014…..7 am.
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10. How do fossils help us know about evolution?
11. What are vestigial organs? Why do organisms possess these structures? 12. "Different organisms have same basic structure" what does this indicate? 13. FIND OUT: Humans, bats and whales have pentadactyl structures (five fingered limbs). Though these three organisms have completely different lifestyle, they have the same basic structure and position of limb bones. How is this important for evolution? |
The evidences for evolution includes:
1. The fossil record.
As the scientists started to study fossils they realised that these were not identical but had similarities with existing organisms. This suggested that organisms changed over time.The existence of fossils of extinct species such as Archaeopteryx (a dinosaur), Trilobites (a crustacean) is evidence that species can become extinct. The transitional fossils demonstrate the presence of intermediate forms showing characteristics of two different groups.
1. The fossil record.
As the scientists started to study fossils they realised that these were not identical but had similarities with existing organisms. This suggested that organisms changed over time.The existence of fossils of extinct species such as Archaeopteryx (a dinosaur), Trilobites (a crustacean) is evidence that species can become extinct. The transitional fossils demonstrate the presence of intermediate forms showing characteristics of two different groups.
2. Homologous structures indicate the range of structures that have radiated from an original design. Comparative anatomy of groups of animals or plants shows certain structural features are basically similar, implying a common ancestor. The pentadactyl (five-fingered) limb with one upper arm bone, two lower arm bones, wrist and 5 sets of tarsals and metatarsals is common to all vertebrates (lost in most fish) and evolved to the wing of a bird, fin of a whale and leg of a dog. Homologous structures are those that are similar in shape in different types of organisms despite being used in different ways.
3. Selective breeding of domestic animals. Man has been artificially selecting and breeding particular animals. This has given rise to new breeds of domestic and farm animals with various inherited characteristics. This demonstrates that breeding causes variation. |
5.4.2 to 5.4.6 Variation and evolution
Darwins theory of natural selection
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14. What are the facts and the inferences of the theory?
15. Who was the other contributor to this theory? 16. FIND OUT According to the facts given by Darwin "Every individual is different from each other". What do you understand by this? What do you think are the causes of these differences? |
Extension to the Darwin's theory- making of the theory
Populations tend to produce more offspring than the environment can support.( populations tend to multiply geometrically, while food sources multiply arithmetically)
Variation refers to the differences between individuals of the same species. These differences may be the result of the genotype or because of environmental influences or both.
Variation refers to the differences between individuals of the same species. These differences may be the result of the genotype or because of environmental influences or both.
5.4.7 and 5.4.8 THE RISE OF SUPER BUGS….
Watch the videos and answer questions 17 to 20. submission 18th Sept 2014…..7 am.
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17. What is natural selection?
18. Why does natural selection happen?
19. How does natural selection lead to evolution?
20. FIND OUT
Natural selection can cause problems. Do you agree? How far are humans responsible for these problems explain with examples other than the one in the videos.
18. Why does natural selection happen?
19. How does natural selection lead to evolution?
20. FIND OUT
Natural selection can cause problems. Do you agree? How far are humans responsible for these problems explain with examples other than the one in the videos.
Natural selection and evolution.
The theory of natural selection was postulated by Charles Darwin who described it as 'survival of the fittest'. The postulates are-
- There is genetic variation within a population and these variations can be inherited.
- There is competition for survival thus populations tend to produce more offspring than the environment can support.
- Environmental selective pressures lead to differential reproduction.
- Organisms with beneficial adaptations will be more suited to their environment and more likely to survive to reproduce and pass on their genes. This is natural selection.
- Over generations there will be a change in allele frequency within a population, leading to evolution.
Examples of evolution
Antibiotic resistance in bacteria is a common problem. It results from the transfer of a gene that gives resistance to a specific antibiotic usually by means of a plasmid to a bacterium. Some bacteria will then have this gene and become resistant to the specific antibiotic while others will lack the gene and so will die if exposed to the antibiotic. Over time, the non-resistant ones will all die off as doctors vaccinate patients, but the resistant ones will survive. Eventually, the resistant ones will be the only ones left as a result of natural selection and so a new antibiotic must be created. However, this has to be done on a regular basis as the bacteria keep evolving and become resistant to multiple antibiotics.
The Peppered Moth is another example of evolution in response to environmental change. There are two types of these moths, one species has a light colour while the other one is darker. When Britain begun industrialising, the soot from the factories would land on trees and so the darker moths then had an advantage over the light ones as they could easily hide from predators. Before the soot, both types of moths were eaten by predators however now that the darker ones were able to hide the lighter ones got eaten more often.The population of the darker moths rapidly increased while that of the lighter ones rapidly decreased until only the dark moths were left. All the lighter moths were less adapted to the environmental change and so they could no longer survive in that new environment.
The Peppered Moth is another example of evolution in response to environmental change. There are two types of these moths, one species has a light colour while the other one is darker. When Britain begun industrialising, the soot from the factories would land on trees and so the darker moths then had an advantage over the light ones as they could easily hide from predators. Before the soot, both types of moths were eaten by predators however now that the darker ones were able to hide the lighter ones got eaten more often.The population of the darker moths rapidly increased while that of the lighter ones rapidly decreased until only the dark moths were left. All the lighter moths were less adapted to the environmental change and so they could no longer survive in that new environment.
References-
Damon, Alan et al, Higher level Biology for the IB diploma. Pearson Baccalaureate
Clegg, CJ, Biology for the IB diploma. London: Hodder Murrray, 2007, 978-0340926529
Taylor, Stephan, Science Video resources Wordpress,
Burell, John. Click 4Biology(online)
http://ibguides.com
http://www.ib.bioninja.com.au/ib-home/
All picture have been downloaded from Google images for educational purpose only
Damon, Alan et al, Higher level Biology for the IB diploma. Pearson Baccalaureate
Clegg, CJ, Biology for the IB diploma. London: Hodder Murrray, 2007, 978-0340926529
Taylor, Stephan, Science Video resources Wordpress,
Burell, John. Click 4Biology(online)
http://ibguides.com
http://www.ib.bioninja.com.au/ib-home/
All picture have been downloaded from Google images for educational purpose only