Topic 5:  Evolution and Biodiversity


DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Trait is a specific characteristic of an individual. For example, their hair color or their blood type. Traits are determined by genes, and also they are determined by the interaction with the environment with genes. And remember that genes are the messages in our DNA that define individual characteristics.

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Natural Selection 

  1. In biology, evolution is the change in the heritable characteristics of a species over many generations and relies on the process of natural selection – This will learn later

  2. The theory of evolution is based on the idea that all species are related and gradually change over time.

  3. Evolution relies on there being genetic variation in a population which affects the physical characteristics (phenotype) of an organism.

  4. Some of these characteristics may give the individual an advantage over other individuals which they can then pass on to their offspring


Evidence of Evolution 






ratificial selection



Archaeological Dig



  1. Fossils are the preserved remains or traces of animals, plants and other organisms from the past

  2. Paleontology, also spelled palaeontology or palæontology, is the scientific study of life that existed in the past. It includes the study of fossils to classify organisms and study interactions with each other and their environments

  3. They can either be direct (body fossils such as bones, teeth and shells) or indirect (trace fossils such as footprints)

  4. The fossil record is the sum of all discovered and undiscovered fossils and their relative placement in rock. Simply the deeper the fossil is the older it is.

  5. In geology and related fields, a stratum (plural: strata) is a layer of sedimentary rock or soil, that was formed at the Earth's surface with internally consistent characteristics that distinguish it from other layers.

  6. Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today. Therefore the fossil record shows a gradual change of a species over time






  1. Simple organism in the older start and complex organism in the new sraata

  2. Fossil appear with given ecological relations ship

  3. Fossil provide the the link between strata





  1. Comparative anatomy of groups of animals or plants show certain structural features are basically similar.

  2. Structures or anatomical features having similar basic structure as in other species are said to be homologous

  3. Homologous structures are similar structures in organisms that evolved from a common ancestor. (Same ancestor and structure, different function) These structures may or may not have the same function in the descendants. However they all have the same basic pattern of bones.

  4. For example, the pentadactyl limb is a bone arrangement all  present in mammals, birds, amphibians and reptiles based on a five digit limb

  5. Despite possessing similar bone arrangement, there are different functions depending on the mode of locomotion:

    1. Human hands are adapted for tool manipulation

    2. Bird and bat wings are adapted for flying

    3. Horse hooves are adapted for galloping

    4. Whale and dolphin fins are adapted for swimming

  1. Analogous structures are similar structures having the same function, but do not share a common ancestor (same function, similar structure, different origin)

  2. The structures are similar because they evolved to perform the same function, not because they were inherited from a common ancestor

  3. For example the wings of a bat and a bird both look similar and have the same function, however their wings evolved independently in the two groups of animals

  4. Vestigial structures are structures that no longer serve a purpose in the organism such as the human tail bone or a whale pelvis. Evolution has reduced their size because the structures are no longer used


ratificial selection


  1. Selective breeding of domesticated animals shows that artificial selection can cause evolution

  2. Selective breeding (also called artificial selection) is the process where humans breed animals or plants for particular traits

  3. Individuals which show the most desirable traits are chosen to breed together, therefore the next generation will have an increased frequency of the desired trait.

  4. This process is repeated for many generations until the entire population shows the desired trait

  5. Selective breeding provides evidence of evolution as targeted breeds can show significant variation in a relatively short period

    1. Selective breeding of plant crops has allowed for the generation of new types of foods from the same ancestral plant source. This includes broccoli (modified flower buds), cabbage (modified leaf buds), and kale (modified leaves)

    2. Example: Carnis Lupus (Gray Wolf) now is the common ancestor for a wide variety of dogs from sheep dogs, beagles and greyhounds

Hugging Monkeys



  1. If two populations of a species become geographically separated then they will likely experience different ecological conditions.

  2. If separated for too long the two populations will adapt to the different environmental conditions and gradually diverge from one another.

  3. When two populations can no longer interbreed and produce fertile, viable offspring they are considered to be separate species.

  4. The evolutionary process by which two related populations diverge into separate species is called speciation

  5. The degree of divergence will depend on the extent of geographical separation and the amount of time since separating occurred.

  6. The degree of divergence will gradually increase the longer they are separated

    1. Populations located in close proximity that separated recently will show less variation (less divergence)

    2. Distant populations that are separated for a longer period of time will show more variation (more divergence)


  1. Define evolution. ​







  1. Define strata and paleontology.











  1. Explain three pieces of evidence that fossils provide that evolution has occurred.​




















to explain how selective breeding has lead to evolution in a species.


















  1. Explain the process of artificial selection using selective breeding.





















  1. Contrast analogous structures and homologous structures.





















  1. Contrast convergent evolution and adaptive radiation.





















  1. State an example of analogous structures.




















  1. State an example of homologous structures.




















  1. Define vestigial structure.




















  1. State an example of a vestigial structure.




















  1. Describe the process of gradual speciation.




















  1. Explain how continuous variation across geographical ranges is evidence of evolutionary




















  1. State an example of recognizably different populations of the same species across a geographical range.


















  1. Define pentadactyl limb.







  1. List the bone structures present in the pentadactyl limb.





















  1. Identify pentadactyl limb structures in diagrams of amphibians, reptiles, birds and mammals.






  1. Relate differences in pentadactyl limb structures to differences in limb function.Explain how natural selection leads to changes in the melanistic variety of insects in polluted areas.




















  1. Propose a mechanism that explains the pattern found in vertebrate limb structure yet allows for the