How Biological Diversity Evolves: Chapter 14

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1. Macroevolution and Speciation.

  • Define macroevolution and speciation
  • Define the biological species concept
  • Explain several limitations of the biological species concept. See p 273
  • Distinguish between prezygotic and post zygotic reproductive barriers
  • Define and  give examples of  the major prezygotic reproductive barriers:
    • habitat isolation
    • temporal isolation
    • behavioral isolation
    • mechanical isolation
    • gametic isolation

Comments: Note that your text treats speciation as part of macroevolution-evolution on a grand scale. See the glossary. Many biologists treat speciation separately from macroevolution since speciation can take place in relatively brief periods of time.

2. Mechanisms of speciation.

  • Distinguish between allopatric and sympatric speciation
  • Give examples of allopatric speciation
  • Explain the concept of a hybrid zone(not in text)
  • Give examples of sympatric speciation
    • Polyploidy in plants
    • Speciation by habitat selection in Cichlids and Apple maggot flies(not in text)
  •  Comment: sympatric speciation by polyploidy is common in plants but appears less common in animals. IN the real world it is often difficult to distinguish species boundaries. For instance in North America many species of birds have hybrid zones where the species overlap in range and occasionally interbreed. This appears to be incomplete allopatric speciation. These sorts of fuzzy situations are exactly what one would predict of evolution is happening!
  • Comment: It is important remember that speciation as a process is well documented and has even been done experimentally in the laboratory with artificial populations and observed in historical time in nature. For a few references see: http://www.talkorigins.org/faqs/speciation.html
3. Tempo of speciation.
  • Distinguish between the gradualist model and punctuated equilibrium.
  • Explain what aspect of the fossil record gave rise to the development of the punctuated equilibrium model.
  • Give examples of sudden speciation.
  • Explain what abrupt means in terms of geological time.
Comment: Note that many times in the fossil record we do not see clear cases of transitional fossils and this may well be due to the reasons discussed in your text on page 279.  The fossil record is very incomplete especially going back to the early history of life when many organisms had soft bodies and did not leave good fossil evidence. We do have good transitional fossil series for important lineages including primates. For instance there is a lot of debate among primatologists as to how to classify the various hominid fossils that have been discovered. The difficulty of assigning these fossils into a neat classification scheme is exactly what one would predict if species arise by the evolutionary process!

A good general reference is by Keith Miller, a geologist from KSU: http://www.asa3.org/ASA/resources/Miller.html
Also see:  http://www.origins.tv/darwin/transitionals.htm

An additional resource is the Talk.Origins archive .

One of the most famous transitional fossils is archaeopteryx. See http://www.talkorigins.org/faqs/archaeopteryx.html

Note:  Empirically, what scientists mean by transitional fossils is often that the fossil has characteristics of both an ancestral and descendent group. For instance Archaeopteryx has teeth and wing claws both of which are absent from modern birds. But this does not mean the this fossil is really a missing link between birds and reptiles. But it does show that boundaries between different kinds of organisms are not clear cut...exactly the sort of situation that one expects if species arise via the evolutionary process.



4.  The Evolution of Biological Novelty.

Comment: An important question in related to evolution is how evolution can lead to new adaptations such as flight in birds?

Explain the concept of exaptation and give examples.

Comment: Evolution does give rise to new adaptations!

Explain what your text means by "Evo-devo"
  • Explain how small changes in developmental rates can give rise to new adaptations
  • Define paedomophosis and give examples.
  • Slight changes in the level of gene expression can bring significant changes in appearance.
  • Check out this article on how mutations related to development can change simple leaves to compound leaves:
  • The Development and Evolution of Compound Leaves
5. Explain the importance of the fossil record in understanding macroevolution:
  • Explain the how the relative age of fossils is determined.
  • Explain how the approximate boundaries of geologic eras are determined
  • Discuss how radioactive isotopes are used to estimate the age of fossils.
  • Discuss the importance of continental drift in understanding evolution.
  • Comment plate tectonics is the theory that explains continental drift.
  • Explain the different lines of evidence that support plate tectonics
    • Orientation of magnetic particles in rocks of different strata
    • Sea floor spreading. Example mid Atlantic ridge.
    • Direct measurement of plate movement using lasers.
6. Explain the concept of mass extinctions.

  • Give examples of mass extinctions.
  • List some of the hypothesized causes of mass extinctions.
  • Explain the 'creative side' of extinctions.
7.  Define systematics and taxonomy.
  • Give reasons for naming and classifying organisms
  • Explain why scientific names are typically based  Latin or Classical Greek. Why not use common names?
  • Define the binomial system for naming species
  • Define the term hierarchical classification
  • List the major levels in hierarchical classification of biodiversity. See figure 14.22

8. Discuss the relationship between clasification and phylogeny.

  • Define the term phylogeny
  • Distinguish between homology and analogy.
  • Explain why homology is important in classification.
  • Define molecular systematics.
  • Explain what cladistic analysis attempts to do.
    • Define clade, in group vs outgroup, primative vs derived character
    • Explain what the book means by saying that cladisitic analysis is 'shaking' phylogenetic trees.

9. Distinguish between the different ways of classifying organisms at the kingdom and domain level.

  • Compare the 5 kingdom vs the 3 domain scheme
  • List the major kingdoms and give examples of organisms in each kingdom
  • Read the evolution connection on pp 292-293 and explain why evolution isn't "just a theory"!!!
    • Explain the two flaws in the evolution is just a theory argument.

Questions and activities

1. Briefly list and give examples of the main types of evidence that support that evolution happens.

 

2. Compare Darwin's ideas concerning evolution to those of Lamarck.

 

3. Trace Darwin's logic in developing his concept of natural selection.

 

4. What is the distinction between directional, stabilizing and disruptive selection?

 

5. Explain how antibiotic resistance arises in bacteria. What can we do to minimize the development of antibiotic resistance?

6. Explain the main steps in allopatric speciation.

7. What is the difference between structures that are homologous versus structures that are analogous? Give examples. What do biologists infer from homologous structures?

8. Something to think about for yourself. Why do some people object to the theory of evolution? What makes some people so reluctant to accept this theory even today?

Some additional evolution- pro and con- sites are listed at: http://staff.jccc.net/pdecell/bioresources/biolres.html#evolution

Also an additional resource is the Talk.Origins archive .

revised 04/19/06