Biology 445/545 EVOLUTION

Lecture 1: Major Concepts and Evidence for Evolution

 

I. Course Mechanics.

  • Use of the 445/545 website via Blackboard
  • Lectures and text
  • Exams and grades

 

II. An Overview of Evolutionary Thinking Illustrated with HIV  

          (Chap 1).

 

What Are the Major Concepts in Evolutionary Biology?

 

  • Mutation, variation & inheritance (the process of generating new genetic variants;  the standing crop of genetic variants; correpondence between parents and offspring)

 

  • Competition and natural selection (contest for resources that are crucial for survival and reproduction; correspondence between attributes and reproductive success).

 

  • Adaptation (the state of evolved adjustment of a population to its environment or the evolutionary process of achieving that adjustment)

 

  • Diversification and phylogeny (the process of producing different descendant lineages from a single ancestral lineage; the genealogical relationships of a set of populations or species)

 

What Are the Connections Between These Major Concepts? (see diagram)

 

How Does HIV Illustrate These Concepts?

 

  • Mutation, variation & inheritance  (Transcription errors made by HIV’s reverse transcriptase lead to mutations in the reverse transcriptase gene; these mutations produce variation in enzyme function among virus particles.) Fig. 1.3

 

  • Competition and natural selection   (Some virus particles are better able to survive and reproduce because of differences in their reverse transcriptase; favorable variations are passed on to descendant virus particles.) Fig. 1.4

 

  • Adaptation  (New forms of HIV dominate the HIV population within a host taking anti-AIDS drugs (e.g., AZT).  When AZT treatment is stopped, the HIV population within a host gradually looses its resistance to AZT).

 

  • Diversification and phylogeny (HIV is most closely related to a virus of chimpanzees (SIVcpz) and more distantly related to other SIVs.  Diversification of HIV and SIV in humans and other primates may be driven by adaptation to host defenses.) Fig. 1.6

 

Primary Study Questions:

1.      What are the major concepts in evolutionary biology?

2.      What is the difference between mutation and variation?

3.      Define natural selection.

4.      Define adaptation.

5.      What is diversification?

6.      What is the evidence for adaptation in HIV?

7.      Why is HIV prone to rapid evolution?

8.      How is diversification related to adaptation?

9.      What makes the production of an effective HIV vaccine unlikely?

10.   How are mutation and variation related to adaptation?

 

Secondary Study Questions:

  1. HIV was most recently derived from viruses in what other kind of primate?
  2. What is the difference between HIV and AIDS?
  3. What is a retrovirus?
  4. What do the letters in HIV stand for?
  5. What kinds of host cells are attacked by HIV?
  6. What is CD4 and how does it interact with HIV?
  7. How does HIV cause AIDS?
  8. What is AZT?
  9. What is the evidence that coreceptors are involved in HIV resistance?
  10. What is the evidence that HIV has evolved multiple times from SIV?

 

 

 

III.  The Evidence for Evolution (Chap 2).

 

A Pre-Darwinian view – The Theory of  Special Creation (1820-1860)

  • Species represent independent creations
  • Species do not change through time
  • Species were created recently (e.g., within the last 6,000 yrs)

 

Evidence for Darwin’s Theory (Descent with modification, evolution by natural selection)

 

  • Relatedness of life forms (Diverse organisms often show underlying similarities in development and structure.  These similarities are evidence for common ancestry.) Fig. 2.1a … argues against independent creations

 

  • Change through time (Populations and species are not static entities.  They change through time.  They evolve). Fig. 2.7, Fig. 2.10 … argues against the immutability of species

 

  • The age of the earth (Life on earth is 3.7 billion years old!  Major differences can accumulate between lineages on this time scale.  There is ample time for evolution to occur). Fig. 2.1 … argues against recent creation

 

  • Correspondence among data sets (Different data sets provide complementary evidence for evolution). Fig. 2.13 … Darwin’s theory has synthetic power.

 

Primary Study Questions:

1.      What are the three primary claims of the Theory of Special Creation?

2.      What is the evidence that argues against independent creations?

3.      What is the evidence that argues against the notion that species never change?

4.      What is the evidence against the claim that life on Earth originated within the last few thousand years?

5.      What phylogenetic feature could account for the underlying similarities in the front limbs of humans, horses, birds, bats, seals and turtles?

6.      Why are vestigial structures inconsistent with the Theory of Special Creation?

7.      Why is a phylogenetic tree useful?

8.      Why does the observation of extinct species challenge the Theory of Special Creation?

9.      Why were transitional forms a problem for Darwin?

10.  Why are so many transitional forms known today?

 

 

Secondary Study Questions:

  1. How is the phylogeny of marsupials consistent with continental drift?
  2. Why didn’t humans ever encounter live dinosaurs?
  3. Arrange the following list plant and animal groups in the order in which they appear in the fossil record: whales, daisies, apes, fish, mammals, reptiles.
  4. Why is radiometric dating more informative than relative dating?
  5. How did soapberry bugs respond to the introduction of flat-podded golden rain trees in Florida?
  6. What are pseudogenes and how can we recognize them?
  7. What is the significance of human-like footprints that are 3.6 million years old (text p. 21)?
  8. What are sister taxa?
  9. What did Darwin mean by the phrase ‘descent with modification’?
  10. Is evolution possible without natural selection?