Evolution

Question 1

What is chemical evolution?

Answer 1

• Formation of complex organic molecules from simpler inorganic molecules through chemical reactions
• First step in the development of life on this planet

Question 2

What is organic evolution?

Answer 2

• The process. by which changes in the genetic composition of populations of organisms occur in response to environmental changes
• Descent with modification

Question 3

A new theory: Darwin and Wallace

Answer 3

• Darwin and Wallace independently conceived of the idea of natural selection
• Foundation for this theory already in place
  Geology: History of life on earth is long and changing
  Economics: population pressures
  Embryology: similarities among organisms
• Evolution as a theory was accepted before natural selection

Question 4

What are the 5 theories that summarize Darwins views?

Answer 4

1) Perpetual change
2) Common descent
3) Multiplication of species
4) Gradualism
5) Natural selection

Question 5

What is perpetual change?

Answer 5

• Living world is always changing
• Evidence: fossil record
• However, fossil record is biased
  hard structures are preserved best
  soft-bodied animals such as jellyfish and worms are under-
  represented

Question 6

What is common descent?

Answer 6

• All organisms are descended from a common ancestor
  last universal common ancestor (LUCA)
• Evidence: organismal form, cellular structure and genetics
• Life’s history forms a branching tree called a phylogeny

Question 7

What is the evidence for common descent? (The shared characteristics of living things)

Answer 7

1) chemical uniqueness
2) Complexity and hierarchical organization
3) reproduction
4) possession of genetic program
5) metabolism
6) development
7) environmental interaction
8) movement

Question 8

Possession of a genetic program

Answer 8

• Genetic code: correspondence between sequenced of nucleotides in DNA and sequences of amino acids in protein
• Codon: a sequence of three nucleotides that encode for an amino acid
• Arose early in the history of life

Question 9

Is the genetic code universal?

Answer 9

• No but nearly
• Evidence for single origin of life on earth
  LUCA

Question 10

What is homology?

Answer 10

• Similarity of parts or organs of different organisms caused by evolutionary derivation from a corresponding part or organ in a common ancestor
• homologous features are transmitted to all descendant lineages (unless they are subsequently lost)

Question 11

What is a multiplication of species?

Answer 11

• Evolution produces new species by splitting and transforming older ones
• New specie form through the appearance of reproductive barriers
  biological factors that prevent interbreeding
• Often arise because of geographical barriers

Question 12

What is gradualism?

Answer 12

• Small changes accumulate steadily over time
• Evidence against gradualism:
  it is not supported by fossil record
  animal breeding suggest that changes can be substantial and sudden

Question 13

What is punctuated equilibrium?

Answer 13

• Proposed in response to lack of evidence for gradualism (Niles Eldridge and Stephen Jay Gould)
• Long periods of stasis (equilibrium), punctuated by brief events of speciation
• Speciation: lasts on average 10,000-100,000 years
• Species survive for 5-10 million years on average

Question 14

What is natural selection?

Answer 14

• The process whereby organisms better adapted to their environment tend to survive and produce more offspring
• Natural selection explains adaptation
  adaptation: a change or the process of change by which an
  organism or species becomes better suited to its environment
• There is variation in traits
• There is differential reproduction
• There is heredity
• More advantageous traits become more common in a population