Biol 402 Exam 1

• What is evolution?

  Any change in the inherited traits (genes) of a population that occurs from one generation to the next.
• What was Aristotle (384 –322 BC) known for?

  Scala Naturae

  Life forms arranged on a ladder of increasing complexity.
• What was Linnaeus (1707 –1778) known for?

  Developed a nested classification system.

  Based on pattern of creation, not evolution.
• What was Lamarck (1744 –1829) known for?

  Life driven from simple to complex.

  • Complex species descended from microbes.
  • Microbes continually generated spontaneously.

   

  No extinctions. (Because one organism would just become another organism).

  Thought adaption happened with use and disuse. If parent did not use a trait, it would not be passed onto offspring.
• What was Cuvier (1769 –1832) known for?

  Zoologist, vertebrate paleontology.

  Compared living animals with fossils.

  Believed in extinctions of species.

  Believed no evidence for evolution (Larmarck). Any change would impair organism.

  Proponent of catastrophism –earth’s features shaped by catastrophic natural disasters. (this is because of scriptures and biblical events).

   
• What was Lyell (1797 –1875) known for?

  Geologist.

  Proponent of uniformitarianism –Earth shaped gradually, and mechanisms of past are same as those operating today (erosion, volcanism, etc).

  Age of the earth –older than 300 million.
• What did Darwin (1809–1882) do before scientific research?

  Medical school in Edinburgh.

  • Preferred to study nature.
  • Met marine biologist Robert Grant.

  Trained to become clergyman at Cambridge –met botanist John Henslow.

  Invited to serve as unofficial naturalist for HMS Beagle in 1831.
• What did Darwin find on the Galapagos islands that made him think that evolution was real?

  Organisms being adapted to their environment. Niches on islands.

  Considerable variability.

  Variability seemed to result in a match between character and environment.

  Unique tortoise shell pattern for each island.

  Iguanas are clumsy on land. Were marine iguanas.

  Booby's are very clumsy on land. Agile hunters in water. Their diet also makes their feet darker with more nutrition.
• What did Darwin think about population size growth?

  Populations cannot grow indefinitely.

  (so something has to keep these populations small)
• What did Darwin think about selective breeding in plants?

  selectively breeding for desired traits.

  selecting for traits artificially.

  Darwin coined the term, “artificial selection”.

  Example. Brassica was crossed many times to make a lot of the vegetables we know now.
• What was Darwin's logic for natural selection?

  All population sizes would explode if all individuals born go onto reproduce. But populations are stable.

  Resources are limited. But there are still resources left.

  Something is keeping these numbers in check. And survivorship is not random. Some characteristics are better at letting individuals survive.

  Variability among individuals seem to be related. Leads to continual, gradual change over time.

  This causes organisms to change.
• Who did Darwin partner with to go public?

  Letter from Alfred Russel Wallace proposed similar evolutionary ideas. Wallace proposed:

  • Common ancestry.
  • Natural selection.
  • Individuals have differences that mean differences in survivorship.

  Letters from Darwin and Wallace presented at Linnean Society in 1858.
• What book did Darwin publish in 1859?

  On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life.

  Descent with modification.

  • All species share common ancestry.
  • Changes occur through natural selection.
• What did Darwin talk about that ended up being wrong?

  Pangenesis

   

  Proposed by Hippocrates.

  Each part/organ of an organism produces particles of inheritance/ instructions called gemmules.

  Migrate to gonads.

  Parents could pass on traits acquired during their lifetime (Lamarckian).
• What are current debates in evolution about?

  How any change in the inherited traits of a population that occurs from one generation to the next.

  Examples.

  Still debating if inherited traits in a population are from natural selection or random drift. 

  Still debating is slow or fast.

  Gradualism model - small changes over time. Longs periods of small changes.

  Punctuated equilibrium model - a single, dramatic change in phenotype that turns into its own population. Long periods of no change, followed by rapid change.
• What is phylogeny?

  A visual representation of the evolutionary history of populations, genes, or species; similar to a family tree
• What is monophyletic?

  Contains a common ancestor and all its descendants. (dependents on what node you are looking at)
• What is paraphyletic?

  Contains a common ancestor, but not all its descendants. (excludes one or more letters)
• What is polyphyletic?

  Contains taxa with different recent common ancestors (excludes at least one monophyletic group).
• What is a character on a phylogenetic tree?

  any recognizable attribute of an organism
• What is a character state on a phylogenetic tree?

  the value of the character
• What is Pleisiomorphic?

  ancestral character/trait
• What is apomorphy?

  derived character/trait
• What is synapomorphy?

  shared derived character
• What is autapomorphy?

  derived character unique to one taxon
• What is exaptation?

  natural selection co-opts a trait for a new function. One structure evolved for one specific purpose but is not used for a different purpose.
• What is parsimony?

  preference for the simplest of all available explanations.
• Why is parsimony a challenge in phylogenetic trees?

  This means that multiple trees will be valid.
• Why can morphology be misleading when relating organisms?

  Morphological characters can be problematic for phylogenetic reconstruction when related organisms are morphologically very different.
• What is homoplasy?

  character state similarity not due to common descent
• Why is homoplasy a challenge in phylogenetic trees?

  One related trait does not always mean two organisms are actually related, it can just be independent evolution.

  Convergent evolution: independent evolution of similar trait.

   

  Evolutionary reversals: reversion back to an ancestral character state.
• Why is there disagreement with DNA-based trees?

  Each character is a new trait.

  Each species is a new species.

  Can use the shared derived traits to group them.
• Evolution is “just” a theory?

  • Scientific theories are backed by multiple lines of evidence
  • Evolution is a fact
  • Evolutionary theory accepted as fact by most scientists
  • Theory is conceptual framework that is supported by evidence
  • Fact is verifiable
• Evolution explains the origin of life?

  • Evolution deals with how life has changed after it originated
  • Other scientific fields address the origin of life
• Evolutionary biologists search for missing links in the fossil record?

  • Evolution is not a linear chain - not a progression - it's branching
  • Transitional forms are often sought - but fossil record expected to be incomplete
  • Tiktaalik
  • Evolution does not "link" but instead makes a tree of how related organisms are.
• Evolution is natural selection?

  • Natural selection is one mechanism of evolutionary change
  • Others: genetic drift, sexual selection
• Evolution is entirely random?

  • Evolution includes random and non-random components
  • Mutations are random
  • Natural selection is the non-random favouring of particular trait
  • Convergent evolution demonstrates that evolution is non-random
  • Phenotypes are predictable when environments are similar
  • Not random itself, but has a random component to it.
• Organisms evolve adaptations they “need”?

  • Evolution cannot identify needs
  • Mutations do not occur because they would be adaptive in an environment
  • If beneficial mutations happen to occur they may increase in frequency through selection
  • Mutations are random. If they give an advantage, they will keep it
• Evolution moves from simple to complex?

  • Evolution is not a march of progress (not linear - it's branching)
  • Evolution can also move from complex to simple (ex. Mitochondria)
  • Less optimal to more optimal
  • Adapting to current conditions
  • It is easiest to go through the simplest way.
• Evolution results from individuals adapting to environment?

  • Evolution only works on inherited traits
  • Any traits that can be passed to offspring
  • Populations evolve, individuals do not
  • Evolution results from changes in allele frequencies.