Biol-1070

• Heritability 


  A measure of how important genetics are to determininga trait
• Phenotypic Plasticity


  When the same genotype produces different phenotypes under different environments
• Sexual Dimorphism


  Traits that vary between male and female biological species.
• What types of traits are most useful for identifying different species ofan organism?

  Heritable traits
• Evolution 


  The process that results in changes in the proportion of heritable traitswithin populations from one generation to the next.
• Four mechanisms that drive evolution:

  Natural Selection, mutation, genetic drift, gene flow
• Mutations are random changes in DNA sequence that occur during cell division.
• Genetic Drift


  Occurs when chance events cause some genes to become more common than others.

  there is always genetic drift occuring.

  (eg. there are two types of genes and a fox comes and eats most of one of the genes, now the most common gene is gene 2)
• Natural Selection

  The only evolutionary mechanism that leads to adaptation of a species
• When does Evolution through Natural Selection Occur?

  When:

  1. there is phenotypic variation in a population

  2. when there is differential survival based on that phenotypic variation

  3. when that variation is heritable
• Natural Selection is not need-based, it happens when there is a change in the environment that affects the survival of some traits in a species and increases the frequency of other traits.
• Which organisms are most successful at passing on their genes?

  The fittest organisms are the most successful organisms.

  "Fittest" means the organism with the most surviving offspring or reproductive success. It does NOT mean fittest in the traditional sense of who is "strongest" or "fastest"
• What are the three types of Natural Selection?

  Directional selection, Stabilizing selection and Disruptive selection.
• Directional Selection


  This is when one specific phenotype is favored over others due to environmental changes.

  (the general trend of the populations phenotype moves in one direction - directional)
• Stabilizing Selection


  When the less extreme phenotype is favored over extreme phenotypes.

  (eg. beak depth: if the medium-sized beaks are more favorable for survival, that is Stabilizing Selection)
• Disruptive Selection

  When both extreme phenotypes are favored over average phenotypes for survival.
• Mutation


  Random error in the DNA sequence which usually occurs in DNA replication.
• Gene flow


  When two populations mix and introduce new genetic variation.

  If gene flow is maintained, the two populations will become more genetically similar over time.
• Phylogenetic Trees


  Depict the relationships and history of species.

  Are based on common ancestry - the more common ancestors that are present between 2 species, the more closely related they are.
• Phylogeny Jargon


  understanding the parts:

  
• Monophyletic 


  A clade of all its common ancestors and descendants.
• Paraphyletic

  Not a full clade since it's for multiple species that don't share all the same ancestors and descendants.