EVOLUTION

EVOLUTION

Adaptation
1. The adjustment of an organism to its environment, or the process by which it enhances its fitness for that environment.
Adaptive Radiation
1. Special case of divergent evolution. Occurs when one ancestral species gives rise to many new species (occupying different niches)
Allopatric and Sympatric Speciation
1. Allopatric
  1. New species forming because they are geographically isolated from the parent population.
2. Sympatric
  1. Closely related species whose distribution overlaps with the parent population
Analogous and Homologous structures
1. Analogous
  1. Similar structures developed by species that are not related but instead faced the same selection pressures and share similar environment. Usually have same functions
2. Homologous
  1. Are remnants of ancestor species, and are present in related animals - pentadactyl limb. Does not always serve same purpose
Types of Evolution
1. Convergent
  1. Similarity present in appearence of organisms that are not closely related by share similar habitat type
  2. Parallel Evolution
    1. Development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.
2. Divergent
  1. One ancestral species, over time, giving rise to several new species each in their own niche.
  2. Cladogenesis
    1. The branching off of a new taxa
3. Macroevolution
  1. Evolution above the species - on a greater scale
4. Microevolution
  1. Small scale - changes in allele frequencies that occur over time within a population
Natural slelection
1. One of the basic mechanisms of evolution, along with mutation, migration, and genetic drift
Evolutionary Change
1. Gradualism
  1. Populations slowly diverge by accumulating adaptive characteristics in response to different selective pressures.
2. Punctuated Equilibrium
  1. Most species in existence spend time in stasis and little time is spent in active evolutionary change
Isolation and Speciation
1. Reproductive isolation
  1. Prevents interbreeding and therefore gene flow between species. Most species have more than one
  2. Temporal
    1. Individuals may be active during different times of the day/week/month/season
  3. Gamete Isolation
    1. Gametes may be incompatible
  4. Behavioural
    1. Different courtship rituals
  5. Mechanical Isolation
    1. Structural differences in the anatomy of the reproductive organs
  6. Postzygotic
    1. Sterility
    2. Inviability
    3. Hybrid breakdown
Phylogeny
1. The history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms
Population
1. A summation of all the organisms of the same group or species, who live in the same geographical area, and have the capability of interbreeding
Speciation
1. The formation of a new biological species
Extinct
1. Extant
  1. Still in existence
2. Having no living member or no longer being in existence

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	Created by Crystal D'Souza over 10 years ago