EVOLUTION

EVOLUTION

1. Adaptation

   • The adjustment of an organism to its environment, or the process by which it enhances its fitness for that environment.

2. Adaptive Radiation

   • Special case of divergent evolution. Occurs when one ancestral species gives rise to many new species (occupying different niches)

3. Allopatric and Sympatric Speciation

   • Allopatric
     • New species forming because they are geographically isolated from the parent population.
   • Sympatric
     • Closely related species whose distribution overlaps with the parent population

4. Analogous and Homologous structures

   • Analogous
     • Similar structures developed by species that are not related but instead faced the same selection pressures and share similar environment. Usually have same functions
   • Homologous
     • Are remnants of ancestor species, and are present in related animals - pentadactyl limb. Does not always serve same purpose

5. Types of Evolution

   • Convergent
     • Similarity present in appearence of organisms that are not closely related by share similar habitat type
     • Parallel Evolution
       • Development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.
   • Divergent
     • One ancestral species, over time, giving rise to several new species each in their own niche.
     • Cladogenesis
       • The branching off of a new taxa
   • Macroevolution
     • Evolution above the species - on a greater scale
   • Microevolution
     • Small scale - changes in allele frequencies that occur over time within a population

6. Natural slelection

   • One of the basic mechanisms of evolution, along with mutation, migration, and genetic drift

7. Evolutionary Change

   • Gradualism
     • Populations slowly diverge by accumulating adaptive characteristics in response to different selective pressures.
   • Punctuated Equilibrium
     • Most species in existence spend time in stasis and little time is spent in active evolutionary change

8. Isolation and Speciation

   • Reproductive isolation
     • Prevents interbreeding and therefore gene flow between species. Most species have more than one
     • Temporal
       • Individuals may be active during different times of the day/week/month/season
     • Gamete Isolation
       • Gametes may be incompatible
     • Behavioural
       • Different courtship rituals
     • Mechanical Isolation
       • Structural differences in the anatomy of the reproductive organs
     • Postzygotic
       • Sterility
       • Inviability
       • Hybrid breakdown

9. Phylogeny

   • The history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms

10. Population

    • 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

11. Speciation

    • The formation of a new biological species

12. Extinct

    • Extant
      • Still in existence
    • Having no living member or no longer being in existence