occurence of evolution

• Evolve


  To change gradually
• Jean Baptiste de Lamarck


  • He proposed that organism evolve in response to their environment
• Lamarck's theories


  1. Theory of Need

  2. Theory of Use and Disuse

  3. Theory of Acquired Characteristics
• Theory of Need


  Organisms change in response to the changes in their environment
• Theory of Use and Disuse


  Organs that are not used will disappear while those that are constantly used will be developed
• Theory of Acquired Characteristics (Traits)


  Lamarck believed that short-necked giraffes strained their necks to reach food from trees causing their necks to become longer, and the acquired long necks were passed on to their offspring
• Population genetics


  Deals with the hereditary factors affecting a population
• Gene flow


  Occurs whether an individual migrates from one population to another or even without migration
• Allele frequencies


  Represent the fraction or percentage of the population carrying the allele
• Non-random mating


  Sexual selection is not merely by chance, the individual's choice of mate is influenced by some physical and behavioral characteristics
• Synthetic theory


  Describes the evolution of life in terms of genetic changes occurring in the population that leads to the formation of new species
• Mutation


  Any change in chromosomes or genes
• Gene mutations


  Changes in the genes composition or order
• Chromosomal mutations


  Changes in the structure or number of chromosomes
• Hardy-Weinberg equilibrium


  In stable population, allele frequencies remain constant from one generation to another if several conditions are met
• Natural selection


  Organisms with favorable traits or those who are best suited in the environment have a better chance of survival
• Genetic drift


  A change in gene pool due to chance alone, certain traits in the population could be reduced or eliminated through some unpredictable disasters or accidents
• Speciation


  A process within evolution that results in the formation of new, and distinct species that are reproductively isolated from other population when there is no gene flow
• Punctuated equilibrium


  Populations demonstrate rapid change when there is a need to survive sudden or abrupt environmental changes
• Microevolution


  A changed in gene frequency that occurs within a population in short periods
• Coevolution


  The process wherein a species adapts or evolve in tandem with another species as they interact with each other
• Convergent Evolution


  The evolution of morphological similarities in organism that are not closely related because they have similarities in their habitats
• Adaptive Radiation


  The process by which the species diversifies rapidly into different types of closely related species with, each type occupying a new environment