Speciation

Speciation

• 1.
  SPECIATION A species isa population of organisms consisting of similar individuals which can breed together and produce fertile offspring. The process by which new species develop from the existing species is known as speciation.
• 2.
  FACTORS  Geographical isolationof a population caused by various types of barriers. The geographical isolation leads to reproductive isolation due to which there is no flow of genes between separated groups of population.  Genetic drift caused by drastic changes in the frequencies of particular genes by chance alone.  Variations caused in individuals due to natural selection.
• 3.
  GENETIC DRIFT  Geneticdrift or allelic drift is the change in the frequency of a gene variant (allele) in a population due to random sampling. The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation.
• 4.
  EVOLUTION OF EYES RUDIMENTARYEYES IN PLANARIA THEY CAN DETECT LIGHT.
• 5.
  EVOLUTION OF FEATHERS Pterosaurs were flying reptiles  The presence of feathers on birds tells us that birds are very closely related to reptiles.
• 6.
  EVOLUTION BY ARTIFICIAL SELECTION
• 7.
  KOHLRABI &KALE
• 9.
  EVOLUTION SHOULD NOTBE EQUATED WITH PROGRESS EVOLUTION IS JUST THE PRODUCTION OF DIVERSITY OF LIFE FORMS AND SHAPING OF THIS DIVERSITY BY THE ENVIRONMENTAL SELECTION. THE ONLY PROGRESS IN EVOLUTION APPEARS TO BE THAT MORE AND MORE COMPLEX BODY DESIGNS OF ORGANISMS HAVE EMERGED OVER THE AGES.
• 10.
  HUMAN EVOLUTION