BY5.5 Population Genetics

Population Genetics

Over production

• all oragnisms reproduce to increase the population size
• as the population increases various factors keep the number down

• intra specific competition:
  • competition within a species
  • basis of natural selection

• interspecific competiton
  • competition between different species
  • predator prey relationships

Selection pressures

• selection pressures increase the chances of some alleles being passed on and decrease the chances of others being passed on
• natural selection is the effect of such pressures on the frequency of alleles in a population
• it is a process in which the organisms better adapted to the environment survive and reproduce
• the better adapted the organism s, the more likely it is to pass o their characterisitcs to their offspring and future generations

• the organisms environment  exerts a selection pressure and this determines the spread of any alleles in the gene pool

Population genetics:

• organisms are members of a local population where mating occurs randomly
• the study of inheritance factors in a population is concerned with the freqeuncy of phenotypes and genotypes in the whole population rather than the ratio of characteristics

• population: a group of organisms that can freely interbreed
• some populations are open and so immigration of genes from overlapping populations can occur
• some populations are closed by being cut off from others by barriers

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