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A-Level Biology OCR A

Process Natural Evolution Organisms Species Characteristics Survival Allele

Adaptations evolve through natural selection, where variation within a species leads to differential survival and reproduction based on advantageous traits, with these traits passed to offspring over generations.

Adaptations evolve through natural selection, where variation within a species leads to differential survival and reproduction based on advantageous traits, with these traits passed to offspring over generations.

Front Describe the steps in the process of adaptations evolving by natural selection.
Back Evolution by natural selection:
  • Organisms within species show variation in their characteristics caused by differences in their genes. New alleles can arise by mutation
  • Those with characteristics that are best adapted to a selection pressure have increased chance of survival and successfully reproducing - 'survival of the fittest'
  • Successful organisms pass on the allele encoding the advantageous characteristic into offspring. 
  • Process repeated for many generations, over time proportion of individuals with adv. adaptation increases -> frequency of adv. allele increases in gene pool
  • Over very long period of time, can lead to evolution of a new species

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