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Adaptation and Evolution of Populations


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Adaptation and Evolution of Populations






Biological Evolution


Natural Selection


An explanation of how adaptations develop

An explanation of how adaptations develop.



  • Changes in the genetic makeup of a species may result in a new species.



2. How does natural selection work?

Going Further

The text above strongly emphasizes the role of natural selection. While natural selection is extremely important, it is not the only mechanism for evolution.

Many people mistakenly think of evolution simply as "survival of the fittest," but in some cases populations experience chance introductions or losses of genes or the gradual change in frequency of a certain gene due to chance alone; both are mechanisms of evolution. This article provides further info on these more complex genetic mechanisms:  http://www.nature.com/scitable/knowledge/library/natural-selection-genetic-drift-and-gene-flow-15186648

Another mechanism overlooked by the "survival of the fittest" simplification is sexual selection. Consider this thought experiment:

  • I capture 100 peacocks and humanely remove the tails from 50 of them. 
  • Without their large, brightly colored tails behind them the 50 tail-less peacocks are faster and less obvious to predators, so more of them survive. However, without tails they also fail to attract mates ("peahens") and do not reproduce.
  • The entire next generation of peacocks and peahens comes from the peacocks that retained their tails. 

Thus, biological "fitness" is not just about survival, it's also about managing to reproduce. 

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