Natural Selection Image Map

Is evolution occurring today? You bet. Modern genetics allows us to map changes in genes of many species and to document the degree of genetic similarity among species and which genes change over time. Genetic scientists crank out new species of fruit flies almost every day. Bacteria adapt to antibiotics and turn into species that are resistant. Humans have domesticated plants and animals in just the last six thousand years.  There are examples of species being created in our time.  Of course, these are examples of artificial selection, not natural selection. Either way, heritable traits of descendants are changed by the force of selection.

We change and even destroy habitats. Can you think of examples? 

We move species into new habitats that they would not have access to without being moved by humans. Can you think of some examples? 

But these are signs of "micro-evolution," not the macro-evolution of whole new groups of plants and animals.

 

Humans change the balance of selection forces in nature by forcing many species into extinction. Between 1600 and 1900, humans eliminated about 75 bird and mammal species. Another 75 species were eliminated between 1900 and modern times. It now appears that humans are eliminating plant and animal species at a rate of about one species per day. Remember,  that humans have affected evolution mostly in the last few thousand years. Macro-evolution of new species becomes possible when natural selection is operating during years that are measured in the millions.

Back to Previous PageNext to Following Page

 

 

Introduction | Why It Matters | How We Find Out | What We Know | Story Time
Common Hazards | Activities | Self-Study Game | Teachers Pages | Standards (TEKS)


Peer Curriculum | Ecosystems Home Page | Communication Exercises
Copyright 2001-2003
Web Site Privacy Statement