evolution occurring today? You bet.
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.
change and even destroy habitats. Can you think of examples?
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.
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.