Adaptation Theories
Lamarck vs. Darwin
Lamarck “Acquired Characteristics”
 “Acquired Characteristics” – Desired changes that occurred
during a parent’s lifetime were passed on to offspring
o example: Parents that developed large muscles
through exercise was thought to be passed on to
offspring
 Organisms have changed over time
 Organisms changed because they wanted to survive
 Organisms can never become extinct
 The environment had something to do with why organisms
changed
 Parents are able to pass on at least some of their traits to
their offspring
 Organisms could decide to change something about their
body and pass on that change to their offspring
 Organisms are still changing
Darwin “Natural Selection”
 “Natural Selection” - The process by which individuals that
are better adapted to their environment are more likely to
survive and reproduce than other members of the same
species
 Organisms have changed over time
 There was variation in population
 Certain traits helped organisms survive and reproduce better
than other organisms without those traits
 The environment had something to do with why organisms
changed
 Parents are able to pass on at least some of their on traits to
their offspring
 Parents are only able to pass on traits that they were born
with
 Organisms are still changing
4 Principles of Natural Selection
1. overproduction – producing more offspring than can
survive
2. competition – offspring will compete for food another
resources, such as territory and mates
3. variations – a difference between members of same
species that may help it to survive
4. selection – over time, the environment “selects” organisms
with helpful traits to be parents of the next generation
Over a long period of time, natural selection can lead to the evolving
of new species. Helpful variations remain and unfavorable ones
disappear.
Other vocabulary:
adaptations: any structural or behavioral change that helps an
organism survive in its particular environment
gradualism: model describing evolution as a slow process by which
one species changes into a new species through a continuing series
of mutations and variations over time
punctuated equilibrium: model describing the rapid evolution that
occurs when mutation of a few genes results in a species suddenly
changing into a new species
species: group of organisms that share similar characteristics and
can reproduce among themselves producing fertile offspring