Transcript Evolution - Marengo Community Middle School

Evolution
Myths and Misconceptions
Individuals Evolve
• WRONG
– Why is this wrong?
• Change can only be measured in a population when the
particular adaptation becomes more common.
– EX: peppered moths
• Just because one individual has a new adaptation does not
mean that they have evolved
– Adaptation may not be useful
– Adaptation does not give reproductive advantage
– Adaptation may not be heritable
• CORRECT: POPULATIONS Evolve
Evolution Produces Perfection
• WRONG
– Why is this wrong?
– No organism is perfectly adapted
– Every adaptation has a cost and a benefit
• EX: Turtle shell
• CORRECT: Organisms are not perfectly
adapted.
Evolution can produce brand new
adaptations from nothing.
• WRONG
– Why is this wrong?
• Evolution and natural selection can only work on genes that
are present in the population; it cann not produce new
adaptations
• Evolution “tinkers”. It remodels old adaptations which are
beneficial in changing environments
– EX: human limbs and vestigial organs
• Correct: Evolution is best described as descent
with modification. In other words, evolution
remodels old adaptations.
More Evolved Equals Better
• WRONG
– Why is this wrong?
• Any living species is alive because it has survived
in it’s environment and reproduced
• “Recently” evolved species are not “better”
because they are “newer”
• EX: Bacteria vs. Humans—Who will be more
successful?
• CORRECT: New species are NOT better
than older species.
Evolution has a Purpose for Every
Organism
• WRONG
– Why is this wrong?
• How evolution acts upon an organism depends on the environment
AT THE TIME
• Useful adaptations in one environment can be useless in another
– EX: Polar bears, white rabbits, albinos, Darwin’s finches
• An organism’s phenotype is determined randomly (due to laws of
segregation and independent assortment and crossing over.
– Natural selection selects phenotypes that give organisms a
reproductive advantage. If the environment changes, the adaptation
may be useless.
• CORRECT: Evolution is situational. Organisms do not
have adaptations because they “need” them.
What is the Misconception?
• Humans are better adapted to survive on Earth
because we are very complex organisms.
• The ancestors of birds grew feathers because
they wanted to fly.
• If a cow produces more and more nutritious milk
than others in the herd, it has evolved.
• Humans represent the best adaptations that
evolution has produced.
• Human adaptations will work in any
environment.