Evidence for Evolution
What is a common ancestor?
ancestor that two species share in common.
Example - humans and gorillas shared a common ancestor in the past
What is natural selection?
individuals that have an advantageous trait survive and pass on their genes to offspring
What is overproduction?
more offspring than can survive are made
If a species cannot adapt to an environmental change, what will happen to the species?
Go extinct
How can structures in an organism provide evidence for evolution?
Similar structures indicate evolution from a common ancestor.
What is an adaptation?
a feature of an organism that has evolved through natural selection, allowing it to better survive and reproduce in its specific environment
Why is variation important for evolution?
Without variation, there would never be changes in the population. If the environment changed, the species would not be able to adapt.
How can you tell species are closely related when looking at a phylogenetic tree?
What is the best type of evidence to determine evolutionary relationships between species?
Biochemical evidence - DNA, proteins
What are the two sources of variation?
Mutations
Sexual Reproduction (meiosis)
What is a selecting agent?
External factor in the environment that drives evolution
Male peacocks have bright feathers to attract females. Explain why over time, male peacocks have not evolved to have shorter and less colorful tails, even though having large feathers may make them more likely to be killed by predators.
Males have a higher chance of passing on their traits with long feathers. Sign of fitness of the male peacock
How has the study of fossils supported the theory of evolution?
provides clues to the history of earths organisms, provides proof of intermediate species
The shark has changed very little in the past 50 million years. Why?
They are well adapted to their environment
Why isn't selective breeding an example of evolution?
Driven by humans, not naturally selected by environment
Explain how antibiotic resistance works in bacteria
Most die, some bacteria survive, those that survive reproduce and pass on resistance trait
True or False: Mutations happen because of natural selection.
Explain.
False, mutations drive natural selection due to an advantage an organism has in a specific environment.
State what could happen to a species in a changing environment if the members of that species do not express any genetic variations.
extinction, wont be well adapted and die
How did the beaks of finches lab model evolution?
Natural selection - survival of the fittest. those with better suited traits survived versus those that did not
Name two ways speciation may occur.
-geographical isolation
-behavioral isolation