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Honors environmental week 17 pt 4
Terms in this set (30)
changes in the genetic makeup of a species over time
what is a mechanism for evolution?
traits become more or less common in a population depending on whether they are beneficial or harmful
an example of natural selection
mouse is brown - glaciers carried lighter sand over the darker soil and predators could more easily spot dark mice. Natural selection favored lightt mice
how do adaptations develop?
mutation creates variation. Unfavorable mutations elected against. Reproduction and mutation. Favorable mutations more like to survive and reproduce
ways to go extinct?
Dying out completely or evolve into a different species
when a large number of species go extinct in a short amount of time
name some causes of mass extinction
collisions with comets or asteroids, massive volcanic eruptions, rapidly changing climate
what happens to habitats after mass extinction
they are no longer inhabited by organisms because they went extinct
What happens with the new habitats after mass extinction?
some species will adapt to new environment. Evolutionary processes act rapidly during these times and many new species evolve to fill their habitats
process where many new species evolve in a short period of time to fill available niches
What happens to the life forms at the end of the period of rapid evolution in a short period of time
the life forms don't look much like the ones that were around before the mass excitation
after mass extinction of dinosaurs
mammals underwent adaptive radiation and became the dominant life form
What provides evidence of evolution?
Comparing anatomy, embryos, DNA of modern organisms characterizing similarities and differences
study of the similarities and differences in the structure of DIFFERENT species
in comparative anatomy similar body parts...
may be homologies or analogies. Both provide evidence for evolution
structures that are similar in RELATED organisms because they were inherited from a common ancestor
What happens to the function of similar body parts in homologous structures?
they may or may not have the same function in the descendants.
Example of homologous structures
Hands of several different mammals. Have same basic pattern of bones. Inherited pattern from common ancestor. However, forelimbs now have different functions
structures similar in urelated organisms.
what are analogous structures similar?
because they were evolved to do the same job, not from same ancestor, like the wings of bat and birds
study of similarities and differences of embryos of different species
In comparative embryology, similarities mean
evidence of common ancestry
Examples of embryos
all vertebrate embryos have gill slits and tails. Most lose this stuff by adulthood.
evolution reduces their size because the structures are no longer used. Ca
Examples of vestigial structures
human tail bone, whale pelvis appendix (it's a remnant of a once larger organ needed to digest food)
Similar DNA sequences are
strongest evidence for evolution from a common ancestor. More similarities in DNA sequence = evidence for closer evolutionary relationship
Humans are very similar to
chimpanzee and gorilla, not so much to baboon according to cladogram. Which shows how humans + apes are related based on DNA sequence
How is David Haussler searching for LUCA?
comparing genomes of living mammals to construct map of our common ancestors DNA
David Haussler studies DNA of extinct species and
asking how DNA has changed over mill of years to create today's species.
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