Evolution Flashcards
Define Evolution.
the process by which all living organisms have developed and diversified from earlier forms over time.
Is evolution JUST a theory?
No
Define scientific theory.
well-substantiated explanation of some aspect of the living world that is confirmed through observation and experimentation.
What was Darwin’s 1st observation?
organisms in similar environments around the world had similar characteristics.
Australia & Africa both have different plants and animals. Although, they have similar grassland environments. The plants and animals have similar characteristics even though they are different.
What was Darwin’s 2nd observation?
species always seemed well-suited for their environment.
Animals on different islands seemed to have changed to match their environment.
What was Darwin’s 3rd observation?
ancient organisms resemble modern organisms.
Define fossils.
preserved remains or traces of ancient organisms.
What can you infer by studying fossils?
Why the ancient organism no longer exists.
Geologists began gathering evidence that the continents have been forming for a few million years. How did this help Darwin and his theory of evolution?
It showed him that the Earth was old enough to let organisms evolve.
Define natural variation.
individual organisms of the same species can have different characteristics.
Define artificial selection.
nature provides the variation while the humans select those they find useful.
How did natural variation & artificial selection help Darwin’s theory of evolution?
it showed him that some traits can be passed from parents to offspring.
How did information about population growth help Darwin develop his theory of evolution?
it showed him that if there is a stuggle for for existence, not everyone can survive.
What did Darwin propose as the mechanism of evolution?
natural selection
Define natural selection.
the process by which organisms with variations most suited to their environment survive and reproduce.
Name the 3 criteria for natural selection to occur.
- natural variation
- struggle for existence
- survival of the fittest
Define fitness.
the organism’s ability to survive and reproduce.
Define adaptation.
any inherited characteristic that increases an organism’s fitness.
Who proposed the theory of evolution first?
Lamark
What were Lamark’s 2 ideas?
- the inheritance of accquired traits
- use & disuse
Explain the inheritance of accquired traits.
traits accquired during an organism’s life could be passed on to the next generation.
Explain use & disuse.
body parts that were not being used gradually disappeared.
Name the patterns of evolution.
- adaptive radiation
- speciation
- convergent evolution
- gradualism
- punctuated equilibrium
Define adaptive radiation.
when a single species evolves into several different species over time
Define speciation.
the formation of a new species through evolution
Define convergent evolution.
unrelated organisms evolve similar adaptations because they live in similar environments.
Define gradualism.
organisms evolve at a slow and steady rate.
Define punctuated equilibrium.
species do not evolve for long periods of time and then go through short periods of rapid evolution.
Name the 2 things that caused the period of rapid evolution.
- mass extinction
- isolation
Define mass extinction.
large number of species die out in a short time.
Define isolation.
group of individuals get seperated from the main population.
Define coevolution.
evolution of 2 or more species, each adapting to changes in the other.
occurs when species interact closely with each other
What are homologous body structures?
body structure shared by related species that have a similar structure but different function.
Homologous body structures support the theory that ….
organisms evolved from a common ancestory.
What is are analogous body structures?
body parts in different species that is similar in function but not in structures.
Analogous body structures also support …
convergent evolution
What are vestigal body structures?
structures that have no apparent function and appear to be residual parts from past ancestors
The end of an era is probably caused by ….
mass exinction
True or False? 99% of all species that ever lived are extinct.
true
Miller and Urey conducted an experiment to determine if organic molecules could be formed under the conditions of early Earth. From this, what did they think?
they thought it was possible for life to spontaneously form under the conditions of the early Earth.
Earliest forms of life were …
prokaryotic cells
Were the earliest forms of life anaerobic or aerobic? Explain.
The earliest forms of life were anaerobic because there was no oxygen in the atmosphere.
Cellular respiration does what
releases ATP from food
Anaerobic organisms used ____ to produce energy without oxygen.
fermentation
1st organism to do photosynthesis.
Cynobacteria
How did photosynthesis affect the environment?
it added oxygen to the environment
What is the endosymbiotic theory?
the mitochondria and chloroplasts of eukaryotic cells were once independent prokaryotic cells
Does natural selection affect polygenic traits and single gene traits differently or similarly?
differently
single-gene traits
controlled by one gene that has 2 alleles
polygenic traits
controlled by more than one gene with many alleles.
Natural selection can affect the distributions of polygenic phenotypes in any of 3 ways :
- directional selection
- stabalizing selection
- disruptive selection
What is directional selection?
when individuals at one end of the curve have a higher fitness than individuals in the middle or other end
favors one of the extreme variations
What is stabilizing selection?
individuals in the center of the curve have higher fitness than those at the ends of the curve.
favors average individuals
What is disruptive selection?
when individuals at each end of the curve have higher fitness than those in the middle
favors both extreme variations and it creates 2 distinctive phenotypes which leads to speciation
Define evolution in genetic terms.
a change in the allele frequency of a population over time.
What is a gene pool?
the combined genetic info of all the members of a population
What is relative freuquency?
the number of times that an allele occurs in a gene pool compared to the total number of alleles.
What is a genetic drift?
random change in allele frequency of small population due to chance.
-doesn’t increase the overall fitness of population
-more likely to occur in small populations
What is genetic equilibrium?
when the allele frequencies in a population remain constant over time.
Hardy-Weinberg Principle - a population will not evolve if the follwing conditions are met….
- random mating
- large population
- no migration
- no mutations
- no natural selection
Does genetic drift increase the overall fitness of population?
NO
Is genetic drift more likely to occur in small populations or big populations?
small populations
