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Ch19 History of Life
Terms in this set (22)
What do fossils reveal about ancient life?
They show the structure of ancient organisms, their environments and the ways in which they lived.
researchers who study fossils to learn about ancient life
places rock layers and their fossils in temporal sequence so paleontologists can determine whether a fossil is older or younger than other fossils.
A way to date rocks and fossils using radioactive isotopes which decay into stable isotopes at a steady rate. Uses the proportion of radioactive to stable isotopes to calculate the age of a sample.
the time required for half the radioactive atoms in a sample to decay.
What processes influence whether species and clades survive or become extinct?
Macroevolutionary patterns influence this. If the rate of speciation in a clade is equal to or greater than the rate of extinction, the clade will continue to exist.
The ways new species emerge through speciation and the ways species disappear through extinction.
Example of a highly successful clade
Reptilia: most species of the clade dinosauria are now extinct, but the clade survive because it produced new species that successfully adapted to changing conditions (snakes, lizards, birds)
Background extinction versus mass extinction
Background: slow and steady process of natural selection.
Mass: an entire ecosystem or food web collapses.
How fast does evolution take place?
It proceeds at different fates for different organisms at different times.
a model of evolution that Darwin suggested that is slow and steady.
when equilibrium is interrupted by brief periods of more rapid change. Most new species are produced at this time.
What are two patterns of macroevolution?
adaptive radiation and convergent evolution
the process by which a single species or a small group of species evolves over a relatively short time into several different ways (Ex. species migrate to a new environment. Ex.Galapagos finches adapted different beaks for different areas)
the process by which unrelated organisms independently evolve similarities when adapting to similar environments. (Ex. mammals that feed on ants evolved 5 times in different regions...armadillo, anteater, aardvark, echidna, pangolin)
the process by which two species evolve in response to changes in each other over time (Ex. monarch caterpillars can tolerate the toxins in milkweed).
distinctive fossils use to establish and compare relative ages of rock layers and their fossils. Useful if they lived for a short time but found in many places.
What do scientists hypothesize about early Earth and the origins of life?
Earth's early atmosphere contained little or no oxygen. Mostly CO2, water vapor, nitrogen, and less CO, hydrogen sulfide and hydrogen cyanide. You would die!
Miller and Urey's early experiments about life on Earth.
...suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds found on a primitive Earth.
RNA world hypothesis
Proposes that RNA existed before DNA. From a simple RNA-based system, several steps could have led to DNA-directed protein synthesis. Still being tested.
What is the evolutionary significance of sexual reproduction?
The development of sexual reproduction sped up evolutionary change because sexual reproduction increases genetic variation.
proposes that a symbiotic relationship evolved over time between primitive eukaryotic cells and the prokaryotic cells within them.
THIS SET IS OFTEN IN FOLDERS WITH...
Chapter 19: 19.1-19.3
Ch16 Darwin's Theory of Evolution
Ch17 Evolution of Populations
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