Biology 100B Review #2 (Exam I)
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What is the biological species concept?
What are limitations to this concept?
Name 3 other species definitions in addition to the biological species definition.
- biological species concept
- I. Species = population or group of populationswho can interbreed in nature to produceviable, fertileof spring; but do not produce viable, fertile offspringwith other populations
- -Prezygotic barriers
- -Postzygotic barriers
- Other Species Definitions
- - Morphological species (“Linnaeus type”)
- Paleontological species
- Ecological species
Describe prezygotic and postzygotic barriers that lead to reproductive isolation.
- -mechanical isolation (different sizes and shapes of reproductive organs)
-temporal isolation (mating seasons)
-behavior isolation (mating calls, colors and shapes)
-gametic isolation (sperm not able to attach to egg)
- Postzygotic barriers
- - Low zygote viability
- - Low adult viability
- - Hybrid infertility
Compare/contrast allopatric and sympatric speciation.
What are the mechanisms for reproductive isolation with in each?
Sympatric Speciation (together homeland)
- - Geographic separation
- - Gene flowinterrupted or reduced
- - One or both populations may undergo evolutionary change
- - Not Geographically isolated
- - Reproductively isolated
- - Mechanisms of reproductive isolation
- Mechanisms of reproductive isolation
- - Disruptive selection: Ecological isolation due to habitat differentiation & sexual selection
: Extra sets of chromosomes, hybrid often sterile.
What is adaptive radiation?
Describe 3 outcomes of species overlap in hybrid zones over time
1. Hybrid ZoneReinforcement: strengthening reproductive barriers
2. Hybrid Zone Fusion: weakening reproductive barriers
3. Hybrid Zone Stability:Continued Formation of Hybrid Individuals
Where did life likely start?
What were the raw materials necessary for it?
What is the currently most accepted 4-step hypothesis for the origin of life?
Explain each step. Is there any evidence to support this hypothesis?
- - Water
- - Methane, Ammonia, Hydrogen sulfide
- 4-step hypothesis for the origin of life
- 1. Synthesis of non--living organic molecules
- 2. Joining of monomers to form polymers
- 3. Packaging of polymers into protocells
- 4. Origin of self--replicating molecules
When did earth form?
- Earth formed about 4..6 billion years ago
How do sedimentary strata, index fossils, isotope dating and magnetism of rocks elucidate evolution in the fossil record?
-Sedimentary strata reveal relative age of fossils
- Absolute age of fossil—radiometric dating (isotope)
- Magnetism of rock (reversal of poles)
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