4 - Ch 22: Origin Of Species Flashcards
Species meaning
group of organisms that can interbreed and produce fertile offspring
Who gave the definition of species and what year
Ernst mayr, 1942
__ the process by which one species splits into two or more new species over time.
—This happens when groups of the same species become so different that they can no longer interbreed.
Speciation
Name the 5 types of reproductive barriers: prezygotic
- Habitat isolation
- Temporal isolation
- Behavioural isolation
- Mechanical isolation
- Gametic isolation
Name the 3 types of reproductive barriers (postzygotic)
- Hybrid inviability
- Hybrid sterility
- Hybrid breakdown
A type of postzygotic barrier:
When the grandkids are weak or sterile
Hybrid breakdown
A type of postzygotic barrier:
When the offspring cant have babies
Reduced Hybrid fertility
A type of postzygotic barrier:
When the offspring can develop but too weak to survive (zygote stops growing)
Reduced hybrid variability
A type of prezygotic reproductive barriers:
Occupy diff habitats
Habitat isolation
Type of reproductive barriers:
Species breed at different times
Temporal isolation
Type of reproductive barriers
Courtship rituals and behaviours keep species apart
Behavioural isolation
Type of reproductive barriers
Form differences prevent mating (reproductive structure prevent them)
Mechanical isolation
Type of reproductive barriers
Gametes unable to fuse
Gametic isolation
3 diff ways to define species
- Morphological - physical appearance
- Ecological - role in community
- Phylogenetic - genetic history
Who came up with punctuated equilibrium
Stephen jay gould
Explain punctuated equilibrium
species remain mostly unchanged for long periods then undergo rapid burst of change due to environmental shifts or genetic
Term used for how fast new species form over time
Speciation rates
2 main pattern of speciate rates and describe them
Gradualism - slow and steady evolution
Punctuated equilibrium - long periods of no change then rapid change
Term used for large scale evolutionary changes that happen over long perioeds
• lead to new species or higher taxonomic groups
Macroevolution
3 patterns with hybrid zones
- Occur in band (meet in middle)
- Reduced fitness compared to parent
- Complicated habitat - complicated hybrid zones
3 possible outcomes from hybrid zones
- Strengthen reproductive barrier
- Weaken reproductive barrier
- Continued formation of hybrid individual
3 ways hybrid zones can occur
- Reinforcement
- Fusion
- Stability
What type of hybrid zone is this
Barriers get stronger because hybrids are less fit than parents.
• Parent species stay separate.
Reinforcement
What type of hybrid zone is this
Barriers weaken because hybrids are just as fit as parents.
• Parent species merge into one.
Fusion
