Chapter ?? (Macroevolution) Flashcards
What are the four popular definitions of species?
- Biological Species concept
- Morphological Species Concept
- Genetic Species Concept
- Ecological Species Concept
What are some cons of the Morphological Species Concept
- Very Subjective
- Species are arbitrary with no threshold
What are some cons of the Genetic Species Concept
- DNA sequencing may not be available
- How similar is same?
Cons of Ecological Species Concept
- Multiple Organisms may be adapted to the same niche in the environment
What are the cons of the Biological Species concept
- It ignores fossils
- It ignores asexual species
Prezygotic Barriers
Barriers of speciation that occur before fertilization
Postzygotic Barriers
Barriers of speciation that occur post fertilization
What are some prezygotic barriers
- Habitat Isolation
- Temporal Isolation (Diff. mating times)
- Behavioral Isolation (Diff. Mating dance)
- Mechanical Isolation (diff. sexual organs?)
- Gametic Isolation (Sperm cannot fertilize egg)
What are some post-zygotic barriers
- Reduced hybrid viability (Produced offspring is not fit)
- Reduced Hybrid Fertility (Hybrid is fit, cannot reproduce)
- Hybrid Breakdown (1st gen survives, 2nd gen unviable)
Allopatric speciation
Gene flow is interrupted when a population is geographically isolated
Sympatric Speciation
new species evolve from a single ancestral species while inhabiting the same geographic region
Why is sympatric speciation less common
The individuals in a species need to reproduce within the same small group long enough where change is made
Describe three possible ways for Sympatric Speciation to occur
- Polyploidy
- Habitat Differentiation
- Sexual Selection
