Speciation

Question 1

What is the Biological Species Concept (BSC)?

Answer 1

The most widely used species concept. All members have the potential to interbreed naturally and produce viable, fertile offspring.

Question 2

What are the limitations of BSC?

Answer 2

It does not apply to asexual organisms, cannot be applied to fossil records, and no clear boundary on “too much hybridization”

Question 3

The 5 Prezygotic barriers

Answer 3

1. Habitat Isolation
2. Temporal Isolation
3. Behavioral Isolation
4. Mechanical (Lock and Key) Isolation
5. Gametic Isolation

Question 4

The 3 Postzygotic barriers

Answer 4

1. Reduced Viability
2. Infertility
3. Generational Hybrid Breakdown

Question 5

What is the difference between Allopatric and Sympatric speciation?

Answer 5

Allopatric is due to a physical barrier
Sympatric has no physical barriers

Question 6

What are the characteristics of Allopatric speciation?

Answer 6

A physical barrier divides populations–vicariance event
Populations differ through genetic drift and natural selection

Question 7

What are the characteristics of Sympatric speciation?

Answer 7

No physical barrier separates populations
Autopolyploidy–more than 2 sets of chromosomes from the same species
or Allopolyploidy–more than 2 sets from different species

Question 8

What are the 2 main macroevolutionary patterns?

Answer 8

Gradualism (Anagenesis) –evolution by jerks
Cladogenesis – evolution by creeps

Question 9

What are the differences between Gradualism/Anagenesis and Cladogenesis?

Answer 9

Anagenesis is slow, constant change over long periods of time
Cladogenesis emphasizes periods of stasis with periods of rapid change. Original species isn’t gone, but branched off

Question 10

What is stasis and its possible causes?

Answer 10

Stasis is a long period of subtle evolutionary changes.
This may be caused by stabilizing selection restricting major change, directional selection that fluctuates around a mean, or genetic and developmental constraints.

Question 11

What are the causes of Rapid Diversification?

Answer 11

Environmental change
Ecological Opportunity–Extrinsic: Opportunities to occupy previously unavailable niches
Ecological Opportunity–Intrinsic: Traits in organisms open up new opportunities, novel characteristics

Question 12

What are the 6 origins of evolutionary novelty?

Answer 12

Exaptation–Tinkering: Gradual refinement of existing structures for new, different functions
Duplication: Duplicated genes can evolve novel functions
Serial Homology: Repetitive parts in the same organism–duplicated parts can specialize
Heterochrony: Changes in developmental timing
Lateral Gene Transfer: Horizontal movement of individual genes
Homeotic genes and Pattern formation: Simple genetic changes that alter organism body plans