Speciation - Ch. 14

Question 1

What’s the difference between microevolution and macroevolution?

Answer 1

Microevolution- adaptation of populations

Macroevolution- multiplication of species, generating biological diversity

Question 2

What is speciation?

Answer 2

the divergence of 1 species into 2 or more; the origin of new species

Question 3

What does the biological species concept state, and what are it’s problems?

Answer 3

Populations/organisms belong to the same species if they can: 1. interbreed (mate) and 2. produce fertile offspring in a natural setting.
Problems: Extinct species, asexual species, remote populations
Solutions/other ways to define species: Observable + measurable traits, ecological niches (role in environment), genetic similarities (DNA)

Question 4

How can populations become different species?

Answer 4

Reproductive barriers/Reproduction Isolation prevents individuals of closely related species from interbreeding.

Question 5

What are the prezygotic barriers? (Prezygotic barriers are barriers that prevent mating or fertilization between species)

Answer 5

The prezygotic barriers are:

1. Temporal Isolation- mating/fertilization occurs at different seasons or times of day
2. Habitat Isolation- populations live in different habitats and do not meet
3. Behavioral Isolation- little to no sexual attraction exists between populations; change in behavior reproductively isolates them
4. Mechanical Isolation- structural/morphological differences prevent fertilization
5. Gametic Isolation- female and male gametes fail to unite in fertilization; they are incompatible

Question 6

What are the postzygotic barriers? (Postzygotic barriers are barriers that operate if interspecies mating actually occurs and results in HYBRID zygotes)

Answer 6

1. Reduced Hybrid Viability- hybrids fail to develop or reach sexual maturity
2. Reduced Hybrid Fertility- hybrids fail to produce functional gametes
3. Hybrid Breakdown- hybrids are sterile

Question 7

What are the 2 mechanisms of speciation?

Answer 7

1. Allopatric- geographic barrier physically separates populations; gene flow is blocked
2. Sympatric- takes place within habitat or parent species; reproductive barrier forms within a subset of population

Question 8

What’s a polyploid?

Answer 8

Accidents during cell division results in an extra set of chromosomes (polyploid).