Ch.24

Question 1

Speciation

Answer 1

-formation of new/distinct species in the course of evolution
Origin of new species are a focal point of revolutionary theory
-can occur rapidly/ slowly and can result in a few/many changes in genes
-can occur with/without geographic operation

Question 2

Macroevolution

Answer 2

broad patterns in evolutionary change above species level
-larger changes over a longer period of time
-can result in speciation

Question 3

Biological species concept

Answer 3

-emphasizes reproductive isolation
-characterizes a group as a pop. whose members have the potential to interbreed in nature and produce viable fertile offspring ( don’t successfully breed with other pop.)

Question 4

Gene flow between pop.

Answer 4

holds phenotype of a pop. together

Question 5

Reproductive isolation

Answer 5

-the existence of barriers that impede two species from producing fertile offspring
-prezygotic barriers
-postzygotic barriers

Question 6

Prezygotic barriers (before)

Answer 6

-prevent members of different species from meeting to produce zygote in the first place
-habitat, temporal, behavioral, mechanical, and gametic barriers

Question 7

Postzygotic barriers (after)

Answer 7

reduced hydra viability and fertility, and hybrid breakdown

Question 8

Imitations of biological species concept

Answer 8

-Can’t be applied to fossils or asexual organisms
-emphasizes absence of gene flow

Question 9

Morphological species concept

Answer 9

-Define species by structural features
-applies to sexual and asexual
-relies on subjective criteria
–difficult to determine the degree of difference required for separate species

Question 10

Ecological species concept

Answer 10

-Use a species in terms of its ecological niche
-sexual/asexual
-emphasizes the role of disruptive selection

Question 11

Phylogenetic species concept

Answer 11

-Defines a species of smallest group of individuals on phylogenic tree
-sexual/asexual
-difficult to determine the degree of difference required for separate species

Question 12

Speciation can occur in 2 ways

Answer 12

-allopatric
-sympatric

Question 13

behavioral isolation

Answer 13

Courtship rituals and other behaviors you need to species are effective barriers

Question 14

allopatric speciation (AS)

Answer 14

-“other homeland”
-gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations
-driven by sexual selection
- in AS, Geographic isolation restrict gene flow between populations

Question 15

Sympatric speciation

Answer 15

“together homeland”
-takes place in geographically overlapping populations
-can result from appearance of new ecological niches
-can result from polyploidy, natural selection, or sexual selection

Question 16

Definition of a barrier depends on..

Answer 16

ability of a pop. to disperse
-ex: canyon may be a barrier for mice but not for birds

Question 17

reproductive isolation

Answer 17

-May arise as a result of genetic divergence (evolution caused to be too different to breed), which won’t allow for fertile offspring
-increases as distance between populations increase
-may arise by natural selection, genetic drift, or sexual selection and isolated populations

Question 18

polyploidy

Answer 18

Presents an extra set of chromosomes due to accidents during cell division
-more common in plants (crops, cotton, potatoes, tobacco, and wheat)

Question 19

autopolyploid

Answer 19

Individual with more than two chrome zone sets derived from one species

Question 20

allopolyploid

Answer 20

Species with multiple sets of chromosomes derived from different species sex

Question 21

hybrid zone

Answer 21

Region in which members of different species meat and produce hybrids
-can occur in a single band where adjacent species meet

Question 22

Hybrids

Answer 22

Results of the meeting between species with incomplete reproductive barriers
-often have reduced fitness

Question 23

3 possible outcomes for hybrid zones

Answer 23

-reinforcement
-fusion
-stablilty

Question 24

Reinforcement

Answer 24

-strengthening reproductive barriers
-hybrids less fit than parents
-overtime, rate of hybridization decreases
-reproductive barriers are stronger for sympatric than allopatric species

Question 25

Fusion

Answer 25

-weakening reproductive barriers
-hybrids are as fit as parents
-if gene flow is enough, parent species confuse into a single species

Question 26

Stability

Answer 26

-continued formation of hybrid individuals
-extensive gene flow from outside of hybrid zone can overwhelm selection for increased reproductive isolation inside hybrid zone

Question 27

Punctuated equilibria

Answer 27

Corned by Niles Eldredge and Stephan Jay Gould
-described. Apparent stasis punctuated by sudden change

Question 28

microevolution

Answer 28

smaller changes over a shorter period of time