PCB4674 Final Exam NEW Material
Study online at https://quizlet.com/_e2xe4f
1. Genetic Drift: changes in gene frequency owing to chance, greater importance in smaller populations but
ubiquitous
2. Does genetic drift inncrease or decrease genetic differentiation/: increase
3. how often does genetic drift occur?: all of the time in every population and every species
4. natural selection: higher fitness for genes conferring traits that enhance survival or reproduction
5. does natural selection increase or decrease genetic differentiation?: increase
6. gene flow (migration): migration tends to counter the diversifying effects of drift and selection which is
critical to speciation
7. does gene flow/migration increase or decrease genetic differentiation?: de-
crease
8. what occurs if you were to stop gene flow?: you will eventually get two species, no matter what!
9. what are the two ways to stop gene flow?: reproductive barrier and geographic isolation
10. reproductive barriers: are intrinsic, internal, property of the organisms themselves
11. geographic isolation: extrinsic, external, organisms don't control this but the environment does
12. geographic variation (a consenquence): adds structure to the genetic organization of species
owing to divergent (directional) natural selection and drift with geographic isolation
13. 3 steps to speciation: 1. Isolation
2. Divergence
3. Reproductive Barriers
14. Step 1: isolation of populations: reduces gene flow typically due to geography
needs to be dropped to a low value so it is effective in causing speciation, and allows populations to be independent
15. Step 2: divergence of populations: natural selection and genetic drift; individuals are free to adapt
to their own populations and diverge
phenotypic and reproductive divergence
slow process
, PCB4674 Final Exam NEW Material
Study online at https://quizlet.com/_e2xe4f
16. step 3: evolution of reproductive barriers: makes any divergence permanent
without this, divergence can go away or revert back
17. Does the BSC need all three steps of speciation to occur?: yes
18. does the PSC need all three steps of speciation to occur?: no, only to step 2
19. allopatric speciation: non-overlapping with a gap, form into two different species A and B, none or very
limited gene flow
20. Allopatric speciation occurs via vicariance. What is vicariance?: the geographical
separation of a population, typically by a physical barrier such as a mountain range or river, resulting in a pair of closely
related species
21. example of allopatric speciation?: isthmus of Panama cut off Pacific populations from Caribbean
populations, species are sister in Caribbean and Pacific like the Snapping Shrimp
22. Peripatric speciation: a special case of allopatric, peripheral isolate; this is an extreme case, none or very
limited gene flow
there are two species, A and B, but one is smaller, isolated, has high genetic drift and selection which makes that species
more likely to go faster
23. parapatric speciation: non-overlapping without a gap; there is some gene flow between the populations,
natural selection pulls the populations apart because of the environmental factors (cline), requires strong selective
differences/differential selection
24. sympatric speciation: overlapping, shared; a species within another species maybe with a smaller
distribution, hard to achieve, requires the evolution of intrinsic (reproductive barriers) methods to prevent interbreeding
25. closely related species typically have what type of geographic speciation/dis-
tribution?: allopatric
26. what are the three types of geographic speciations/distributions?: allopatric,
parapatric, sympatric
27. which is most common? allopatric, peripatric or sympatric: allopatric
28. which is the rarest? allopatric, peripatric, or symptraic: sympatric
Study online at https://quizlet.com/_e2xe4f
1. Genetic Drift: changes in gene frequency owing to chance, greater importance in smaller populations but
ubiquitous
2. Does genetic drift inncrease or decrease genetic differentiation/: increase
3. how often does genetic drift occur?: all of the time in every population and every species
4. natural selection: higher fitness for genes conferring traits that enhance survival or reproduction
5. does natural selection increase or decrease genetic differentiation?: increase
6. gene flow (migration): migration tends to counter the diversifying effects of drift and selection which is
critical to speciation
7. does gene flow/migration increase or decrease genetic differentiation?: de-
crease
8. what occurs if you were to stop gene flow?: you will eventually get two species, no matter what!
9. what are the two ways to stop gene flow?: reproductive barrier and geographic isolation
10. reproductive barriers: are intrinsic, internal, property of the organisms themselves
11. geographic isolation: extrinsic, external, organisms don't control this but the environment does
12. geographic variation (a consenquence): adds structure to the genetic organization of species
owing to divergent (directional) natural selection and drift with geographic isolation
13. 3 steps to speciation: 1. Isolation
2. Divergence
3. Reproductive Barriers
14. Step 1: isolation of populations: reduces gene flow typically due to geography
needs to be dropped to a low value so it is effective in causing speciation, and allows populations to be independent
15. Step 2: divergence of populations: natural selection and genetic drift; individuals are free to adapt
to their own populations and diverge
phenotypic and reproductive divergence
slow process
, PCB4674 Final Exam NEW Material
Study online at https://quizlet.com/_e2xe4f
16. step 3: evolution of reproductive barriers: makes any divergence permanent
without this, divergence can go away or revert back
17. Does the BSC need all three steps of speciation to occur?: yes
18. does the PSC need all three steps of speciation to occur?: no, only to step 2
19. allopatric speciation: non-overlapping with a gap, form into two different species A and B, none or very
limited gene flow
20. Allopatric speciation occurs via vicariance. What is vicariance?: the geographical
separation of a population, typically by a physical barrier such as a mountain range or river, resulting in a pair of closely
related species
21. example of allopatric speciation?: isthmus of Panama cut off Pacific populations from Caribbean
populations, species are sister in Caribbean and Pacific like the Snapping Shrimp
22. Peripatric speciation: a special case of allopatric, peripheral isolate; this is an extreme case, none or very
limited gene flow
there are two species, A and B, but one is smaller, isolated, has high genetic drift and selection which makes that species
more likely to go faster
23. parapatric speciation: non-overlapping without a gap; there is some gene flow between the populations,
natural selection pulls the populations apart because of the environmental factors (cline), requires strong selective
differences/differential selection
24. sympatric speciation: overlapping, shared; a species within another species maybe with a smaller
distribution, hard to achieve, requires the evolution of intrinsic (reproductive barriers) methods to prevent interbreeding
25. closely related species typically have what type of geographic speciation/dis-
tribution?: allopatric
26. what are the three types of geographic speciations/distributions?: allopatric,
parapatric, sympatric
27. which is most common? allopatric, peripatric or sympatric: allopatric
28. which is the rarest? allopatric, peripatric, or symptraic: sympatric
