Lecture 22 - Speciation

Question 1

Modes of Speciation

Answer 1

1. ) Allopatric Speciation
2. ) Peripatric Speciation
3. ) Parapatric Speciation
4. ) Sympatric Speciation

Question 2

Allopatric Speciation

Answer 2

reproductive isolation occurs in complete geographic isolation (NO GENE FLOW)
- outcome of isolation and divergence

Question 3

Peripatric Spectiation

Answer 3

population that’s at the edge of main rainge of species

-will eventually diverge to different species

Question 4

Parapatric Speciation

Answer 4

reproductive isolation occurs without complete geographic isolation (some gene flow)

Question 5

Sympatric Speciation

Answer 5

reproductive isolation evolves with complete geographic overlap

Question 6

Requirements for Sympatric Speciation

Answer 6

1. ) sympatric distribution
2. ) history of Allopatry is unlikely!
3. ) monophyletic sister taxa
4. ) Reproductive System
5. ) Pre-Zygotic isolation

Question 7

What evolutionary processes are involved in speciation?

Answer 7

1. ) Natural Selection
2. ) Sexual Selection
3. ) Random Genetic Drift

Question 8

Natural Selection

Answer 8

driven by different abiotic conditions (temp/alt) and biotic conditions (parasites/competitors)

Question 9

Sexual Selection

Answer 9

both female choice and male-male competition can promote rapid divergence

Question 10

Random Genetic Drift

Answer 10

may involve founders effect and genetic bottle neck;alleles that are neutral in one environment may not be neutral in another

Question 11

Haldane’s Rule

Answer 11

In early stages of speciation, hybrid sterility or inviability is almost always seen in heterogametic sex

Question 12

Magnitude of Prezygotic and Postzygotic Isolation both ______ with the time

Answer 12

INCREASE

Question 13

Among recent separted groups, prezygotic isolation is generally _________ than postzygotic isolation

Answer 13

STRONGER

Question 14

Major mode of speciation in PLANTS

Answer 14

POLYPLOIDIZATION

Question 15

Polyploidization

Answer 15

Retention of extra sets of chromosomes. Two types: autoploids and allopolyploids

Question 16

Autoploids

Answer 16

add chromosomal sets from same species

Question 17

Allopolyploids

Answer 17

add chromosomal sets from different species

Question 18

3 Possible Outcomes of Secondary Contact

Answer 18

1. ) No interbreeding occurs
2. ) Introgression - populations merge completely
3. ) Partial Interbreeding - less fit hybrids forms

Question 19

The geographic distribution of salamander species belonging to the genus Ensatina throughout California is thought to have been generated by: ____speciation

Answer 19

Parapatric Speciation

Question 20

Ring species are believed to be formed by the process of: ____speciation

Answer 20

Parapatric Speciation

Question 21

Isolation in allopatric speciation is created by:

Answer 21

reductions in gene flow

Question 22

What is created when mutation, genetic drift, and selection act on populations separately?

Answer 22

Dvergence

Question 23

A series of geographically neighboring populations that are closely related:

Answer 23

Ring species

Question 24

Evidence for secondary invasion hypothesis for sticklebacks

Answer 24

1. ) only low elevation lake possess limnetic and benthic species pairs
2. ) cores from lakes with limnetic and benthic species pairs show evidence of salt water influx
3. ) higher elevation lakes have neither limnetic and benthic species pairs nor evidence of salt water influx

Question 25

Secondary Contact

Answer 25

occurs when two formerly allopatric populations meet

Question 26

Reinforcement should occur to “complete the process by the:

Answer 26

Evolution of additional prezygotic barriers