Ch14

Question 1

Define species according to the evolutionary species concept

Answer 1

a lineage of populations that maintains its identity from others & has its own evolutionary fate

Question 2

Can the evolutionary species concept be used to identify species or understand their boundaries?

Answer 2

No

Question 3

Define phenetic/morphological species concept

Answer 3

Individuals that cluster in phenotype space can be assigned to the same species

Question 4

Define biological species concept

Answer 4

Groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups

Question 5

State the difficulties of using the biological species concept

Answer 5

• hard to apply to extinct animals
• does not apply to asexual species
• hybridization is happening more often

Question 6

Define phylogenetic species concept

Answer 6

The smallest monophyletic groups distinguished by a shared derived character

Question 7

State the difficulties of using the phylogenetic species concept

Answer 7

• Traits used do not need to be ecologically, physiologically, or morphologically significant
• Opportunity for over-splitting
• some traits may be cause by local adaptation & polymorphic for a given species

Question 8

Does all 3 concepts agree with one another?

Answer 8

No

Question 9

List the concepts needed to define species

Answer 9

• evolutionary fate
• distinguishable characters
• lack of gene flow
• shared derived characters

Question 10

Define allopatric speciation

Answer 10

Speciation caused by geographic isolation

ex. snapping shrimp Alpheus

Question 11

Define parapatric speciation

Answer 11

speciation caused by diverging populations joining at a common border
ex. black & red spruce

Question 12

Are hybrids caused by parapatric speciation always at fitness disadvantage?

Answer 12

No

ex. Artemisia tridentata in hybrid zone

Question 13

Define ring species

Answer 13

species or species complex whose distribution spreads around geographical barriers, or areas of unsuitable habitat
*they have some gene flow

Question 14

Define sympatric speciation

Answer 14

speciation that occurs within the same location

ex. cichlids, Amphilophus

Question 15

Why don’t two separate species merge back together if they overlap in range?

Answer 15

due to prezygotic & postzygotic isolating mechanisms

Question 16

State the function of prezygotic isolating mechanisms

Answer 16

prevents mating or fertilization

Question 17

State the function of postzygotic isolating mechanisms

Answer 17

prevents zygote or offspring from surviving

Question 18

If a barrier disappears & populations

come back into contact, what can occur?

Answer 18

blending or reinforcement

Question 19

List the genetics of reproductive isolation

Answer 19

• Changes in chromosome number
• Chromosomal rearrangement
• Dobzhansky-Muller hybrid incompatibility
• Sex chromosomes & Haldane’s rule

Question 20

Define Haldane’s rule

Answer 20

If among hybrid offspring one sex is absent, rare or sterile, it will be the heterogametic sex