Speciation

Question 1

Define species

Answer 1

the smallest evolutionary independent unit

Question 2

What are the 3 species concepts

Answer 2

1. biological SC
2. morphospecies C
3. phylogenetic SC

Question 3

Define the biological species concept

Answer 3

defining species as groups that can interbreed and produce viable offspring and are reproductively isolated from other groups

Question 4

strength of BSC

Answer 4

strength = confirms lack of gene flow

Question 5

limitations of BSC

Answer 5

1. assumes sexual reproduction
2. in allopatric populations

Question 6

Define morphospecies concept

Answer 6

defining species based on morphological differences

Question 7

what are strengths of morphospecies concept

Answer 7

1. can be sex or asexual
2. can be living or extinct

Question 8

what are limitations of morphospecies concept (4)

Answer 8

1. may consist of arbitrary designations, may have some disagreement
2. fossils, the difference in colour and soft tissue
3. does not work well for bacteria or archea (all small round species)
4. cryptic species - that have no morphological difference, but cannot reproduce

Question 9

Define phylogenetic species concept

Answer 9

defining species by identifying the smallest monophyletic group in a phylogeny of a closely related population/species

Question 10

Strength of PSC

Answer 10

strengths = can be applied to many groups

Question 11

limitation of PSC

Answer 11

varies if looking at gene tree vs. species tree

Question 12

What are the 2 categories for the tempo of speciation

Answer 12

1. gradualism model
2. punctuated equilibrium model

Question 13

define gradualism vs. punctuated equilibrium models

Answer 13

gradualism = small changes building over time leading to separation in speciation
punctuated = everything stays the same until sudden extreme changes occur and cause speciation

Question 14

What are the 3 simple steps to forming a species

Answer 14

1. populations become isolated
2. traits diverge
3. reproductive isolation (could not reproduce IF brought back together)

Question 15

What are the 2 categories in which population isolation can occur

Answer 15

1. allopatric model
2. sympatric model

Question 16

Define allopatric vs. sympatric model
and examples

Answer 16

allopatric = populations are physically isolated
ex. mountains
sympatric = populations are not physically isolated but reproductively isolated
ex. divergent selection - behaviour, polyploidy, sexual selection

Question 17

explain the difference of isolation and divergence steps in allopatric vs. sympatric models

Answer 17

allopatric has isolation as the first step and then divergence
whereas sympatric has isolation and divergence occurring at the same time

Question 18

what 3 factors cause populations to diverge

Answer 18

1. genetic drift
2. natural selection
3. sexual selection

Question 19

how does genetic drift cause populations to diverge

Answer 19

the random movement of a small groups of individuals to a new area can drive the affects of speciation (ex. founder effect)

Question 20

how does natural selection cause populations to diverge

Answer 20

preferences are heritable and non-random mating occurs which can effect factors such as allele frequencies, genetic marking, timing, to cause sympatric speciation

Question 21

how does sexual selection cause populations to diverge

Answer 21

it affects gene flow directly, speciation can result from nonrandom mating

Question 22

What are the 3 reproductive isolating mechanisms and explain

Answer 22

1. premating = never mate
2. prezygotic = mate, but no zygote forms
3. postzygotic = zygote forms but is not born

Question 23

What are the 3 results of populations being brought back together after speciation

Answer 23

1. reinforcement
2. hybrid speciation
3. stable hybrid zone

Question 24

Explain reinforcement

Answer 24

populations stay isolated and hybrids are selected against

Question 25

Explain hybrid speciation

Answer 25

form a 3rd hybrid species that is favoured for in areas that the parents aren’t found

Question 26

Explain stable hybrid zone

Answer 26

3rd hybrid species forms that is selected for in hybrid zone but not in other areas, do not colonize new areas