speciation

Question 1

phylogenetic species concept

Answer 1

species = one or more populations that share a trait derived from a common ancestor which sets them apart from other organisms
can be physically separate populations

Question 2

biological species concept

Answer 2

a species includes only individuals that could potentially produce fertile offspring in nature and are isolated from others (can’t/don’t reproduce with others).

Question 3

Speciation requires

Answer 3

1) Reproductive Isolation of some type
2) Genetic divergence(evolution) due to different selective pressures or genetic drift
3) Evolution of differences that prevent interbreeding even if reintroduced to original home land

Question 4

Speciation occurs when 2 populations become reproductively isolated by

Answer 4

geographic barriers
prezygotic mechanisms= before zygote forms
Postzygotic mechanisms= after zygote forms

Question 5

PREzygotic mechanisms of reproductive isolation

Answer 5

mechanical
temporal
behavioral
ecological/habitat
gametic

Question 6

Mechanical Isolation

Answer 6

parts don’t fit snail shells twist in different directions

Question 7

Temporal Isolation

Answer 7

mate at dif. times seasons, years, nocturnal vs diurnal

Question 8

Behavioral Isolation

Answer 8

courtship/recognition

Question 9

Ecological/habitat Isolation

Answer 9

field vs forest

Question 10

Gametic Isolation

Answer 10

sperm fail to survive or penetrate egg

Question 11

what type of reproductive isolation:

Song birds change their mating song

Answer 11

behavioral isolation & sexual selection

Question 12

what type of reproductive isolation:

Female fish select mates that are most similar in color to themselves

Answer 12

sexual selection

Question 13

what type of reproductive isolation:
One group of fish feed at the top of the lake the other feeds at the bottom. They seldom encounter each other and do not mate.

Answer 13

ecological isolation also called Habitat isol

Question 14

what type of reproductive isolation:

One population of flowers blooms earlier than another

Answer 14

temporal isolation

Question 15

Postzygotic mechanisms …zygote forms and then

Answer 15

Embryo mortality
Death before maturity
Reduced hybrid fertility
Hybrid breakdown:

Question 16

Hybrid breakdown:

Answer 16

offspring of hybrid weak or sterile

Question 17

Polyploidy

Answer 17

Plants can be 3n or 4n or more

B) Polyploid individuals no longer interbreed with the 2n population = reproductive isolation = new species.

Question 18

Autopolyploidy

Answer 18

just keep two full sets of your own chromosomes (4n can self pollinate)

Question 19

Allopolyploidy

Answer 19

hybridize with other species

Question 20

Patterns of Evolution defined by

Answer 20

rates of change
(gradual or punctuated equilibrium model)
number of species formed

Question 21

punctuated equilibrium model

Answer 21

no change for long time then rapid change for ‘short’ time (10,000 – 100,00 years

Question 22

anagenesis =

Answer 22

single line of descent

Question 23

cladogenesis =

Answer 23

branching line of descent

1) lineage splits
2) adaptive radiation
3) graphical models

Question 24

cladogenesis lineage splits due to

Answer 24

reproductive isolation and genetic divergence (evolution)

Question 25

cladogenesis graphical models

Answer 25

Cladograms and Phylogenetic Trees

1) mathematical models - computer generated
2) based on morphological homologies and molecular data (amino acid/DNA sequence)
3) show when traits are derived or lost

Question 26

cladogenesis: Each branch point shows an

Answer 26

extinct common ancestor of the organisms further down the branch

Question 27

Outgroup =

Answer 27

group at base
One that branched off first
Most different
Used as comparison

Question 28

cladogenesis: lines that do not reach the top of the page show

Answer 28

lineages that went extinct

Question 29

cladogenesis: Lines crossing the cladogram show

Answer 29

when derived traits showed up.

All organisms further along the branch will have those traits unless they were lost due to natural selection

Question 30

Types of cladistic grouping

Answer 30

Monophyletic group
Paraphyletic group
Polyphyletic group

Question 31

Monophyletic group

Answer 31

All the descendants of a common ancestor in one group

Question 32

Paraphyletic group

Answer 32

All members of group share a common ancestor but not all descendants included in the group

Question 33

Polyphyletic group

Answer 33

includes descendants from more than one common ancestor

Question 34

Molecular Clock Theory

Answer 34

A) Attempts to measure absolute time of evolutionary change
B) # nucleotide substitutions proportional to time since divergence
C) Assumes constant rate of evolution of genes
D) Δ rates depend on importance of gene/mutation