ch18

Question 1

Darwin’s Observation

Answer 1

Geographic distinction of organisms
Galápagos Islands (finches and tortoises)

Question 2

Darwin vs Lamarck

Answer 2

Lamarck - giraffes stretched their necks from short to long

Darwin - both short and long necks, natural selection favored long necks (more resources)

Question 3

Natural Selection

Answer 3

1) Organisms have heritable traits
2) Competition of resources
3) Individuals vary with reproductive success
4) Organisms may adapt with environmental change

Variation through genes

Competition, Fitness, and Adaptation

Question 4

Fossil Evidence

Answer 4

Transitional species preserved

Question 5

Anatomical Evidence

Answer 5

Homologous, Analogous, and Vestigial structures

Question 6

Homologous structure

Answer 6

Inherited from common ancestor

Ex: Vertebrate forelimb

Question 7

Analogous structure

Answer 7

Originated individually (over many times)

Ex: Wings

Question 8

Vestigial structure

Answer 8

Important to ancestor and remains in derived species

Ex: Pelvic bone in whales and snakes

Question 9

Biochemical evidence

Answer 9

All organisms have DNA
DNA -> RNA -> Protein

Question 10

Biogeographical Evidence

Answer 10

Similar global strata
Evidence of Pangea

Question 11

Misconceptions of Evolution

Answer 11

1) Evolution is just a theory
2) Individuals in a population evolve
3) Evolution is a theory tied to origin of life
4) Transitional fossils remain unknown
5) Organisms evolve on purpose
6) Random chance alone guides evolution
7) Evolution is not testable
8) Humans evolve directly from apes

Question 12

Species Concept

Answer 12

Species - Latin for “kind”/”appearance”

Same “kind” of organism that may interbreed naturally and produce viable offspring

Limited to reproduction definition

Question 13

Speciation

Answer 13

Formation of two species from one
(Allopatric or Sympatric)

Question 14

Allopatric speciation

Answer 14

Geographic isolation between species and two species form

Question 15

Sympatric speciation

Answer 15

Within the same area
Gene flow can occur or be disturbed
(Polyploidy, Autopolyploid, Allopolyploid, Sexual seletion, Habitat differentiation)

Question 16

Polyploidy

Answer 16

more than 2 chromosome pairs

Question 17

Autopolyploid

Answer 17

Cell division error creates a tetraploid cell
Yields new species

Question 18

Allopolyploid

Answer 18

Interbreeding species
Hybrids often sterile

Question 19

Sexual selection

Answer 19

Females select males and males differ by color

Question 20

Habitat differentiation

Answer 20

Subpopulations that exploit different resources

Question 21

Prezygotic Barriers

Answer 21

Habitat isolation
Temporal isolation
Behavioral isolation
Mechanical isolation
Gametic isolation

Question 22

Habitat isolation

Answer 22

Two species in two habitats within the same area

Prevents mating

Question 23

Temporal isolation

Answer 23

Seasonality of breeding
Prevents mating

Question 24

Behavioral isolation

Answer 24

Courtship rituals performed by males
Prevent mating

Question 25

Mechanical isolation

Answer 25

Mating attempted, but mismatched copulation Prevents fertilization

Question 26

Gametic isolation

Answer 26

Physical or biochemical barrier even when multiple eggs/sperms present Prevents fertilization

Question 27

Postzygotic Barrier

Answer 27

Fertilization has occurred Reduced hybrid viability (low survival rate) Reduced hybrid fertility (often sterile) Hybrid breakdown - 1st generation sterile, but subsequent generations may not be

Question 28

Hybrid Zones

Answer 28

Overlapping areas of two species that allow the two species to interbreed Climate change shifts zones Three possible outcomes (Reinforcement, Fusion, Stability)

Question 29

Reinforcement

Answer 29

Strengthens reproductive barriers Natural selection is the agent of change

Question 30

Fusion

Answer 30

Weakening of reproductive barriers Gene pool becomes more alike Hybrids may further stress existing species

Question 31

Stability

Answer 31

Continued formation of hybrid individuals and both species regularly enter hybrid zones Narrow hybrid zone -> higher mating chances Wide hybrid zone -> lower mating chances

Question 32

Punctuated model

Answer 32

Short speciation period, prolonged stability, and abrupt extinction

Question 33

Gradual model

Answer 33

Small, incremental changes over entire period and produces two species