lecture 20

Question 1

what is microevolution

Answer 1

changes in allele frequencies in a
population (with in the same species)

Question 2

what is macroevolution

Answer 2

Evolutionary change above the species level
– Includes the origin of a new group of organisms (speciation) or the cumulative evolutionary change over a long period of time
- phenotypic differences are so great that the new species are assigned to different taxonomic categories

Question 3

what is speciation

Answer 3

the process by which one species splits into 2 or more species, i.e. new species

Question 4

what must a evolutionary theory explain

Answer 4

how new species originate in addition to how populations evolve

Question 5

what is a species

Answer 5

Traditionally, morphological differences have been used to distinguish species

Question 6

what is the biological species concept

Answer 6

a population / group of populations whose members have the potential to breed with each other in nature to produce viable, fertile offspring,
- but who cannot produce viable, fertile offspring with members of other species.
(emphasizes reproductive isolation)

Question 7

what is reproductive isolation

Answer 7

• the existence of biological factors that impede members of two species from producing viable, fertile hybrid
• Preserves genetic integrity (gene flow prevented)

Question 8

what are reproductive isolation methods

Answer 8

• prezygotic barriers
• postzygotic barriers

Question 9

what is a prezygotic barriers

Answer 9

• prevent zygote formation
• Impede mating between species or hinder the fertilization if members of
  different species attempt to mate

Question 10

what is a postzygotic barrier

Answer 10

Often prevent the hybrid zygote from developing into a viable, fertile adult
- zygot is produced, but once developed, cannot reproduce or does not survive

Question 11

what are the types of prezygotic barriers

Answer 11

• habitat isolation : not same habitat
• temporal isolation: breed at diff times of year
• behavioral isolation: female will only mate with male with a certain courtship ritual
• mechanical isolation: cannot mate
• gametic isolation : sperm will not fertilize egg of another spicies

Question 12

what are the types of postzygotic barriers

Answer 12

• reduced hybrid viability: hibrid is frail
• reduced hybrid fertility: hybrid cannot reproduce
• hybrid breakdown: hybrid survives, reproduces, but F2 generation is feeble or sterile

Question 13

who can the biological species concept not be applied to

Answer 13

• asexual organisms
• organisms about which little is known regarding their rep (fossils)

Question 14

what is the morphological species concept

Answer 14

Characterizes a species in terms of its body shape, size, and other structural features

Question 15

what is the ecological species concept

Answer 15

Views a species in terms of its ecological niche

Question 16

what is the phylogenic species concept

Answer 16

trace phylogenetic history of organisms (comparing morphology & molecular sequences)

Question 17

what are the 2 types of speciation

Answer 17

• Allopatric speciation
• sympatric speciation

Question 18

what is allopatric speciation

Answer 18

geographic separation of populations restricts gene flow.

Question 19

what is sympatric speciation

Answer 19

Speciation takes place in geographically overlapping populations

Question 20

in what ways does sympatric speciation occur

Answer 20

• change in ploidy (plants)
• change in ecology (animals)

Question 21

what are the two changes in poidy possible in sympatric speciation , what group is concerned

Answer 21

• autoploidy :Is an individual that has more than two chromosome sets, all derived from a single (SAME) species
• alloploidy : Is an individual that has more than two chromosome sets, all derived from different species

Question 22

what specifically contributes to sympatric speciation related to change in ecology

Answer 22

• habitat
• sexual selection

Question 23

what are the 2 different models that have been developed to explain evolution as observed in the fossil record models

Answer 23

• gradualism: evolution continuous over long periods
• punctuated equilibrium : evolution over short periods

Question 24

explain gradualism

Answer 24

Fossils records are incomplete * so we rarely see all stages
Evolution is slow

Question 25

explain punctuated equilibrium

Answer 25

- suggests that fossil record accurately reflects evolution as it actually occurs * In the history of a species there are long periods of stasis (no evolutionary) change * these are punctuated (or interrupted) by short periods of rapid speciation * thatmaybetriggeredbyenvironmentalchanges * speciation occurs in a relatively short period (Short = 1000s of years!)

Question 26

Macroevolution: where can evolutionary novalties arise from

Answer 26

- gradual refinement of existing structure - Major changes in body can result from changes in a) genes that control development b) genes that control the spatial organization of body parts

Question 27

explain gradual refinement of existing structures

Answer 27

It is important to recognize that natural selection can only improve a structure in the context of its current utility, not in anticipation of the future. ex: The fossil record indicates that light bones predated flight. – Therefore, they must have originally had some function on the ground, * perhaps as a light frame for agile, bipedal (2-legged) dinosaurs. – Feathers originally were used for courtship, thermoregulation, or camouflage. * Once flight became an advantage, natural selection would have gradually changed the structures to be adapted for flight.

Question 28

explain mutation in genes that control development

Answer 28

A change in the rate or timing of developmental events has led to many striking evolutionary transformations. ex: The feet of the tree-dwellers are adapted for climbing vertically, with shorter digits and more webbing.  Stunted feet may have resulted if mutations in regulatory genes switched off foot growth early.

Question 29

explain mutation in genes that control spacial organization

Answer 29

-The products of one class of genes called the Hox genes, provide positional information in an animal embryo. -This information prompts cells to develop into structures appropriate for a particular location.

Question 30

What are hox genes

Answer 30

provide positional information in an animal embryo. – This information prompts cells to develop into structures appropriate for a particular location.

Question 31

what are adaptive zones

Answer 31

ecological niches that are not filled by ancestral organism

Question 32

what does speciation do to adaptive zones

Answer 32

fills them

Question 33

what is adaptive radiation

Answer 33

Periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles or niche