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Biology Exam #2 > lecture 20 > Flashcards

lecture 20 Flashcards

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1
Q

what is microevolution

A

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

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2
Q

what is macroevolution

A

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

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3
Q

what is speciation

A

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

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4
Q

what must a evolutionary theory explain

A

how new species originate in addition to how populations evolve

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5
Q

what is a species

A

Traditionally, morphological differences have been used to distinguish species

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6
Q

what is the biological species concept

A

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)

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7
Q

what is reproductive isolation

A
  • the existence of biological factors that impede members of two species from producing viable, fertile hybrid
  • Preserves genetic integrity (gene flow prevented)
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8
Q

what are reproductive isolation methods

A
  • prezygotic barriers
  • postzygotic barriers
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9
Q

what is a prezygotic barriers

A
  • prevent zygote formation
  • Impede mating between species or hinder the fertilization if members of
    different species attempt to mate
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10
Q

what is a postzygotic barrier

A

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

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11
Q

what are the types of prezygotic barriers

A
  • 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
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12
Q

what are the types of postzygotic barriers

A
  • reduced hybrid viability: hibrid is frail
  • reduced hybrid fertility: hybrid cannot reproduce
  • hybrid breakdown: hybrid survives, reproduces, but F2 generation is feeble or sterile
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13
Q

who can the biological species concept not be applied to

A
  • asexual organisms
  • organisms about which little is known regarding their rep (fossils)
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14
Q

what is the morphological species concept

A

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

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15
Q

what is the ecological species concept

A

Views a species in terms of its ecological niche

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16
Q

what is the phylogenic species concept

A

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

17
Q

what are the 2 types of speciation

A
  • Allopatric speciation
  • sympatric speciation
18
Q

what is allopatric speciation

A

geographic separation of populations restricts gene flow.

19
Q

what is sympatric speciation

A

Speciation takes place in geographically overlapping populations

20
Q

in what ways does sympatric speciation occur

A
  • change in ploidy (plants)
  • change in ecology (animals)
21
Q

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

A
  • 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
22
Q

what specifically contributes to sympatric speciation related to change in ecology

A
  • habitat
  • sexual selection
23
Q

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

A
  • gradualism: evolution continuous over long periods
  • punctuated equilibrium : evolution over short periods
24
Q

explain gradualism

A

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

25
Q

explain punctuated equilibrium

A
  • 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!)
26
Q

Macroevolution: where can evolutionary novalties arise from

A
  • 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
27
Q

explain gradual refinement of existing structures

A

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.

28
Q

explain mutation in genes that control development

A

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.

29
Q

explain mutation in genes that control spacial organization

A

-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.

30
Q

What are hox genes

A

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

31
Q

what are adaptive zones

A

ecological niches that are not filled by ancestral organism

32
Q

what does speciation do to adaptive zones

A

fills them

33
Q

what is adaptive radiation

A

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

Biology Exam #2 (23 decks)

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