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AP Biology Semester 1 > Chapter 24 > Flashcards

Chapter 24 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

speciation

A

the origin of new species, is at the focal point of evolutionary theory
-evolutionary theory must explain how new species originate and how populations evolve

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2
Q

microevolution

A

consists of changes in allele frequency in a population over time

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3
Q

macroevolution

A

refers to broad patterns of evolutionary change above the species level

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4
Q

biological species concept

A

states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations

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5
Q

reproductive isolation

A

the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring

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6
Q

hybrids

A

offspring of crosses between different species

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7
Q

prezygotic barriers

and 3 ways it occurs by

A

block fertilization from occurring by

  1. impeding different species from attempting to mate
  2. preventing the successful completion of mating
  3. hindering fertilization if mating is successful
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8
Q

habitat isolation:

A

two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

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9
Q

temporal isolation

A

species that breed at different times of the day, different seasons, or different years cannot mix their gametes

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10
Q

behavioral isolation

A

courtship rituals and other behaviors unique to a species are effective barriers

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11
Q

mechanical isolation

A

morphological differences can prevent successful mating

different sexual organs

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12
Q

gametic isolation

A

sperm of one species may not be able to fertilize eggs of another species

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13
Q

postzygotic barriers

3 preventions

A

prevent they hybrid zygote from developing into a viable, fertile adult:

  1. reduced hybrid viability
  2. reduced hybrid fertility
  3. hybrid breakdown
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14
Q

reduced hybrid viability

A

genes of the different parent species may interact and impair the hybrid’s development
ex) a mule

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15
Q

reduced hybrid fertility

A

even if hybrids are vigorous, they may be sterile

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16
Q

hybrid breakdown

A

some first generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile

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17
Q

the biological species concept cannot be applied to _____ or ______ organisms

A
  • fossils

- asexual organisms

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18
Q

the biological species concept emphasizes ________

A

absence of gene flow

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19
Q

morphological species concept

A

defines a species by structural features

-applies to sexual and asexual species but relies on subjective criteria

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20
Q

ecological species concept

A

views a species in terms of its ecological niche

-it applies to sexual and asexual species and emphasizes the role of disruptive selection

21
Q

phylogenetic species concept

A

defines a species as the smallest group of individuals on a phylogenetic tree
-it applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species

22
Q

in what two ways can speciation occur?

A
  • allopatric speciation

- sympatric speciation

23
Q

allopatric speciation

A

gene flow is interrupted or reduced when a population is divided into geographic isolated subpopulations

  • a population forms a new species while geographically isolated from its parent population
  • -ex) the flightless cormorant of the galapagos likely originated from a flying species on the mainland
24
Q

true or false:

a definition of barrier depends on the ability of a population to disperse

A

true!

ex) a canyon may create a barrier for small rodents, but not birds, coyotes, or pollen

25
Q

separate populations may evolve independently through what three things

A
  1. mutation
  2. natural selection
  3. genetic drift
26
Q

reproductive isolation may arise as a result of ______

A

genetic divergence

27
Q

genetic divergence

A

the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period of time. This means that the populations of species live independently of each other long enough that they can no longer produce offspring that can survive.

28
Q

true or false:

Regions with many geographic barriers typically have more species than do regions with fewer barriers

A

true

29
Q

sympatric speciation

A

speciation takes place in geographically overlapping populations

30
Q

polyploidy

A

the presence of extra sets of chromosomes due to accidents during cell division

31
Q

true or false:

polyploidy is more common in animals than plants

A

false: polyploidy is more common in plants than animals

32
Q

what can result from the appearance of new ecological niches

A

sympatric speciation

33
Q

sexual selection can drive _____

A

sympatric speciation

34
Q

in allopatric speciation, geographic isolation restricts _____

A

gene flow between populations

35
Q

in isolated populations, reproductive isolation may arise by ____,____, or ______

A
  • natural selection
  • genetic drift
  • sexual selection
36
Q

true or false:
in sympatric speciation, a reproductive barrier isolates a subset of a population without geographic separation from the parent species

A

true

37
Q

sympatric speciation can result from ____, _____, or _____

A

polyploidy, natural selection, or sexual selection

38
Q

hybrid zone

A

a region in which members of different species mate and produce hybrids

39
Q

hybrids often have reduced ____ compared with parent species

A

fitness

40
Q

when closely related species meet in a hybrid zone, there are three possible outcomes

A
  1. reinforcement
  2. fusion
  3. stability
41
Q

reinforcement

A

barriers occurs when hybrids are less fit than the parent species
-over time, the rate of hybridization decreases

42
Q

if hybrids are fit as parents, there can be substantial _____ between species

A

gene flow

43
Q

Fusion….

if gene flow is great enough, the parent species can _______

A

fuse into a single species

44
Q

Stability….
True or false:
extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone

A

true

45
Q

broad patterns in speciation can be studied using what three things

A
  1. fossil record
  2. morphological data
  3. molecular data
46
Q

the fossil record includes examples of species that ______, ______, and then______

A
  1. appear suddenly
  2. persist essentially unchanged for some time
  3. apparently disappear
47
Q

puncuated equilibrium

A

describe periods of apparent stasis punctuated by sudden change
-contrasts with a model of gradual change in a species’ existence

48
Q

true or false:

speciation may require the change of only a single allele

A

false

-may require EITHER change in only a single allele or many alleles

49
Q

macroevolution

A

the cumulative effect of many speciation and extinction events

AP Biology Semester 1 (21 decks)

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