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24 Flashcards

1
Q

speciation

A

origin of new species

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2
Q

_______ is the source of biological diversity

A

appearnace of new species

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3
Q

______ is at the focal point of evolutionary theory

A

speciation

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4
Q

microevolution

A

evolutionary change below the species level; change in the genetic makeup of a population from generation to generation

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5
Q

___ reveals the cumulative effects of speciation over vast tracts of time

A

the fossil record

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6
Q

macroevolution

A

evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight, that was use to define higher taxa

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7
Q

2 basic patterns of evlutionary change

A

cladogenesis and anagenesis

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8
Q

anagensis

A

(ana - new ; genos - race)

accumulation of changes that gradually transform a given species into a species w/ different characteristics

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9
Q

anagensis is aka as

A

phyletic evolution

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10
Q

cladogensis is aka as

A

branching evolution

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11
Q

cladogenssi

A

(klados - branch)

the splitting of a gene pool into two or more separate pools, which each give rise to one or more new species

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12
Q

only cladogensis can

A

promote biological diversity by increasing the number of species

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13
Q

species is a latin word meaning

A

kind / appearance

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14
Q

biological species concept

A

defines a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are unable to produce viable, fertile offspring w/ other members of other populations

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15
Q

reproductive isolation

A

the existence of biological factors that impede members of 2 species from producing viable, fertile hybrids

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16
Q

reproductive barriers are classified according to whether

A

they contribute to reproductive isolation before or after fertilization

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17
Q

prezygotic barriers

A

“before the zygote”

impede mating between species or hinder the fertilization of ova if members of different species attempt to mate

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18
Q

postzygotic barriers

A

often prevent the hybrid zygote from developing into a viable, fertile adult

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19
Q

5 types of prezygotic barriers

A 
habitat
temporal 
behavioral 
mechanical
gametic isolation
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20
Q

3 types of postzygotic barriers

A

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

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21
Q

habitat isolation

A

2 species that occupy diff habitats w/in the same area may encounter e/o rarely, if at all, even though they aren’t islated by obvious physical barriers

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22
Q

temporal isolation

A

species that breed during diff times of day, seasons, or years; ==> they cant mix their gametes

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23
Q

behavioral isolation

A

courtship rituals that attract mates and other behaviors unique

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24
Q

mechanical isolation

A

morphological differences can prevent successful mating

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25
Q

gametic isolation

A

sperm of one species may not be able to fertilize the eggs of another species. ex: sperm can’t survive in other species’ female reproductive tract, biochemical mechanisms may prevent sperm from penetrating the membrane surrounding other species’ eggs

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26
Q

reduced hybrid viability

A

genes of diff parent species may interact and impair the hybrid’s development

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27
Q

reduced hybrid fertility

A

vigorous hybrids may be sterile. if chromosomes of the 2 parent species differ in number of structure, meiosis in the hybrids may fail to produce normal gametes. since the infertile hybrids can’t produce offspring when they mate w/ other parental species, genes can’t flow freely

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28
Q

hybrid breakdown

A

some first-generation hybrids are viable and fertile, but when they mate w/ one another or w/ either parent species, offspring of the next generation are feeble/sterile

29
Q

limitations of biological species concept (2)

A
  1. there’s no way to evaluate the reproductive isolation of fossils or asexual organisms (such as prokaryotes)
  2. it’s difficult to apply the concept to the many sexual organisms about which little is known regarding their ability to mate w/ diff kinds of organisms
30
Q

the biological species concept emphasizes

A

the separateness of species from one another due to reproductive barriers

31
Q

morphological species concept

A

characterizies a species by its body shape, size, and other structural features

32
Q

advantages of morph. species concept: (2)

A
  1. can be applied to sexual and asexual organisms

2. can be useful even w/o info on the extent of gene flow

33
Q

disadvantage of morph species concept

A

definition relies on subjective criteria; researchers may disagree on which structural features distinguish a species

34
Q

paleontological species concept

A

focuses on morphologically discrete species known only from the fossil record

35
Q

we are forced to distinguish many species using the paleon. species concept b/c

A

there’s little or no info on their mating compatibility

36
Q

ecological species concept

A

views a species in terms of its ecological niche, its role in a biological community

37
Q

unlike the biological species concept, the ecol. species concept

A

can accommodate asexual as well as sexual species

38
Q

phylogenetic species concept

A

defines a species as a set of organisms w/ a unique genetic history – that is, as one branch on te tree of life

39
Q

biologists trace the phylogenetic history of a species by

A

comparing its physical characteristics or its molecular sequences w/ those of other organisms

40
Q

phylogenetic info sometimes reveals

A

the existence of sibling species

41
Q

sibling species

A

species that appear so similar that they cannot be distinguished on morphological grounds

42
Q

the ___ species concept is partcularly valuable for studying how species originate

A

biological

43
Q

speciation can occur in 2 main ways:

A

allopatric, sympatric

44
Q

allopatric speciation

A

(allos - other; patra - homeland)

gene flow is interrupted when a population is divided into geographically isolated subpopulations

45
Q

_____ are more likely to experience allopatric speciation

A

small, isolated populations

46
Q

to confirm a case of allopatric speciation, it is necessary to determine

A

whether the allopatric populations have changed enough that they no longer have the potential to interbreed and produce fertile offspring

47
Q

isolating mechanisms are intrinsic

A

to the organisms themelves

48
Q

____ is not in itself a biological isolating mechanism

A

geographic isolation

49
Q

isolating mechanisms prevent interbreeding even

A

in the absence of geograhpic isolation

50
Q

sympatric speciation

A

(syn - together)

speciation takes place in geographically overlapping populations

51
Q

machanisms of sypmpatric speciation include

A

chromosomal changes

nonrandom mating that reduces gene flow

52
Q

polyploidy

A

condition caused by a mutational change that results in extra sets of chromosomes

53
Q

autopolyploid

A

an individual that has more than 2 chromosome sets, all derived from a single species

54
Q

the triploid (3n) offspring of tetraploid (4n) and diploid (2n) parents are sterile b/c

A

their unpaired chromosomes result in abnormal meiosis

55
Q

a common form of polyploidy

A

when 2 diff species interbreed and produce a hybrid

56
Q

interspecific hybrids are often sterile b/c

A

the set of chromosomes from one species can’t pair during meiosis w/ the set of chromosomes from the other species

57
Q

though infertile, hybrids may be able to ____, as many _____ do

A

propagate itself asexually, as many plants do

58
Q

allopolyploid

A

A polyploid organism, usually a plant, that contains multiple sets of chromosomes derived from different species.

59
Q

many important agricultural crops such as potatoes, tobacco, wheat, oats, and coton are

A

polyploids

60
Q

today, plant geneticists create new polyploids in the laboratory by

A

using chemicals that induce meiotic and mitotic errors

61
Q

polyploid speciation is more common in

A

plants than in animals

62
Q

in allopatric speciation, the isolated population evolves by __ and __

A

natural selection and genetic drift

63
Q

what is another way sympatric speciation can occur?

A

when a subset of a population becomes reproductively isolated b/c of a switch to a habitat, food source, or other resource not used by the parent population

64
Q

adaptivve radiation

A

the evolution of many diversely adapted species from a common ancestor upon introduction to various new environmental opportunities and challenges

65
Q

adaptive radiation typically occurs when

A

a few organisms make their way to new, often distant areas when environmental changes cause numerous extinctions, opening up ecological niches for the survivors

66
Q

punctuated equilibrium

A

in evolutonary theory, long periods of apparent stasis (no change) interrupted by relatively brief periods of sudden change

67
Q

by necessity, paleontologists base hypotheses about descent almost entirely on __ and __

A

external anatomy and skeletons

68
Q

during periods of apparent equilibrium, changes in __, __, and __ may go undetected

A

behavior, internal anatomy, and physiology

69
Q

exaptations

A

structures that evolve in one context but become co-opted for another function

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