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Systematics > Species Concepts & Mechanisms of Speciation > Flashcards

Species Concepts & Mechanisms of Speciation Flashcards

1
Q

All species on earth thought to share a ___

A

single common ancestor

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2
Q

when did life arise on Earth?

A

3.8 billion years ago

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3
Q

the generation of species-level diversity

A

speciation

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4
Q

the evolutionary biology subfield that deals with taxonomy, understanding speciation, describing species, inferring phylogenies, and similar endeavors

A

systematics

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5
Q

smallest independently evolving unit

A

species

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6
Q

occurs when gene flow between populations ceases (or becomes very low); and when drift, mutation, and selection operate on populations separately

A

evolutionary independence

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7
Q

Independent evolution occurs when

A

mutation, selection, gene flow, and drift operate independently in different populations

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8
Q

speciation involves at least two stages:

A
  • genetic isolation
  • differentiation
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9
Q

The essence of speciation is ____

A

lack of gene flow

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10
Q

Who listed 24 different named species concepts

A

Mayden (1997)

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11
Q

How many species concepts did Mayden list?

A

24

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12
Q

defines a species taxon as a group of organisms that can successfully interbreed and produce fertile offspring. According to that concept, a species’ integrity is maintained by interbreeding within a species as well as by reproductive barriers between organisms of different species.

A

Biological Species Concept (BSC)

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13
Q

first modern attempt to define species, but numerous problems with this concept, on both theoretical and practical grounds

A

Biological Species Concept (BSC)

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14
Q

Problems with Biological Species (Practical Problems)

A
  • Allopatric Species - borderline cases
  • Geologic Time - fossil species not accounted
  • Reproductive Isolation - degree of isolation
  • Asexual species
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15
Q

many cases, sister lineages are _____, but distantly related lineages are not

A

reproductively isolated

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16
Q

Theoretical problems with BSC

A
  • Character
  • Isolation
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17
Q

speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration.

A

Allopatric speciation/geographic speciation

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18
Q

The theoretical problem of BSC: reproductive compatibility is a _____; reproductive isolation is ____

A

primitive character; derived

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19
Q

Relies on morphological data and emphasizes groups of physical traits that are unique to each species

A

Morphological Species Concept

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20
Q

“a group of organisms that shares anatomical characteristics within the group, which are not shared with other groups of organisms”. Basically, organisms that look similar to each other and different from everything else.

A

Morphological Species Concept

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21
Q

Advantages of Morphological Species Concept

A
  • Simple - traditional and simple
  • Applicability - applicable for living and extinct groups
  • Reproductive strategies - applicable for asexual and sexual groups
  • On-Spot - ready to use as reference
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22
Q

Disadvantages of Morphological Species Concept

A
  • Cryptic species - comprise two or more taxa under a single name
  • Genetic differences - does not address genetic differences
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23
Q

Environment and Niche as Factors

A

Ecological Species Concept (ESC)

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24
Q
  • Species are groups of phonetically similar organisms occupying a given ecological niche or set of niches
  • Species integrity is maintained not so much by reproductive isolation but by selection to adapt each species to its niche
A

Ecological Species Concept (ESC)

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25
Q

Weakness of Ecological Species Concept (ESC)

A

Hard to define niches independently of the species that occupy

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26
Q
  • Closer to defining species as individuals and as lineages that have beginnings and ends
  • “A single lineage of ancestor-descendent populations which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate”
A

Evolutionary Species Concept (ESC)

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27
Q

Lineages may separate, become species, and come back together in the future (at which time they are no longer different species).

A

Evolutionary Species Concept (ESC)

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28
Q

All organisms, past and present, belong to some ___

A

evolutionary species

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29
Q

In Evolutionary Species Concept, the _____ in the BSC sense is not required

A

reproductive isolation

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30
Q

Evolutionary species may or may not exhibit ____

A

recognizable phenetic differences

31
Q

Benefits of the Evolutionary Species Concept

A
  • clear conceptually
  • applies to asexual species
  • through time
  • allopatric species
32
Q

Problems of Evolutionary Species Concept

A
  • application (difficult to know the future)
  • asexual species (too many independent
    lineages)
33
Q

separates the idea of what species are from how they are recognized.

A

Evolutionary Species Concept (ESC)

34
Q

The practical approach to dealing with the more philosophically grounded Evolutionary Species Concept

A

Phylogenetic Species Concept

35
Q

a two-step process to define species that the Phylogenetic species concept uses

A
  • Grouping taxa (regardless of rank) ) using the criterion of
    monophyly, or at least potential monophyly
  • Ranking groups by the criterion of finding the smallest diagnosable monophyletic groups
36
Q

In Phylogenetic Species Concept, the problem is

A
  • almost any population can be diagnosed
  • the gene trees may not follow the species trees
37
Q

Phylogenetic Species Concept can be applied to

A

asexual organisms

38
Q

it requires a lot of information to construct good trees that will identify monophyletic groups

A

Phylogenetic Species Concept

39
Q

means that individuals of different species will not mate and produce offspring, or offspring will be sterile

A

reproductive isolation

40
Q

a group of interbreeding (or potentially interbreeding) individuals, that is reproductively isolated from other groups of interbreeding individuals

A

biological species

41
Q

the “textbook” standard definition of species

A

Biological Species Concept (BSC)

42
Q

Phylogenetic species concept = ___

A

genealogical species concept

43
Q

What species concept? “species is the smallest monophyletic group”

A

Phylogenetic Species Concept

44
Q

If individuals from population A can interbreed with individuals from population B, then we have ____

A

one biological species but two phylogenetic species (PSC)

45
Q

What species concept? “species a group of phenotypically similar individuals”

A

Morphological Species Concept

46
Q

Isolation based on differential resource use without geographic isolation

A

sympatric speciation

47
Q

Isolation by selection and limited gene flow in continuously distributed populations

A

parapatric speciation

48
Q

Isolation based on changes in chromosome number or chromosomal rearrangements

A

chromosomal speciation

49
Q

Geographic (physical) isolation

A

allopatric speciation

50
Q

one of two or more morphologically indistinguishable biological groups that are incapable of interbreeding compare to physiologic race.

A

cryptic species

51
Q
  • important populations for genetic diversity in a species, important to conservation efforts
  • a population of organisms that is considered distinct for purposes of conservation
A

Evolutionary significant units (ESU)

52
Q

the “classic” process of speciation

A
  • isolation (physical barriers - allopatry: dispersal, vicariance)
  • divergence (drift, natural or sexual selection)
  • secondary contact (hybridization: reinforcement, fusion)
53
Q

anything that causes a reduction in gene flow between two potential species (populations) can be an _____

A

isolating factor

54
Q

tends to homogenize population frequencies and reduce the differentiation of populations

A

gene flow

55
Q

Allopatry can be due to

A
  • dispersal (movement of individuals)
  • vicariance (an encroaching physical feature)
56
Q

Changes in chromosome number due to mutation during meiosis can result in a ____

A

new species without any physical isolation (sympatric speciation)

57
Q

the number of sets of chromosomes in a cell, or in the cells of an organism.

A

ploidy

58
Q

an extra set of chromosomes ups the ploidy to a
___

A

tetraploid

59
Q

Polyploidy: When _______ occurs during meiosis in humans, an individual can end up with an extra chromosome or missing chromosome

A

non-disjunction

60
Q

Polyploidy: when one of the two cells produced during Meiosis I gets all of the chromosomes. The other cell is not viable and is reabsorbed. This results in two (2n) daughter cells from meiosis instead of the usual four (n) daughter cells.

A

Total non-disjunction

61
Q

Tetraploid offspring cannot mate with

A

diploid organisms

62
Q

triploid offspring tend to be

A

infertile

63
Q

can be different times for reproduction (flowering time in plants, pupation time in insects)

A

timing isolation

64
Q

Biotic factors examples

A

competition, predation, prey

65
Q

abiotic factor example

A

climate

66
Q

Heliconius butterflies are a classic example
of

A

Mullerian mimicry

67
Q
  • a type of mimicry whereby one or more species develop a similar appearance.
  • sharing common predators, have come to mimic each other’s honest warning signals, to their mutual benefit.
A

Mullerian mimicry

68
Q

Strong assortative mating can lead to

A

isolation and speciation

69
Q

Traits influence how species choose mates, where individuals choose partners with traits most similar to their own

A

assortative mating

70
Q

the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.

A

genetic linkage

71
Q

zygotes never form because of no mating

A

prezygotic isolation

72
Q

mating occurs but offspring less fit than either parental species

A

postzygotic isolation

73
Q

Any of a group of different types of individuals of the same species in a population

A

morphotype

74
Q

What drives diversification?

A

Larger range size, more opportunities to
get into new habitats

Systematics (15 decks)

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