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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
Weakness of Ecological Species Concept (ESC)
Hard to define niches independently of the species that occupy
26
- 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"
Evolutionary Species Concept (ESC)
27
Lineages may separate, become species, and come back together in the future (at which time they are no longer different species).
Evolutionary Species Concept (ESC)
28
All organisms, past and present, belong to some ___
evolutionary species
29
In Evolutionary Species Concept, the _____ in the BSC sense is not required
reproductive isolation
30
Evolutionary species may or may not exhibit ____
recognizable phenetic differences
31
Benefits of the Evolutionary Species Concept
- clear conceptually - applies to asexual species - through time - allopatric species
32
Problems of Evolutionary Species Concept
- application (difficult to know the future) - asexual species (too many independent lineages)
33
separates the idea of what species are from how they are recognized.
Evolutionary Species Concept (ESC)
34
The practical approach to dealing with the more philosophically grounded Evolutionary Species Concept
Phylogenetic Species Concept
35
a two-step process to define species that the Phylogenetic species concept uses
- 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
In Phylogenetic Species Concept, the problem is
- almost any population can be diagnosed - the gene trees may not follow the species trees
37
Phylogenetic Species Concept can be applied to
asexual organisms
38
it requires a lot of information to construct good trees that will identify monophyletic groups
Phylogenetic Species Concept
39
means that individuals of different species will not mate and produce offspring, or offspring will be sterile
reproductive isolation
40
a group of interbreeding (or potentially interbreeding) individuals, that is reproductively isolated from other groups of interbreeding individuals
biological species
41
the “textbook” standard definition of species
Biological Species Concept (BSC)
42
Phylogenetic species concept = ___
genealogical species concept
43
What species concept? "species is the smallest monophyletic group"
Phylogenetic Species Concept
44
If individuals from population A can interbreed with individuals from population B, then we have ____
one biological species but two phylogenetic species (PSC)
45
What species concept? "species a group of phenotypically similar individuals"
Morphological Species Concept
46
Isolation based on differential resource use without geographic isolation
sympatric speciation
47
Isolation by selection and limited gene flow in continuously distributed populations
parapatric speciation
48
Isolation based on changes in chromosome number or chromosomal rearrangements
chromosomal speciation
49
Geographic (physical) isolation
allopatric speciation
50
one of two or more morphologically indistinguishable biological groups that are incapable of interbreeding compare to physiologic race.
cryptic species
51
- important populations for genetic diversity in a species, important to conservation efforts - a population of organisms that is considered distinct for purposes of conservation
Evolutionary significant units (ESU)
52
the "classic" process of speciation
- isolation (physical barriers - allopatry: dispersal, vicariance) - divergence (drift, natural or sexual selection) - secondary contact (hybridization: reinforcement, fusion)
53
anything that causes a reduction in gene flow between two potential species (populations) can be an _____
isolating factor
54
tends to homogenize population frequencies and reduce the differentiation of populations
gene flow
55
Allopatry can be due to
- dispersal (movement of individuals) - vicariance (an encroaching physical feature)
56
Changes in chromosome number due to mutation during meiosis can result in a ____
new species without any physical isolation (sympatric speciation)
57
the number of sets of chromosomes in a cell, or in the cells of an organism.
ploidy
58
an extra set of chromosomes ups the ploidy to a ___
tetraploid
59
Polyploidy: When _______ occurs during meiosis in humans, an individual can end up with an extra chromosome or missing chromosome
non-disjunction
60
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.
Total non-disjunction
61
Tetraploid offspring cannot mate with
diploid organisms
62
triploid offspring tend to be
infertile
63
can be different times for reproduction (flowering time in plants, pupation time in insects)
timing isolation
64
Biotic factors examples
competition, predation, prey
65
abiotic factor example
climate
66
Heliconius butterflies are a classic example of
Mullerian mimicry
67
- 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.
Mullerian mimicry
68
Strong assortative mating can lead to
isolation and speciation
69
Traits influence how species choose mates, where individuals choose partners with traits most similar to their own
assortative mating
70
the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.
genetic linkage
71
zygotes never form because of no mating
prezygotic isolation
72
mating occurs but offspring less fit than either parental species
postzygotic isolation
73
Any of a group of different types of individuals of the same species in a population
morphotype
74
What drives diversification?
Larger range size, more opportunities to get into new habitats

Systematics (15 decks)

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