24 Speciation Flashcards

1
Q

Species

A

an evolutionary independent population or group of populations; generally distinct from other species in appearance, behaviour, habitat, ecology, genetic characteristics etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the four criteria for identifying species?

A

(1) biological species concept (2) morphospecies concept (3) ecological species concept (4) phylogenetic species concept

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Biological species concept

A

a species as a population or group of populations that are reproductively isolated from other groups (no gene flow occurs between them); members of a species can potentially interbreed in nature to produce viable, fertile offspring but cannot interbreed successfully with members of other species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Prezygotic isolation

A

prevents individuals of different species from mating successfully

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Postzygotic isolation

A

the hybrid offspring of matings between members of different species either do not survive or cannot reproduce

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the mechanisms of prezygotic isolation?

A

temporal, habitat, behavioural, gametic barrier, and mechanical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Temporal mechanism

A

populations are isolated because they breed at different times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Habitat mechanism

A

populations are isolated because they breed in different habitats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Behavioural mechanism

A

populations do not interbreed because their courtship displays differ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Gametic barrier

A

matings fail because eggs and sperm are incompatible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Mechanical mechanism

A

matings fail because male and female reproductive structures are incompatible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the mechanisms of postzygotic isolation?

A

hybrid viability and hybrid sterility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Hybrid viability

A

hybrid offspring do not develop normally and die as embryos

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Hybrid sterility

A

hybrid offspring mature but are sterile as adults

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Morphospecies “form species” concept

A

a species as a population or group of populations that have measurably different anatomical features from other groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ecological species concept

A

a species as a set of organisms exploiting a single set of resources, having the same range of environmental tolerances, and facing the same predators and parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Phylogenetic species concept

A

a species as the smallest monophyletic group in a phylogenetic tree

18
Q

What are phylogenetic species made up of?

A

populations that share one or more unique synapomorphies

19
Q

What are the advantages and disadvantages of the biological species concept?

A

Advantage: reproductive isolation = evolutionary independence; Disadvantages: not applicable to asexual or fossil species, difficult to assess if populations do not overlap geographically

20
Q

What are the advantages and disadvantages of morphospecies concept?

A

Advantage: widely applicable; Disadvantages: subjective, misidentifies polymorphic species, misses cryptic species

21
Q

What are the advantages and disadvantages of ecological species concept?

A

Advantage: applicable to sexual species; Disadvantage: different species may have similar ecological roles

22
Q

What are the advantages and disadvantages of phylogenetic species concept?

A

Advantages: widely applicable, based on testable criteria; Disadvantage: relatively few well-estimated phylogenies currently available

23
Q

Cryptic species

A

a species that cannot be distinguished from similar species by easily identifiable morphological traits

24
Q

Polymorphic species

A

a species that has two or more distinct phenotypes in the same interbreeding population at the same time

25
Q

What are the ways geographical isolation can occur?

A

dispersal and vicariance

26
Q

Vicariance

A

the physical splitting of a population into smaller, isolated populations by a geographic barrier

27
Q

Dispersal

A

colonists establish a new population in a novel location

28
Q

Allopatric “different homeland” speciation

A

speciation that occurs when populations of the same species become geographically isolated, often due to dispersal or vicariance

29
Q

Allopatry

A

condition in which two or more populations live in different geographic areas

30
Q

Sympatry

A

condition in which two or more populations live in the same geographic area, or close enough to permit interbreeding

31
Q

Sympatric speciation “together homeland’

A

divergence of populations living within the same geographic area into different species as the result of their genetic (not physical) isolation

32
Q

What types of events can initiate the process of sympatric speciation?

A

external events like disruptive selection and internal events like chromosomal mutations

33
Q

Niche

A

range of resources that a species can use and the range of conditions that it can tolerate i.e. the role that a species plays in its ecosystem

34
Q

Sympatric speciation by disruptive selection

A

sympatric populations may become reproductively isolated by adapting to different ecological niches

35
Q

Reinforcement of divergence

A

If hybrid offspring have low fitness, natural selection favors the evolution of traits that prevent interbreeding between the populations

36
Q

Hybrid Zone

A

a geographic area where interbreeding occurs between two species, sometimes producing fertile hybrid offspring; may move over time or be stable

37
Q

What are the possible outcomes of secondary contact between populations?

A

fusion of the populations, reinforcement of divergence, hybrid zone formation, extinction of one population, creation of new species

38
Q

Fusion of the populations

A

the two populations freely interbreed; occurs whenever populations of the same species come into contact

39
Q

Extinction of one population

A

if one population or species is a better competitor for shared resources, then the poorer competitor may be driven to extinction

40
Q

Creation of new species

A

if the combination of genes in hybrid offspring allows them to occupy distinct habitats or use novel resources, they may form a new species