Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIOLOGY 108 > Topic 8: Speciation > Flashcards

Topic 8: Speciation Flashcards

1
Q

Darwin envisioned speciation as a ____ event

A

branching

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

New species arise through the process of

A

speciation

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

Speciation

A

an ancestral species splits into two or more descendant species that are genetically different from one another and can no longer interbreed

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

Macroevolution

A

broad patterns of evolutionary change above the species level over geologic time scales

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

Examples of macroevolution

A

origin of new traits like wings, new groups like flowering plants, extinction

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

Speciation occurs between

A

microevolution and macroevolution

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

Macroevolution is the cumulative event of:

A

gradual compounding of small changes, cumulative new genetic variations, and speciation and extinction events

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

What is a species

A

a group of actually (or potentially) interbreeding individuals that produce viable, fertile offspring, and are reproductively isolated from other species

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

Capacity for ______ between populations of a species holds a species together genetically

A

gene flow

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

Limits of BDC (biological species concept)

A

cannot be applied to follis or asexual organisms, emphasizes the absence of gene flow when it can still happen (think grolar bears)

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

Other definitions for species

A

ecological species, morphological species, phylogenetic species,

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

morphological species

A

defines a species by structural features.

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

ecological species concept

A

defines a species as a set of organisms adapted to a particular set of resources, called a niche, in the environment

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

phylogenic species

A

defines a species as the smallest group of individuals on a phylogenetic tree

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

EBC emphasizes reproductive _____

A

isolation

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

Reproductive isolation is caused by

A

caused by biological factors (barriers) that impede two species from interbreeding and producing viable, fertile offspring (hybrid)

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

Reproductive isolation can be caused by (two types):

A 
prezygotic barriers (before fertilization) 
postzygotic barriers (post-fertilization)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Ways prezygotic barriers block fertilization

A
  • impeding different species from attempting to mate
  • preventing the successful completion of mating
  • preventing fertilization if mating is successful
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Prezygotic reproductive barriers

A

habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Habitat isolation

A

two species encounter each other rarely because they occupy different habitats even if not separated by different barriers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Temporal isolation

A

species that breed at different times of the day/seasons/ years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Behavioral isolation

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Mechanical isolation

A

morphological differences can prevent successive mating (autonomically incompatible)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Gametic isolation

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Postzygotic barriers prevent a hybrid zygote from developing into a viable fertile adult by:
- reduced hybrid viability - reduced hybrid fertility - hybrid breakdown
26
Reduced hybrid viability
genes of the different species may interact to impair the hybrid's development or survival (results in death)
27
reduced hybrid fertility
hybrids come out sterile due to chromosomes of different numbers or structure
28
hybrid breakdown
some 1st-generation hybrids are vigorous and fertile, but when these hybrids mate with one another or with either parent species, offspring of subsequent generations are feeble or sterile
29
Allopatric speciation
occurs when gene flow between geographically isolated subpopulations is interrupted
30
barrier
stops the ability of a population to disperse
31
geographic isolation arises by
dispersion and vicariance
32
dispersal
results in the establishment of a new and distant population
33
vicariance
the range of a species is split by a change in the environment creating two subpopulations
34
productive isolation between subpopulations generally increases as the distance between them ____
increases
35
Allopatric speciation
the evolution of a new species following geographic isolation of two or more subpopulations of an ancestral species
36
As subpopulations diverge, they may evolve traits that act as:
prezygotic and/or postzygotic barriers to reproduction
37
The majority of speciation events occur due to
allopatric speciation
38
Sympatric speciation
the evolution of a new species from an ancestral species while both continue to inhabit the same geographic region
39
For sympatric speciation to occur the subpopulations occupying the same geographic region must become ___ ___ from each other.
reproductively isolated
40
Overlapping subpopulations can become reproductively isolated from each other by:
- chromosomal errors during meiosis or hybridization of closely related species - natural selection for reproductive isolation
41
Polyploid speciation
occurs when changes in the number of chromosomes sets create genetically distinct descendants that are reproductively isolated from parental forms
42
Polyploidy is common in
plants
43
Hybrid speciation occurs when:
interbreeding between two related species creates genetically distinct descendants that are reproductively isolated from the parent species
44
Polyploids have different number of ____ than their parental forms
chromosome sets
45
Polyploids can only interbreed with individuals of the same ____
ploidy
46
polyploids arise from
- hybridization of related species to form allopolyploids | - chromosomal error during meiosis forming autopolypoids
47
An ____ is a species with multiple sets of chromosomes derived from the hybridization of different species
allopolyploid
48
Allopolyploid hybrids have ____ the number of chromosome sets than the parent species
double
49
Autopolyploids can arise due to:
by genome doubling or by fusion of 2n gametes (failure of cell division during meiosis and creates gametes with double the number of chromosomes)
50
Hybridization between different taxa is a trigger for:
polyploidization forming allopolyploids
51
Homoploid hybrid speciation
Hybrid speciation can also occur with no change in chromosome number (ploidy)
52
Homoploids
arise when hybridization produces novel combinations of genes that can adapt hybrids to new habitats that cause them to be reproductively isolated from parental populations
53
Habitat differentiation increases:
reproductive isolation between subpopulations
54
Natural selection for _______ between subpopulations can occur after the appearance of new ecological niches
reproductive isolation
55
Sexual selection
natural selection for reproductive isolation between subpopulations
56
Sexual selection leads to
evolution of traits that increase an individual’s access to members of the opposite sex.
57
Sexual selection often leads to
sexual dimorphism
58
Sexual dimorphism
marked differences between the sexes in secondary sexual characteristics
59
Darwin separated sexual selection | and natural selection because:
some sexually selected traits would act against naturally selected ones
60
Sexual selection is natural selection for | _______
mating success.
61
Sexual selection can drive:
sympatric speciation
62
Sympatric speciation occurs when
a reproductive barrier isolates a subset of a population without geographic separation from the parent species
63
Sympatric speciation can arise following
- Chromosomal errors during meiosis or hybridization of closely related species - Natural selection for reproductive isolation or following habitat differentiation
64
Hybrid zone
a region where members of a different species interbreed and produce hybrids
65
Hybrids result from
the mating between species with incomplete reproductive barriers
66
Hybridization can result in ____
speciation
67
Outcomes of hybrid zones
reinforcement of hybrid barriers, stability of hybrid barriers, and fusion of hybrid barriers
68
reinforcement of reproductive barriers
occurs when hybrids are less fit than parent species resulting in the selection for prezygotic barriers
69
Where reinforcement occurs, reproductive barriers should be stronger for _____ than _____ species
sympatric than allopatric
70
stability of hybrid barriers
Continuous formation of hybrid individuals
71
Continuous gene flow from outside the hybrid zone can:
overwhelm natural selection for increased reproductive isolation inside the hybrid zone
72
Fusion ____ reproductive barriers
weakens
73
If hybrids are as fit as parents there will be ____
gene flow between species and possibly the parent species will fuse back to one species
74
Speciation is caused by
accumulation of genetic differences between populations
75
How genetic drift is important in allopatric speciation:
Genetic drift is important in allopatric speciation when a new population arises following the dispersal of a few individuals to an isolated location
76
Incomplete reproductive isolation between related species allows for ______.
hybridization
77
Selection for increased reproductive | isolation is strongest when
during sympatric speciation when hybrids between the sympatric populations are of lower fitness, i.e. reinforcement of reproductive barriers
78
Two patterns for the rate of speciation observed in fossil records
gradual, punctual models
79
Gradual speciation model
species diverge slowly by natural selection over many generations
80
punctuated speciation model
new species diverge quickly from a parent species but change little for the remainder of their existence
81
What causes speciation to happen
1. gene flow between populations is interrupted 2. population diverges genetically to become reproductively isolated 3. there is no event that causes gene flow to resume

BIOLOGY 108 (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions