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BIO 1306 Spring 2025 > Chapter 24 - The Origin of Species > Flashcards

Chapter 24 - The Origin of Species Flashcards

1
Q

Darwin was fascinated by _____

A

…speciation

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2
Q

What is speciation?

A

The process by which one specie splits into 2 species (and makes new ones)

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3
Q

Speciation produced the tremendous ______ of life

A

…diversity…

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4
Q

Speciation forms a conceptual bridge btwn the processes of ______

A

microevolution & macroevolution

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5
Q

Microevolution consists of…

A

…changes in allele frequency in a population over time

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6
Q

Macroevolution refers to broad patterns of…

A

…evolutionary change above the species level

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7
Q

The biological specie concept emphasizes…

A

…reproductive isolation

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8
Q

The world “species” is Latin for…

A

kind/appearance

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9
Q

Biologists compare _____________ to confirm that, morphologically (size, shape, structure), different species are discrete groups

A

…physiology (function, biochem (molecular/chem), and DNA sequences…

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10
Q

The biological species concept states that a species is a group of populations whose members:

A
  1. Have the potential to interbreed in nature
  2. Produce viable, fertile offspring
  3. Don’t produce viable, fertile babies w/ other groups
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11
Q

Interbreed definition

A

Breed w/ different species

(ex: horse + donkey = mule)

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12
Q

Inbreed defintion

A

Breed w/ same species

(ex: horse + horse = horse)

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13
Q

(Different species) The eastern meadowlark & the western meadowlark have similar body shapes & colorations. However, they’re distinct/different biological species bc…

A

…they behave differently

So, they can’t interbreed if they met in the wild

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14
Q

Human species name?

A

Homo sapines

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15
Q

Humans can interbreed (T/F)

A

True

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16
Q

Why can’t humans & chimps interbreed?

A

Cuz chimps have 24 chromosomes & we have 23 & other reasons

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17
Q

Reproductive isolation?

A

The existence of biological factors/barriers that inhibit 2 species from producing viable, fertile offspring

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18
Q

Reproductive isolation classifications:

A

Prezygotic (before fertilization) & postzygotic (after fertilization)

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19
Q

What’s a zygote?

A

sperm + egg

a eukaryotic cell formed by a fertilization event by 2 gametes (sperm & egg)

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20
Q

[Reproductive isolation] Biological barriers limit formation of _____

A

…hybrids

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21
Q

What are hybrids?

A

Offspring from mating btwn different species

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22
Q

Prezygotic barriers:

A

-Habitat isolation
-Temporal isolation
-Behavioral isolation
-Mechanical isolation
-Gametic isolation

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23
Q

Habitat isolation?

A

They live in different habitats & will meet rarely/not at all even tho no physical barriers

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24
Q

Example of habitat isolation

A

Apple maggot flies & Blueberry maggot flies don’t mate bc they prefer different fruit plants even if they’re in the same area

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25
Temporal isolation?
Timing/Species that breed at different times can't mix their gametes/mate (ex: spring/winter)
26
Behavior isolation?
Courtship rituals & other behaviors unique to a species are effective barriers to mating/They don't speak the same language or act the same for mating (ex: different bird calls/courtship rituals)
27
Mechanical isolation?
Genitals don't work together/morphological difference prevent successful completion (mating attempt has been made)
28
Gametic isolation?
Sperm + egg of the different species doesn't mix/Sperm of one species might not be able to fertilize eggs of another species (mating attempt has been made)
29
Post-zygotic barriers:
-Reduced hybrid viability -Reduced hybrid fertility -Hybrid breakdown
30
What is Reduced hybrid viability?
Resulting hybrid has weak vitality & much lower chance of surviving and maturing into an adult
31
What is Reduced hybrid fertility?
Resulting hybrid has significantly lower chances of reproducing/is sterile Meiosis may fail to produce normal gametes if parent species have different chromosomes amounts/structures
32
What is Hybrid breakdown?
First gen hybrids are viable & fertile but their kids are weak/sterile
33
All the biological barriers involve individuals of different species that don't or can't mate due to _____
...biological reproductive isolation
34
Prezygotic barriers block fertilization from occuring by...
-Hindering different species from attempting to mate -Preventing the successful completion of mating -Hindering fertilization if mating is successful
35
Biological species concept can show how speciation can occur by reproduction isolation, but there's a limitation, which is...
There's no way to evaluate reproduction from fossils/asexual organisms
36
The biological species concept emphasizes...
...absence of gene flow due to isolation, but gene flow CAN OCCUR btwn many morphologically & ecologically distinct species (ex: grizzly + polar bears)
37
The biological species concept also emphasizes the _______ of different species due to reproductive barriers
...separateness...
38
The morphological species concept distinguishes a species by its...
...structural features, which applies to sexual & asexual species and doesn't require info on the extent of gene flow
39
The ecological species concept defines a species by its...
...location/environment -interactions btwn living & nonliving parts of environment -emphasizes role of disruptive selection (2 extremes survive)
40
Speciation can happen in 2 ways:
Allopatric speciation & Sympatric (same) speciation
41
What is Allopatric speciation?
Populations get geographically isolated from each other & turn into different species
42
What is Sympatric speciation?
Populations aren't geographically isolated & still turn into different species (includes migration) Less common than allopatric speciation
43
Isolated/highly subdivided regions usually have more species than those w/ fewer barriers (T/F)
True
44
Allopatric speciation can occur w/o geographic change bc the definition of barrier (for this) depends on...
...the ability of a population to separate (ex: canyon separates mice but not birds)
45
Sympatric speciation occurs less than allopatric speciation (T/F)
True
46
Sympatric speciation can only occur if gene flow is reduced by factors like:
-Polyploidy (extra chromosomes) -Sexual selection (ex: female can select male based on color, which would become a reproductive barrier) -Habitat differentiation (isolation)
47
Accidents during cell division can cause...
...polyploidy (the presence of extra sets of chromosomes)
48
Polyploidy can form a new _____ w/in single generation w/o geographic separation
...species...
49
Polyploidy is common in ____ but rare in _____
plants, animals
50
New polyploid agricultural species are produced using chemicals to _____
...induce errors in cell division
51
2 types of polyploids:
autopolyploids & allopollyploids
52
Autopolyploids have more than 2 sets of chromosomes from ____ species
ONE
53
In plants, mitotic errors can result in the production of a _______ (4n) cell from a diploid (2n) cell
...tetraploid...
54
Fertile offspring (4n) can be produced thru...
...self-fertilization/mating among tetraploids
55
Mating btwn tetraploids & diploids produces triploid (3n) offspring w/ reduced fertility (T/F)
True
56
Allopolyploids have more than 2 sets of chromosomes from _____ species
DIFFERENT
57
Chromosomes from different species don't pair during meiosis, resulting in hybrid ______
sterility
58
Sterile hybrids (plants) can reproduce ______
asexually
59
Allopolyploids are formed if the chromosome # ______ in subsequent generations
doubles
60
Allopolyploids can/may successfully bread w/ each other, but not with either ____ species
parent
61
The diploid # of new allopolyploid species =
the sum of the diploid # of both parents
62
What is a diploid?
A cell that has 2 complete sets of chromosomes
63
At least ______ new plant species have originated by polyploid speciation since 1850
5
64
What is a hybrid zone?
A region in which members of different species mate & produce hybrid offspring Often occurs as isolated patches scattered across the landscape, rather than a continuous band
65
_______ reveal factors that cause reproductive isolation
Hybrid zones...
66
Some hybrid zones form as narrow bands where habitats of two or more ________ species meet
...closely related...
67
Changes in environmental conditions can result in the ______ of existing hybrid zones or the production of new hybrid zones
...relocation...
68
Over time, hybrids may become isolated from parents & form new species (T/F)
True
69
If hybrids don't become reproductively isolated from their parent species, then 3 outcomes are possible:
Reinforcement Fusion Stability
70
What is reinforcement?
Reproductive barriers can be reinforced/strengthened when hybrids are less fit to reproduce than parent species Reduced formation of hybrid production bc of decreased reproductive success amongst hybrids
71
Reinforcement should be stronger for _____ than _____ populations
sympatric, allopatric Why? Bc there's a higher chance for interbreeding in sympatric populations & natural selection favors traits that prevent interbreeding when hybrids are less fit, making the two parent species more distinct from each other
72
What is fusion?
Reproductive barriers weaken & the gene pools merge (everyone becomes one species), reversing speciation. Substantial gene flow btwn species if hybrids are as fit as parents, weakening the barrier
73
What is stability?
Hybrid zones are stable & healthy hybrids survive and reproduce better than either parents' species, resulting in ongoing hybridization
74
Speciation can occur rapidly/slowly & can result from changes in few/many genes (T/F)
True
75
The rate of speciation can be studied using the _______
...fossil record, morphological data, or molecular data
76
The fossil record includes many episodes where new species appear _______ or ________ over time
suddenly, gradually
77
Punctuated (rapid) model
describes periods of apparent stasis punctuated by SUDDEN CHANGE when the specie branched from a parent species and then changed little for the rest of their existence
78
Gradual (slow) model
describes species that changed gradually over time

BIO 1306 Spring 2025 (5 decks)

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