Speciation Flashcards

1
Q

Species-

A

group of individuals capable of interbreeding and reproducing the same type of offspring

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

Reproductive isolating mechanisms

A

prevent interbreeding (and gene flow) between two different species even though they may live in the same area

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

Prezygotic barriers-

A

reproductive isolating mechanisms that prevent fertilization from taking place

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

Temporal isolation-

A

the two species reproduce at different times of the day, season, or year

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

Habitat isolation-

A

two related species that live in the same area but live and breed in different habitats

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

Behavioral (sexual) isolation-

A

animal species exchange distinctive signals before mating. Another species would not recognize these signals and therefore would not mate

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

Mechanical isolation

A

structural differences (incompatible genital organs) prevent successful mating if it is attempted

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

Gametic isolation-

A

even if mating does occur

the egg and sperm of different species are incompatible

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

Postzygotic barriers-

A

if fertilization does take place between closely related species, this increases likelihood of reproductive failure

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

Hybrid inviability-

A

Postzygotic barrier. genes of different species do not interact properly and embryo spontaneously aborts

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

Hybrid sterility-

A

Postzygotic barrier. if a hybrid animal does survive, gametes are often abnormal

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

Hybrid breakdown-

A

if two hybrid animals survive and mate with each other, their offspring might not be able to reproduce

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

Speciation

A

formation of a new species

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

Allopatric speciation

A

Population is divided by a geographic barrier so that 2 populations cannot interbreed

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

Sympatric speciation

A

formation of new species without the presence of a geographic barrier

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

Causes of speciation

A

Polyploidy, Hybridization, Ecology

17
Q

Polyploidy

A

possession of more than the normal 2 sets of chromosomes

18
Q

polyploidy in plants–why does it happen?

A

Takes place because of nondisjunction of all tetrads during meiosis (or spontaneous doubling of chromosomes before meiosis); therefore diploid organisms produce diploid gametes.

19
Q

Where does polyploidy often occur?

A

Occurs often in plants- can be triploid (3n), tetraploid (4n), or higher.

20
Q

what can polyploid plants reproduce with?

A

These new species can only reproduce with other members of its group but not with its parents

21
Q

Hybridization-

A

two different forms of a species from different areas mate + produce offspring. This mating only occurs (and offspring can only survive) in a small overlap area called a hybrid zone.

22
Q

hybrid zone

A

a geographically overlapping area where two different forms of a species can mate and reproduce.

23
Q

Ecology-

A

can cause 2 different species to form

24
Q

Balanced polymorphisms–>speciation

A

can lead to speciation in which each polymorphism each variety splits off into a different species

25
Adaptive radiation
many related species come from one ancestral species in a relatively short period
26
When does adaptive radiation happen?
Occurs when a species enters an area where there are many unoccupied habitats. The ancestral species then branches off to form new species as each population occupies different environments
27
adaptive zones
when a species enters an area where there are many unoccupied habitats and adaptive radiation happens, those areas are called adaptive zones.
28
Extinction
occurs when the last individual of a lineage dies. Today, only one species is alive for every 2000 that have become extinct
29
Background extinction
continuous lowlevel extinction of species
30
Mass extinction
kills numerous species (last of which was 65m yrs ago when dinosaurs) only happened 5-6 times
31
Divergent evolution-
two or more species that originate from a common ancestor
32
Convergent evolution
two unrelated species that share many related traits or analogous features bc of adaptation to similar living environments
33
Parallel evolution
two related species that evolved in similar ways after divergence from a common ancestor
34
Parallel evolution--marsupial v placental
species of marsupial mammals and placental mammals, which evolved from a common ancestor, independently evolved similar adaptations when encountering similar environments
35
Coevolution-
one species evolves adaptations in response to another species' adaptations
36
Punctuated equilibrium-
problem: fossil record seems incomplete- does not contain any transition fossils from animals that appear to be mid-evolution. So, punctuated equilibrium states that in the history of a species, there were long periods of stasis. evolution therefore occurs in spurts
37
stasis
no evolutionary change followed by short periods of rapid speciation.
38
Gradualism
evolution proceeds continuously over long periods, with populations slowly changing due to natural selection in different environments