Speciation

Question 1

Species-

Answer 1

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

Question 2

Reproductive isolating mechanisms

Answer 2

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

Question 3

Prezygotic barriers-

Answer 3

reproductive isolating mechanisms that prevent fertilization from taking place

Question 4

Temporal isolation-

Answer 4

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

Question 5

Habitat isolation-

Answer 5

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

Question 6

Behavioral (sexual) isolation-

Answer 6

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

Question 7

Mechanical isolation

Answer 7

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

Question 8

Gametic isolation-

Answer 8

even if mating does occur

the egg and sperm of different species are incompatible

Question 9

Postzygotic barriers-

Answer 9

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

Question 10

Hybrid inviability-

Answer 10

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

Question 11

Hybrid sterility-

Answer 11

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

Question 12

Hybrid breakdown-

Answer 12

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

Question 13

Speciation

Answer 13

formation of a new species

Question 14

Allopatric speciation

Answer 14

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

Question 15

Sympatric speciation

Answer 15

formation of new species without the presence of a geographic barrier

Question 16

Causes of speciation

Answer 16

Polyploidy, Hybridization, Ecology

Question 17

Polyploidy

Answer 17

possession of more than the normal 2 sets of chromosomes

Question 18

polyploidy in plants–why does it happen?

Answer 18

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

Question 19

Where does polyploidy often occur?

Answer 19

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

Question 20

what can polyploid plants reproduce with?

Answer 20

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

Question 21

Hybridization-

Answer 21

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.

Question 22

hybrid zone

Answer 22

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

Question 23

Ecology-

Answer 23

can cause 2 different species to form

Question 24

Balanced polymorphisms–>speciation

Answer 24

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

Question 25

Adaptive radiation

Answer 25

many related species come from one ancestral species in a relatively short period

Question 26

When does adaptive radiation happen?

Answer 26

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

Question 27

adaptive zones

Answer 27

when a species enters an area where there are many unoccupied habitats and adaptive radiation happens, those areas are called adaptive zones.

Question 28

Extinction

Answer 28

occurs when the last individual of a lineage dies. Today, only one species is alive for every 2000 that have become extinct

Question 29

Background extinction

Answer 29

continuous lowlevel extinction of species

Question 30

Mass extinction

Answer 30

kills numerous species (last of which was 65m yrs ago when dinosaurs)
only happened 5-6 times

Question 31

Divergent evolution-

Answer 31

two or more species that originate from a common ancestor

Question 32

Convergent evolution

Answer 32

two unrelated species that share many related traits or analogous features
bc of adaptation to similar living environments

Question 33

Parallel evolution

Answer 33

two related species that evolved in similar ways after divergence from a
common ancestor

Question 34

Parallel evolution–marsupial v placental

Answer 34

species of marsupial mammals and placental mammals, which evolved from a common ancestor, independently evolved similar adaptations when encountering similar environments

Question 35

Coevolution-

Answer 35

one species evolves adaptations in response to another species’ adaptations

Question 36

Punctuated equilibrium-

Answer 36

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

Question 37

stasis

Answer 37

no evolutionary change followed by short periods of rapid speciation.

Question 38

Gradualism

Answer 38

evolution proceeds continuously over long periods, with populations slowly changing due to natural selection in different
environments