Name ______Date ______Period ______
Species/Speciation
A species consists of one or more populations of individuals that can ______
Isolating Mechanisms Maintain Separate Species
Define Geographic Isolation. Write the term for the isolation events to the right of Reproductive Isolation
ALLOPATRIC SPECIATION:Geographic Isolation
SYMPATRIC SPECIATION:
Reproductive Isolation / ______Isolation (mating or zygote formation is blocked)
Potential mates occupy overlapping ranges but
reproduce at different times
Potential mates meet but cannot figure out what to do about it
Potential mates attempt engagement but sperm cannot be successfully transferred
Sperm is transferred but egg is not fertilized (gametes dies or are incompatible)
Potential mates occupy different local habitats within the same area
Potential mates are separated by geographical barriers (oceans, mountain ranges, etc.)
______Isolation (Hybrids don’t work)
Egg is fertilized but zygote or embryo dies
First-generation hybrid forms but shows very low fitness
Hybrid is sterile or partially so
For the following examples, which reproductive barrier is used? Note: Barrier can be pre- or post-zygotic.
1. ______Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile.
2. ______Two species of pine shed their pollen at different times
3. ______Two species of orchids with different floral anatomy
4. ______Two species of trout that breed in different seasons
5. ______Two species of meadowlarks with different mating songs
6. ______A horse and a donkey create a mule, which is sterile (infertile)
7. ______A farmer plants two crops of the same plant three weeks apart. The first crop each crop flowers for about a week, approximately four weeks after planting.
8. ______Two species of garter snakes live in the same region, but one lives in water and the other lives on land
9. ______A species of flowering plant is successfully fertilized with pollen from a different species of plant. Seeds form and are dispersed by the wind. These seeds germinate and give rise to young hybrid plants. However, these hybrid plants are not very strong and are easily killed by drought and disease and rarely survive to reproductive age.
10. ______Mating fruit flies recognize the appearance, odor, tapping motions, and sounds of members of their own species, but not of other species
11. ______The scarlet oak is adapted to moist bottomland, whereas the black oak is adapted to dry upland soils
12. Several closely related frog species of the genus Rana can be found in the forests of the southeastern United States.
a. ______Males of one species sing only during rainy conditions; males of another species sing only when it is not raining.
b. ______One species lives only in tree holes; another species lives only in streams.
c. ______Females of one species choose mates based on song quality; females of another species choose mates on the basis of size.
d. ______One species mates for two weeks in early April; another species mates for three weeks in early May.
e. ______Males of one species are too small to perform amplexus (an action that stimulates ovulation) with females of all other species.
13. ______Rocky Mountain juniper (Juniperus scopulorum) and one–seeded juniper (J. monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species.
14. ______The male of a given species of frog uses distinctive calls to attract mates. Two populations of these frogs coexist in a single pond but never interbreed because their mating calls are different. Females of one population will not respond to the calls of a male of the other populations.
15. ______A certain species of flea feeds only on pronghorn antelopes. In rangelands of the western United States, pronghorns and cattle often associate with one another. Some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood.
16. ______Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females.
17. ______A lion and tiger mate and create a Liger, which is usually sterile and in poor health.
18. ______Some species of Anopheles mosquito live in brackish water, some in running fresh water, and others in stagnant water.
19. Rocky Mountain juniper (Juniperus scopulorum) and one–seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms are applicable?
1. sympatric species
2. prezygotic isolation
3. postzygotic isolation
4. allopatric species
5. habitat isolation
6. reduced hybrid fertility
A) / 1 and 2 B) 2 and 4 C) 1, 3 and 6 D) 2, 4, and 5 E) 1, 2, 5, and 6Reproductive Barriers
Prezygotic Barriers
· Geographic isolation-species occur in different places
· Ecological isolation-species utilize different resources
· Behavioral isolation-species perform different courtship behavior
· Temporal isolation-species breed at different times
· Mechanical isolation-structural differences prevent sperm or pollen transfer
· Gametic isolation-sex cells incompatible; no fusion of egg & sperm
Postzygotic Barriers
· Hybrids do not develop properly
· Hybrids do not survive in environment