Download Species/Speciation - Ms Kim`s Biology Class

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
__________________________ 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
SYMPATRIC
SPECIATION:
Reproductive
Isolation
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
and 6
B) 2 and 4
C) 1, 3 and 6
Reproductive Barriers
D) 2, 4, and 5
E) 1, 2, 5,
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