Download Chapter 6 Content FRQ

Chapter 6 Content FRQ
The California Department of Fish and Game
is developing a plan to connect mountain
“habitat islands” that are separated by open
areas of flat, arid land in the deserts of
southeastern California. These mountain
areas are habitats for desert bighorn sheep
(Ovis Canadensis), which move extensively
among the islands through habitat corridors.
The habitat corridors provide opportunities
for recolonization, seasonal migration, and
maintenance of genetic variation among the
metapopulation of desert bighorn sheep.
(a) Explain what is meant by a
metapopulation and how it relates to
the desert bighorn sheep. (1 point)
A metapopulation is a group of
separate, isolated populations that
have individuals occasionally
disperse between the habitat
islands, allowing recolonization of
islands that might go extinct.
(b) Identify two density-dependent factors
and one density-independent factor that could
affect the populations of desert bighorn
sheep. (3 points)
Density-dependent
factors:
• Scarcity of food
resources
• Disease
• Crowding
• Increase in
predators
• Competition for
mates
Density-independent
factors:
• Drought
• Fires
• Storms
• Mudslides
• Freezes
(c) Explain the consequences to the desert
bighorn sheep population if the plan to
connect the mountain habitat islands is not
implemented. (2 points)
If the plan to connect the mountain “islands”
is not implemented, the following could occur:
• Because the smaller isolated populations are
more prone to extinction. They could not be
recolonized without dispersal from
neighboring islands.
• Dispersal from neighboring islands could
also bring additional genetic diversity which
could help an isolated population persist.
(d) Explain how the theory of island
biogeography applies to the mountainous
areas of southeastern California. (4 points)
• The larger the area of the mountain “island”
with more different types of habitats, the
greater is the number of species that will be
present.
• The larger the area of the mountain “island,”
the larger are the populations of given species;
larger populations are less prone to extinction.
• The more connected the mountain “islands,”
the greater the chance for dispersal or
migration of species, resulting in higher rates
of immigration of new species.