Download Lecture 02 Ch 05 BIOMES

ANSWERS FOR PRACTIVE QUESTIONS: EXAM 1 2007
1) Lecture 02 Ch 05 BIOMES
1. A A. Tropical seasonal forest (2pts.)
B. Temperate seasonal forest or temperate grassland (2pts.)
C. Tundra (2pts.). (one point for boreal)
B A. Precipitation (1 pt)
B. Temperature or temperature and precipitation (1 pt)
C. Temperature and/or precipitation (1 pt)
C 1 point for correctly identifying the location of the biomes they
identified in 1A. (3 pts) See pg 109
2) Lecture 03 Ch 04 CLIMATE
A I would prefer to establish my garden on the west side (3pts.) of the Cascade
Mountains (3pts.). (one point was given for Appalachian Mountains).
B In temperate latitudes, the prevailing winds are from the West. The Cascades are on
the west coast of North America and receive moist air from the Pacific Ocean. As
these air masses cross the mountains, they rise and cool. This reduces the waterholding capacity, and abundant rainfall results. As the air crosses the mountains, it
descends and warms again, increasing the water holding capacity, resulting in a dry
climate (rain shadow) on the eastern side. High rainfall on the western side would
promote growth of a lush temperate garden. In addition, temperatures on the western
side would be moderated by the Pacific Ocean. (2pts.)
Prevailing winds also move from west to east over the Appalachian and Ural
Mountains. However, the Urals are far from any oceanic moisture source and would
have a more extreme continental climate. The Appalachians are near the Atlantic
Ocean and Gulf of Mexico, which provide moisture to both sides of the mountains.
Because the prevailing winds are westerly, and the Appalachians are far removed from
western moisture sources, no rain shadow will develop. In addition annual
precipitation in the Cascades would exceed that of the Appalachians. (2pts.)
C No, my choice would still be on the west side of a mountain range that is near the
west coast of a continent or island because the prevailing winds in the Southern
temperate region (30-60 S) are also from the west.
3) LECTURE 4 ECOLOGICAL RESPONSES TO CLIMATE CHANGE
A. Do these species have the ability to acclimate their photosynthetic rates when exposed
to different temperatures.
B. Larrea: The moderate temperature plants have their peak photosynthetic rate at a
lower temperature than the high temperature plants, but the value of these
maximum rates are similar.
Tidestromia:The moderate temperature plants’ photosynthetic rate peaks at a lower
temperature than the high temperature plants, but the high temperature plants have
a much higher rate of PS, especially at high temperatures.
C. Larrea: moderate or high mean; high range
Tidestromia: high mean; low range
D. Larrea: high range. This species was able to maintain a high photosynthetic rate at
two different ranges of temperature. Species that experience changing environments
often evolve the ability to acclimate.
Tidestromia: low range. This species was unable to maintain a high photosynthetic
rate a low range of temperatures. It normally experiences little range in temperatures.
Species that live in relatively unchanging environments experience no selection to
evolve the ability to acclimate.
E. A plant species, such as Larrea, that normally experiences seasonal changes in
temperature, can acclimate, i.e. change their phenotype as temperature changes enabling
them to maintain high photosynthetic rates in a variable environment. In contrast, a plant
species, such as Tidestromia, that normally experiences little seasonal change in
temperature cannot acclimate to a new temperature.
4) LECTURE 4 ECOLOGICAL RESPONSES TO CLIMATE CHANGE
The previous author argued that warming temperatures are not affecting
organisms because they normally experience a wide range of temperature. Furthermore,
she claimed that organisms are not showing responses to the rising in temperatures. I
differ and suggest that she did not have sufficient knowledge of biology to make such
claims.
Most organisms have optimal performance within a narrow temperature range. At
higher temperatures, enzyme structure can be affected negatively, lowering the enzymes
effectiveness in catalyzing biochemical reactions, thus resulting in sub-par physiology
and affecting negatively the organisms’ reproduction and survival. Therefore, rising
temperatures place organisms under greater stress and act as both an ecological force
and/or evolution force via natural selection on the organism. They must adjust locally or
move to a location with temperatures resembling the ones to which they evolved.
Many organisms are already showing ecological responses to the global rise in
temperature. If they remain in the same area, they are showing acclimatory responses in
their physiology or phenology. Natural selection is acting causing evolutionary responses
as well. Alternatively, organisms that cannot tolerate the warming conditions locally are
migrating to the north or upward on mountains. Organisms that do not adjust locally or
move to more favorable temperatures are unlikely to persist and their species may go
extinct in its current location.
5) LECTURE 5 EVOLUTION
A. Natural selection determines which units live or die, reproduce or not reproduce.
Populations are slow to respond in this way and often entire populations do not respond
as a group. Hence natural selection is not often effective at the population level.
Natural selection acts most strongly at the individual level.
B. Selection determines which individuals leave more offspring than others. It does not
act to ‘benefit’ the species. It does not ensure a species’ survival as it may result in no
individuals living to reproduce. The history of life is species extinction, not survival.
Selection acting at the individual level does not act to benefit any species as a whole and
has no ability to ensure the survival of the species.
C. Necessity can’t induce a mutation in the DNA nucleotide sequence. No mechanism
connects necessity to this change.
Mutations arise by chance at no predictable time and may or may not be present when
the need arises.
D. Adaptations arise from existing genetic variation. The variant needed for the
changing environment may or may not be present at the time of change. Therefore, no
mechanism is available to ensure that a species survives. In fact, history shows that the
vast majority of species go extinct.
Genetic variants may or may not be present as the environment changes and thus
adaptations may or may not arise to deal with the change.
E. Adaptations result from selection in the past. They may or may not work for the
present or for the future, depending on the extent to which the environment changes.
Furthermore, adaptations may change in response to new selective forces and so the first
adaptation may be no longer present.
Adaptations arise from past selection and are not static through time. Therefore,
adaptations do not necessarily remain adaptive through time as the environment
changes.
F. Adaptations arise from chance mutations that may or may not provide the best
possible phenotype for the environment. Furthermore, gene combinations are shuffled
via sexual reproduction and the adaptation may or may not persist. Also selection acts on
the whole organism and results in some good, some bad, and some neutral adaptations to
be present in the individual who is far from perfect. A given trait is not acted upon
separately from the entire organism.
Natural selection acts on the entire organism, not individual traits. Therefore, a given
trait may or may not be ‘perfect’.
6) LECTURE 5 EVOLUTION
A. If the insect is adapted to its specific tree, then it will survive more poorly when
transplanted to another tree than to another branch of its own tree.
Or: If the insect is adapted to feed on pine tree fluids, then it should survive equally well
on another pine tree as on a different branch of the same pine tree.
B. % survival is lower when transplanted between trees than when transplanted between
branches of its own tree.
C. Yes
D. Natural selection would be a more powerful force. Gene flow is very limited because
the insect has limited movement. Therefore, natural selection would result in adaptation
of the insect to specific conditions in a very low environment, i.e. its own tree.
E. The genetic makeup of the population of scale insects would be differentiated. The
fact that insects moved between trees were more likely to die shows that they are not
adapted to neighboring trees. Assuming natural selection would be different between
trees, then the two subpopulations of insects would have different combinations of genes.
7) LECTURE 5 EVOLUTION
A. A mutation arises in an individual in the grass population that results in its being
copper-tolerant.
B. This individual is pre-adapted to be able to de-toxify the copper, should the
environment change to include a high concentration of copper.
C. Within the grass population, genetic variation exists; most individuals have alleles
that are copper-intolerant and a rare individual has an allele that is copper-tolerant.
D. Mining arises and mine tailings with a high concentration of copper are dumped in
the area of the grass population.
E. Phenotypic variation exists in the grass population on the tailings. The physiology of
some individuals are negatively affected by the copper; others are unaffected.
F. Natural selection (= copper) acts on this phenotypic variation causing all Cu-intolerant
individuals to die and Cu-tolerant individuals to survive and reproduce.
G. Over time, the allelic frequency of grass population changes.
H. The population evolves to be composed of only Cu-tolerant individuals.
I. The individuals with Cu-tolerance have an adaptation for the copper environment.
8) LECTURE 6 LIFE HISTORIES
A. Seed size and seed number are inversely related (negative slope). (Either variable
could be on the X axis). Because of limited resources, a plant can either put all its effort
into producing a few large seeds or it can distribute the same amount of resources among
many small seeds. Generall, not enough resources are available for the plant to produce
many large seeds.
B. Adult survival (Y axis) is negatively affected (negative slope) by increasing the
number of offspring in any given breeding event (X axis). Successfully raising offspring
requires a lot of energy ad resources for the parent(s). As limited resources are available,
the parent cannot raise offspring without sacrificing some of its own resources. For
example, collecting more food for the offspring means that the parent is collecting less
food for itself. Because raising offspring is so resource-draining on the parent, it
increases the change that the parent will not survive to the next breeding event.
C. The key assumption in the trade-off hypothesis is that resources are limited.
9) LECTURE 7 POPULATION STRUCTURE (AND BIOMES)
A. Kangaroo abundance varies widely within its range.
Kangaroos are restricted primarily to the interior of the continent.
B. Desert at 30 degrees S.
The dry air in the Hadley cell descends at 30 degrees and absorbs any moisture, resulting
in a desert at that latitude.
C. West: S to N; East: N to S
Subtropical vegetation is on the East.
The ocean currents to the E bring warm equatorial water; the warm air picks up moisture,
resulting in rainfall supporting subtropical vegetation. In contrast, the currents to the W
bring cold Antarctic water; cold air absorbs little moisture and so a desert occurs on the
W.
D. The Blue Mts. lie just to the E of the desert boundary. The moist air from the ocean
rises and drops moisture on the windward side. On the leeward side a rainshadow occurs;
hence the beginning of the desert.