Download Exam_ final question.. - The Department of Ecology and

Herpetology
EEB 465
Final Exam Questions
A selection of these questions will appear on the exam to be given in this room on
Thursday, May 5 at 1:00 PM. You will not be able to bring any reference materials with
you to the exam. However, you may use any materials you wish to prepare these
questions ahead of time. I am mainly interested in getting well-organized, thoughtful
answers with adequate reference to specific examples and studies. Do not attempt to
guess which questions will appear, since I won't decide this until the last minute. You
should cite specific examples from papers assigned as readings in class whenever
possible (although you don’t have to remember the exact journal citations, since this is
not a take-home exam).
1. Although the mating systems of amphibians and reptiles often fall into definable
categories such as scramble competition, mate searching, leks, or resource defense,
males of many species exhibit considerable plasticity in the behavioral tactics used to
acquire mates. This can be plasticity among populations in different environmental
conditions or alternative tactics used by different males in the same population.
Using examples from salamanders, frogs, lizards, and snakes, discuss the
evolution of plasticity in mating tactics of males, both within and between
populations. What is the role of sperm competition in the evolution of mating tactics?
What is the role of morphological, physiological, and behavioral variation among
males in determing what tactics a male will use?
2. On the islands of Fiji, one can find a number of ranid frogs in the genus Platymantis,
a group that is widely distributed from New Guinea to the Solomon Islands. Some
are terrestrial frogs found on the rainforest floor, while others are more arboreal and
live higher in the tree canopy. Propose some physiological experiments or
measurements that might be done to understand (a) how this group of amphibians got
to islands surrounded by salt water, and (b) how different species have adapted to
conditions found in different microenvironments (forest floor vs. tree canopy).
Discuss what results you might expect to find in your physiological measurements,
but also discuss alternative hypothesis if your experiments do not yield the expected
results. Use literature on the physiological responses of other frogs to support your
arguments.
3. The aquatic larvae of anurans and urodeles are very different in basic morphology
and ecology. Describe these differences and discuss how such differences affect (a)
the ecological role of these larvae in aquatic communities, (b) the process of
metamorphosis from larva to terrestrial juvenile, and (c) the tendency to remain for
long periods in the larval stage and in some cases, become sexually mature as larvae
(paedomorphosis).
2
4. Many frogs, such as spring peepers, can sustain very high calling rates for many
hours. Describe the morphological and physiological features of these frogs that
enable them to sustain such high levels of activity. How does the metabolic support
for call production differ from that used in locomotion? What sources of energy
(fuels) are used in calling by male frogs? How do these features differ in species with
lower calling rates? Why have salamanders not evolved this sort of expensive
courtship behavior?
5. In all organisms, phylogenetic history plays an important role in determining what
morphological, physiological, or behavioral adaptations are likely to evolve in
particular lineages. Select one of the following examples and discuss in some detail
how knowledge of the phylogenetic history of the group enhances our understanding
of trait evolution: (a) The evolution of chemical communication and courtship in
salamanders. (b) The evolution of call structure in frog and toads. (c) The evolution
of community structure in island lizards. (d) The evolution of viviparity in lizards.
(e) The evolution of foraging mode and sensory biology in squamate reptiles. You
will need to refer to specific class readings from the original literature in your answer.
6. Many experimental studies have revealed the importance of competition in the
structuring of amphibian and reptile communities and the interaction between
predation and competition. Using specific examples from both amphibians and
reptiles, describe the results of some of these experimental studies. How do physical
factors in the environment influence the interactions between a species and its
competitors or predators? Why do species with similar ecology and morphology tend
to evolve independently in assemblages of species in different parts of the world?
Want are some examples of this type of convergent evolution?
7. The evolution of an elongate body form is a common theme among many lineages of
amphibians and reptiles. Identify major lineages of amphibians and reptiles that have
evolved this body form. What sorts of selection pressures or environments tend to
favor an elongate body, and what advantages do such shapes provide? How does an
elongate body constrain the physiology, ecology, and behavior of these animals?
How do the details of body morphology differ among elongate amphibians and
reptiles with fundamentally different lifestyles (for example, burrowing vs. surfacedwelling)?
8. Amphibians and reptiles exhibit considerable variation in life history traits,
particularly the number and size of offspring produced each year. Some species
produce large numbers of very small eggs or offspring, whereas others produce
smaller numbers of larger eggs or offspring. Species also vary in the frequency of
reproduction and the way in which energy is partitioned among reproductive events.
Discuss the various selective pressures that affect the evolution of egg or offspring
size, clutch size, and the timing of reproduction in these animals, including the
influence of both the physical and biological environments. Give some specific
examples.
3
9. Discuss the fundamental differences in the structure of amphibian and reptile eggs.
How do these differences affect the interaction between the egg and the surrounding
environment, and how do these interactions in turn constrain the choice of oviposition
sites by females? What sorts of factors interact to determine the way in which
amphibians lay their eggs (in surface films vs. submerged clumps, etc.)? Also discuss
the way in which amphibians, despite the limitations imposed by their eggs, have
managed to live and reproduce in a wide variety of habitats, including deserts and
regions without access to ponds and other standing water.
10. The fossil record for both amphibians and reptiles is full of very large animals, and in
some cases, such as the dinosaurs, truly gigantic species. Yet, with a few
conspicuous exceptions (giant salamanders, crocodilians, sea turtles, giant snakes and
tortoises, Komodo dragons), modern amphibians and reptiles tend to be relatively
small. In some lineages, such as plethodontid salamanders, several families of frogs,
leptotyphlopid snakes, and gymnothalmid lizards, there has been an evolutionary
trend toward even further miniaturization. Discuss both the costs and benefits of
small and very small body size in amphibians and reptiles, including implications for
their physiology, ecology, reproductive biology, and behavior. Why have these
animals been so successful at small body sizes, and how do you account for the few
exceptions cited above?