purcc 2012 - University of the Pacific

Poster Session Abstracts
than H. chrysoscelis because the former
possesses greater ploidy, which results in larger
cells. The evidence from field studies is,
however, scarce and inconclusive. In this study,
we compare the laryngeal morphology of these
two species via dissection and histology. Tissues
of leopard frogs (Rana pipiens) were initially
employed for adjustment of the techniques,
especially with relation to the decalcification of
the posterior processes of the hyoid bone, which
is necessary for the production of good sections
of the larynx. Preliminary data from Rana
pipiens indicate that our method will allows us to
obtain precise measurements of the sizes and
thicknesses of the laryngeal structures and of the
cell sizes in epithelia and cartilages, besides the
thicknesses of muscular fibers. These
measurements should unveil the effects of cell
size on laryngeal function, expanding the current
understanding of the design and evolution of the
vocal apparatus in vertebrates.
The Effect of Energetic Costs on Calling
Strategies of the House Cricket, Acheta
domesticus
Moid Khan
Faculty Mentor: Marcos Gridi-Papp
Much is known about the acoustic
communication of the house cricket (Acheta
domesticus), through both laboratory studies of
its neurobiological basis and field studies of its
ecology. We ask how ecological and neural
factors influence the calling strategies of house
crickets. Males chirp to attract mates by rubbing
a pair of wings, and chirping is energetically
expensive. In a signaling strategy, crickets divide
their energetic budget in various dimensions of
sound production: chirp intensity, chirp rate and
number of hours chirping per night. If the wings
are moderately loaded with weight, the animal
might: 1) maintain the chirping behavior and
experience altered sound and energetic cost; 2)
maintain its energetic cost by altering the
chirping behavior and sound; 3) maintain its
sound with altered behavior and energetic cost.
In order to determine which of these three
strategies the cricket will actually employ, we
will compare the chirping of a control group to
that of a group of crickets whose wings are
loaded with a coat of glue. We have developed a
16-channel, 32-bit recording studio which houses
16 crickets and monitors them individually and
continuously. Each cricket is housed in a
semisoundproof box. We are currently adjusting
the software to identify and measure individual
chirps in the recordings. The results will provide
insight into the complexity of the brain circuits
that define the signaling strategies of male
crickets.
The Relationship Between Auditory
Morphology and Tuning in Three Species
of Frogs
Pauline Montemayor, Stephanie Nguyen,
Yutian Zeng
Faculty Mentor: Marcos Gridi-Papp
Rana pipiens is a frog that has been extensively
used as a model to learn about the auditory
capabilities of anurans. Due to the lack of
comparative studies of the auditory system
among frogs, we used R. pipiens as a reference to
assess differences in ear morphology between
species indigenous to other areas of the world,
specifically Engystomops pustulosus (found in
Central America), and Leptopelis flavomaculatus
(found in Africa). Theoretically, there should be
an inverse relationship between the size of a frog
and the sound frequencies that it can hear and
produce. Engystomops pustulosus, being the
smallest of the three species, would
hypothetically be tuned to the highest
frequencies; likewise, the large R. pipiens would
hear and produce sound at the lowest
frequencies. Dissections were conducted to
isolate the middle and inner ears. To compare
species’ ear anatomy, histological methods were
used which allow for precise measurement of
cells and larger structures under the microscope.
Tissues were fixated and decalcified, dehydrated,
paraffin embedded, sectioned with a microtome,
mounted onto slides, rehydrated, and finally,
stained. The highly ossified nature of auditory
structures required additional adjustment of the
decalcification protocol, including acids, EDTA,
and microwaving. The expected results are
quantitative descriptions of the morphology of
the auditory pathway, that should explain the
size relations and specializations presented by
the species in this study.
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