fthomas at mobile.gulf.net
Thu Nov 27 12:08:08 EST 1997
Post-doc available for 2-2.5 years. The position is to work on an NSF funded
project to explore the role of hydordynamic stresses on the fertilization ecology of
free-spawning marine invertebrates. The research is very interdisciplinary and could
be appropriate for someone trained in any of the following areas: biomechanics,
reproducive ecology, systematics, molecular and cellular structure of gametes. Below
is a description of the research. If you are interested please contact, Dr. Florence
Thomas, fthomas at jaguar1.usouthal.edu, P.O. Box 369, Dauphin Island, Alabama, 36528.
Free-spawning organisms release eggs and sperm directly into the water column
posing a particular set of obstacles to successful reproduction. First, after release
from the adults, gametes must survive physical stresses present in the external
environment. Second, sperm must meet eggs -- the probability of which decreases with
dilution rates of gametes in sea water. Third, the fertilized eggs must undergo
normal embryonic development.
The research is to investigate the possibility that eggs have undergone
selection for specific properties that help overcome hydrodynamic stresses by: (1)
reducing damage and loss of eggs; (2) decreasing rates of dilution after spawning; and
(3) reducing abnormal development of eggs exposed to physical stress. The aim of this
research is to further our understand of the importance of hydrodynamics and physical
stress to fertilization biology of free-spawning organisms.
This research program integrates biomechanics and an analysis of cell
structure within a phylogenetic context. Physical properties of eggs (viscosity,
Youngs modulus and compressive strength, and dilution rates), and physical exposure
of adult habitats are being measured using techniques from biomechanics. Light and
electron microscopy are being used to characterize specific egg traits, (thickness,
organic content, and ultrastructure of jelly coats and other egg features).
Phylogenetic and statistical analyses are being used to test the hypothesis that
physical stresses have led to selection for specific gamete properties. The plan is
to determine if there is a general pattern in the relationship between egg properties
and adult habitat characteristics. We will then compare these patterns for geminate
species across the Isthmus of Panama to establish causality.
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