post-doc available

Flo Thomas fthomas at
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, P.O. Box 369, Dauphin Island, Alabama, 36528.

Research description:

	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, 
Young’s 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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