Effects of Hydric Conditions During the Incubation of Common Snapping Turtle (Chelydra serpentina serpentina) Eggs on Hatchling Evaporative Water Loss and Microhabitat Selection During a Simulated Nest Exodus
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Authors
Knickerbocker, Debra Lynn
Issue Date
1997
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Abiotic factors during incubation can influence embryonic
development in ways which may have serious consequences for the resulting
hatchlings. It has been shown in aquatic turtles that incubation on a substrate
with a positive osmotic gradient (favoring water movement from the soil
into the egg) causes hatchlings that are larger than those incubated on a
substrate with a negative gradient (favoring water movement from the egg to
the soil). To discover possible survival differences accompanying this
difference in size, I incubated 16 clutches of Chelydra serpentina eggs in
vermiculite with two different water potentials (-150 kPa for the wet
("positive") and -850 kPa for the dry ("negative")). Resultant hatchlings were
released in an enclosure containing 3 different degrees of vegetational cover
to simulate a nest exodus. Wet hatchlings were significantly larger than the
dry hatchlings. Under field conditions, wet-incubated hatchlings had a
significantly higher evaporative water loss than did the dry-incubated
hatchlings. The percentage of total distance traveled was higher for dryincubated
hatchlings in high vegetational cover than for wet-incubated
hatchlings and significantly higher in low vegetational cover for the wetincubated
hatchlings than for the dry-incubated hatchlings. These results
suggest that dry-incubated hatchlings can avoid dehydration (to which they
are more susceptible) by selecting habitats for migration which retard
evaporative water loss. Considering most size differences in hatchling turtles
in natural nests are caused more often by initial egg size, it seems unlikely
that hydric conditions in the nest have a significant effect on the survival of
hatchling turtles under field conditions.
Description
vi, 53 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.