Experimental evidence that nest attendance benefits female marbled salamanders
(Ambystoma opacum) by reducing egg mortality
DEAN
A. CROSHAW1 and DAVID E. SCOTT
Author Affiliations
DEAN A. CROSHAW
Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29802
and Department of Zoology, University of Oklahoma, Norman 73019
and
DAVID
E. SCOTT
Savannah River Ecology Laboratory, Drawer E, Aiken, South Carolina 29802
Abstract
To understand the selective pressures that have influenced the evolution
and maintenance of parental care, it is necessary to assess the consequences
and function(s) of specific behaviors. We used field and laboratory experiments
to investigate possible fitness benefits and proximate functions of female
nest attendance in marbled salamanders (Ambystoma opacum). In
the first field experiment, nests at which females remained until flooding
had higher hatching success than those without attendant females, but
results were somewhat equivocal. In the second field experiment we used
unattended eggs in artificial
clutches randomly assigned to one of four treatment groups: eggs physically
agitated to possibly reduce developmental malformations and/or fungal
growth, eggs protected from predators, eggs moistened by addition of water
and eggs in an unmanipulated control group. Clutches that were protected
from predators had significantly higher hatching success than control,
agitation and supplemental water groups. In the laboratory experiment,
nests in which fungal infection was controlled had higher hatching success
than those without sterilized substrates. Also, physical agitation and
increased moisture did not confer higher hatching success when fungi were
eliminated in the laboratory. Predation and fungal infections appear to
decrease hatching success in this species, and female nest attendance
may reduce these risks.
1Corresponding author present address: Savannah River Ecology
Laboratory, Drawer E, Aiken, South
Carolina 29802; Telephone: (803) 725-5873; e-mail: croshaw@srel.edu
SREL Reprint #2900
Croshaw, D. A. and D. E. Scott 2004. Experimental evidence that nest attendance
benefits female marbled salamanders (Ambystoma opacum) by reducing
egg mortality. The American Midland Naturalist 154:398-411.
