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Topping off: A mechanism of first-male sperm precedence in a vertebrate

Summary: Topping off: A mechanism of first-male sperm
precedence in a vertebrate
Adam G. Jones*, Erika M. Adams, and Stevan J. Arnold
Department of Zoology, 3029 Cordley Hall, Oregon State University, Corvallis, OR 97331
Edited by David B. Wake, University of California, Berkeley, CA, and approved December 18, 2001 (received for review September 26, 2001)
Competition among the sperm of rival males is an important
evolutionary phenomenon in many organisms. Yet, despite exten-
sive research on sperm competition in some vertebrate taxa, very
little progress has been made on this topic in amphibians. Urodele
amphibians (newts and salamanders) are of particular interest to
theories of sperm competition because most urodele females--in
contrast to other vertebrate females--control the transfer of
sperm from the male. Here we present a molecular study of sperm
precedence and storage patterns in the rough-skinned newt
(Taricha granulosa). First, we used microsatellite markers to show
that female newts typically use sperm from 13 males under
natural and seminatural conditions. Second, we mated experimen-
tal females sequentially to two males and collected fertilized eggs
in a temporal series. Patterns of paternity were consistent with
first-male sperm precedence and complete mixing of sperm within


Source: Arnold, Stevan J. - Department of Zoology, Oregon State University
Jones, Adam - Department of Biology, Texas A&M University


Collections: Biology and Medicine; Environmental Sciences and Ecology