NANFA-L-- Skewed Sex Ratio in Shiners?

Bruce Stallsmith (fundulus-in-hotmail.com)
Tue, 16 May 2006 21:02:41 -0400

I've been writing up work I've done on the reproductive biology of two
shiner species, Notropis asperifrons (burrhead) and N. stilbius
(silverstripe). We collected a number of individuals of both species from
Borden Creek in Alabama in 2004. One thing that has struck me is that by
random sampling we collected 29 male and 42 female burrheads, and 70 male
and 66 female silverstripes. A chi-square test doesn't quite show
statistically significant difference from a 50/50 ratio for the burrheads,
and in truth it's a fairly small sample to work with. But it's still
intriguing.

My question for the list is, has anyone encountered sex ratio skew in North
American cyprinids before, either in your own observations or in the
literature? I haven't come across any such information in my own experience
or searches. With the diversity of freshwater species in North America I'm
surprised that no species have evolved a reproductive strategy involving
some kind of skewed sex ratio such as has been observed in a variety of
marine species.

--Bruce Stallsmith
along the still dank Tennessee
Huntsville, AL, US of A
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