Spawning Behavior and Genetic Parentage in the Pirate Perch (Aphredoderus sayanus), a Fish with an Enigmatic Reproductive Morphology
DEAN E. FLETCHER, ELIZABETH E. DAKIN, BRADY A. PORTER, AND JOHN C. AVISE
We describe
for the first time reproductive behaviors in the Pirate Perch (Aphredoderus
sayanus), a secretive nocturnal fish whose urogenital opening is
positioned far anteriorally, under its throat. Some naturalists had speculated
that this peculiar morphological condition might serve to promote egg
transfer to the fish's branchial chamber for gill-brooding; others hypothesized
that Pirate Perch spawn in the substrate of streams but offered no adaptive
rationale for the odd placement of the fish's urogenital pore. Here we
solve the conundrum through a combination of intensive field investigations,
underwater filming, and molecular parentage analyses. We show that Pirate
Perch spawn in underwater root masses, the first documentation of such
nesting behavior in any species of North American fish. Female Pirate
Perch thrust their heads and release their eggs into sheltered canals
of these masses. Males congregate at these sites and likewise enter the
narrow canals headfirst, to release sperm. Thus, the forward-shifted urogenital
pore may facilitate spawning under this special nesting circumstance.
We found no evidence of extended parental care. Fish formed their own
canals or used burrows made by aquatic macro-invertebrates and salamanders.
Genetic analyses based on three polymorphic microsatellite loci demonstrate
that a total of at least five to 11 sires and dams were the parents of
embryos within each of three assayed root-mass nests (of a total of 23
nests found). Males defended the oviposition sites by body-plugging canal
entrances after spawning. This and more direct aggressive behaviors by
males probably relate to selection pressures imposed by intense competition
for fertilization success under these group-spawning
conditions.
SREL Reprint #2723
Fletcher, D. E., E. E. Dakin, B. A. Porter and J. C. Avise. 2004. Spawning behavior and genetic parentage in the pirate perch (Aphredoderus sayanus), a fish with an enigmatic reproductive morphology. Copeia 1:1-10.
