New Zealand Journal of Marine and Freshwater Research abstracts
Morphogenesis during sexual and asexual reproduction in Amphipolydora
vestalis (Polychaeta: Spionidae)
Glenys D. Gibson*
Ian G. Paterson
Department of Biology
Acadia University
Wolfville, NS B4P 2R6
Canada
email: glenys.gibson@acadiau.ca
email: ian.paterson@acadiau.ca
*Author for correspondence
Abstract Both sexual and asexual reproduction occur
in Amphipolydora vestalis, a small, sponge-dwelling spionid polychaete.
Sexual reproduction occurs through adelphophagy, where offspring are provided
with extra-embryonic yolk in the form of nurse eggs. Ingestion of nurse eggs
sustains development until offspring hatch at late larval and early juvenile
stages (22 days). Hatched young have an advanced morphology and alternatively
crawl and swim, suggesting that a dispersive phase is brief or absent. Asexual
reproduction occurs through architomy, in which a parent fragments into 4-6
pieces and each regenerates a complete body plan within 8 days. Asexual propagules
remain within the parental tube until growth and differentiation are almost
complete. Both reproductive modes were found at the same time in the same
population, and asexual fragments often had well developed gametes in the
coelom. Both reproductive modes facilitate local recruitment and a reduced
dispersal potential. This is the first description of development within
the genus Amphipolydora. Aspects of morphogenesis during asexual reproduction
suggest that Amphipolydora is closely related to Polydorella,
and that architomy in the Spionidae evolved from a widespread ability to
regenerate, while paratomy is secondarily derived.
Keywords adelphophagy; embryogenesis; larva; blastema;
regeneration; Amphipolydora; spionid; Polydora complex; architomy;
paratomy
M02030 Received 24 April 2002; accepted 27 June 2003; Online publication
date 31 October 2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37:
741-752
0028-8330/03/3704-0741 $7.00 © The Royal Society of New Zealand
2003
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