New Zealand Journal of Marine and Freshwater Research abstracts

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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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