Evolutionary radiation in polychaete ovaries and vitellogenic mechanisms: their possible role in life history patterns

Abstract

Two types of oogenesis have evolved in polychaetes: one (extraovarian) in which germ cells are ovulated into the coelomic cavity where they undergo vitellogenesis, and another (intraovarian) in which the germ cells are released from the ovary after or near the completion of vitellogenesis. There are many mechanisms of yolk synthesis and significant variation as to the sources of yolk precursors, their route of entry into developing oocytes, and the oocytic organelles involved in yolk synthesis. The evolution of the coelom and its role in nutrient storage and transfer, as well as the origin of germ cells, are intimately related to the evolution of vitellogenic mechanisms in polychaetes. Comparative studies have revealed a correlation between mechanisms of yolk synthesis and the breeding patterns of polychaetes with the rate and type of vitellogenesis being related to the frequency of breeding. Vitellogenic mechanisms in polychaetes are compared with those of other metazoans in an effort to better understand the evolution of this important process and to identify primitive and derived features of yolk synthesis within the Polychaeta.

Gametogenesis and spawning of Spirobranchus tetraceros (Polychaeta, Serpulidae) in Abu Kir Bay, Egypt

“…Gametogenesis of several polychaetes have been studied (FRANZÉN, 1956DUMONT, 1969, OLIVE & GARWOOD, 1981CHRISTIE, 1984CHRISTIE, & 1986KOPP,1985, ECKELBARGER, 1983& 1988FRANZÉN & RICE, 1988;JAMIESON & ROUSE,1989;GIANGRANDE & PETRAROLI, 1994;KUPER & WESTHEIDE, 1997;ROUSE & TZETLIN, 1997;GAMBI et al, 2000 andKUPRIYANOVA et al, 2001). Nevertheless, in Egypt comparatively limited studies have been carried out on gametogenesis of polychaetes.…”

Ultrastructural study of oogenesis in <em>Marphysa sanguinea</em> (Annelida: Polychaeta: Eunicida) from the Lagoon of Tunis

“…As observed for the majority of polychaetes with extraovarian oogenesis, oocytes rupture through the epithelium prior to vitellogenesis and disperse independently in the coelom. Polychaetes belonging to other families (Dorvillaeidae, Onuphidae) in the order Eunicida studied until now are also characterized by an extraovarian oogenesis (Eckelbarger, 1983). Nevertheless, contrary to what occurs in other eunicids studied up to now, previtellogenic oocytes are not associated with nurse cells in M. sanguinea.…”

“…Two basic patterns of oogenesis have evolved in the polychaetes: one (extraovarian) in which oocytes leave the ovary and undergo vitellogenesis while free floating in the coelomic fluid, with or without the aid of attached accessory cells or associated amoebocytes and another (intraovarian) in which oocytes undergo most of vitellogenesis while retained within the ovary in close association with follicle cells, nurse cells or blood vessels from which they may derive nutrients (Eckelbarger, 1983).…”

“…Comprehensive studies of oogenesis have been conducted in only 0.1% of described species (reviewed in Schroeder and Hermans, 1975, Eckelbarger 1983, 1988, 1992, 2005, 2006. Information about Eunicida oogenesis is very scarce.…”

<i>Dodecaceria carolinae</i> n. sp. (Polychaeta: Cirratulidae), a shallow-water species from the northwestern Caribbean Sea

“…They have 1-2 rounded pits along cha- etigers 55-86, and the coelom is completely full of oocytes, which apparently belong to the solitary type (Eckelbarger, 1983) and measured 45-55 μm in diameter. No epitokal transformation or chaetal modification was observed.…”