Spermcast mating with release of zygotes in the small dioecious bivalve Digitaria digitaria
Metadatos
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Nature Research
Fecha
2020-07-28Referencia bibliográfica
Marina, P., Urra, J., de Dios Bueno, J., Rueda, J. L., Gofas, S., & Salas, C. (2020). Spermcast mating with release of zygotes in the small dioecious bivalve Digitaria digitaria. Scientific Reports, 10(1), 1-11. [https://doi.org/10.1038/s41598-020-69457-2]
Patrocinador
Junta de Andalucia; Spanish Government CGL2010-20748-CO2-01 CGL2010-20748-CO2-02 PB 92-0415Resumen
Digitaria digitaria, a small astartid usually less than 10 mm in length, has a non-brooding behaviour
in spite of its limited space for gonad development. This species lives in highly unstable environments
with strong currents, which represent a challenge for fertilization and larval settlement. The
studied population of D. digitaria from the Strait of Gibraltar area was dioecious, with signifcant
predominance of females and sexual dimorphism, where females are larger than males. The
reproductive cycle is asynchronous throughout the year, without a resting period, but with successive
partial spawning events. The presence of stored sperm in the suprabranchial chamber and inside the
gonad of some females, together with the release of eggs along the dorsal axis of both gills, points
to internal oocyte fertilization. Bacteriocytes were found in the female and male follicle walls, but
no bacteria were observed inside any of the gametes. Digitaria digitaria could represent a “missing
link” between spermcast mating bivalves with brooded ofspring and bivalves with broadcast release
of eggs and sperm. The small size, limiting the oocyte production, together with the unstable
environment could represent evolutionary pressures towards sperm uptake in D. digitaria.