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Mating strategy in the male common dolphin Delphinus delphis: what gonadal analysis tells us

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Author(s)

Sinead Noirin Murphy, A Collet, E Rogan

School/Research organisations

Abstract

Gonadal development in immature, pubertal, young mature, and sexually mature male common dolphins (Delphinus delphis) was assessed for 212 dolphins collected between 1991 and 2003. The sample consisted of animals stranded along the Irish and French coasts, and also bycatch samples from Irish and French observer programs. Through histological analysis of the testes, individuals were categorized into reproductive stages by using characteristics of their gonadal morphology. These stages were immature. pubescent, young mature, and sexually mature. Male common dolphins were 102-233 cm in length and 0-28 years of age. Sexually mature individuals were 195-233 cm in length and 8-28 years of age, and the average age at attainment of sexual maturity was 11.86 years. Combined testes weight for mature male dolphins ranged from 0.45 to 5 kg, which is relatively large considering the overall size of the dolphin. Reproductive seasonality was found to occur, as evidenced by marked seasonal changes in both testes weights and cellular activity in testes outside the mating period; the mating period was estimated to take place during May-September. Moderate sexual dimorphism and large testes suggest sperm competition and a promiscuous mating system, with female common dolphins mating with multiple mates.

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Details

Original languageEnglish
Pages (from-to)1247-1258
Number of pages12
JournalJournal of Mammalogy
Volume86
Issue number6
Publication statusPublished - Dec 2005

    Research areas

  • cetaceans, mating systems, promiscuity, reproductive seasonality, rut, SPERM COMPETITION GAMES, SEXUAL-DIMORPHISM, PHOCOENA-PHOCOENA, HARBOR PORPOISES, TESTES SIZE, BODY SIZE, MAMMALS, SYSTEM, GROWTH, REPRODUCTION

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