Advancing marine conservation
The paucity of our knowledge of marine organisms and ecosystems is becoming an ever more acute problem as we struggle to ensure the health of marine environments, which now face a formidable array of problems. A recent meeting on the causes and consequences of marine biodiversity (30 August-2 September 1994, York University, UK) went some …
Any perception of seahorses and pipefishes as cute but rather irrelevant fishes is about to change. These fishes are now the targets of a large international trade, the scale of which is probably unsustainable. They are also victims of wholesale destruction of their offshore habitats. Seahorses and pipefishes (syngnathids) are sold primarily for use as …
In an aquarium, a female seahorse was presented with a choice of mates: her previous mate to whom she had just transferred her eggs and who was placed in a separate aquarium or new mates in the same aquarium with whom she socially interacted and greeted on a daily basis. In 6 experiments, the female …
Over the past 20 years, long-term studies have shown that mammalian fathers, brothers and even unrelated males may contribute substantially to the care of the young. Recently, more field studies of mammals with male care have further expanded interest in male care potential. Male mammals can never be sole care-givers because offspring depend on maternal …
In the pipefish Syngnathus typhle, only males brood embryos in specially developed brood pouches, supplying oxygen and nutrients. Laboratory studies have shown that this elaborate paternal care has led to sex-role reversal in this species: males limit female reproductive rate, females are the primary competitors for mates and males exercise greater selectivity in accepting mates. In …
Contrary to all expectations based on their male pregnancy, recent work shows that seahorses exhibit conventional sex roles in mating competition: male seahorses compete more to obtain eggs than females do to give their eggs away. This suggests that the operational sex ratio (OSR: the relative number of males and females available to mate) might …
In seahorses, only males undergo a pregnancy. It had been tacitly and explicitly assumed that seahorses were sex role reversed (that females competed more intensely than males for access to mates), on the basis that male pregnancy so limited male reproduction as to produce a female-biased operational sex ratio (OSR). However, this supposition had never …
Adaptive arguments about mating patterns should focus on and evaluate the costs and benefits relating to both female and male mating patterns. To date, most work on mating systems (using prevalent terminology) has concentrated on males, with mating systems categorized as to whether males mate with females once or multiply, sequentially or simulataneously (EMlen and …
Vincent, A.C. (1992). Prospects for sex role reversal in teleost fishes. Netherlands Journal of Zoology 42(2-3):392-399.… Read more
The male pregnancy of pipefishes and seahorses has led to the inference that females compete most intensely for access to mates, because males limit female reproduction. However, recent work has shown that in different species either sex may be the predominant competitor for mates. In this family, there is an apparent association between the mating …