title: Why pair? Evidence of aggregative mating in a socially monogamous marine fish (Siganus doliatus, Siganidae).
abstract: Many species live in stable pairs, usually to breed and raise offspring together, but this cannot be assumed. Establishing whether pairing is based on mating, or an alternative cooperative advantage, can be difficult, especially where species show no obvious sexual dimorphism and where the act of reproduction itself is difficult to observe. In the tropical marine fishes known as rabbitfish (Siganidae), half of extant species live in socially monogamous, territorial pairs. It has been assumed that partnerships are for mating, but the reproductive mode of pairing rabbitfish is currently unconfirmed. Using passive acoustic telemetry to track movements of fishes belonging to one such species (Siganus doliatus), we provide the first evidence that paired adult fish undertake highly synchronized migrations with multiple conspecifics on a monthly cycle. All tagged individuals migrated along the same route in three consecutive months and were absent from home territories for 2-3 days just after the new moon. The timing and directionality of migrations suggest that S. doliatus may form spawning aggregations, offering the potential for exposure to multiple reproductive partners. The finding raises fundamental questions about the basis of pairing, mate choice and partnership longevity in this family.
authors.affiliation: School of Life Sciences , University of Technology Sydney , Ultimo, New South Wales 2007, Australia ; College of Marine and Environmental Sciences and ARC Centre of Excellence for Coral Reef Studies , James Cook University , Townsville, Queensland 4811, Australia ; Division of Evolution Ecology and Genetics, Research School of Biology , Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Fox
authors.affiliation: College of Marine and Environmental Sciences and ARC Centre of Excellence for Coral Reef Studies , James Cook University , Townsville, Queensland 4811, Australia.
authors.forename: David R
authors.initials: DR
authors.lastname: Bellwood
authors.affiliation: Division of Evolution Ecology and Genetics, Research School of Biology , Australian National University , Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jennions
keywords: coral reef fish; pairing; reproduction; social systems; spawning aggregation