Do female zebrafish withhold reproductive resources for future mating opportunities?

Abstract

Because polyandry often confers substantial direct and indirect benefits, females might be advantaged if they limit their reproductive investment in a single male when additional partners are available. We tested whether females of the externally fertilizing zebrafish Danio rerio would withhold more of their clutch when immediate further matings were likely. We tested females in three treatments: overnight visual and olfactory exposure to either a single male, two males, or three males. Females were then allowed to mate with one of the males; in the two-male and threemale treatments, the additional males remained in visual and olfactory contact to simulate a high likelihood of additional mating. Available clutch was measured by leaving females to spawn with two novel males for an additional 60 min. In contrast to our expectations, females did not release a greater proportion of their clutch when only a single male was present. Instead, females in the single male treatment released significantly fewer eggs per spawning event and significantly fewer eggs over the full 70 min of the trial. The hypothesis that females adjust current reproductive investment support in relation to the likely availability of mating partners is not supported. Instead, females appear to lay fewer eggs when only one male is available, most likely as a result of physiological stimulation of oocyte maturation, or in response to the likely fertilization capacity of a single individual.

The zebrafish (Danio rerio) as a model organism, with emphasis on applications for finfish aquaculture research

“…This change in body coloration has been also observed in some cultured species such as common dentex (Dentex dentex) (Loir et al 2001) or Arctic char (Salvelinus alpinus) (Janhunen et al 2011). In zebrafish, there is also a sexual selection whereby females choose their mating males and spawning takes place usually in pairs rather than in groups (Hutter et al 2010). However, the number of released eggs is lower per spawning when sexual stimulation originates from a single male only (Vaughan & Thom 2012).…”

“…). However, the number of released eggs is lower per spawning when sexual stimulation originates from a single male only (Vaughan & Thom ).…”