Constraints on paternal care capacity favor a monogamous mating system in the group-living gobiid fish Trimma marinae

Abstract

We examined why Trimma marinae is monogamous despite high potential for polygyny. Previous work suggested males can care for up to three clutches, but four may exceed their capacity. We therefore tested whether a single female can saturate a males care capacity. In established pairs, 49 spawning intervals had a median interval of 2 days. Because eggs hatch on day 3, 75.5% of intervals produced clutch overlap. Under these conditions, mating with an additional female would require care of four clutches, likely exceeding male capacity. These findings support female mate guarding as a strategy to monopolize limited paternal care.