Defense against outside competition is linked to cooperation in male-male partnerships

Male-male competition is a well-known driver of reproductive success and sexually-selected traits in many species. However, in some species, males work together to court females or defend territories against male competitors. Dominant (nesting) males sire most offspring, but subordinate (satellite) males are better able to sneak fertilizations relative to unpartnered males. Because satellites only gain reproductive success by sneaking, there has been much interest in identifying the mechanisms enforcing satellite cooperation (defense) and reducing satellite sneaking. One such potential mechanism is outside competition: unpartnered satellites can destabilize established male partnerships and may force partnered satellites to restrain from cheating to prevent the dominant male from replacing them with an unpartnered satellite. Here, we manipulated perceived competition in the Mediterranean fish Symphodus ocellatus by presenting an “intruding” satellite male to established nesting and sate...

雄性间竞争是许多物种繁殖成功与性选择性状的公认驱动因素。然而，在部分物种中，雄性会协同求偶雌性或联合防御领地以对抗其他雄性竞争者。优势（筑巢）雄性孕育大部分后代，但从属（卫星）雄性相比无配偶雄性更擅长偷偷完成受精。由于卫星雄性仅能通过偷偷受精获得繁殖成功，因此识别强化卫星雄性合作（防御）并减少其偷偷受精行为的机制备受关注。其中一种潜在机制是外部竞争：无配偶卫星雄性可破坏已建立的雄性伙伴关系，并可能迫使有配偶卫星雄性克制作弊行为，以防优势雄性用无配偶卫星雄性取代它们。在此，我们通过向已建立的筑巢雄性和卫星雄性呈现“入侵”卫星雄性，操纵地中海鱼类眼斑隆头鱼（Symphodus ocellatus）的感知竞争...