Abstract
Pair bonding is generally linked to monogamous mating systems, where the reproductive benefits of extended mate guarding and/or of bi-parental care are considered key adaptive functions. However, in some species, including coral reef butterflyfishes (f. Chaetodonitidae), pair bonding occurs in sexually immature and homosexual partners, and in the absence of parental care, suggesting there must be non-reproductive adaptive benefits of pair bonding. Here, we examined whether pair bonding butterflyfishes cooperate in defense of food, conferring direct benefits to one or both partners. We found that pairs of Chaetodon lunulatus and C. baronessa use contrasting cooperative strategies. In C. lunulatus, both partners mutually defend their territory, while in C. baronessa, males prioritize territory defence; conferring improvements in feeding and energy reserves in both sexes relative to solitary counterparts. We further demonstrate that partner fidelity contributes to this function by showing that re-pairing invokes intra-pair conflict and inhibits cooperatively-derived feeding benefits, and that partner endurance is required for these costs to abate. Overall, our results suggest that in butterflyfishes, pair bonding enhances cooperative defense of prey resources, ultimately benefiting both partners by improving food resource acquisition and energy reserves.
Highlights
Pair bonding, a selective pro-social and enduring affiliation between two individuals that is maintained beyond reproduction[1], has independently evolved numerous times across the animal kingdom[2,3,4]
The overall aim of this study was to test whether pair bonding in two species of common coral-feeding butterflyfishes (C. lunulatus and C. baronessa) may be attributed to benefits of assisted defense of dietary resources, and whether pair bond endurance enhances the effectiveness of assisted resource defense
We provide field-based observational evidence for the assisted resource defense hypothesis (ARDH) for pair bonding in two species of butterflyfishes
Summary
A selective pro-social and enduring affiliation between two individuals that is maintained beyond reproduction[1], has independently evolved numerous times across the animal kingdom[2,3,4]. Aside from mate-guarding and bi-parental care, pair bonding might be attributed to the benefits of social assistance during ecological processes that are directly conferred to one or both partners[15,16,17] One such process may be cooperative defense of high value resources; such as food, shelter, or nesting sites[18,19]; by one or both partners. Resources may be mutually defended, or “co-defended” by male and female partners[12,22], presumably because both partners directly benefit from sharing this responsibility[22] This cooperative or assisted resource defense hypothesis (ARDH) for pair bonding makes several fundamental predictions. Pair bonding butterflyfishes are presumed to have very high levels of partner fidelity (up to 7 yrs) (Supplementary Table S2), the ecological basis of pair bond fidelity among these organisms remains unknown
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
