How individual and relative size affect participation in territorial defense and cortisol levels in a social fish. Issue 4 (16th January 2019)

• Record Type: Journal Article
• Authors: Ligocki, Isaac Y.; Earley, Ryan L.; Hamilton, Ian M.
• Is Part Of: Journal of experimental zoology. Volume 331:Issue 4(2019)
• Page Start: 217
• Page End: 226
• Publication Date: 2019-01-16
• Subjects: cooperative breeding -- cortisol -- Neolamprologus pulcher -- size -- territory defense; Zoology -- Periodicals; Zoology; Animal Population Groups -- physiology; Zoology; Electronic journals; Periodical; Periodicals; 590
• DOI: 10.1002/jez.2255
• Languages: English
• ISSNs: 2471-5646

Abstract

Abstract: For many species, behaviors such as territory defense and parental care are energetically costly, but are nonetheless can provide substantial fitness gains. In systems in which both parents provide parental care, each of the parents benefits from exhibiting (or having their partner exhibit) these behaviors. However, in many cases, costs and benefits differ between parents due to factors such as size or sex. Different intruder types may also impose different costs on parents. Predatory intruders might consume offspring, whereas conspecifics might threaten the social status of a parent, or provide benefits as a potential group joiner or mate. Responses to these intrusions may also be associated with variation in individual stress responses. We investigated associations among male and female sizes, and the interaction between these, with defense against conspecific and heterospecific territorial intruders by members of successfully breeding pairs in the cichlid fish Neolamprologus pulcher . We also investigated whether cortisol levels were associated with size or participation in territory defense because each may be a cause or consequence of individual variation in the stress response. We found that females paired with large males performed fewer defensive behaviors than females paired with smaller males. Males paired with relatively large females had higher baseline cortisol levels than those paired with smaller females. Collectively, individual characteristics such as size have consequences for each individual's behavior, and also influence the behavior, and endocrine state of social partners. Abstract : We investigated how individual and relative size influence participation in territory defense in a social fish in which both parents perform territory defense and various forms of parental care. We identified both behavioral and physiological consequences of individual size and social partner size in successfully mated pairs. These consequences were different for males and females, indicating that there are sex‐specific responses depending on an individual's size, and that of their mate.