Social Reversal of Sex‐Biased Aggression and Dominance in a Biparental Cichlid Fish (Julidochromis marlieri)

Abstract

In biparental species, aggression, dominance, and parental care are typically sexually dimorphic. While behavioral dimorphism is often strongly linked to gonadal sex, the environment-either social or ecological-may also influence sex-biased behavior. In the biparental cichlid fish Julidochromis marlieri, the typical social environment for breeding pairs consists of large females paired with smaller males. While both sexes are capable of providing territory defense and parental care, the larger female provides the majority of defense for the pair, while the smaller male remains in the nest guarding their offspring. We examine the contributions of sex and relative mate size to these sex-biased behaviors in monogamous J. marlieri pairs. Both female-larger and male-larger pairs were formed in the laboratory and were observed for territorial aggression (against conspecifics and heterospecifics), dominance, and parental care. In female-larger pairs, territorial aggression and intra-pair dominance were female-biased, while in male-larger pairs this bias was reversed. For both pairing types, the presence of an intruder amplified sex differences in territorial aggression, with the larger fish always attacking with greater frequency than its mate. Though less robust, there was evidence for plasticity of sex-bias for some egg care related behaviors in the inverse direction. Our study suggests that relative mate size strongly influences the sex bias of aggression and dominance in J. marlieri and that this aspect of the social environment can override the influence of gonadal sex on an individual's behavior. The remarkable plasticity of this species makes Julidochromis an exciting model that could be used to address the relationship between proximate and ultimate mechanisms of behavioral plasticity.Ethology 120 (2014) 540-550

Dissecting the Transcriptional Patterns of Social Dominance across Teleosts

“…The evolvability of mating systems in cichlids (Koblmuller et al 2005) is evident in the genus Julidochromis, comprised of biparental substrate brooding species (Koning 1998) that show either conventional or reversed sex-biased behaviors, with sex roles enforced through aggression from the dominant territorial individual toward the subordinate individual that provides egg care. Julidochromis transcriptus exhibits the conventional sex-biased behavior, with males primarily performing the territory defense and females the egg care; the sister species J. marlieri exhibits reversed sex-biased behavior, where females tend to be larger, behave aggressively, and engage in the territory defense (Yamagishi and Kohda 1996;Barlow and Lee 2005;Wood et al 2014). Therefore, the ranked gene list for J. marlieri female versus male (Schumer et al 2011) represents an expression profile of female dominance that, according to inspection of the RRHO analysis, shares a weak but significant correlation with the expression profile of female social dominance in A. burtoni Fig.…”

Sex Differences in How Territory Quality Affects Aggression in Convict Cichlids

“…In black chin tilapia, Sarotherodon melanotheron , females demonstrate more aggression than males in competition for mates ( Balshine-Earn and McAndrew 1995 ). This is also true in other cichlids ( Wood et al 2014 ; Ito et al 2017 ) as well as pipefish ( Berglund et al 2005 ; Rosenqvist 2009 ) and gobies ( Swenson 1997 ; Amundsen 2018 ). However, all of these systems are generally considered “sex-role reversed,” due to males providing significant parental investment through paternal care of eggs and/or young ( Trivers 1972 ) and the high levels of aggression are observed within the context of competing for mates.…”

The behavioural pattern and variation in parental care of Aequidens rivulatus

“…In the early stages of the experiment, females were the primary protectors, and with the development of larva, males began to take on the responsibility of protection. The adjustment right of parents during the parental care is not equal, but shows sex‐biased (Wood et al, 2014). In cases of biparental care, the role played by males and females may depend on several factors, such as brood development stage, number and proximity of potential predators, relative size between parents and sex ratio (Teresa & Gonçalves‐de‐Freitas, 2011).…”