Shoal sex composition affects exploration in the Mediterranean killifish

Abstract

As a consequence of sexual selection, males and females may exhibit wide behavioural differences, for example, spatial behaviour. In fish, the two sexes often show different exploratory tendencies. This sex difference has been usually studied by testing individual fish. As many fish species live in social groups with different sex composition, the aforementioned approach might not picture the natural variation of the exploratory behaviour expressed by males and females. Here, we observed shoals of four Mediterranean killifish, Aphanius fasciatus, with three different sex compositions (4 females, 4 males, or 2 females and 2 males) during the exploration of a novel environment. Sex composition of the shoals did not predict the latency to emerge from a shelter into the novel environment. However, once emerged, shoals composed by four males displayed reduced exploratory behaviour compared to 4‐female and mixed‐sex shoals. These results indicated that sex differences in exploration subsist also at group level and highlighted the importance of sex composition in determining the behaviour of the entire shoal.

Social environment affects inhibitory control via developmental plasticity in a fish

“…Chouinard-Thuly et al (2018) did not detect any effect of acute social isolation on the stress response in guppies. The stress mediated explanation does not seem to fit with the effects of group stability in experiment 2 because social fish prefer familiar conspecifics (Griffith & Magurran, 1999;Magurran et al, 1994), and social disruption is likely to be more stressful than consistent group membership (Bhat & Magurran, 2006;Chivers et al, 1995;Lucon-Xiccato & Griggio, 2017), yet the fish from the socially unstable treatment showed lower inhibitory control. It should be also noted that a recent study has suggested that early social experience has no effect on stress-induced cortisol levels in another species of fish (Antunes et al, 2020).…”

Within-shoal phenotypic homogeneity affects shoaling preference in a killifish

“…We used the Mediterranean killifish (Aphanius fasciatus) to test whether within-shoal homogeneity in the number of vertical bars affected shoaling preference. In this species, females are particularly social [10,11] and show a series of vertical narrow black bars on a light-grey background (figure 1a) that remain expressed throughout the whole year [12], suggesting a possible functional role in shoaling behaviour. The Mediterranean killifish inhabits shallow brackish waters, organized in a network of intertidal creeks [13].…”

Comparison of anxiety-like and social behaviour in medaka and zebrafish

“…In addition, for fish, a number of studies have revealed how behavioural assessment can be altered by small changes in the experimental setting and the apparatus 34 , 35 . For example, studies in eastern mosquitofish, Gambusia holbrooki , and the Mediterranean killifish, Aphanius fasciatus , indicated that fish open-field behaviour is altered by the size of the experimental arena 36 , 37 .…”