Boldness in extreme environments: temperament divergence in a desert-dwelling fish

Shoal sex composition affects exploration in the Mediterranean killifish

“…The direction of the sex difference in our experiment is apparently consistent with the one observed in the Australian desert goby (Moran et al., ), but opposed to the sex difference reported for three other fish species ( B. episcopi : Brown et al., ; guppies: Irving & Brown, ; sticklebacks: King et al., ). Similar between‐species differences in the pattern of sex difference are present in other vertebrates (Joseph, Hess, & Birecree, ; Schuett & Dall, ) and might be related to differences in ecological and life history traits.…”

“…The absence of sex differences in the latency to emerge into the novel environment was rather unexpected because experiments testing fish individually have often reported sex differences in the emergence test (Brown et al., ; Irving & Brown, ; Moran et al., ). As we did not find correlation between time taken to emerge into the open field and the subsequent exploratory behaviour, it is possible that latency to emerge was due to factors other than exploratory behaviour (e.g., boldness; Beckmann & Biro, ), which might not be affected by shoal sex composition.…”

“…It is also possible that the emergence test is not useful to assess shoals’ exploration. Although the use of this test is considered valid in most cases (Brown et al., ; Irving & Brown, ; Moran et al., ; White, Meekan, & McCormick, ), in some species individuals’ emergence is affected by several different factors (Burns, ). In the case of testing shoals, when one individual emerges, the other individuals might follow independently from their exploratory tendency.…”

“…It is also possible that the emergence test is not useful to assess shoals' exploration. Although the use of this test is considered valid in most cases (Brown et al, 2007;Moran et al, 2016;White, Meekan, & McCormick, 2015), in some species individuals' emergence is affected by several different factors (Burns, 2008).…”

“…A commonly‐used paradigm to study behavioural sex differences in novel environments is the “emergence test”, in which the fish is moved into a shelter in an unfamiliar environment to measure time taken to emerge. This test has revealed greater male exploratory tendency in guppies and Brachyrhaphis episcopi (Brown, Jones, & Braithwaite, ; Irving & Brown, ) and an opposite sex difference in Chlamydogobius eremius (Moran, Mossop, Thompson, & Wong, ). Exploiting another procedure commonly used in fish and other animals, the open‐field test (Vošlajerová Bímová, Mikula, Macholán, Janotová, & Hiadlovská, ; Ward, ; Warren & Callaghan, ), King, Fürtbauer, Mamuneas, James, and Manica () measured the amount of activity of three‐spined sticklebacks, Gasterosteus aculeatus , in an unfamiliar tank, finding that males were more explorative than females.…”