Sex Differences in Discrimination of Shoal Size in the Guppy (Poecilia reticulata)

Abstract

For a diversity of species, differences in sexual and parental roles, along with differences in body morphology, often result in males and females having different diets, distinct predators and even different patterns of habitat use. As a consequence, the two sexes often face different environmental challenges and selection may favour the evolution of sex differences in cognition. We tested this prediction in the guppy (Poecilia reticulata). Under perceived hazard, individual guppies join the larger available social group, a behaviour that is thought to minimise predation risk. In this species, females are more frequently exposed to predation and more averse to predation risk; we therefore expected greater accuracy in shoal size discrimination in females. We compared the accuracy of male and female guppies in discriminating shoals of 4 and 6 conspecifics, which represents the upper limit of discrimination for this species. Overall, we found no sex differences in the accuracy of discriminating the two shoals. However, while females showed this ability at the beginning of the test, males began to select the larger group only after several minutes. In three control experiments, we found indications that this sex difference cannot be accounted for by differences in motivation or antipredator strategies between the two sexes, suggesting female guppies are more efficient at rapidly estimating shoal size.

Sex differences in cognitive performance, style and domain relationships in mosquitofish (Gambusia affinis)

“…Moreover, we predicted that the sexes would diverge in cognitive style where a ‘fast-exploratory’ learning type (e.g. faster decision making, shorter latencies to sample) would be more associated with males as has been found in other poeciliids [7]. Lastly, we predicted that the sexes would diverge in their relationship between cognitive domains.…”

“…In previous fish studies examining sex differences in cognitive styles during associative learning assays with food rewards (T maze [43], visual discrimination of shapes and colors [44]) researchers have found a fast-exploratory cognitive style associated with males , not females. Only during shoal discrimination tasks in poeciliids (guppies, Gambusia ) have females been shown to make faster decisions than males [7]. If strong sexual selection pressures have shaped female Gambusia shoaling decision-making processes, perhaps this has influenced the cognitive style in general numerical discrimination tasks.…”

“…a fast-exploring cognitive style) should predict an individual’s performance (accuracy) in a learning task [2]. Empirical studies have shown variable support for this hypothesis with some taxon revealing a positive relationship [4] between fast-exploratory styles and learning performance, others revealing a negative relationship [5–6], and yet other studies find that a fast-exploratory cognitive style is unrelated to performance [7]. Furthermore, relationships between cognitive style and performance are often domain-specific [8].…”

Visual Discrimination of Geometric and Complex 2D Shapes in Goldfish (Carassius auratus)

“…We should use caution in interpreting results from few subjects because within-species differences between fish can occur (Gierszewski et al, 2013;Lucon-Xiccato, Dadda, & Bisazza, 2016;Miletto Petrazzini & Agrillo, 2016;Schluessel et al, 2012Schluessel et al, , 2015Siebeck et al, 2009;Wyzisk & Neumeyer, 2007). However, other studies have utilized two to five goldfish per experiment or test (Douglas, Eva, & Guttridge, 1988;Freche et al, 2012;Neumeyer, 1992Neumeyer, , 2003Wyzisk & Neumeyer, 2007).…”

Equal performance but distinct behaviors:Astatotilapia burtonisex differences in a novel object recognition task and spatial maze

“…Sex differences have been previously described in spatial learning in fish, and most studies have found greater male performance (Carazo et al 2014, Fabre et al 2014, Saucier et al 2008, Jonasson 2005 but see Jones et al 2003, Healy et al 1999. Importantly, behavior exhibited during a task can vary by sex independently of cognitive performance (Burns & Rodd 2008, Mamuneas et al 2015Lucon-Xiccato & Bisazza 2016;Etheredge et al 2018;Titulaer 2012, Dougherty & Guillette 2018, for instance due to where males are typically identified as the "bolder" or "more exploratory" sex (Lucon-Xiccato & Dadda 2016, Han et al 2015, Harris et al 2010, Overli et al 2006, Gagnon et al 2016, but see Hughes 1968& Swanson 1966. Regardless, if the ecological demands of the social environment are largely invariant over time for one or both sexes, one might expect robust sex differences in cognition.…”