Individual guppies differ in quantity discrimination performance across antipredator and foraging contexts

Abstract

The ability to discriminate between different quantities is useful to an animal since it allows adaptive decisions in several contexts. In humans, some individuals are generally better at solving different numerical and mathematical problems, but we currently ignore whether other species also show individual differences in quantitative abilities across different contexts. Aiming to investigate this possibility, we observed the performances of individual guppies (Poecilia reticulata) in an antipredator task that required the discrimination between shoals made of a different number of conspecifics (4 versus 6 fish) and, successively, in two foraging tasks that required the discrimination between different numbers of food items (4 versus 6 items) and food items with different sizes (0.67 ratio between the two surface areas). Overall, guppies achieved comparable performances in the discrimination of shoal size and food item size, but showed reduced accuracy in the discrimination between different numbers of food items. Performances of guppies were correlated between the discrimination of shoal size and food item size, suggesting the existence of individual differences in quantity discrimination abilities in different contexts in this species. Unexpectedly, this relationship was negative, and some guppies were better in the antipredator task, while others were better in the foraging task. Our results agree with the general trend of the literature on animals that suggests the existence of multiple cognitive functions whose activation are task specific, and also introduce the possibility that some of these functions are subject to constraints. Significance statementIn this work, we provided the first clear evidence of individual differences in the ability to solve quantity discriminations in a fish. Guppies were observed in three quantity discrimination tasks: recognising and joining the larger shoal of conspecifics among two options, a behaviour that confers protection from predators; selecting the larger number of food items between two sets; and selecting the food item with larger size. Guppies that were more accurate in the shoal size discrimination achieved lower scores in the food item size discrimination. Some individuals gain advantage from cognitive abilities that confer defence against predators, while other individuals from those abilities that improve foraging success.

Guppies learn faster to discriminate between red and yellow than between two shapes

“…However, further research is needed to confirm this hypothesis. For example, it would be interesting to investigate whether guppies show individual differences in colour discrimination ability, as observed for other cognitive skills (Lucon-Xiccato & Dadda, 2017a, 2017b, and to verify whether these individual differences are associated with genetic bases and fitness advantages.…”

Quantity discrimination in angelfish, Pterophyllum scalare: a novel approach with food as the discriminant

“…Other researchers have also tried to reduce the stressors that may confound the results in this type of tests, however, their procedures required periods of individual training and habituation of each subject, as well as several trials for each discrimination contrast (Lucon-Xiccato & Dadda, 2017;Lucon-Xicatto et al, 2015).…”

“…Lucon-Xicatto et al (2015) reported that the guppies were able to distinguish between different number of food items up to a 2:1 ratio (4 versus 1 and 4 versus 2 items), but not between smaller ratios (number of elements in the larger set divided by the number of elements in the smaller set). For example, they were unable to discriminate between 6 versus 4 sets of discrete food items (Lucon-Xiccato & Dadda, 2017). However, no study has examined the abilities of fish to discriminate between food quantities in the large versus the small number range using multiple contrasts systematically varied.…”

Personality and Cognition: Sociability Negatively Predicts Shoal Size Discrimination Performance in Guppies

“…The second reason for focusing on the discrimination of shoal size is that this is the only cognitive task in which guppies have been tested for individual differences in performance. Thought guppies show an average preference for the larger shoal among options (Agrillo et al, 2012), previous studies have demonstrated that when the numerical difference between two shoals is subtle (e.g., four versus six fish), some guppies consistently achieve better performance than others (Miletto Petrazzini and Agrillo, 2016; Lucon-Xiccato and Dadda, 2017). Regarding sociability, it is considered a personality trait in guppies and could be associated to shoal size discrimination ability (Magurran and Seghers, 1991; Brown and Irving, 2013; Irving and Brown, 2013; Cattelan et al, 2017).…”