Male and female guppies differ in problem-solving abilities

In a number of species,males and females have different ecological roles and therefore might be required to solve different problems.Studies on humans have suggested that the 2 sexes often show different efficiencies in problem solving tasks;similarly,evidence of sex differences has been found in 2 other mammalian species.Here,we assessed whether a teleost fish species,the guppy.Poecilia reticulata,displays sex differences in the ability to solve problems.In Experiment 1,guppies had to learn to dislodge a disc that occluded a feeder from which they had been previously accustomed to feed.In Experiment 2,guppies had to solve a version of the detour task that required them to learn to enter a transparent cylinder from the open sides to reach a food reward previously freely available.We found evidence of sex differences in both problem-solvingi tasks.In Experiment 1,females clearly outperformed males,and in Experiment 2,guppies showed a reversed but smaller sex difference.This study indicates that sex differences may play an important role in fish's problem-solving similar to what has previously been observed in some mammalian species.

Personality traits covary with individual differences in inhibitory abilities in 2 species of fish

In a number of animal species,individuals differ in their ability to solve cognitive tasks.However,the mechanisms underlying this variability remain unclear.It has been proposed that individual differences in cognition may be related to individual differences in behavior(i.e.,personality);a hypothesis that has received mixed support.In this study,we investigated whether personality correlates with the cognitive ability that allows inhibiting behavior in 2 teleost fish species,the zebrafish Danio rerio and the guppy Poecilia reticulata.In both species,individuals that were bolder in a standard personality assay,the open-field test,showed greater inhibitory abilities in the tube task,which required them to inhibit foraging behavior toward live prey sealed into a transparent tube.This finding reveals a relationship between boldness and inhibitory abilities in fish and lends support to the hypothesis of a link between personality and cognition.Moreover,this study suggests that species separated by a relatively large phylogenetic distance may show the same link between personality and cognition,when tested on the same tasks.

Vegetation cover induces developmental plasticity of lateralization in tadpoles

Lateralization of cognitive functions influences a large number of fitness-related behaviors and shows,in most species,substantial variation in strength and direction.Laboratory works and field data have suggested that this variation is often due to adaptive phenotypic plasticity.Strong lateralization should be favored in some ecological conditions,for example,under high risk of predation.For anuran tadpoles,the presence of cover affects predation risk,with tadpoles being more exposed to predators in environments with reduced cover.We tested the hypothesis that the amount of cover experienced early in life affects lateralization in the edible frog,Pelophylax escu-lentus,tadpoles.We exposed embryos and larvae to high or low vegetation cover environments.For half of the subjects,the treatment was constant whereas the remaining subjects were switched to the opposite treatment after hatching.In agreement with the theoretical expectation,tadpoles exposed to low vegetation cover for the entire development were more lateralized and showed a stronger alignment in directionality of lateralization compared with tadpoles exposed to high vege-tation cover.This indicates a possible role of natural variation in vegetation abundance and deve卜opmental plasticity as determinants of between-population and between-individual differences in lateralization.We also found that shifting from high to low vegetation cover treatments and vice versa disrupted lateralization alignment,suggesting that developmental trajectories for this trait are determined at the embryonic stage and need environmental stability to be fully expressed.