Predator-inspection behaviour in female three-spined sticklebacks Gasterosteus aculeatus is associated with status of gravidity

Differences in predator-inspection behaviour between gravid and non-gravid female as well as between male and female three-spined sticklebacks Gasterosteus aculeatus were investigated. Gravid females confronted with a live rainbow trout Oncorhynchus mykiss showed bolder inspection behaviour than non-gravid ones. The behaviour of gravid females was comparable with that of males, maybe because both face a high risk of predation. The results indicate that antipredator behaviour in female G. aculeatus is not fixed but adjusted to their reproductive state.

Cain and Abel reloaded? Kin recognition and male-male aggression in three-spined sticklebacks Gasterosteus aculeatus L

The influence of relatedness on male-male aggression was tested in three-spined sticklebacks Gasterosteus aculeatus. The intensity of aggression against brothers and non-kin males did not differ significantly, indicating that kin recognition plays at most a minor role in aggressive interactions between male G. aculeatus.

Computer animation as a tool to study preferences in the cichlid Pelvicachromis taeniatus

Four choice experiments were conducted with both sexes of the cichlid Pelvicachromis taeniatus using computer-manipulated stimuli of digital images differing in movement, body shape or colouration. The results show that computer animations can be useful and flexible tools in studying preferences of a cichlid with complex and variable preferences for different visual cues.

A predator's dilemma: prey choice and parasite susceptibility in three-spined sticklebacks

The acanthocephalan parasite Pomphorhynchus laevis is transmitted by a suitable intermediate host such as the amphipod Gammarus pulex to its definitive fish host. Parasite-induced alterations in both appearance and behaviour concur to render infected gammarids more vulnerable to predation, thus promoting parasite transmission. Experimental infection of laboratory bred full- and half-sib groups of three-spined sticklebacks (Gasterosteus aculeatus) provided evidence that the parasite imposes a survival cost proportional to the severity of infection on its final host. Variation among sibships in the susceptibility to infection was consistent. When given a choice, fish consumed significantly more infected than uninfected prey. Overall, more resistant fish did not prey upon infected gammarids more often than did relatively susceptible fish. Only fish with a relatively high physical condition properly adjusted prey selection to the extent of their parasite susceptibility, thus exploiting the enhanced profitability of infected prey.

Inbreeding and developmental stability in three-spined sticklebacks (Gasterosteus aculeatus L.)

Fluctuating asymmetry, small non-directional departures from perfect symmetry in bilateral traits, results from the inability of individuals to buffer development against genetic and environmental perturbations. Fluctuating asymmetry is a widely used measure of developmental stability, and developmental stability has been hypothesised to be inversely related to heterozygosity. We compared male three-spined sticklebacks (Gasterosteus aculeatus L.) that had been inbred for one generation to outbred control males with respect to the asymmetry of a set of bilateral morphometric traits. Inbred fish developed significantly more asymmetric pectoral fins than their outbred counterparts, whereas neither the magnitude of asymmetry for pelvic spines nor for gill covers significantly responded to the treatment. Our results conform to a pattern of heterogeneity amongst traits in their tendency to develop asymmetrically in response to stress.

Mutual mate choice in sticklebacks: attractive males choose big females, which lay big eggs

Brighter red three-spined stickleback, Gasterosteus aculeatus, males have been shown to be preferred by females in the laboratory but in the field, these males did not receive more eggs. Instead, they had heavier eggs in their brood. We investigated the hypothesis that sexual selection for red coloration in male sticklebacks acts through mate choice by preferred males, who can afford to be choosy, for high-quality females which lay heavier eggs. We assume here that heavier eggs provide a direct fitness advantage. In simultaneous choice tests males were presented with two females differing in size. The number of zigzags directed to and the time spent orienting to each female were measured. After the test the females laid eggs, which we counted and weighed. Bigger (i.e. longer and heavier) females laid significantly more and heavier eggs than smaller females. For all 23 males pooled together, the preferred female was the bigger of the two in 17 cases, laid more eggs in 18 cases, but laid heavier eggs in only 13 cases. When bright and dull males were analysed separately, we found that bright but not dull males spent more time oriented to the bigger female, and to the female that laid more eggs. Females preferred by bright males tended to lay heavier eggs than nonpreferred females, although this result was not quite significant. We conclude that in nature this preference for bigger females results in brighter males receiving on average heavier eggs. Assuming higher survival of bigger offspring, we propose that this can explain how brightness can be sexually selected in spite of brighter males not receiving more eggs. Copyright 1998 The Association for the Study of Animal Behaviour.

How to quantify embryo survival in nest-building fishes, exemplified with three-spined sticklebacks

Egg survival in manipulated nests of three-spined sticklebacks Gasterosteus aculeatus in the field was not significantly different from that in unmanipulated nests.