ABSTRACT
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.
Subject(s)
Cichlids/physiology , Computers , Mating Preference, Animal/physiology , Zoology/methods , Animals , Color , Female , Male , Random Allocation , Video Recording , Zoology/instrumentationABSTRACT
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.
Subject(s)
Escape Reaction/physiology , Reproduction/physiology , Smegmamorpha/physiology , Animals , Female , Male , Oncorhynchus mykiss/physiologyABSTRACT
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.
Subject(s)
Aggression/physiology , Smegmamorpha/physiology , Animals , MaleABSTRACT
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.
Subject(s)
Disease Susceptibility , Fish Diseases/parasitology , Fishes/physiology , Fishes/parasitology , Predatory Behavior , Acanthocephala/physiology , Animals , Choice Behavior , Disease Vectors , Female , Fish Diseases/mortality , Fish Diseases/transmission , Host-Parasite Interactions , MaleABSTRACT
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.
Subject(s)
Inbreeding , Smegmamorpha/anatomy & histology , Smegmamorpha/genetics , Animals , Female , Gills/anatomy & histology , Male , Netherlands , Smegmamorpha/growth & developmentABSTRACT
Egg survival in manipulated nests of three-spined sticklebacks Gasterosteus aculeatus in the field was not significantly different from that in unmanipulated nests.
