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Courtship of Drosophila Melanogaster : Rejection Without Extrusion
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1. The experiments reported were designed to study the courtship behaviour of male D. melanogaster with virgin and inseminated decapitated females, which do not extrude their genitalia in response to courtship, and do not move. 2. Two new elements of behaviour which occur during the male's courtship were described. The names suggested for these are 'grasping' and 'rubbing'. 3. A clear distinction was seen in the behaviour of males towards virgin and inseminated decapitated females. Fewer males courted the latter, and those males which did court did so for a shorter period. 4. The courtship to the inseminated females contained a relatively lower proportion of attempted copulation than that to virgin females. 5. Operations were conducted on the tarsi of the fore legs and sex combs of the males to elucidate aspects of their possible role in courtship. 6. Males lacking both tarsi and sex combs performed very little courtship either to virgin or to inseminated decapitated females. Males with tarsi removed below the sex combs, and those with the tarsi of the hind legs removed did not court significantly less than normals, but the relative frequency of attempted copulation in courtship was changed. 7. Removal of the sex combs, leaving the tarsi intact, led to the total absence of attempted copulation, although other elements of courtship occurred frequently. 8. Hypotheses are offered concerning the evolution of the behaviour of extrusion, and concerning the possible roles of the sex combs in courtship.
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Studies On the Behaviour of Cyprinodont Fish. Ii the Evolution of Aggressive Behaviour in Old World Rivulins
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The aggressive behaviour of eighteen species of Old World rivulins is described. The phylogenetic relationship of these species is known and thus the evolution of the behaviour patterns can be elucidated. Comparisons of behaviour were made using transition matrices and the changes in behaviour that occurred during the course of aggressive encounters. It is possible to construct an archetypal pattern of aggressive behaviour from which all existing patterns can be derived. The following types of behavioural change have occurred during evolution. a. Changes in the importance and thus the frequency of occurrence of individual elements of the behaviour. In some species certain of the elements have become eliminated from the repertoire. However the order in which the individual components of aggression reach maximum frequency during the course of encounters is essentially the same in all the species. b. The acquisition of novel transitions between elements often in the form of higher order interactions involving more than two elements. c. Changes in the form and orientation of the elements. Differences between closely related species are mainly in minor variations in frequency of elements and transitions between them; more distantly related species differ more fundamentally and thus the differences in behaviour are in accordance with the taxonomic status of the species.
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Prior Exposure To Light and Pecking Accuracy in Chicks
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Two groups of day-old domestic chicks were exposed to constant white light for one hour. Chicks in one group were socially isolated but unrestrained; the others were unable to move their heads. Later the accuracy of their pecking at millet seed was compared with chicks kept in the dark up to the time of testing. The unrestrained chicks exposed to light were markedly more accurate than the dark-reared birds. The restrained chicks were intermediate in performance between the other two groups hitting seeds more frequently than the dark group but missing more and picking up and swallowing less than the unrestrained Light group. The effects of light on pecking accuracy are interpreted primarily in terms of non-specific stimulation of the visual pathways.
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Chemical Prey Preference Polymorphism in Newborn Garter Snakes Thamnophis Sir Talis
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Newborn, previously unfed garter snakes (Thamnophis sirtalis) respond with prey attack and tongue flicking to water based extracts prepared from the surface substances of normally eaten prey and presented on cotton swabs. The present experiments demonstrate reliable individual differences in preferred stimuli among members of the same litter. (I) Of 12 snakes tested on six different days with redworm extract, minnow extract, and distilled water, six responded reliably more to worm and one reliably more to minnow. Redworm was overall more effective than minnow. Using two ranking procedures, individual responsivity to redworm was not correlated with responsivity to minnow. Although distilled water was relatively ineffective, correlations of individual snake scores to extracts and water were high and often significant, in contrast to the low correlations between extracts. (2) Of an entire litter of 13 snakes tested on seven days with extracts from two species of earthworms and two species of fish, 11 responded significantly more to worm extracts and one significantly more to fish extracts. The two worm extracts gave almost identical overall scores and the same occurred for the two fish extracts, with the worm being more effective. While individual responsivities to the two worm or two fish extracts were highly correlated, responsivities across worms and fish were not. A few snakes discriminated between individual worm or fish extracts. (3) In 15 sibling newborn snakes tested on three concentrations (100%, 10%, 1%) of earthworm and fish extracts, most responded more to worm regardless of concentration, a 1% worm extract being more effective than 100% fish. The method of limits was used in both ascending and descending sequences. (4) In all three litters, the snakes could be divided into a few discrete groups based on the relative preference for fish or worm extracts. However, there was wide individual variation in attack frequency, attack latency, and tongue flicking in absence of prey attack. (5) The results are discussed in terms of a genetically based perceptual polymorphism. The phenomenon's possible role in the natural history and evolution of snakes, especially the interaction with feeding experience, is elaborated.
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Aggressive Behaviour in the Zebra Finch Taeniopygia GuttataI. Fighting Provoked By Male and Female Social Partners
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In the domesticated Zebra Finch, unpaired males behaved sociably towards one another, but could be provoked to fight by the sight of a female nearby; the amount of fighting shown depended on the distance to the female. Qualitatively similar aggressive behaviour was provoked between males by the sight of a male, and between a male and female by the sight of another female. However, males were less effective than females in provoking fighting between females, and pair-bonded females were more effective than non-bonded females in provoking fighting in mixed or male dyads. Homosexual pair bonds had a similar effect to heterosexual ones in stimulating attacks on a male, but had not effect on aggressive behaviour towards a female. The aggressive behaviour seen could not be due to redirection of aggression, since the stimulus properties which were necessary to provoke attack on another individual were those relevant to sexual behaviour, and were different from those necessary to elicit attack on the individual itself. It is shown that in other cases of apparent redirection of aggression in sexual contexts, a similar conclusion can be drawn, indicating a link between the motivational systems controlling sexual and aggressive behaviour. Since stimuli from an individual may both sensitize a bird to respond aggressively to stimuli from other individuals, and elicit attack by the bird on the individual itself, a distinction between these modes of action (similar to TINBERGEN'S distinction between releasing and motivational effects) is necessary.
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Individual Distance in the Hermit Crabs Clibanarius Tricolor and Clibanarius Antillensis
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The distances at which individual hermit crabs (Clibanarius tricolor and C. antillensis) showed agonistic behavior patterns was recorded after the animals had been held at one of two densities for a week. 1) Behavior patterns differed significantly in the average distance of separation when they were executed. 2) For almost all patterns, there was considerable variability in the distances at which they were shown. 3) Part of this variance in distances was due to the behavior of the other crab. 4) Density treatment affected the distances at which behavior patterns were shown, the crabs held at the lower density having greater distances. Apparently as a result, lower density crabs lost more interactions. 5) The distances at which behavior patterns were shown were not correlated with either absolute or relative size of the acting crab. 6) Comparison of distances in intraspecific and interspecific interactions indicated very similar behavior in the two species, except that C. antillensis was not as clearly affected by the density treatment.
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Défense Du Territoire Et Reconnaissance Individuelle Chez Xiphophorus (Pisces, Poeciliidae)
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On sait que chez les poissons du genre Xiphophorus, l'établissement d'une relation hiérarchique peut être déterminé par les effets de la priorité de résidence: les poissons qui ont été isolés dans un nouvel environnement réagissent agressivement à l'intrusion d'un congénère et dominent le plus souvent des intrus de même taille. L'objet de ce travail était de savoir si la reconnaissance individuelle était susceptible d'inhiber l'effet de la priorité de résidence sur l'agressivité et la dominance des Xiphophorus ♂ ♂. Nous avons réalisé deux expériences différentes (exp. i, exp. 2), dont le schéma expérimental était identique. Après une phase pré-expérimentale, au cours de laquelle un membre de chaque paire était dominant (α) envers l'autre, les poissons dominés de chaque paire (ω) étaient séparés de leur despote et isolés pendant 3 heures. Ensuite, les anciens poissons α étaient introduits dans les aquariums qui étaient occupés par des anciens poissons ω. Dans les paires du groupe Expérimental (E), les résidents et les intrus s'étaient connus lors de la phase pré-expérimentale; dans les paires du groupe Contrôle (C), les intrus étaient transférés dans l'aquarium d'un résident inconnu, qui avait été dominé par un autre poisson α au cours de la phase pré-expérimentale. De la sorte, l'expérience sociale immédiate était comparable pour les poissons des paires E et pour ceux des paires C ; les différences de taille entre les membres des paires E et C n'étaient jamais statistiquement significatives, et les membres des paires E et C étaient de morphologie semblable. Les résultats de la phase pré-expérimentale ont démontré que l'agressivité et la dominance des poissons ne présentaient aucune différence significative avant l'application de la variable indépendante. Dans les paires de l'exp. 1 (48 paires), la durée de la phase pré-expérimentale était de 24 heures, alors que pour les paires de l'exp. 2 (60 paires), la durée de ce contact social était de seulement 3 heures. Les résultats de la variable dépendante ont fait apparaître que les poissons des paires E et C présentaient des différences significatives dans la fréquence de leurs comportements agressifs et de leur dominance. - Dans les paires de l'exp. i, les résidents ont effectué beaucoup plus fréquemment les premiers comportements agressifs (nages de menace, attaques) devant un intrus inconnu (paires C) que devant leur ancien dominant (paires E). Ces résultats ne sont pas apparus pour l'exp. 2. - Dans les paires de l'exp. I, le nombre des nages de menace réciproques était significativement plus élevé entre les poissons des paires C qu'entre les poissons des paires E. Ce résultat ne s'est pas confirmé pour l'exp. 2. - Dans l'exp. i comme dans l'exp. 2, la dominance des résidents fut beaucoup plus fréquente au sein des paires C qu'au sein des paires E. Dans la grande majorité des paires E, les intrus furent les poissons dominants; dans les paires C, au contraire, les résidents ont dominé deux fois plus souvent environ que les intrus inconnus. - Après l'apparition d'une relation hiérarchique nette, les poissons dominants de l'exp. i ont effectué un nombre total de comportements agressifs significativement plus élevé à l'égard d'un congénère inconnu qu'à l'égard d'un dominé connu. Dans les paires de l'exp. 2, les dominants ont attaqué davantage un congénère inconnu qu'un congénère connu. Au contraire, les approches des poissons dominants furent plus nombreuses au sein des paires E qu'au sein des paires C; par rapport au nombre de leurs attaques, les dominants de l'exp. 2 ont plus fréquemment effectué des nages de menace devant un congénère connu que devant un congénère inconnu. Les résultats de nos deux expériences permettent donc de conclure que la reconnaissance individuelle inhibe les réactions aggressives et la dominance des poissons avantagés par la priorité de résidence. En conséquence, la reconnaissance individuelle constitue un facteur plus important que la défense d'un territoire individuel dans la détermination de la dominance chez Xiphophorus. Les résultats des paires C démontrent que l'effet de la priorité de résidence sur la dominance est déterminant après un isolement de seulement 3 heures; les résultats des paires E démontrent que la reconnaissance d'un congénère individuel persiste après un isolement de 3 heures. Dans notre discusson générale, nous envisageons les relations qui existent entre la priorité de résidence et la territorialité; le fait que la reconnaissance individuelle favorise la stabilité temporelle des hiérarchies au sein des paircs de Xiphophorus suggère qu'une véritable territorialité est absente chez nos poissons et chez d'autres Poecilides.
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An Apparatus for Recording Animal Motor Activity
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An actograph for continuous recording of the animal's position on the floor of its cage is described. The sensitive devices are slightly flexible blades according to the position X, Y of the animal being tested, on the floor, are recorded by strain gauges cemented on. The main interesting features of this actograph are: - a non-disturbance of the tested animal's behaviour, - a complete space-time analysis of its motor-activity.
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