Aggression between weanling Peromyscus and Microtus

Microtus pennsylvanicus were attacked by weanling Peromyscus of all three species tested: P. leucopus noveboracensis, P. maniculatus bairdii, and P. polionotus (colemani). However, defensive behaviours were more frequent than aggressive behaviours. Of the three species of Peremyscus tested, P. m. bairdii are most likely to meet Microtus in the field and displayed more agonistic behaviours in the laboratory. Female Peromyscus of all species tested were as likely to engage in all agonistic behaviours as were males. Inter-generic aggression developed before intra-generic aggression.     

Agonistic behaviour over food and perch space in male Quelea quelea

A measure commonly used in previous studies of fighting in Quelea quelea (the Dominance Index) was found to be unsuitable for the ranking of animals in small groups. It is argued as preferable to study interactions between pairs of individuals within groups. Rank relationships between individuals were found to be similar in competition over food and perch space in two series of observations 8 weeks apart. Fights within the groups did not show an overall decrease with time since group formation but were related to flight activity (between perches) and time spent at the food hopper. Success in competition at the food hopper gave priority of access to the food, but success in competition over perching space did not lead to those birds winning more encounters sitting in a central position within the resting groups. These results are discussed in relation to possible advantages to individuals and to the ecology of Quelea.     

Phenolics of five yam (dioscorea) species

Cyanidin-3-glucoside, (+)-catechin and the procyanidin dimers ‘B-1’ and ‘B-3’ were identified as phenolic constituents of Dioscorea alata tubers, and strong evidence for the presence of a procyanidin trimer and a tetramer was found. The quantity of (+)-catechin and relative proportions of the procyanidin dimers were determined in 10 cultivars of five of the main edible yam species.     

The behaviour of mature and immature male bank voles (Clethrionomys glareolus)

Neutral-arena encounters were staged between pairs of sexually mature male bank voles (Clethrionomys glareolus), between pairs of immature males, and between pairs consisting of one of each. Mature males exhibited more aggressive components of behaviour to each other than did immature males, but mature males did not attack immature males in ‘mixed’ encounters. The relevance of these results to the population ecology of voles is discussed.     

The development of social behaviour between siblings and non-siblings of the voles Microtus ochrogaster and Microtus pennsylvanicus

It has been suggested that the strength and duration of sibling relations during the juvenile period may reflect the social structure of mammal species. Two Microtus species with contrasting social systems, M. ochrogaster and M. pennsylvanicus, were chosen for a comparative study of juvenile social behaviour. Young were observed in sibling and non-sibling dyadic encounters from the second until the seventh week of age. Social interactions consisted mainly of body nosing of the partner, and included behaviours interpreted as investigation, socialization and settling. Only minor sex differences in body nosing scores occurred, but some ontogenetic trends were noted. When the species were compared, M. ochrogaster received higher scores for body nosing and sitting in contact, and displayed more reciprocity in their nosing, than did M. pennsylvanicus, whether siblings or non-siblings were considered. When the sibling types were compared, non-sibling dyads received higher nosing scores than did siblings in both species, but the disparity was greater in M. ochrogaster than in M. pennsylvanicus. These results are interpreted with reference to known behavioural and developmental correlates of the extended family system in naturally occurring M. ochrogaster and the less communal social system in M. pennsylvanicus.     

Genetics of social behaviour in charrs (Salvelinus species)

Juvenile brook charr (Salvelinus fontinalis) are territorial and have high levels of agonistic behaviour. Juvenile lake charr (S. namaycush) rarely show any indication of territoriality and have very low levels of agonistic behaviour. The inheritance of behaviour in their reciprocal hybrids was investigated by multivariate stepwise discriminant analysis. Lateral display, charge, chase, and forage composed the first canonical axis (87.2% of total dispersion). Pooled hybrid means were closer to that of brook charr, suggesting either directional dominance or modification of the behaviour of hybrids in response to water flow. The mean values of reciprocal hybrids were skewed towards the maternal parent, suggesting a maternal effect in the phenotypic expression of behaviour in these fish.     

Starch gel electrophoresis of certain enzymes from five species of Fomes

The electrophoretic banding patterns of five enzymes (esterase, catechol oxidase, peroxidase, alkaline phosphatase, and acid phosphatase) from eleven isolates of five species of the wood-rotting basidiomycete, Fomes, were subjected to mathematical analysis in order to examine taxonomic relationships. Generally, greater similarity was observed between the banding patterns for isolates of the same species than between those for isolates of different species. The experimental and analytical technique used in this study could be an aid for the determination of taxonomic relationships among these and other fungi.     

Pheromone production and mating behaviour by allatectomized males of the cockroach, Nauphoeta cinerea

Males of Nauphoeta cinerea produce a volatile pheromone which attracts the female for mating. Allatectomy of males either 5 days prior to or within 12 hr following the imaginal ecdysis does not impair pheromone production, pheromone release, nor any observable aspect of mating behaviour. It is proposed that in N. cinerea, and in other cockroach species where the male releases a volatile pheromone to attract the female, pheromone production is not controlled by the corpora allata, and pheromone release is under direct motor control.     

Female dimorphism and mating behaviour in a damselfly, Ischnura ramburi: females mimicking males

Females of the damselfly Ischnura ramburi exhibit a simple genetic colour dimorphism in which one form is cryptic (heteromorph), and the other closely resembles the more conspicuously colourful males (andromorph). Andromorphs also mimic male behaviour in interactions with males. Consequently they copulate half as often as do heteromorphs, which may give them a frequency-dependent selective advantage. Assuming that females need only mate once, excessive copulations, which average 3 h in duration, waste time for heteromorphs and may expose them to increased predation. The peculiar biology and mating behaviour of ischnurans provides a possible evolutionary context for this mimicry. The polymorphism is probably balanced by a frequency-independent selective disadvantage suffered by the more conspicuous andromorphs, through increased predation.     

Ploidy levels and reproductive behaviour in natural populations of five Paspalum species

Knowledge of variation in ploidy levels and reproductive behaviour in natural populations is essential in order to understand the functioning of agamic complexes. The aim of this study was to analyse the ploidy level and mode of reproduction in several wild Paspalum populations. A total of 19 populations representing five different species (P. alcalinum, P. denticulatum, P. lividum, P. nicorae, and P. rufum) were collected. Ploidy level was determined in 1,187 individuals by using flow cytometry. Among these individuals, 2x, 3x, 4x, 5x, 6x, and 7x chromosome constitutions were observed. Diploid sexual cytotypes of P. denticulatum were detected for the first time; this will allow the development of future breeding strategies for this particular species. Flow cytometry seed screen (FCSS) in bulked and single seeds revealed the reproductive diversity of these species, ranging from complete sexuality in diploids and varying levels of facultative apomixis in most tetraploids, to obligate apomixis in pentaploids and hexaploids. A fully sexual tetraploid plant was never detected. Nevertheless, most tetraploid genotypes produced both maternal (by apomixis) and non-maternal (by sexuality) progeny. This residual sexuality is very interesting from an evolutionary point of view, since it would allow the creation of new genotypic combinations in natural populations. In addition, the residual sexuality found in some apomictic tetraploid populations can be used as a source of variability for genetic improvement.     

Age-differential homing tendencies in displaced bank voles, Clethrionomys glareolus

Escape movements of three different age classes of encaged bank voles, Clethrionomys glareolus Schreber, were studied in modified Emlen funnels. While there was a concentration about the mean direction in the adult and overwintered subadult groups (i.e. homing) when tested in darkness, no such concentration was found when testing yearling subadult bank voles. When tested in the light no concentration about the mean direction occurred in any age class. The differences in homing tendencies between the tested age classes are consistent with known differences in their behaviour. While adults and overwintered subadults about to become adults have fixed home ranges, yearling subadults generally do not have well-defined activity areas and hence lack a homing goal. In the light, all animals behaved as if running for the nearest cover rather than in any particular direction.     

Foraging behaviour and feeding habits in five species of Trinervitermes in West Africa

Foraging habits of five species of Trinervitermes occurring in W. Africa are described. The five species can be divided into two groups, comprising those which store grass fragments in the mounds and those which do not. Size distributions of stored grass fragments differ specifically. Experiments indicated that selective foraging of grass species may occur. Survival on various foods suggested adaptation to differing conditions in each species. The occurrence of all five species in one area seems to depend on a suitable mosaic of conditions.

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Resume Ce travail est l'un d'une série d'études comparatives de biologie et d'écologie de cinq espèces de Trinervitermes en Afrique Occidentale. On y décrit les habitudes d'approvisionnement et les différences spécifiques. Les cinq espèces forment deux groupes, contenant l'un, T. ebenerianus, T. carbonarius et T. suspensus, lesquels entassent dans leur nids des fragments d'herbe; l'autre, T. oeconomus et T. auriterrae, lesquels n'en entassent pas. Les fragments d'herbe entassés sont de taille différente selon les trois espèces. Les expériences sur les deux espèces T. ebenerianus et T. carbonarius suggèrent que des approvisionnements sélectionnés d'espèces d'herbe peuvent se produire quand c'est possible. L'adaptation aux différentes conditions pour chaque espèce est suggerée par la survie des ouvriers qui se nourrissent différemment. On pense que T. auriterrae se rapproche le plus d'un ancêtre qui ressemble à Nasutitermes. La coexistence des cinq espèces dans un même habitat étendu, paraîtrait dépendre de la présence d'une mosaïque de conditions approprées sur une plus petite échelle

     

Allatectomy and food selection in males of Locusta

Removing the corpora allata from young males of Locusta does not alter the overall amount of food they consume or the quantity of faeces they produce. However, allatectomized males eat less fresh grass and more dry bran than the control males. This observation is discussed in relation to the maturation process and other events in the adult male.     

Agonistic behaviour of juvenile gulls,a neuroethological study

The results relating to agonistic behaviour obtained during an exploration of the brain of juvenile herring and lesser black-backed gulls (Larus argentatus and fuscus) with electrical stimulation are reported. As an introduction the normal agonistic behaviour of immature gulls is described. While the flight and aggressive behaviour is largely unritualized the threat behaviour is more stereotyped. Three basic threat patterns are distinguished: the arched, hunched, and squat postures. The relationship of these juvenile agonistic patterns with adult courtship is considered. A large number of sites evoking fear behaviour were found, anatomically widely and incoherently distributed. It is demonstrated that the spontaneous fearfulness levels of individual subjects influences the likelihood of obtaining escape eliciting loci. Stimulation of a nubmer of these sites had an after-effect: a persistent, increased probability of escape behaviour. It seems likely that a proportion of the fear sequences elicited were secondary responses to evoked sensory hallucinations and forced small movements. None of the sites explored yielded outright attack behaviour. Thirteen sites yielded characteristic threat sequences. About half of them produced changes in ‘mood’ persisting for some 15 min. The sites were clustered in a paleostriatal-septal periventricular and an infundibular area. Histological differentiation of the neuroventricular interface at these areas is noted. Based on these it is argued that the secretion of ‘liquormones’ is responsible for the changes in ‘mood’ that followed stimulation.     

Comparison of stress susceptibility of in hospite and isolated zooxanthellae among five coral species

Coral species in a similar habitat often show different bleaching susceptibilities. It is not understood which partner of coral-zooxanthellae complexes is responsible for differential stress susceptibility. Stress susceptibilities of in hospite and isolated zooxanthellae from five species of corals collected from shallow water in Okinawa were compared. To estimate stress susceptibility, we measured the maximum quantum yields (F_v/F_m) of in hospite and isolated zooxanthellae after 3-h exposure to either 28 or 34 °C at various light intensities and their recovery after 12 h under dim light at 26 °C. Significant reduction in photochemical efficiency (F_v/F_m) of photosystem II (PSII) was observed in in hospite zooxanthellae exposed to high light intensity (1000 μmol quanta m⁻² s⁻¹), while PSII activity of isolated zooxanthellae decreased significantly even at a lower light intensity (70 μmol quanta m⁻² s⁻¹). The recovery of the PSII activity after 12 h was incomplete in both in hospite and isolated zooxanthellae, indicating the presence of chronic photoinhibition. The stress susceptibility of isolated zooxanthellae was more variable among species than in hospite zooxanthellae. The order of stress susceptibility among the five coral species was different between in hospite and isolated zooxanthellae. The present results suggest that the host plays a significant role in determining bleaching susceptibility of corals, though zooxanthellae from different host have different stress susceptibilities.     

Hebeloma species associated with Cistus

The genus Hebeloma has a number of species highly specific to Cistus and others that occur with several host genera. This paper discusses the species of Hebeloma that appear to be ectomycorrhizal with Cistus, judging from their occurrence when Cistus is the only available host. The previously unknown species H. plesiocistum spec. nov. is described. We also provide a key to the known Hebeloma associates of Cistus. Molecular analyses based on ITS sequence data further illustrate the distinctness of the newly described species and difficulties in the species delimitation with view to H. erumpens. Specific associations with Cistus may have evolved more than once within the genus Hebeloma.     

Agonistic behaviour and endogenous plasma hormones in male Japanese quail

Agonistic relationships established among male Japanese quail (Coturnix coturnix) in shortterm dyadic encounters of a round-robin tournament were stable and appeared to be maintained by a form of recognition. The aggressive or submissive behaviour displayed by competitors throughout the tournament did not relate to their circulating levels of luteinizing hormone, androstenedione, 5 α-dihydrotestosterone or corticosterone. However, plasma levels of testosterone were correlated with fighting success in the early phases of the tournament, before agonistic associations were defined. Once relationships stabilized, levels of plasma testosterone in winners declined to values comparable with those of the losers and the qualitatively distinct displays observed in winners or losers were no longer correlated with plasma levels of testosterone. In light of other work, these data suggest that androgens, primarily testosterone, influence the aggressiveness of an individual in initial encounters, helping in turn to determine dominance relationships between opponents. Thereafter, other factors such as learned response biases take precedence. The maintenance of stable social relationships appears to be independent of circulating levels of testosterone in adult male Japanese quail.