Positional behavior,selective use of habitat substrate and associated non-positional behavior in free-rangingColobus guereza (Rüppel, 1835)

Positional behavior (posture and locomotion), associated social/maintenance behaviors and selective utilization of available habitat structure were recorded for free-rangingColobus guereza occupying a remant montane forest near Limuru, Kenya. This research design focuses on relationships between anatomy, behavior, and the environment and provides a framework for interpreting adaptations inColobus. Quantitative analyses show daily activity patterns. These monkeys spend most of their time in above branch postural activities, primarily in sitting postures. Locomotion accounts for less than one-fifth of positional behavior. In both postural and locomotor sequences, the forelimbs may be placed above the shoulder complex, often in abducted positions. Suspensory positional behavior is rare. Most activity occurs within Zone II, flexible branches of medium diameter and less than 45° in grade. Selective use of the substrate and preferred positional modes are related to variables such as social/maintenance activities, weight distribution of the link system and substrate configuration. These data suggest that, (a) black and white colobus do not exhibit behavior associated with so-called “semibrachiation” and (b) bio-behavioral adaptations involving foraging and feeding strategies may account, in part, for observed morphological differences among Old World monkeys.     

Locomotor behavior and feeding ecology of the panamanian tamarin (Saguinus oedipus geoffroyi,callitrichidae, primates)

The Callitrichidae are a family of New World primates that exhibit a complex of behavioral and morphological characters reputedly similar to those of tree squirrels of the genus Sciurus.In particular, the locomotor behavior of tamarins and marmosets has been described as “squirrel-like. ” In this paper I describe a field investigation of the locomotor behavior and ecology of the Panamanian tamarin (Saguinus oedipus geoffroyi)and the redtailed squirrel (Sciurus granatensis).From January through August 1978, a total of 1200 hr was spent observing freeranging populations of tamarins and tree squirrels in an area of secondary forest on the Pacific Coast of Panama. Observations were made using an instantaneous time sampling technique. Individual activity records were collected on focal animals and recorded at 2.5-min intervals throughout the day. The following information was collected: (a) nature and structure of the substrate exploited, (b) activities on these supports and/or types of resources procured, and (c) body posture involved in the use of these supports. Data presented indicate major differences in substrate preference and positional behavior in tamarins and tree squirrels. Unlike squirrels, tamarins avoid vertical and sharply inclined supports during travel. Movements through the canopy is accomplished by a series of long leaps which begin and end on thin terminal supports. However, the Panamanian tamarin spent numerous hours clinging to large vertical trunks while feeding on plant exudate. Gums comprise 23.O% of the noninsect portion of the tamarin diet. The relationships between small body size, claw-like nails, substrate preference, and positional behavior are discussed. Claw-like nails enable this primate to exploit a food resource that would otherwise be inaccessible. The interrelationship between environment, behaviour, and morphology provides a frameworks from which to understand callitrichid adaptations. These adaptations are not convergent with those of the sciurid rodents. An earlier draft of this paper was presented at the 48th Annual Meeting of the American Association of Physical Anthropologists, San Francisco, April 1979.     

Density-Dependent Spacing Behaviour and Activity Budget in Pregnant,Domestic Goats (Capra hircus)

Very little is known about the spacing behaviour in social groups of domestic goats (Capra hircus) in the farm environment. In this experiment, we studied interindividual distances, movement patterns and activity budgets in pregnant goats housed at three different densities. Norwegian dairy goats were kept in stable social groups of six animals throughout pregnancy at 1, 2 or 3 m² per individual and their spacing behaviours (i.e. distance travelled, nearest and furthest neighbour distance) and activity budgets (e.g. resting, feeding, social activities) were monitored. Observations were made in the first, second and last thirds of pregnancy in the mornings, at noon and in the afternoons of each of these phases (4.5 hours per observation period). The findings show that goats held at animal densities of 2 and 3 m² moved longer distances when they had more space per animal and kept larger nearest and furthest neighbour distances when compared to the 1 m² per animal density. Less feeding activity was observed at the high animal density compared to the medium and low density treatments. The phase of gestation also had an impact on almost all behavioural variables. Closer to parturition, animals moved further distances and the increase in nearest and furthest neighbour distance was more pronounced at the lower animal densities. During the last period of gestation, goats spent less time feeding and more on resting, social behaviours and engaging in other various activities. Our data suggest that more space per goat is needed for goats closer to parturition than in the early gestation phase. We concluded that in goats spacing behaviour is density-dependent and changes with stages of pregnancy and activities. Finally, the lower density allowed animals to express individual preferences regarding spacing behaviour which is important in ensuring good welfare in a farming situation.     

A method for studying social and reproductive behaviour of subterranean rodents in captivity

A methodology for studying the social and reproductive behaviour of solitary subterranean rodents under laboratory conditions is proposed. A first account ofCtenomys talarum (Thomas, 1898) behaviour is also provided with the aim of evaluating the proposed methodology and to advance presently unknown information on its social behaviour and mating system. The device is a seminatural enclosure, departing from traditional test cages with respect to increased: (1) size, (2) structural complexity, (3) social complexity, and (4) resemblance to natural conditions. It consists of artificial burrows each comprising 3.5 m of tunnel, a resource cage and a nest box, resembling the structural complexity described forC. talarum burrows. Burrows are connected to a common space, which allows social interaction among various individuals. Animals were observed in the seminatural enclosure — 3 females and 2 males, in accordance with sex ratios found in natural populations — for a period of 6 months. We obtained data related to reproductive and social behaviour: marking, aggression, vocalization, courtship and copulation, pregnancy, pup development, and parental care. The proposed system enables the collection of behavioural data as yet unavailable due to the secretive habits and aggressiveness that characterize this group of rodents, coupled with the difficulties associated with simulating subterranean conditions.     

Arboreal locomotor and postural behaviour of European red squirrels (<Emphasis Type="Italic">Sciurus vulgaris</Emphasis> L.) in northern Greece

The study of the locomotion and postures of arboreal squirrels may provide important contextual information on the evolution of the morphology and ecology of sciurids. In this context, we studied the positional behaviour and habitat use of four adult European red squirrels (Sciurus vulgaris L.) in a mixed coniferous forest in northern Greece. Our results show that, during the study period, S. vulgaris extensively used the forest canopy and the terminal branch zone. The use of small and medium supports of all orientations was also particularly frequent. The positional profile of the species was characterized by the dominance of quadrupedal, clawed and airborne locomotion along with seated and standing postures. Quadrupedalism and sitting appeared to promote terminal branch use for food access and manipulation, while claw climbing favored vertical ranging and retreat to trees after terrestrial foraging. Finally, leaping reduced energetic costs during travelling between food sites within the relatively dispersed forest. These results and those of previous research on the positional behaviour of other squirrels reveal several trends related to body size, arboreal or gliding habits and tropical or temperate forest distribution and contribute to the understanding of evolutionary novelty in multiple levels within the sciurid radiation.     

Social behaviour and social structure of Neotropical paper waspsMischocyttarus angulatus Richards andM. basimacula (Cameron)

Social behaviour and social structure of 2 Neotropical polistine wasps,Mischocyttrus angulatus andM. basimacula, were investigated in the Canal Area, Republic of Panama. About 80% ofM. angulatus colonies and a half ofM. basimacula colonies were founted by multiple females having mature eggs in their ovaries. All of single-female colonies examined failed before the emergence of the first progeny. During the pre-emergence period, neither biting nor chasing was observed among females coexisting on the multifemale nests of both species. Although one of the females tended to stay on her nest for most of the time (‘queen-like female’), she was often replaced by a different individual on differrent days. In the post-emergence period, however, frequent aggression among females (including the foundresses and the first brood adults) was observed. The roles of pleometrosis and dominance behaviour in social lives of the 2 species in the wet tropics are discussed.     

Life history and locomotion in Cebus capucinus and Alouatta palliata

As an individual matures from birth to adulthood, many factors may influence the positional repertoire. The biological and behavioral changes that accompany a growing individual are expected to influence foraging strategy, social status and interaction, diet, predator avoidance strategies, and ultimately positional behavior as a behavioral link between anatomy and the environment. In this work, positional behavior is considered as an important feature of life history in juvenile and adult white‐faced capuchins (Cebus capucinus) and mantled howling monkeys (Alouatta palliata) inhabiting the same tropical forest in Costa Rica. During growth and development ontogenetic changes in body size, limb proportions, and motor skills are likely to influence locomotion and posture through the arboreal canopy. I collected data on positional behavior, activity, branch size, branch angle, and crown location during a 12‐month period at Estación Biológica La Suerte in northeastern Costa Rica. Life history timing and differences in rates of growth did not predictably influence the development of adultlike positional behaviors in Cebus and Alouatta. Young Cebus resembled the adult pattern of positional behavior by 6 months of age while howlers exhibited significant differences in several positional behavior categories through 24 months of age. The positional repertoire of both species revealed similarities in the types of modes used during feed/forage and travel in juveniles and adults. Data presented here suggest that the environment exerts different pressures on growing Cebus and Alouatta that may relate to diet, energy expenditure, foraging skill, and/or social learning. Am J Phys Anthropol, 2009 © 2009 Wiley‐Liss, Inc.     

The Social Organization of Feral Ovis aries Ram Groups in the Pre-rut Period

Primates are described as having peculiarly complex social behaviour when compared with other mammals, but the methods and expectations of primatologists also differ from those of other mammalogists, confounding the comparison. A very simple social organization has been described for sheep (Ovis aries). Rams of a long-established feral flock were observed during the pre-rut period of three successive years, and their communicative behaviour was described and quantified using individual-focussed methods commonly applied to primates. Rams were found to form long term relationships and their pattern of interaction was partly determined by these as well as by age and rank. Correlation between the effects of age and rank varied with current demography. There was no correlation between rank and horn size. Rams intervened on behalf of weaker colleagues and supported each other in fights. They showed more affiliative behaviour and associated more closely than did ewes. While the leader of the ewe flock was nearly always the oldest ewe present, leadership of ram flocks was less restricted; when together, rams always followed the ewe flock. Comparison is drawn between monkey and sheep social behaviour, and it is concluded that perceived differences are partly due to differences in the expectations and methods of their respective students.     

The Use and Abuse of Tranquillizing Drugs for Chronic Mental Patients

The purpose of this study was to determine the necessity of administering maintenance doses of tranquillizing drugs to chronic mental patients. The behaviour of 16 female psychotic patients in a mental hospital was measured while they received maintenance doses of chlorpromazine (average dose, 50 mg. q.i.d.) and again while receiving identical doses of a placebo. The double-blind technique was employed. Nurses used a behaviour rating scale to measure noisiness, personal cleanliness, interpersonal relations among patients, occupational activities, hostility, activity, co-operation, dress, eating, and sleeping. Patients'' behaviour over a six-week period of chlorpromazine administration was compared with behaviour over an equal period of placebo administration. There was no evident difference in behaviour in 90% of the cases. Among the others there was a slight trend towards improved behaviour while the patients received placebo. It was concluded that tranquillizing drugs are often used needlessly for chronic mental patients. Implications of the use of tranquillizing drugs with chronic mental patients are discussed.     

Observations on the activity patterns and social interactions of a captive group of blackcapped or brown capuchin monkeys (Cebus apella)

Studies were conducted on a captive group of 16 blackcapped capuchin monkeys (Cebus apella), with observations being carried out for a total of 75 hr over a 6 month period. Records were kept of their activities and spatial distribution according to weather type and time of day. Evidence of a social hierarchy was sought and was characterized primarily by the stability of the environment in which the animals live, dominance playing little part. The behaviour of the blackcapped capuchin has been studied previously in captivity (Dobruruka, 1972;Weigel, 1979); this study is, however, unique in that the troop under observation enjoys more freedom. Weather had no effect on the rank order of behavioural activities but did affect both activity levels and distribution of individuals. TheCebus apella troop spent around 50% of its active time foraging and eating, 7–10% of this time walking and around 30% of the time inactive. These values lie between those reported for caged and wild animals. Social interactions contributed more than 10% of the time budget, which is greater than wild populations. The study here thus provides an interesting link between information collected from wildCebus apella populations and that from rather more restricted troops.     

Social Behaviour of Domestic Cats (Felis lybica f. catus L.): a Study of Dominance in a Group of Female Laboratory Cats

The behaviour of a group of female domestic cats (n = 10) under laboratory conditions is described. Behavioural observations were made on a total of 20 days during a 3-month period; only frequencies were recorded. Analysis of the winner/loser matrix revealed a linear rank order. This rank order correlated with several variables. The higher the rank, the more offensive threats a cat emitted overall, and the more defensive threats it received overall; within a pair, the higher-ranking cat displayed more offensive threats, whereas the lower-ranking cat displayed more defensive threats. The higher a rank, the more bouts of social licking a cat emitted overall, and the more bouts of social sniffing and social rubbing it received overall; within a pair, the higher-ranking cat tended to show more social licking, whereas the lower-ranking cat showed more social sniffing. The higher the rank, the more time a cat tended to spend on the floor, and the less time it spent in a 16-compartment complex; the further animals were apart in rank, the smaller were the proximity scores between them. Finally, higher-ranking cats tended to gain weight, whereas lower-ranking cats tended to lose weight. These data suggest that the concept of dominance may be applied to this group of cats. It is discussed whether the observed rank order is specific for indoor conditions under which the cats were living. The role of social licking is also discussed.     

Reproductive investment and parental roles in Sabine's gulls<Emphasis Type="Italic"> Xema sabini</Emphasis>

More than 90% of avian species exhibit biparental care, though parental activities are often shared unequally between the members of a pair. Among gull species (Laridae), males and females generally share parental activities, although there appear to be considerable differences between species in the relative contribution of each sex. This study examined the behaviour of male and female Sabine's gulls (Xema sabini) during the incubation period and immediately post-hatch; particularly the amount of time they each invested in breeding activities. Although considered an aberrant species in aspects of behaviour and biology, the Sabine's gull showed a high reproductive investment by both sexes, as other gull species do. Males fed females prior to egg laying and contributed equally to incubation and chick provisioning, and females contributed equally to nest defence. Overall, there was no difference between the sexes in the extent of their contributions to parental care, although there was considerable individual variation within pairs. Sabine's gulls are Arctic breeders and the extent of their contributions to parental activities could have been influenced by their extreme breeding environment and short breeding season.     

Domestication effects on behavioural synchronization and individual distances in chickens (Gallus gallus)

Behavioural synchrony (allelomimetic behaviour), and inter-individual distances are aspects of social and anti-predator strategies which may have been affected by domestication. Chickens are known to adjust synchronization and inter-individual distances depending on behaviour. We hypothesized that White Leghorn (WL) chickens would show less synchronized behaviour than the ancestor, the red jungle fowl (RJF). Sixty birds, 15 female and 15 male WL and the same number of RJF (28 weeks old) were studied in groups of three in furnished pens (1 m × 2 m) for 24 consecutive hours per group, following 24 h of habituation. Video tapes covering 4 h per group (dawn, 9-10 am, 1-2 pm and dusk) were analysed. Red junglefowl perched significantly more, but there were no breed effects on the frequency or daily rhythm of any other activities, or on average inter-individual distances. Red junglefowl were more synchronized during perching and a tendency for the same was found for social behaviour. After performance of the two most synchronized behaviours, perching and comfort behaviour, individual distance increased more for RJF than WL. According to this study domestication of chickens appears not to have significantly altered the relative frequencies of different activities or average inter-individual distances, but have caused some changes in behavioural synchronization and maintenance of activity-specific inter-individual distances in chickens. The changes may indicate an adaptive response to captivity and domestication.     

Social Behaviour of Individual Oval Squids (Cephalopoda,Teuthoidea, Loliginidae,Sepioteuthis lessoniana) within a Captive School

The social behaviour of individually identified squids was observed over a period of 4 mo. Squids were reared in captivity and maintained in a shoal of up to 18 animals. Distances between animals averaged 1.6 body lengths, similar to the 1.2 body lengths of wild teleost fish schools. Smaller animals schooled less frequently and were found at the periphery, and familiar and unfamiliar animals shoaled together. Eighty-six apparent reproductive events were observed. This species of squid, Sepioteuthis lessoniana, is not sexually dimorphic to the human eye and male squids copulated with both males and females but they directed their attention disproportionately towards females. Most copulations occurred more than a month before spawning, lasted only a few seconds and, unlike field observations on spawning grounds, were not followed by mate-guarding. Two body patterns are described that were used consistently in social interactions by both males and females; these patterns were both associated with reproductive behaviour but their exact function was unclear. A sister species, Sepioteuthis sepioidea, has been described as showing complex social behaviour; in S. lessoniana, no evidence for such behaviour was seen.     

ECOLOGY AND BEHAVIOUR OF THE LITTLE AUK ALLE ALLE IN WEST GREENLAND

A study of the breeding biology, feeding ecology, and behaviour of the Little Auk was carried out on Horse Head Island (73° 38′ N, 57° 08′ W) in west Greenland between July and August 1974. Distinct subcolony groups were recognized within the colony. During incubation, attendance at the colony increased to a peak between 2100 and 2400 h, with large rafts building up on the sea before engaging in aerial flights and then settling on land. During the nestling period, this pattern changed with further peaks at 0600 and 1800 h, and a decline during the afternoon, particularly during the late nestling period. Little Auks fed exclusively on copepods and amphipods (94%Calanus finmarchicus) usually captured within 2.5 km of the colony. Feeding rhythms fitted closely the known diurnal vertical migrations of Calanus with peaks between 2200 and 0800 h. Some individuals within subcolony groups showed synchrony of feeds, mainly between 1800 and 2400 h. The mean number of feeds to a chick in 24 h was 5.25. Growth rates of young were comparable between all four experimental groups and controls, although the latter attained higher weights. Mean daily weight increases were constant until 18 days of age when they declined sharply. This was not reflected in a change in mean daily weight increases with date and so suggests that food availability had not declined. Instead there was a reduced feeding rate to chicks from age 21 days to fledging. Breeding success was 50 %, mainly the result of egg desertion and predation by Arctic Foxes, and this may have been reduced by our own activities. Behaviour postures and the responses they elicited are described together with the diurnal patterns of different activities. Aerial flights are also described and their possible function discussed. It is concluded that the shortness of the time when abundant food is available has encouraged close breeding synchrony and this is achieved by mass flights and rafting on the sea beside the colony, and subdivision of the colony into groups with communal behaviour close to the nests.     

THE BREEDING BEHAVIOUR OF THE WHITE BOOBY SULA DACTYLATRA*

The aim of this paper is to describe the form and interpret the motivation, function and derivation of breeding behaviour in the White Booby. Attention is paid to adaptive aspects and an effort made to correlate behaviour with environment? particularly colony density and associated degree of competitive behaviour. The absence, simplicity or complexity of certain displays can be correlated with the extent to which highly developed social and /or pair interaction are needed. Throughout I have tried to place White Booby behaviour in the framework of behaviour in the Sulidae as a group and particularly to compare it with Gannet behaviour, since the latter nest more densely than other sulids and show more extreme aggression and greater ritualization of behaviour patterns used in interpair and wider social communications. The White Booby provides an interesting contrast. After a brief account of morphology and voice the points are made that White Booby colonies are generally smaller and much less dense than those of the Gannet or Peruvian Booby and also that White Boobies breed in a wide variety of habitats. Site establishment, pair formation, later pair relations, social interactions, body maintenance behaviour, incubation and care of young are described and an account of behaviour in the young is given. The male establishes the site and shows yes /no headshaking as an aggressive, site-ownership display, often performed after landing. He attracts the female with a sky-pointing display which is homologous with sky-pointing in the Gannet, where, however, it subserves a different and, it is argued, phylogenetically older function, signalling that a bird is about to leave the site rather than serving as an advertizing display. In the White Booby it is thus a good example of a motivationally and functionally emancipated display. When the pair meet, mutual jabbing, a hostile-looking and relatively undifferentiated meeting ceremony, and bill-touching occur. Symbolic nest building plays an important part in White Booby pair behaviour, though the nest is structurally negligible. Nest building is associated with copulation, in which the female is not gripped. Bill-up-face-away is a bill-averting posture used when a booby moves away from its mate. It is probably an appeasement posture and, so far as the situation “I am about to move” is concerned, seems to have taken the place of Gannet sky-pointing, the latter having become the booby's advertizing. Wing rattle is a movement probably partly functional in preparing feathers for flight, but is also used as signal behaviour prior to take-off, particularly during the frequent flights around the breeding area that White Boobies show early in the season. Wing flapping, sometimes with rotary headshaking, is mainly feather maintenance behaviour. The forms of headshaking and head flinging are described. Reciprocal allo-preening occurs; it is suggested that it can do so without disadvantage since White Boobies possess mutual jabbing—an interaction which can accommodate any aggression engendered by the pair pointing bills at each other, as required for reciprocal allo-preening. The average incubation spell in the male is 30 hours and in the female 25 hours; all sulid males show this tendency to spend longer on the site. Seasonally, too, there is a marked sex-difference in site attendance and this is depicted in graphs for different categories of White Boobies. The young are left unguarded from about four weeks of age and move off the site. They are fed about 1.4 times per day. They respond to adult investigation or attack by beak-hiding—an effective appeasement posture. Soon, they perform aggressive territorial behaviour and dispel other young and adults. They return to the site to be fed for around 50 to 60 days after they become free-flying and show all forms of territorial behaviour. The discussion is mainly concerned with the correlation between nesting density, aggression and associated appeasement behaviour. It is concluded that, overall, the White Booby's ritualized postures and displays are less well differentiated than those of the Gannet, though individual behaviour patterns may be more complex. The pair relationship in the White Booby approximates more closely to that normally found in birds, where the male is not outstandingly aggressive to his mate.     

Predator avoidance behaviour in the buffy-headed marmoset,Callithrix flaviceps

The predator avoidance behaviour of a free-ranging group of buffy-headed marmosets,Callithrix flaviceps, was recorded in detail during the course of a long-term study of behavioural ecology at the Fazenda Montes Claros, southeastern Brazil. Four distinct patterns of predator avoidance behaviour, each with specific vocalisations, were recognised and are described here. The selection and use of sleeping sites by the study group are also described. An analysis of the records indicates that these small monkeys are generally most vulnerable to predation by aerial raptors. Variations in the frequency of alarm calls also indicate that the marmosets tend to be more vigilant at higher levels in the forest and when the leaf cover is less extensive. The implications of group size and social structure for both the evolution and the efficacy of the anti-predator behaviour of marmosets are also discussed.     

BEHAVIOUR OF THE BLUE-CROWNED HANGING PARROT LORICULUS GALGULUS WITH COMPARATIVE NOTES ON THE VERNAL HANGING PARROT L. VERNALIS

The maintenance activities of Loriculus galgulus and L. vernalis are described and discussed, and compared with the behaviour of the parrots of the genus Agapornis. Maintenance activities reveal some adaptations to the genus-typical habit of resting and sleeping upside-down. A peculiar defaecation posture ensures that the plumage of hanging birds is not soiled. L. galgulus holds food either in the foot or in the bill, but L. vernalis seems not to use the foot in feeding:there is much regurgitation and remastication of food. Scratching is indirect, as in the Agapornis species, though the foot is brought directly to the bill to be preened. Loriculus is more ready to bathe in standing water than is Agapornis, actually entering the water, and not merely splashing from the edge. There is some evidence that L. galgulus rain-bathes hanging upside down, as does A. cana. Agonistic behaviour is highly ritualized in Loriculus:some actions are identical with those of the more primitive species of Agapornis. Threat displays are described: the so-called Super Threat Display combines all agonistic actions in one. There are three appeasement displays. Group upside-down pseudo-sleeping as a response to the appearance of potential predators is frequent in both species: it is not certain if this is a displacement reaction or a normal escape reaction to the safety of an inaccessible refuge. Little is known about reproductive behaviour in captivity and even less about behaviour in the wild. Pair formation appears to occur late in the period of attaining maturity, and to be initiated and maintained by courtship feeding: homosexual pairing is not unusual n flocks of captive birds. Of the courtship displays, one-Strutting-seems to be common to several Loriculus species. Cutting of nest material is an activity of both male and female Loriculus. A maturing or learning process is seen in the cutting of little “bits” by inexperienced and immature birds, and by the cutting of straight or arcuate strips by those more experienced. In Loriculus galgulus, females were seen to tuck strips of nesting material in the throat and breast feathers, though they have been reported to tuck material into the rump feathers also: L. oernalis females tucked arcuate strips among the rump feathers only. Both male and female L. galgulus and L. vernalis investi- gated nest boxes, but none actually nested. This study in general reinforces the ideas about the relationship of the genera Loriculus and Agapornis but more data on other Loriculus species are needed. At this stage of investigation it appears that both L. galgulus and L. oernalis are behaviourally closest to the more primitive species of Agapornis, namely, cana, tarantu and pullaria.     

Effects of high CO2 on mating success,mating duration,and sperm transfer in the West Indian sweet potato weevil,Euscepes postfasciatus

Most terrestrial animals live in natural atmospheric conditions, but some are also adapted to low oxygen (hypoxic) or high-carbon dioxide (hypercapnic) conditions, such as in social insect nests, soil, caves, wood, and decaying material. Although it is possible that individuals adapt their behaviour to the environmental condition of their habitats, mating behaviour under ecologically possible ranges of CO₂ has not been well studied. We compared walking activity, duration of mating behaviour, and sperm transfer ability in the West Indian sweet potato weevil, Euscepes postfasciatus Fairmaire (Coleoptera: Curculionidae), in high CO₂ (10 000 p.p.m.) vs. normal atmospheric conditions (laboratory air, ca. 800 p.p.m.). We found that high CO₂ enhanced walking activity and mounting frequency. Under such circumstances, we predicted that enhanced activities under a high-CO₂ environment would increase the risk of sperm competition, which induces an extended copulation period and an increase in sperm transfer. However, weevils shortened the mating period and did not alter their sperm transfer ability under high CO₂. These findings are, as far as we are aware, the first report of the effect of ecologically relevant high CO₂ on insect mating behaviour under mass-rearing conditions. The effect of ambient conditions on mating behaviour and sperm transfer is discussed in relation to the intensity of female refusal behaviour directed against males.     

Rhythmic gene expression in somite formation and neural development

In mouse embryos, somite formation occurs every two hours, and this periodic event is regulated by a biological clock called the segmentation clock, which involves cyclic expression of the basic helix-loop-helix gene Hes7. Hes7 expression oscillates by negative feedback and is cooperatively regulated by Fgf and Notch signaling. Both loss of expression and sustained expression of Hes7 result in severe somite fusion, suggesting that Hes7 oscillation is required for proper somite segmentation. Expression of a related gene, Hes1, also oscillates by negative feedback with a period of about two hours in many cell types such as neural progenitor cells. Hes1 is required for maintenance of neural progenitor cells, but persistent Hes1 expression inhibits proliferation and differentiation of these cells, suggesting that Hes1 oscillation is required for their proper activities. Hes1 oscillation regulates cyclic expression of the proneural gene Neurogenin2 (Ngn2) and the Notch ligand Delta1, which in turn lead to maintenance of neural progenitor cells by mutual activation of Notch signaling. Taken together, these results suggest that oscillatory expression with short periods (ultradian oscillation) plays an important role in many biological events.