bluuebunny/crossref_metadata_2025 huggingface dataset:
Roles of homocysteine in cell metabolism
Authors: Medina Miguel Á. , Urdiales José L. , Amores‐Sánchez María I.
Published: March 2003

Mild hyperhomocysteinemia has been suggested as a new, independent risk factor for cardiovascular disease. This fact has produced a new, increased interest in the study of homocysteine metabolism and its relation to pathogenesis. This emergent area of biomedical research is reviewed here, stressing the biochemical and metabolic basis of the pathogenicity of increased levels of homocysteine.
Novel polyketides synthesized with a higher plant stilbene synthase
Authors: Morita Hiroyuki , Noguchi Hiroshi , Schröder Joachim , Abe Ikuro
Published: March 2003

The physiological function of the stilbene synthase (STS) from groundnut (Arachis hypogaea) is the formation of resveratrol. The enzyme uses 4‐coumaroyl‐CoA, performs three condensations with malonyl‐CoA, and folds the resulting tetraketide into a new aromatic ring system. We investigated the capacity for building novel and unusual polyketides from alternative substrates. Three types of products were obtained: (a) complete reaction (stilbene‐type), (b) three condensations without formation of an aromatic ring (CTAL‐type pyrone derailment), and (c) two condensations (BNY‐type pyrone derailment). All product types were obtained from 4‐fluorocinnamoyl‐CoA and analogs in which the coumaroyl moiety was replaced by furan or thiophene. Only type (b) and (c) products were synthesized from other 4‐substituted 4‐coumaroyl‐CoA analogs (‐Cl, ‐Br, ‐OCH3). Benzoyl‐CoA, phenylacetyl‐CoA, and medium chain aliphatic CoA esters were poor substrates, and the majority of the products were of type (c). The results show that minor modifications can be used to direct the enzyme reaction to form a variety of different and new products. Manipulation of the biosynthesis of polyketides by synthetic analogs could lead to the development of a chemical library of pharmaceutically interesting novel polyketides.
Expression of the rabbit cytochrome P450 aromatase encoding gene uses alternative tissue‐specific promoters
Authors: Bouraïma Hélène , Hanoux Vincent , Mittre Hervé , Féral Colette , Benhaïm Annie , Leymarie Pierre
Published: March 2003

The aim of the present study was to analyse the tissue‐specific expression of various promoter‐derived transcripts from the gene encoding rabbit aromatase cytochrome P450. A new promoter, named I.r, was identified, and promoters II and I.r were sequenced. Promoter I.r‐derived transcripts were found in preovulatory granulosa cells, corpus luteum, placenta and adipose tissue. An alternative splice variant of this transcript was found with tissue‐specific preference. Tissue‐specific expression of promoter‐derived variants was studied in the ovary before and after ovulation. While the level of promoter II‐derived transcript decreased dramatically after ovulation, that of promoter I.r‐derived transcript remained unchanged, indicating that promoter II and promoter I.r were not controlled by a single regulation system. The existence of this dual system of regulation suggests that the rabbit ovary could be a useful model to study the promoter‐specific regulation of aromatase.
The Orientation Behaviour of Chaffinches, Fringilla coelebs, Caught during Active Migratory Flight, in Relation to the Sun
Authors: Muheim Rachel , Jenni Lukas , Weindler Peter
Published: March 2003

The few orientation studies that have been carried out with day‐migrating birds show that they are able to use solar and magnetic orientation cues for orientation. Previous orientation experiments in Emlen funnels have been carried out either with hand‐raised birds or with birds caught during resting periods at stop‐over sites. The aim of our study was to test whether birds caught during active flight show a higher concentration of migratory activity in the seasonally appropriate migratory direction in the funnels than birds that had not experienced migration just before the funnel experiments. The topography at the alpine pass Col de Bretolet at the border of Switzerland and France allowed us to capture birds during active migratory flight. These birds were in full migration disposition. Orientation experiments with chaffinches suggested an influence of the sun because chaffinches did not orient in the seasonally expected direction, but probably showed positive phototaxis towards the light of the sun at the opposite side of the funnel. Chaffinches tested under overcast conditions oriented to the north‐west which probably was a ‘nonsense’ orientation and not a reverse migration or compensatory behaviour. We conclude that freshly caught birds are too stressed to show appropriate orientation when tested immediately after catching.
Carolina Chickadee (Aves, Paridae, Poecile carolinensis) Vocalization Rates: Effects of Body Mass and Food Availability under Aviary Conditions
Authors: Lucas Jeffrey R. , Schraeder April , Jackson Curt
Published: March 2003

We evaluated the effect of body mass and several environmental factors on vocalization rates of Carolina chickadees (Poecile carolinensis) housed in an aviary. Two different nonsong vocalizations (tseet and chick‐a‐dee) and song (fee‐bee fee‐bay) were recorded. Food was delivered from a feeder and three different levels of food access were presented to each bird: 10, 40 and 55 min/d. Two scales of body mass were measured: ‘dawn mass’ and ‘focal mass’ (mass during a focal observation divided by dawn mass). Across all birds, there was a significant negative correlation between both nonsong vocalization rates and body mass (both dawn and focal mass) and the effect of mass on call rate was greatest for days when food was relatively abundant. Nonsong vocalizations were also given at higher rates when food was limited (10 min/d) than when food was more abundant (40 and 55 min/d). No changes in call rates with time of day were observed. Overall, song rates were substantially lower than nonsong rates. Unlike nonsong rates, song rates were highest in birds that had relatively high dawn mass. No significant correlation between song rates and focal mass was observed, and no significant correlation between song rates and time of day was observed. Finally, vocalizations from nonfocal birds had little effect on vocalization rates of focal birds. Our results suggest that nonsong communicative signals are more important for birds facing energetic stress, while song is more important for birds that are not energetically stressed.
Aggregation Behaviour of Bufo maculatus Tadpoles as an Antipredator Mechanism
Authors: Spieler Marko , Linsenmair Karl Eduard
Published: March 2003

Most anurans of the species‐rich community of the Comoé National Park (Ivory Coast) use ephemeral savannah ponds to spawn. Owing to the great risk of desiccation and the large number of predators, the mortality for tadpoles is very high in these ponds. Therefore, colonization of other spawning habitats might be highly advantageous. Such spawning sites are presented by the Comoé river, which is characterized by frequent and unpredictable changes of the water level. Only Bufo maculatus (Anura: Bufonidae) and one other bufonid species breed in small and shallow inlets and puddles created by the rising and falling of the predator‐rich Comoé river. We observed that predatory fish advanced to the spawning sites of the toads, when the water level rose. If the toad larvae were attacked by these predators, they formed dense aggregations of up to several thousand individuals. These aggregations were maintained for longer periods on one place at the river’s edge where they are inaccessible to the larger predators. In field experiments we ascertained that this aggregation behaviour in tadpoles was caused by a combination of two stimuli: first, a chemical cue from injured tadpoles and second, a mechanical stimulus caused by rapid movements of aquatic predators. Initial trials indicated that tadpoles aggregating at the bank were, however, disadvantaged compared with free‐swimming larvae in having slower growth and an increased risk of desiccation. This is presumably why aggregations broke up within 24 h after the predators had left these puddles, as the water level fell. At this point these tadpoles either spread out or formed loose swarms near the bottom of the puddles. This swarming behaviour differed considerably from that induced by aquatic predators.
Incompletely Protective Refuges: Selection and Associated Defences by a Lizard, Cordylus cordylus (Squamata: Cordylidae)
Authors: Cooper William E. , Van Wyk Johannes H. , Le F P. , Mouton . N.
Published: March 2003

Despite recent interest in refuge use, refuge characteristics and their relationships to refuge‐associated antipredatory defences have been relatively neglected. These topics were studied experimentally in the Cape girdled lizard, Cordylus cordylus. Lizards used crevices in novel situations under uncertain risk and when confronted by a human simulated predator. They preferred narrow crevices opening on only one side at ground level and orientated horizontally. Narrowness restricts access by predators, reduces detectability to a small visual angle and permits use of crevice‐specific defences, making the lizards difficult to dislodge. Limiting openings to one side decreases detectability by reducing light, limits attacks to one direction and permits further withdrawal from any opening. Crevices at ground level confer greater distance from and reduced visibility to an overhead predator. Horizontal orientation may reduce visibility to an overhead predator, but the preference could be an artefact of the greater ease of entering horizontal crevices. Pheromonal labelling of crevices by conspecific males did not influence short‐term crevice choices by males. Within crevices, C. cordylus pressed their dorsal surfaces against crevice roofs, pushing upward with their legs. They also positioned their tails to block access by predators to their bodies. We discuss these and related crevice‐associated defences in other animals.
Effects of Intermating Interval on Spermatophore Size and Sperm Number in the Simultaneously Hermaphroditic Land Snail Arianta arbustorum
Authors: Locher Rolf , Baur Bruno
Published: March 2003

We examined the effect of intermating interval on spermatophore size and number of sperm delivered in the simultaneously hermaphroditic land snail, Arianta arbustorum. Snails that remated after 6–7 d transferred smaller spermatophores which contained fewer sperm than snails that remated after eight and more days. This indicates that individuals of A. arbustorum need at least 8 d to completely replenish their sperm reserves after a successful copulation. We suggest that the interval between two copulations is also influenced by the energy costs of the long‐lasting courtship behaviour with extensive mucus production.
Pygmy Marmosets Modify Call Structure When Paired
Authors: Snowdon Charles T. , Elowson A. Margaret
Published: March 2003

Pygmy marmosets (Cebuella pygmaea) modified the structure of their trill vocalizations in response to pairing with a new mate. Prior to pairing, individual marmosets displayed different acoustic parameters of trill structure. Within the first 6 wk after pairing, three of four pairs produced trills that were more homogeneous between mates. Pairs that had the greatest individual difference in trill structure prior to pairing displayed convergence on a greater number of parameters than pairs having fewer differences in prepairing trill structure. The vocal structure following pairing remained highly stable in the two pairs that could be recorded 3 yr after initial pairing. Changes in trill structure that occurred within the first 6 wk after pairing were greater than spontaneous changes that occurred during baseline control recording sessions on the same animals. These results suggest that nonhuman primates show subtle modification of vocal structure, especially in response to changes in social environment. Similar findings have been reported in birds and other mammals.
Functional Value of Matriphagy in the SpiderAmaurobius ferox
Authors: Kim Kil Won , Roland Chantal , Horel André
Published: March 2003

The adaptive value of matriphagy, the consumption of the mother by her offspring, in the sub‐social spiderAmaurobius ferox(Araneae, Amaurobiidae) was experimentally evaluated in terms of the benefits to the offspring and the costs to the mother. Matriphagy resulted in a 2.5‐fold weight gain in the offspring over their initial weight, advancement of their moulting time, and larger body mass at dispersal in comparison with clutches deprived of matriphagy, but otherwise well provisioned with prey. Matriphagous offspring were also more successful at capturing large prey items, had a more extended social period, and a higher survival rate at dispersal. Mothers separated from their broods just prior to matriphagy were able to produce second clutches, effectively producing 33% more viable offspring (compared with the first clutches). However, the estimated reproductive outputs of the alternative maternal strategies (being devoted to the first clutch vs. deserting the first and producing a second one) suggest that mothers ofA. feroxthat are cannibalized by their broods enjoy greater reproductive success than those that escape cannibalism and produce second clutches.
Philopatry, Site Fidelity and Local Kin Associations within Grey Seal Breeding Colonies
Authors: Pomeroy P. P. , Twiss S. D. , Redman P.
Published: March 2003

Abstract Colonially breeding animals such as grey seals typically have a discrete number of breeding sites. The extent to which offspring are philopatric (return to breed at their natal site) and the prevalence of philopatry by sex of pup has fundamental consequences for the social and genetic structure within and between each colony.

Grey seals born and marked by tagging and cohort brands at colonies on North Rona, Outer Hebrides since 1960 and at the Isle of May, Firth of Forth since 1981 have shown philopatry. Overall re‐sight rates of 1620 pups tagged at North Rona and 1667 pups at the Isle of May ranged from 0 to 17%. Although most evidence of philopatry relates to females, males at each colony displayed philopatry. In addition, females born at N. Rona pupped closer to their natal sites than would be expected by chance (p = 0.005), providing evidence of fine scale natal site fidelity. Females born at the Isle of May did not show the same degree of fine scale natal site fidelity, but there was considerable individual variation. The spatial scale of philopatry shown by seals differed according to the local area within each island. Fidelity of known adult females to pupping sites at both colonies was high. In addition, we found an instance of mother and daughter pupping together away from the daughter's natal site.

These data: (i) provide evidence of philopatry in both sexes at each site; (ii) describe occurrences of fine scale philopatry at both sites; (iii) show that mothers and offspring occupied the same areas on the colony, suggesting the possibility of highly related groups within colonies, which would provide conditions for kin‐specific altruistic behaviours; (iv) suggest the possibility of individual or kin recognition, even though contact between mothers and offspring has been thought to cease after the 18 d lactation period.
Producer–Scrounger Games in a Spatially Explicit World: Tactic Use Influences Flock Geometry of Spice Finches
Authors: Flynn Robyn E. , Giraldeau Luc‐Alain
Published: March 2003

Group‐foraging animals can either search for their food (producer) or search for opportunities to join the food discoveries of others (scrounger). To maximize food returns, producers should distance themselves from potential competitors whereas scroungers should increase proximity to potential producers. We investigated the extent to which playing one or the other tactic affected an individual’s location in captive flocks of ground‐feeding spice finches (Lonchura punctulata) as they foraged for hidden clumps of food on an aviary floor. We constrained some individuals to use the producer tactic by pre‐training them to find food hidden under lids. Constrained producers foraged significantly further from the center of flocks than constrained scroungers. Flocks with many scroungers were significantly more compact than flocks with fewer scroungers. The results are consistent with published simulations of spatially explicit producer–scrounger models and suggest that the use of producer and scrounger foraging tactics be included as a factor that affects an individual’s position within foraging groups.
Ontogenetic Changes in the Response of Largemouth Bass (Micropterus salmoides, Centrarchidae, Perciformes) to Heterospecific Alarm Pheromones
Authors: Brown Grant E. , LeBlanc Valerie J. , Porter Lindsay E.
Published: March 2003

Juvenile largemouth bass (Micropterus salmoides) undergo an ontogenetic niche shift from invertebrate feeding members of the cyprinid prey guild to piscivory during their first year of growth. We conducted laboratory and field trials to determine whether juvenile bass show a similar ontogenetic shift in their response to the alarm pheromone of finescale dace (Phoxinus neogaeus, Cyprinidae). When exposed to dace skin extract (with alarm pheromone), juvenile bass exhibited a significant positive relationship between standard length and horizontal and vertical area use and time spent moving. Small bass (< 50 mm standard length) tended to reduce area use and time spent moving (indicative of an anti‐predator response), while larger bass (> 50 mm standard length) increased area use and time spent moving (indicating a foraging response). Bass exhibited no change in behaviour when exposed to swordtail (Xiphophorus helleri) skin extract, which lacks Ostariophysan alarm pheromone. During field trials, small (30–45 mm standard length) and medium (46–60 mm standard length) bass actively avoided areas labelled with dace alarm pheromone and exhibited a significant increase in dashing behaviour. Large bass (61–80 mm standard length) were attracted to such areas and exhibited a significant increase in approach behaviour. These data suggest that largemouth bass undergo an ontogenetic shift in response to heterospecific chemical alarm signals.
Male Biases for Male Characteristics in Females in Priapella olmecae and Xiphophorus helleri (Family Poeciliidae)
Authors: Basolo Alexandra L. , Delaney Kevin J.
Published: March 2003

Preexisting receiver biases can affect the evolution of sexually selected traits once traits favored by such biases arise. Female guayacón olmeca, Priapella olmecae, and green swordtail, Xiphophorus helleri, possess a bias favoring sworded conspecific males, despite phylogenetic evidence that the sexually selected sword expressed by male swordtails arose in Xiphophorus after the divergence of the two genera. In this study, we investigated the state of the bias favoring a sword in male Priapella and Xiphophorus to determine whether males also possess a bias that could operate in an intersexual selection context. Male P. olmecae preferred conspecific females with swords to those without swords. Thus, males and females in this unsworded species appear to share a preexisting bias favoring individuals of the opposite sex with swords. Male X. helleri, however, did not express a bias favoring sworded females; instead, in this species in which the sword is restricted to males, males discriminated against conspecific females with swords. Previous work suggests that female mate choice and male–male competition likely contribute to the maintenance of the sword in X. helleri. The sword may also play a role in sex recognition in swordtails. The absence of a sword preference in male green swordtails could reflect the current function of the sword.
The Effects of Experimentally Elevated Testosterone and Food Deprivation on Food Consumption and Prey Size Preferences in Male Dark‐Eyed Juncos (Junco hyemalis, Emberizidae: Passeriformes)
Authors: Clotfelter Ethan D. , Nolan Val , Ketterson Ellen D.
Published: March 2003

Numerous studies have shown that the experimental elevation of circulating levels of testosterone reduces parental behaviour in male birds, particularly the provisioning of young. The mechanisms responsible for this change in behaviour are not fully understood. In this study, we examine the effects of elevated testosterone on food consumption and prey selection, both of which have potential consequences for nestling provisioning behaviour. We manipulated testosterone and performed two experiments on a captive, non‐breeding population of male dark‐eyed juncos (Junco hyemalis) on long day‐lengths. In the first experiment, we subjected juncos to 3 h of food deprivation and compared food consumption and prey size selection by males with elevated testosterone (testosterone males) to that of control males. Testosterone males consumed more food than control males and showed a preference for larger prey. In a second experiment in which small prey were more abundant than large prey, food consumption and prey size preferences did not differ between testosterone and control males. We also manipulated the duration of food deprivation in the second experiment. Males of both treatments consumed more small prey under conditions of mild (1 h) or moderate (5 h) food deprivation and consumed more large prey under conditions of intermediate (3 h) food deprivation. We discuss our results and the effects that testosterone has on self‐maintenance behaviour and male parental effort.
Auditory Perception of Hawks and Owls for Passerine Alarm Calls
Authors: Jones Kerry J. , Hill Wendy L.
Published: March 2003

The auditory perception of eight species of raptors was examined to test the hypothesis of Marler (1955) that these avian predators are unable to locate certain songbird alarm calls. In particular, Marler proposed that mobbing calls have characteristics that enhance their locatability and that these characteristics are absent in the high‐frequency ‘seet’ calls given by individual songbirds. To test this hypothesis, the behavioral responses of four species of owls and four species of hawks, housed at two different raptor rehabilitation sites, to tape recorded alarm calls were examined. Each raptor was exposed to a random order of 10 trials of mobbing calls and 10 trials of a seet call. Responses were scored based upon head angle orientations. Hawks and owls responded more often and more accurately to mobbing calls than to seet calls. In general, owls responded to significantly more calls than hawks. The results are consistent with Marler’s hypothesis that raptors have difficulty locating passerine seet calls. Nevertheless, future studies should test mobbing calls that vary in their frequency and duration (Ficken & Popp 1996) to determine whether some mobbing calls are more difficult to locate than others.
Memory of Location and Site Recognition in the Ant Formica uralensis (Hymenoptera: Formicidae)
Authors: Salo Outi , Rosengren Rainer
Published: March 2003

Spatial recognition cues used in site fidelity in the ant Formica uralensis Ruzsky were studied using outdoor and laboratory arenas. Ant workers visiting symmetrically spaced feeders were colour‐marked corresponding to the initial feeder visited during sampling. The effect of manipulating environmental cues on the mean ‘spatial specialization’ of the population was measured. Site recognition appears to be based on visual landmark/canopy cues. However, ants maintained some fidelity when shielded from these cues, suggesting the involvement of additional cues. When ridding our experimental device of olfactory deposits and shielding visual cues, site fidelity was lost. Idiothetic and/or geomagnetic cues are thought to provide spatial references to visual or olfactory landmarks. Altering nest position relative to the arena and changing the geomagnetic field within the arena in our study, however, did nothing to the site fidelity of visually deprived and non‐deprived foragers.

We conclude that site fidelity is developed in a visually structured environment but supplemented by an olfactory backup system that is probably based on discrete home range markings rather than radial odour trails. We demonstrate furthermore that the visual component involved in site location can be stored in the memory of individual F. uralensis foragers during a 6‐month hibernation period.
Self‐Grooming as a Tactic Used by Prairie Voles Microtus ochrogaster to Enhance Sexual Communication
Authors: Ferkin Michael H. , Leonard Stuart T. , Heath Lori A. , C Guillermo Paz‐y‐Miño
Published: March 2003

Observations of numerous mammals suggest males self‐groom more than females in response to the odours of opposite‐sex conspecifics. Two experiments tested the hypothesis that self‐grooming may be a tactic used by males to attract mates in prairie voles Microtus ochrogaster. In the first experiment, we measured the amounts of time voles self‐groomed during exposure either to male‐scented cotton bedding, female‐scented cotton bedding, or clean cotton bedding. Results from this experiment support the hypothesis and also show that female prairie voles self‐groom in response to odours of males. In addition, male prairie voles groom more in response to male odours than to female odours, suggesting that self‐grooming also serves a role in male–male competition. In the second experiment, male and female voles spent more time investigating scent marks of opposite‐sex conspecifics that recently self‐groomed at a higher rate than those of opposite‐sex conspecifics that self‐groomed at a lower rate. Female, but not male prairie voles, spent more time investigating scent marks of opposite‐sex conspecifics that self‐groomed at a high rate than those of same‐sex conspecifics that self‐groomed at a high rate. For prairie voles, self‐grooming may increase the detection of their scent marks by conspecifics. By self‐grooming, prairie voles may be attempting to attract opposite‐sex conspecifics, and males may also be attempting to deter encounters with male conspecifics.
The Effect of an Experimental Brood Reduction on Male Desertion in the Panamanian Blue Acara CichlidAequidens coeruleopunctatus
Authors: Vélez Manuel J. , Jennions Michael D. , Telford Steven R.
Published: March 2003

Investment in present vs. future reproduction is a life‐history trade‐off faced by many animals. Because males generally pay a higher cost from lost mating opportunities than females, males are expected to react more strongly to changes in brood value. We examined the effect of an experimental brood reduction on male desertion in the substrate‐brooding biparental cichlidAequidens coeruleopunctatusunder field conditions. We tested the prediction that brood reduction should decrease the duration of male care and examined the effect of brood reduction on the quality of male and female parental care. Our results show that males with reduced broods stopped providing parental care earlier than males with control broods. Males with reduced broods, however, also stayed longer with their broods as the season progressed. Brood reduction did not decrease daily investment in male or female parental care. We conclude that males trade off present and future reproduction by changing the duration but not the quality of parental care. The longer duration of male care in the experimental group later in the season suggests that the trade‐off between present and future reproduction changes as the season progresses because the payoffs of desertion progressively decrease.
Chemosensory Recognition of Familiar and Unfamiliar Conspecifics by Juveniles of the Iberian Wall Lizard Podarcis hispanica
Authors: Font Enrique , Desfilis Ester
Published: March 2003

Chemosensory recognition of familiar conspecifics has been reported in studies with members of several lizard families and may be advantageous to distinguish between intruders and neighbors or group members. However, few species have been studied and information on the ability to discriminate between familiar and unfamiliar conspecifics by chemosensory means is lacking for most lizard families. In this paper we ask whether juveniles of the Iberian wall lizard Podarcis hispanica (Lacertidae), can discriminate between chemical signals from familiar conspecifics with whom they have shared a terrarium for several months and those from unfamiliar conspecifics housed in a different terrarium. Experimental trials were conducted by transferring juveniles to a test terrarium with a filter paper substrate. We tested the responses of lizards to paper substrates labeled by familiar cage‐mates, unfamiliar conspecifics, or unlabeled. Tongue‐flicks and other behaviors in response to pheromonal stimuli were recorded for 10 min Juveniles directed more chemosensory behavior towards paper substrates bearing chemicals from familiar conspecifics than towards similar paper substrates labeled by unfamiliar conspecifics. These results indicate that juveniles in this lizard species can recognize familiar conspecifics and discriminate between familiar and unfamiliar individuals using only chemical stimuli. We discuss the role of habituation in familiar conspecific recognition and review possible explanations of the functional significance of this type of discrimination in lizards.
Olfactory Discrimination of Individual Scents in the Subterranean Rodent Ctenomys talarum (tuco‐tuco)
Authors: Zenuto Roxana R. , Fanjul María Sol
Published: March 2003

Biological odours that convey cues regarding individual identity can provide valuable information mediating many aspects of mammalian social relationships such us dominance hierarchies, group memberships, territorial and mating activities. The ability of the subterranean rodent, tuco‐tuco (Ctenomys talarum), to discriminate between soiled shavings, urine and faeces from different individuals was investigated using the habituation–discrimination paradigm. Discrimination by both males and females was tested using scents obtained from same‐ and opposite‐sex individuals. Each test subject was habituated for three consecutive days to odour samples from the same individual; on the fourth day a scent from a novel individual was provided. For all odour sources, animals spent significantly less time investigating the habituation scent over successive trials, indicating that animals perceived the stimulus as familiar. For all stimuli, test subjects spent more time investigating the novel odour, rather than the familiar one. Animals spent more time investigating soiled shavings than urine or faeces. Both males and females discriminated novel from familiar odours in shavings and urine regardless of the gender of the odour donors. In contrast, test animals discriminated between familiar and novel odours in feces only when the fecal donors were of different sex from subjects. Possible territorial and reproductive functions of individual scent discrimination are discussed.
Intra‐Colonial Variability in the Dance Communication in Honeybees (Apis mellifera)
Authors: Arnold Gérard , Quenet Brigitte , Papin Christian , Masson Claudine , Kirchner Wolfgang H.
Published: March 2003

Honeybees have evolved numerous mechanisms for increasing colony‐level foraging efficiency, mainly the combined system of scout‐recruit division of labour and recruitment communication. A successful forager performs waggle dances on the surface of the comb where it interacts with nectar receivers and dance followers. A forager uses tremble dance when it experiences difficulty finding a receiver bee to unload food upon return to the hive. A bee colony containing numerous subfamilies may increase its efficiency in dance communication if dances are realized by particular groups of specialized individuals or subfamilies rather than by undifferentiated workers. In this study, we determined the subfamily frequencies of waggle and tremble dancers in a colony headed by a naturally mated queen, where the 17 subfamilies can be identified by microsatellite genetic markers. Our results demonstrate that a genetic component is associated with the dance communication in honeybees. More than half of the waggle dances and the tremble dances were performed by workers from only four subfamilies in each case.
Responses of Snow Voles, Chionomys nivalis, Towards Conspecific Cues Reflect Social Organization during Overwintering Periods
Authors: Luque‐Larena Juan J. , López Pilar , Gosálbez Joaquim
Published: March 2003

Among microtine rodents, reaction to chemical cues from conspecifics is assumed to reflect social and spatial relationships. Generally, strong attraction of particular odours correlates with non‐aggressive behaviour and high spatial tolerance towards odour donors, whereas weak attraction correlates with greater levels of aggression and spatial segregation. In the present study, we examined whether winter odour preferences of the snow vole Chionomys nivalis, a rock‐dwelling microtine principally found at high‐mountainous regions, differ from that of other vole species, owing to their different social organization during overwintering periods. The social structure of C. nivalis over the winter period is relatively unusual among vole species in that they become nomadic and solitary. In odour choice trials under laboratory conditions, we found that both males and females avoided zones with conspecific odours of both sexes in comparison with unscented control zones or own odours. These results are consistent with the elevated levels of intraspecific aggression and spatial isolation of C. nivalis during overwintering periods. Furthermore, scent‐elicited self‐grooming increased when their own odour was offered against conspecific cues. This, in combination with an active avoidance of conspecific odours, might functionally contribute to minimize direct confrontations between solitary individuals, thereby reducing the risks of aggressive encounters during overwintering periods.
Individual and Contextual Variation in Thomas Langur Male Loud Calls
Authors: Wich Serge A. , Koski Sonja , de Vries Han , van Schaik Carel P.
Published: March 2003

Individual and contextual differences in male loud calls of wild Thomas langurs (Presbytis thomasi) were studied in northern Sumatra, Indonesia. Loud calls were given in the following contexts: morning calls, vocal responses to other groups, between‐group encounter calls and alarm calls. Loud call spectrograms were analysed for a large number of variables. With discriminant analyses, 14 variables were found to be important in distinguishing individuals and contexts. Loud calls were assigned to the correct individual in 95.6% of the cases (91.8% with ‘leave‐one‐out’ validation) and to the correct context in 52.2% of the cases (39.0% with ‘leave‐one‐out’ validation). Further analyses with two‐way anovas showed significant differences in both temporal and frequency variables between individuals and contexts. Loud calls seemed to differ between the contexts in functionally meaningful ways, relating to the distance of the intended receivers and to the urgency of the message. Observation showed that females in the caller's group collected infants more often in the between‐group encounter context and in the alarm call context than in the vocal exchange context. These differential responses suggest that the monkeys also perceive the measurable differences in loud call characteristics between the various contexts.
Experimental Manipulation of Intraclutch Variation in the Great Reed Warbler Shows No Effect on Rejection of Parasitic Eggs
Authors: Karcza Zsolt , Moskát Csaba , Cherry Michael I. , Kisbenedek Tibor
Published: March 2003

In the continuing arms race between hosts and brood parasites, hosts are expected to reduce variation in the appearance of their own eggs within clutches, as it facilitates recognition of parasitic eggs. At the same time, by increasing interclutch variation, hosts should make it more difficult for parasites to evolve perfectly mimetic eggs. In this study, we experimentally manipulated intraclutch variation in the great reed warbler,Acrocephalus arundinaceus, in Hungary, where this species is heavily (c. 64%) parasitized by the common cuckoo,Cuculus canorus. We placed artificial cuckoo eggs, which appeared moderately mimetic to humans, in two groups of nests; in one group we increased variability of egg appearance within clutches by exchanging host eggs among nests. These clutches showed a significantly higher intraclutch variability than natural clutches, which we used as a control group. Our results indicate that it has no effect on rejection behaviour in this species, neither when variation was increased experimentally, nor within the natural range of variation displayed by our population. We suggest that when parasitism is high, selection for reduced intraclutch variation may be less important than frequency‐dependent selection for increased variation between individuals within a host population.
Do Experience and Body Size Play a Role in Responses of Larval Ringed Salamanders, Ambystoma annulatum, to Predator Kairomones? Laboratory and Field Assays
Authors: Mathis Alicia , Murray Kevin L. , Hickman Caleb R.
Published: March 2003

Prey may experience ontogenetic changes in vulnerability to some predators, either because of changes in morphology or experience. If prey match their level of antipredator behavior to the level of predatory threat, prey responses to predators should reflect the appropriate level of threat for their stage of development. For larval salamanders, responses to predators may change with body size because larger larvae are less vulnerable to predation by gape‐limited predators or because fleeing responses by large salamanders may be more effective than for smaller salamanders. In a field experiment, small larval ringed salamanders, Ambystoma annulatum, responded to chemical stimuli (‘kairomones’) from predatory newts, Notophthalmus viridescens, with an antipredator response (decreased activity). Laboratory‐reared larvae decreased their activity following exposure to newt kairomones, indicating that larval ringed salamanders do not require experience with newts to recognize them as predators. In both experiments, larvae distinguished between chemical stimuli from newts and stimuli from tadpoles (non‐predators) and a blank control. In a third experiment, field‐caught (experienced) larvae showed a graded response to newt kairomones based on their body size: small larvae tended to decrease their activity while larger larvae showed no change or an increase in activity. This graded response was not observed for neutral stimuli, indicating that it is predator‐specific. Therefore, ringed salamander larvae exhibit threat‐sensitive ontogenetic changes in their response to chemical stimuli from predatory newts.
Mating Call Discrimination in Female European (Coturnix c. coturnix) and Japanese Quail (Coturnix c. japonica)
Authors: Derégnaucourt Sébastien , Guyomarc'h Jean‐Charles
Published: March 2003

Each year, thousands of domestic Japanese and hybrid quails are released within the breeding range of the European quail. We showed recently that no post‐zygotic isolating mechanisms have yet been established between these subspecies. The aim of this study was to investigate whether pre‐zygotic mechanisms are strong enough to prevent hybridization. We tested the level of subspecies selectivity in females of European and Japanese quail respectively using playbacks of European, hybrid and Japanese male mating calls. European quail females emitted the greatest number of rally calls in response to mating calls by conspecific males. Their responses were the weakest to mating calls produced by males of the other subspecies and intermediate to mating calls by hybrid males. In contrast, Japanese quails produced similar responses to all types of mating calls. These results suggest that mixed pairs could form in the wild. The European quail could thus become one of the most endangered galliforms of the Western Palearctic.
Mouth Color Signals Thermal State of Nestling Dark‐Eyed Juncos (Junco hyemalis)
Authors: Clotfelter Ethan D. , Schubert Kristin A. , Nolan Val , Ketterson Ellen D.
Published: March 2003

In many species of birds, nestlings have brightly colored mouths. Some studies have found that mouth color is related to hunger, and may serve to solicit feedings from parents. We devised two experiments to test the hypothesis that mouth color is an indicator of hunger in nestling dark‐eyed juncos (Junco hyemalis), and neither experiment produced results to support the hypothesis. We did find, however, that mouth redness saturation increased for the duration of our experiments (60 min). We devised a third experiment to investigate the effect of a different stressor, temperature. In the third experiment, mouth redness decreased in saturation when microenvironment temperature increased following a period of cooling. These findings suggest that mouth color indicates thermal state of nestling dark‐eyed juncos and may function as a signal to the female to brood them.
Production of aggressive electrocommunication signals to progressively realistic social stimuli in male Apteronotus leptorhynchus
Authors: Dunlap Kent D. , Larkins‐Ford Jonah
Published: March 2003

Brown ghost knife fish, Apteronotus leptorhynchus, produce a continuous electric organ discharge (EOD) that they use for communication. While interacting aggressively, males also emit brief EOD modulations termed chirps. The simplicity of this behaior and its underlying neural circuitry has made it an important model system in neuroethology. Chirping is typically assayed by confining a fish in a tube (‘chirp chamber’) and presenting it with sine wave electrical stimuli that partially mimic EODs of other fish. We presented male fish with progressively more realistic social stimuli to examine whether some of the stimulus complexities during dyadic interaction influence the production of chirps. In a chirp chamber, fish chirped less to a recording of an EOD containing chirps than to a recording of an EOD alone and to sine wave stimuli. Free‐swimming fish chirped more to stimulus fish than to sine wave stimuli presented through electrodes. Fish chirped more when interacting directly than when interacting across a perforated barrier. Together, these studies demonstrate that the presence of chirps, electric field complexity, and/or non‐electric social stimuli are important in eliciting chirp production in brown ghosts.
Spread of white hypovirulent strains of Cryphonectria parasitica on grafted American chestnut trees exhibiting a high level of blight control
Authors: Robbins N. , Griffin G. J.
Published: March 2003

In 1982 and 1983, natural blight cankers, located in a zone extending from the ground to 183 cm on the main stem of grafted American chestnut trees, were inoculated with a mixture of dsRNA‐containing, white (European) and pigmented hypovirulent strains of Cryphonectria parasitica (H‐inoculated zone). In 1996, white isolates (34% of 156 C. parasitica isolates) were recovered from superficial cankers throughout the grafts and as far as 564 cm from the H‐inoculated zone. Lloyd's index of patchiness value (1.36) indicated that white isolates were slightly aggregated in cankers on the grafts. Forty‐five percent of 95 C. parasitica isolates, recovered 5–50 months after inoculating the grafts with pigmented virulent strain WK, were white and some converted strain WK to the white phenotype in vitro. All cankers and bark cores yielding only pigmented isolates, vegetatively compatible with virulent strain WK, had superficial necrosis 5 and 11 months after inoculation with strain WK. All white isolates of C. parasitica assayed contained a 12.7 kbp dsRNA in high concentrations, and were hypovirulent in pathogenicity trials. Twenty‐eight vegetative compatibility groups were identified among 65 pigmented graft area isolates; none of 48 pigmented isolates contained dsRNA. In addition to host resistance factors, spread of white strains may be responsible for the unusually high level of blight control on the grafts.
Use of random amplified polymorphic DNA (RAPD) for detection of genetic variation and proof of the heterothallic mating system in Hypoxylon mediterraneum
Authors: Vannini A. , Mazzaglia A. , Anselmi N.
Published: March 2003

The efficiency of RAPD analysis in the evaluation of genetic variability in Hypoxylon mediterraneum has been tested on 49 monoascospore isolates of the fungus from different localities. A large genetic variability was detected within single stromata and among monoascospore isolates in a restricted area. The large variability in restricted populations can be explained by the heterothallic mating system and the life cycle of the fungus and its ecological adaptations. RAPD markers can discriminate monoascospore isolates both in the single stromata and among stromata. The application of RAPD markers for epidemiological studies is discussed.
Production of a polyclonal antibody to Phellinus pini and examination of its potential use in diagnostic assays
Authors: Hunt R. S. , Ekramoddoullah A. K. M. , Zamani A.
Published: March 2003

In order to differentiate among Phellinus pini, Inonotus tomentosus and Inonotus circinatus a polyclonal antibody was raised to a N‐terminal part of 25‐kDa P. pini‐specific protein. The specificity of the polyclonal antibody produced against a synthetic N‐terminal peptide of this protein was investigated for diagnostic purposes using Western immunoblot, indirect enzyme‐linked immunosorbent assay (ELISA), and inhibition ELISA techniques. The N‐terminal synthetic peptide, used as the immunogen, was found to be more than 80% pure by reverse‐phase high‐performance liquid chromatography. Following immunization, antisera were collected at three different time intervals. The antibody molecules were purified from the crude antisera using immunoaffinity gel chromatography. Following one‐dimensional sodium dodecylsulfate‐polyacrylamide gel electrophoresis, Western immunoblot analysis showed that the P. pini I polyclonal‐antibody detected the immunogen, the 25‐kDa protein, in all but one of the P. pini isolates examined, but in none of the isolates of the nontarget species I. tomentosus and I. circinatus. Nevertheless, cross‐reactivity was a problem because the P. pini I polyclonal‐antibody also recognized bands at other molecular weights in nearly all of the isolates of the other species tested. With the indirect ELISA the P. pini isolates tended to have higher affinity for the polyclonal antibody than the nontarget species, but some cross‐reactivity did occur. Inhibition ELISAs, performed over a range of soluble antigen concentrations (1.56–400 ng/100 μl), failed to show a clear distinction between P. pini and the two Inonotus spp. The low level of cross‐reactivity observed for I. tomentosus isolate 52 (9%) was also apparent in the indirect ELISA analysis. All three assays indicated that P. pini isolate 41 was the most antigenic. Despite cross‐reactivity, the antibody is useful in Western immunoblots for the diagnosis of most P. pini isolates.
Co‐occurrence of the ascomycete Lophodermium piceae and the rust fungus Chrysomyxa abietis in Norway spruce needles
Authors: Lehtijärvi A. , Swertz C. , Barklund P.
Published: March 2003

The frequency of needles and the proportion of needle segments infected by Lophodermium piceae were compared in symptomless and Chrysomyxa abietis‐infected, 1‐year‐old needles of Picea abies. In late spring, symptomless needles from both rust‐infected and healthy saplings were sampled. In addition, rust‐infected, totally chlorotic needles and needles with chlorosis along about half their length from the diseased trees were examined. In all three stands, the proportion of segments infected by L. piceae was larger in the rust‐infected half of the needle than in the symptomless half; but the difference was statistically significant in only one of the stands. The proportion of L. piceae‐infected segments among the nonrust‐infected needles was the same as that found for the uninfected half of rust‐infected needles (after correction for size differences). No differences in the proportion of L. piceae‐infected segments were found between the totally chlorotic, rust‐infected needles and the green needles of diseased or healthy trees.