bluuebunny/crossref_metadata_2025 huggingface dataset:
Blood digestion in the malaria mosquito Anopheles gambiae
Authors: Vizioli Jacopo , Catteruccia Flaminia , della Torre Alessandra , Reckmann Ingeborg , Müller Hans‐Michael
Published: March 2003

The elucidation of digestive processes in the Anopheles gambiae gut leading to the utilization of the blood meal will result in a deeper understanding of the physiology of blood digestion and its impact on parasite–vector interactions. Accordingly, the identification of digestive serine proteases in A. gambiae has implications for the development of alternative strategies for the control of mosquito‐borne diseases. We report here on the cDNA and genomic cloning and on the expression analysis of two closely related chymotrypsin genes, Anchym1 and Anchym2. Genomic cloning revealed that Anchym1 and Anchym2, which map on chromosomal division 25D, are clustered in tandem within 6 kb, both genes being interrupted by two short introns. After blood feeding, transcription of Anchym1 and Anchym2 is induced in the midgut epithelium, followed by secretion of the translated products into the midgut lumen where the Anchym1 and Anchym2 zymogens are activated by partial tryptic digestion. The amino‐acid residues forming the substrate pocket of Anchym1 and Anchym2 suggested chymotryptic cleavage specificity. This was confirmed by mass spectrometry analysis and Edman degradation sequencing of proteolytic products generated by the recombinant, trypsin‐activated Anchym1.
Binding interactions between barley thaumatin‐like proteins and (1,3)‐β‐D‐glucans
Authors: Osmond Ronald I. W. , Hrmova Maria , Fontaine Fabien , Imberty Anne , Fincher Geoffrey B.
Published: March 2003

The specificity and kinetics of the interaction between the pathogenesis‐related group of thaumatin‐like proteins (PR5) in higher plants and (1,3)‐β‐d‐glucans have been investigated. Two thaumatin‐like proteins with 60% amino‐acid sequence identity were purified from extracts of germinated barley grain, and were designated HvPR5b and HvPR5c. Purified HvPR5c interacted with insoluble (1,3)‐β‐d‐glucans, but not with cellulose, pustulan, xylan, chitin or a yeast mannoprotein. Tight binding was observed with unbranched and unsubstituted (1,3)‐β‐d‐glucans, and weaker binding was seen if (1,6)‐β‐linked branch points or β‐glucosyl substituents were present in the substrate. The HvPR5b protein interacted weakly with insoluble (1,3)‐β‐d‐glucans and did not bind to any of the other polysaccharides tested. This indicated that only specific barley PR5 isoforms interact tightly with (1,3)‐β‐d‐glucans. The complete primary structures of HvPR5b and HvPR5c were determined and used to construct molecular models of HvPR5b and HvPR5c, based on known three‐dimensional structures of related thaumatin‐like proteins. The models were examined for features that may be associated with (1,3)‐β‐d‐glucan binding, and a potential (1,3)‐β‐d‐glucan‐binding region was located on the surface of HvPR5c. No obvious structural features that would prevent binding of (1,3)‐β‐d‐glucan to HvPR5b were identified, but several of the amino acids in HvPR5c that are likely to interact with (1,3)‐β‐d‐glucans are not present in HvPR5b.
Cellulose‐binding modules from extracellular matrix proteins of Dictyostelium discoideum stalk and sheath
Authors: Wang Yingzi , Slade Martin B. , Gooley Andrew A. , Atwell Brian J. , Williams Keith L.
Published: March 2003

Cellulose‐binding modules (CBMs) of two extracellular matrix proteins, St15 and ShD, from the slime mold Dictyostelium discoideum were expressed in Escherichia coli. The expressed proteins were purified to > 98% purity by extracting inclusion bodies at pH 11.5 and refolding proteins at pH 7.5. The two refolded CBMs bound tightly to amorphous phosphoric acid swollen cellulose (PASC), but had a low affinity toward xylan. Neither protein exhibited cellulase activity. St15, the stalk‐specific protein, had fourfold higher binding affinity toward microcrystalline cellulose (Avicel) than the sheath‐specific ShD CBM. St15 is unusual in that it consists of a solitary CBM homologous to family IIa CBMs. Sequence analysis of ShD reveals three putative domains containing: (a) a C‐terminal CBM homologous to family IIb CBMs; (b) a Pro/Thr‐rich linker domain; and (c) a N‐terminal Cys‐rich domain. The biological functions and potential role of St15 and ShD in building extracellular matrices during D. discoideum development are discussed.
A novel heat stress‐responsive gene in the marine diatomChaetoceros compressumencoding two types of transcripts, a trypsin‐like protease and its related protein, by alternative RNA splicing
Authors: Kinoshita Shigeharu , Kaneko Gen , Lee Jeen H. , Kikuchi Kiyoshi , Yamada Hiroshi , Hara Takeya , Itoh Yasuo , Watabe Shugo
Published: March 2003

We investigated the change of mRNA expression patterns in the laboratory‐grown diatomChaetoceros compressumunder heat‐stress conditions by mRNA arbitrarily primed (RAP) RT‐PCR. Cells grown at 20 °C were subjected to heat treatment at 30 °C for 15 min and subsequently maintained at 20 °C for 8 h. Four genes includingHI‐5were detected as heat stress‐responsive genes by fingerprint analysis of RAP RT‐PCR. Cloning for full‐length cDNA sequences ofHI‐5transcripts and related genomic DNA analysis revealed that two types of mRNA,HI‐5aandHI‐5b, were transcribed from the singleHI‐5gene. While the HI‐5a protein contained a catalytic domain characteristic to trypsin‐like proteases, the HI‐5b protein lacked this domain due to an insertion in the associated mRNA of 112 nucleotides; this insertion sequence contained a stop codon near the central region. Quantitative RT‐PCR was performed to investigate the changes in expression levels of the two types of mRNA following heat treatment. TheHI‐5btranscripts were constitutively expressed in both unstressed and heat‐stressed cells. In contrast, the number ofHI‐5atranscripts markedly increased in cells immediately after heat stress, reaching levels 19‐fold higher at 8 h after heat stress than that in unstressed cells. These results suggest that RNA splicing plays a key role in heat stress‐dependent expression of theHI‐5aandHI‐5btranscripts from the singleHI‐5gene in the diatom.
Hepatocyte growth factor/scatter factor stimulates migration of rat mammary fibroblasts through both mitogen‐activated protein kinase and phosphatidylinositol 3‐kinase/Akt pathways
Authors: Delehedde Maryse , Sergeant Nicolas , Lyon Malcolm , Rudland Philip S. , Fernig David G.
Published: March 2003

Hepatocyte growth factor/scatter factor (HGF/SF) is considered to be a mesenchymal‐derived factor that acts via a dual system receptor, consisting of the MET receptor and proteoglycans present on adjacent epithelial cells. Surprisingly, HGS/SF stimulated the migration of rat mammary (Rama) 27 fibroblasts, although it failed to stimulate their proliferation. HGF/SF stimulated a transient activation of mitogen‐activated protein kinases p44 and p42 (p42/44MAPK), with a maximum level of dual phosphorylation of p42/44MAPK occurring 10–15 min after the addition of the growth factor, which was followed by a rapid decrease to near basal levels after 20 min. Interestingly, a second phase of p42/44MAPK dual phosphorylation was observed at later times (3 h to 10 h). PD098059, a specific inhibitor of MEK‐1, prevented the dual phosphorylation of p42/44MAPK and also the phosphorylation of p90RSK (ribosomal subunit S6 kinase), which mirrored the kinetics of p42/44MAPK phosphorylation. Moreover, PD098059 prevented the HGF/SF‐induced migration of Rama 27 cells. HGF/SF also induced an early increase in the phosphorylation of protein kinase B/Akt. Akt phosphorylation was elevated 15 min after the addition of HGF/SF and then declined to basal levels by 30 min. Wortmannin, an inhibitor of phosphatidylinositol 3‐kinase (PtdIns3K), prevented the increase in Akt phosphorylation and abolished HGF/SF‐induced migration of fibroblasts. PD098059 also inhibited the stimulation of Akt phosphorylation by HGF/SF and wortmannin similarly inhibited the stimulation of p42/44MAPK dual phosphorylation. These results suggest that HGF/SF‐induced motility depends on both the transient dual phosphorylation of p42/44MAPK and the activation of PtdIns3K in Rama 27 fibroblasts and that these pathways are mutually dependent.
ADAM‐HCV, a new‐concept diagnostic assay for antibodies to hepatitis C virus in serum
Authors: Minenkova Olga , Gargano Nicola , De Tomassi Amedeo , Bellintani Francesca , Pucci Andrea , Fortugno Paola , Fuscaldi Elena , Pessi Antonello , Rapicetta Maria , Miceli Michela , Iudicone Paola , Cortese Riccardo , Felici Franco , Monaci Paolo
Published: March 2003

We screened phage libraries using sera from noninfected individuals and patients infected by hepatitis C virus (HCV). By applying different selection and maturation strategies, we identified a wide collection of efficient phage‐borne ligands for HCV‐specific antibodies. The selected ligands retained their antigenic properties when expressed as multimeric synthetic peptides. Peptides that mimic several immunodominant epitopes of the virus were used to develop a novel type of diagnostic assay which efficiently detects antibodies to HCV in serum. This type of analysis provides a conclusive diagnosis for many patients identified as indeterminate according to presently available serological assays.
Structural characterization of the C2 domain of novel protein kinase Cε
Authors: García‐García Josefa , Gómez‐Fernández Juan C. , Corbalán‐García Senena
Published: March 2003

Infrared spectroscopy (IR) and differential scanning calorimetry (DSC) were used to study the biophysical properties of the PKCε‐C2 domain, a C2 domain that possess special characteristics as it binds to acidic phospholipids in a Ca2+‐independent manner and no structural information about it is available to date. When the secondary structure was determined by IR spectroscopy in H2O and D2O buffers, β sheet was seen to be the major structural component. Spectroscopic studies of the thermal denaturation in D2O showed a broadening in the amide I′ band starting at 45 °C. Curve fitting analysis of the spectra demonstrated that two components appear upon thermal denaturation, one at 1623 cm−1 which was assigned to aggregation and a second one at 1645 cm−1, which was assigned to unordered or open loop structures. A lipid binding assay has demonstrated that PKCε‐C2 domain has preferencial affinity for PIP2 although it exhibits maximal binding activity for phosphatidic acid when 100 mol% of this negatively charged phospholipid was used. Thus, phosphatidic acid containing vesicles were used to characterize the effect of lipid binding on the secondary structure and thermal stability. These experiments showed that the secondary structure did not change upon lipid binding and the thermal stability was very high with no significant changes occurring in the secondary structure after heating. DSC experiments demonstrated that when the C2‐protein was scanned alone, it showed a Tm of 49 °C and a calorimetric denaturation enthalpy of 144.318 kJ·mol−1. However, when phoshatidic acid vesicles were included in the mixture, the transition disappeared and further IR experiments demonstrated that the protein structure was not modified under these conditions.
Binding of Thermomyces (Humicola) lanuginosa lipase to the mixed micelles of cis‐parinaric acid/NaTDC
Authors: Yapoudjian Stéphane , Ivanova Margarita G. , Brzozowski A. Marek , Patkar Shamkant A. , Vind Jesper , Svendsen Allan , Verger Robert
Published: March 2003

The binding of Thermomyces lanuginosa lipase and its mutants [TLL(S146A), TLL(W89L), TLL(W117F, W221H, W260H)] to the mixed micelles of cis‐parinaric acid/sodium taurodeoxycholate at pH 5.0 led to the quenching of the intrinsic tryptophan fluorescence emission (300–380 nm) and to a simultaneous increase in the cis‐parinaric acid fluorescence emission (380–500 nm). These findings were used to characterize the Thermomyces lanuginosa lipase/cis‐parinaric acid interactions occurring in the presence of sodium taurodeoxycholate.

The fluorescence resonance energy transfer and Stern–Volmer quenching constant values obtained were correlated with the accessibility of the tryptophan residues to the cis‐parinaric acid and with the lid opening ability of Thermomyces lanuginosa lipase (and its mutants). TLL(S146A) was found to have the highest fluorescence resonance energy transfer.

In addition, a TLL(S146A)/oleic acid complex was crystallised and its three‐dimensional structure was solved. Surprisingly, two possible binding modes (sn‐1 and antisn1) were found to exist between oleic acid and the catalytic cleft of the open conformation of TLL(S146A). Both binding modes involved an interaction with tryptophan 89 of the lipase lid, in agreement with fluorescence resonance energy transfer experiments.

As a consequence, we concluded that TLL(S146A) mutant is not an appropriate substitute for the wild‐type Thermomyces lanuginosa lipase for mimicking the interaction between the wild‐type enzyme and lipids.
Song Tutor Choice in Polyandrous Dunnocks
Authors: Langmore N. E.
Published: March 2003

The songs of a population of wild dunnocks,Prunella modularis, were recorded over 3 yrs to investigate song tutor choice by first year males. Young males often settled on occupied territories as subordinates and most of their earliest territorial interactions were with the male on whose territory they settled (the co‐male). Yearlings learned their song repertoire from their comales and territorial neighbours. This supports results of laboratory studies which suggest that social interactions influence song tutor choice and that yearlings are most likely to learn from the males that are most aggressive towards them. Repertoire overlap between neighbouring males was high (76%), so learning the repertoire of the comale may provide yearling males with a ‘short cut’ route to learning a few of the songs of every neighbour.
Solitary is not Asocial: Effects of Social Contact in Kangaroo Rats (Heteromyidae: Dipodomys heermanni)
Authors: Yoerg Sonja I.
Published: March 2003

Social interactions in solitary animals, such as Heermann’s kangaroo rat (Dipodomys heermanni), have been little studied. In three experiments, the effect of social housing on levels of aggression and maintenance of estrous cycling was studied as part of a captive breeding program for an endangered form of this species. Expt 1 demonstrated that mixed‐sex pairs of rats that were neighbors in social housing were no friendlier during staged encounters than unfamiliar pairs also housed socially. In expt 2, rats that had been isolated for several months were transferred to social housing and paired at weekly intervals with an opposite‐sex neighbor. Initial encounters were highly aggressive and socialized partners retreated from previously isolated rats more often than vice versa, regardless of sex. By the third week, encounters resembled pairings of fully socialized rats, as in expt 1. Thus, social exposure may produce a general socializing effect rather than promote familiarity between specific individuals. In expt 3, the clear, perforated barriers that separated rats in social housing were replaced with solid, opaque barriers for 6 wk. Estrous cycle length immediately doubled and cycles of most females were disrupted for months. Taken together, the results reveal the influential role of social contact in this solitary species and highlight the need for more such work both for developing comprehensive theories of sociality and for guiding captive propagation efforts.
Whistle Convergence among Allied Male Bottlenose Dolphins (Delphinidae, Tursiops sp.)
Authors: Smolker Rachel , Pepper John W.
Published: March 2003

Dolphins are adept at learning new vocalizations (whistles) throughout life, an ability thus far demonstrated in few nonhuman mammals. In dolphins, this ability is well documented in captivity but poorly studied in the wild, and little is known of its role in natural social behavior. This study documents the previously unknown phenomenon of whistle convergence among habituated free‐living male bottlenose dolphins (Tursiops sp.). Over a 4 yr study period, three male subjects formed an alliance, spending most of their time together and cooperating to herd females. Within individuals, whistle repertoires were more variable than expected based on previous studies, mostly performed with captive dolphins, but became less so during the course of the study. Among individuals, the distinctiveness of individual repertoires decreased such that the three males were virtually indistinguishable by the end of the study. Initially, some whistle types were shared. By the end of the study, the three males had formed a close alliance, and had all converged on one particular shared whistle form which they had rarely produced before forming the alliance. The results are discussed in terms of their implications for the prevailing ‘signature whistle’ hypothesis, as well as possible mechanisms and functional significance of whistle convergence among cooperating males.
Provisioning of Young in Golden Lion Tamarins (Callitrichidae,Leontopithecus rosalia): A Test of the Information Hypothesis
Authors: Rapaport Lisa G.
Published: March 2003

Provisioning of young after weaning or fledging is a highly variable phenomenon. Among cooperative breeders, such as marmosets and tamarins, both parents and natal adults may provision immatures. Experiments designed to measure the effects of food familiarity on food‐transfer interactions were conducted on zoo‐living golden lion tamarin,Leontopithecus rosalia, families to test one proposed benefit of provisioning to recipient young — that immature callitrichids learn food preferences through exposure to food items obtained from older group members. Adults transferred to immatures foods that were known to adults, but novel to immatures, and foods that were novel to all more frequently than foods that were familiar to both adults and immatures. Results suggest that adults alter their behavior such that learning by immatures is fostered. Immatures also were less likely to reject new foods acquired from other group members, compared with those obtained independently, suggesting the possibility that immatures attend to food transfer to facilitate incorporation of new foods into the diet. In contrast, anecdotal accounts of wild marmoset and tamarin food transfer have indicated that infants receive from adults foods that primarily are high in lipids and/or protein, as expected if provisioning acts to supplement nutrition. These apparently contradictory findings may reflect the differing effects of the captive and wild environment on food‐transfer behavior or may point to a dual function of provisioning dependent on age of the recipient.
Antipredator Responses to a Previously Neutral Sound by Free‐living Adult Golden‐mantled Ground Squirrels, Spermophilus lateralis (Sciuridae)
Authors: Shriner Walter McKee
Published: March 2003

I investigated whether free‐living adult golden‐mantled ground squirrels (Spermophilus lateralis) could learn to associate a novel sound with the appearance of a predator. Using a classical conditioning protocol, I presented adult squirrels with a novel tone followed by the appearance of a model hawk. After repeated trials, I again measured the squirrels’ behavioral responses to the tone and compared them with their pretraining responses. Individuals that experienced the tone paired with the hawk responded with antipredator behavior of longer duration after pairing than before and these responses were indistinguishable from responses to natural, conspecific alarm calls. By examining the process, rather than simply the pattern, of call recognition ontogeny, this study provides new evidence for a mechanism by which animals can develop the ability to respond to both conspecific and heterospecific calls.
Meadow Voles (Microtus pennsylvanicus, Arvicolidae) Over‐mark and Adjacent‐mark the Scent Marks of Same‐sex Conspecifics
Authors: Ferkin Michael H.
Published: March 2003

Scent over‐marking occurs when an animal deposits its scent mark on top of the scent mark of a conspecific; adjacent‐marking occurs when an animal deposits its scent mark next to the scent mark of a conspecific. Given that male rodents usually scent mark more than females and that animals spend more time investigating the odor of the top‐scent donor of an over‐mark, I tested the following three hypotheses. First, male meadow voles deposit more scent marks than female meadow voles. Second, male meadow voles will deposit more over‐marks and adjacent‐marks in response to the scent marks of a same‐sex conspecific than females would. Third, meadow voles spend more time investigating the odor of the second vole placed in the arena than that of the first vole placed in the arena. To test these hypotheses, two age‐matched, like‐sex conspecifics (first vole and second vole) were placed successively into an arena in which they were allowed to freely explore and scent mark for 15 min. The first hypothesis was not supported. The first and second vole, independently of sex, deposited a similar number of scent marks. The second hypothesis was also not supported by the data: more conspecific scent marks were over‐marked by the second female than by the second male. The third hypothesis was supported by the data. After investigating a scented arena, males and females spent more time investigating the odor of the second vole than that of the first vole. Sex differences in scent‐marking behaviors of meadow voles are unlike those reported for other species of rodents.
Randomization Analyses: Mimicry, Geographic Variation and Cultural Evolution of Song in Brood‐Parasitic Straw‐Tailed Whydahs, Vidua fischeri
Authors: Payne Robert B. , Woods Jean L. , Siddall Mark E. , Parr Cynthia S.
Published: March 2003

Although bird song has been an important model for investigating questions of behavior development, cultural evolution and population differentiation, the quantitative methods of analysis have been problematic. Here we develop and apply quantitative randomization methods to test hypotheses about these processes in a natural population of birds. Songs of the African brood‐parasitic straw‐tailed whydahs (Vidua fischeri) and songs of their host species, the purple grenadier (Granatina ianthinogaster), were compared in audiospectrograms for similarity to test the following hypotheses: Whydahs mimic the songs of their host species, they have local song dialects, neighboring males match their song themes, local males match the songs of local hosts, remote populations have different songs according to their geographic distance, and songs undergo cultural evolution over time across generations. Randomization analyses were completed using (1) Mantel matrix statistics and (2) tree‐based measures employing Sankoff optimization of Manhattan matrices and approximate randomizations. Our results provide evidence for song mimicry, local song dialects, matching song themes between neighboring males, song matching of local whydah mimics and grenadier song models, correspondence of song differences and geographic distance, and cultural continuity with change in song traditions within a local population. These randomization methods may be useful in other studies of animal communication, and they are sufficiently general for use both with distance matrices derived either from naturalistic impressions of song similarity as in our example or from acoustic measurements.
Postural Changes Accompany Perch Location Changes in Male Butterflies (Asterocampa leilia) Engaged in Visual Mate Searching
Authors: Rutowski Ronald L.
Published: March 2003

Males of the nymphalid butterfly Asterocampa leilia perch and wait during the morning at places where females are likely to appear. Males leave their perches to court passing females and chase away intruding males. As air and ground temperatures rise during the morning, males switch from perching on the ground to perching off the ground (average height = 0.87 m) for thermoregulatory reasons. To evaluate how this switch in perch location might affect mate detection, I have investigated how the three‐dimensional posture of the male's body and head varies with perch location and how conspecifics fly through male perching areas. The body posture of males varies with perch location, as measured by pitch and roll relative to gravity, and yaw relative to the sun. Moreover, the pitch and roll of the head relative to the body is adjusted in a way that compensates for variation in body pitch and roll. These results, along with information on conspecific flight altitudes, suggest that when a male is perched on the ground his visual system is positioned in such a way that he is less likely to detect conspecifics flying nearby than when he is perched off the ground. Hence, it appears that early in the morning visual detection of mates and intruding males may be compromised by thermoregulatory concerns.
Costs of Refuge Use Affect Escape Decisions of Iberian Rock Lizards Lacerta monticola
Authors: Martín José , López Pilar
Published: March 2003

Theoretical models of anti‐predator escape behaviour suggest that prey may adjust their escape response such that the optimal flight distance is the point at which the costs of staying exceed the costs of fleeing. Anti‐predatory decisions should be made based also on consequences for long‐term expected fitness, such as the costs of refuge use. For example, in lizards, the maintenance of an optimal body temperature is essential to maximize physiological processes. However, if unfavourable thermal conditions of refuges can decrease the body temperature of lizards, their escape decision should be influenced by refuge conditions. Analyses of the variation in flight distances and emergence latency from a refuge for the lizard Lacerta monticola under two different predation risk levels, and their relationship with the thermal environment, supported these predictions. When risk increased, lizards had longer emergence latencies, and thus costs of refuge use increased (a greater loss of time and body temperature). In the low‐risk situation, lizards that were farther from the refuge had longer flight distances, whereas thermal conditions were less important. When risk increased, lizards had longer flight distances when refuges were farther off, but also when the external heating rate and the refuge cooling rate were lower. The results suggest that, in addition to the risk of predation, expected long‐term fitness costs of refuges can also affect escape decisions.
Perception of Vocal Tract Resonances by Whooping Cranes Grus americana
Authors: Fitch W. Tecumseh , Kelley J. Patrick
Published: March 2003

Although formants (vocal tract resonances) can often be observed in avian vocalizations, and several bird species have been shown to perceive formants in human speech sounds, no studies have examined formant perception in birds’ own species‐specific calls. We used playbacks of computer‐synthesized crane calls in a modified habituation—dishabituation paradigm to test for formant perception in whooping cranes (Grus americana). After habituating birds to recordings of natural contact calls, we played a synthesized replica of one of the habituating stimuli as a control to ensure that the synthesizer worked adequately; birds dishabituated in only one of 13 cases. Then, we played the same call with its formant frequencies shifted. The birds dishabituated to the formant‐shifted calls in 10 out of 12 playbacks. These data suggest that cranes perceive and attend to changes in formant frequencies in their own species‐specific vocalizations, and are consistent with the hypothesis that formants can provide acoustic cues to individuality and body size.
‘Sympathetic Song’: the Silent and the Overt Vocal Repertoire, Exemplified with a Dueting Pair of the African Slate‐Coloured Boubou, Laniarius funebris
Authors: Seibt Uta , Wickler Wolfgang
Published: March 2003

In many bird species the total song repertoire consists of an overt repertoire normally uttered, and a silent repertoire produced only under special circumstances. A silent repertoire can be inferred from specific vocal responses of an individual to hearing parts of its own silent repertoire uttered by another bird (‘sympathetic song’). The silent repertoire plays a prominent role in dueting birds, in particular those with sex‐specific overt song repertoires, where the overt repertoire of one partner is the silent repertoire of the other. This is here exemplified with a pair of the slate‐coloured boubou L. funebris. Silent repertoires should be taken into consideration when relating the complexity of birds' vocal behaviour to the size or structure of their forebrain vocal control areas.
Male Alpine Chamois Occupy Territories at Hotspots Before the Mating Season
Authors: von Hardenberg Achaz , Bassano Bruno , Peracino Alberto , Lovari Sandro
Published: March 2003

Ungulate mating systems vary broadly both between and within species. Studies on mating systems in different habitats can provide clues to the ecological factors determining this diversity. Despite its abundance in the European Alps and its importance as a game species, surprisingly little is known about the mating system of Alpine chamois Rupicapra rupicapra rupicapra. We tested the hypothesis that adult males first defend mating territories in late spring, when females segregate from males and well before the Nov. rut. In the Gran Paradiso National Park (north‐western Italian Alps), adult males shared a winter range but occupied individual ranges in summer and early autumn. Males were more aggressive to each other in the summer than in the spring. A strong site fidelity from one year to the next was found for the summer and early autumn months. Those males that occupied the same territories both in the summer and during the rut (Nov.) appeared to be at hotspots, attractive to females during the rut because of reduced snow cover. Other males appeared to cluster around these hotspots during the rut. Territories that were first occupied during the summer were visited by more females than those that were not established until the rut began. Our results suggest that the mating system of this population of Alpine chamois consists of the early occupation of clustered mating territories. The early establishment of mating territories in areas frequented by females during the rut may lead to reproductive benefits for male chamois.
Confusion Effect in a Reptilian and a Primate Predator
Authors: Schradin Carsten
Published: March 2003

The confusion effect is claimed to be one benefit of group living with respect to predator avoidance: it is more difficult for predators to capture prey that is surrounded by other conspecifics than to capture an isolated individual. So far, the predictions of the confusion effect have been tested mainly in aquatic predators. As the confusion effect is seen to be a general problem for predators, terrestrial predators of two different vertebrate classes were used to test it. The prey (mealworms and black beetles, Tenebrio molitor) was harmless and had no chance of predator avoidance. Thus, confounding effects of group defence and enhanced vigilance were controlled. Both leopard geckos (Eublepharis macularius) and common marmosets (Callithrix jacchus) took longer to catch one out of several prey compared to one single prey. Leopard geckos showed more fixations (changing of head position) when confronted with 20 mealworms than when confronted with only one mealworm, thus showing indications of being ‘confused’.
Nest, but Not Egg, Fidelity in a Territorial Salamander
Authors: Peterson Megan G.
Published: March 2003

Egg recognition and subsequent egg brooding are costly forms of parental investment in many species of vertebrates. Life history factors, such as coloniality or risk of brood parasitism, may constrain egg recognition in vertebrates. Female red‐backed salamanders (Plethodon cinereus) from my study site are territorial and do not share nest sites with other females. They are terrestrial and neither they nor their eggs are likely to be displaced by environmental factors such as flooding. I experimentally tested, in the laboratory, the hypothesis that female red‐backed salamanders can discriminate between their own eggs and the eggs of unfamiliar females. Each female was allowed to move about a test chamber containing two clutches of eggs, one clutch with which it was found in the forest and one that had been found with a distant female. Most females remained with one clutch of eggs, which they brooded during the entire observation period. However, they did not significantly prefer to brood their own eggs over the eggs of another female. In a corollary field experiment, I tested whether brooding females that were displaced 1 m from their nest sites would return to their territories and commence brooding behaviour within 3 d. All 10 displaced females returned to their own nest within this time period and were found brooding their eggs. Because female red‐backed salamanders at my study site do not tend to share nest sites with other females and because their eggs remain in stationary nests, selection may not have favoured egg recognition. However, the results suggest that female salamanders indirectly recognize their own eggs by actively recognizing their territorial nest sites.
Acoustic Competition in Physalaemus pustulosus, a Differential Response to Calls of Relative Frequency
Authors: Bosch J. , Rand A. S. , Ryan M. J.
Published: March 2003

The response of the male túngara frog (Physalaemus pustulosus) to conspecific whines of different frequencies was examined. In the first series of playback experiments (fixed frequency), three types of synthetic stimuli were used, corresponding to calls of high frequency (HFF;
x + 2 SD), mid‐frequency (MFF;
x), and low frequency (LFF;
x− 2 SD) for the study population. In the second series of interactive playback experiments (relative frequency), whines of frequency relative to that of the male subject were used: male frequency + 2 SD (HRF), male frequency (MRF), and male frequency −2 SD (LRF). In the fixed frequency experiments, male vocal response did not vary among treatments. However, in the relative frequency experiments, males responded with more whines, and above all, with more chucks, to stimuli of similar or higher frequency than to stimuli of lower frequency than their own. In other words, male vocal competition escalates when competitors have whines with similar or relatively higher frequencies to their own, but does not increase when competitors have call frequencies that are at the mean or higher for the population. This differential response might result from competition between males of different sizes, since the frequency of the whine and male size is significantly correlated.
Microgeographic Variation and Sharing of the Gargle Vocalization and Its Component Syllables in Black‐Capped Chickadee (Aves, Paridae, Poecile atricapillus) Populations
Authors: Baker Myron C. , Howard Trina M. , Sweet Paul W.
Published: March 2003

Throughout the year during agonistic encounters, black‐capped chickadees (Poecile atricapillus) emit a vocal signal known as the gargle call. Each bird has a repertoire of structurally differing gargle calls; some are shared with others in the local area. As a basis for understanding the cultural evolution of this social signal, we initiated a study of gargle call repertoires of birds living in a narrow belt of continuous riparian habitat occupied throughout by a resident population of chickadees. During two consecutive winter seasons, we sampled repertoires at three locations over a distance of 8.4 km to quantify micro‐geographical variation. Analyses of vocal sharing and population differentiation were carried out on whole gargle calls and on the individual acoustic units (syllables) from which the whole calls are constructed. We analysed 28 380 calls of 46 subjects in the two seasons of study. Birds averaged 7.6 different calls in their gargle repertoires. Calls were composed of about 10 syllables on average. Fifty‐six different syllables were used to construct the calls of all birds. Each study site had some gargle calls unique to the local birds and some that were shared with one or both of the other two sites. There was significantly greater sharing of both calls and syllables among birds within sample sites than between sample sites. The frequencies of the different kinds of gargles and syllables were significantly correlated across the 2 yr of the study, but the correlation was stronger (r2 = 0.93) for syllables than for whole gargle calls (r2 = 0.61).
Changes In Rhesus Macaque ‘Coo’ Vocalizations during Early Development
Authors: Hammerschmidt Kurt , Newman John D. , Champoux Maribeth , Suomi Stephen J.
Published: March 2003

In order to test whether ‘coo’ calls of young rhesus macaques, Macaca mulatta, undergo some modifications during early development, and to explore which factors may influence these changes, we studied the ontogeny of their contact call, the ‘coo’ call. Vocalizations were recorded during brief periods of social separation. Infants were either raised with their mothers and other conspecifics, or separated from their mothers at birth and housed in a nursery with other infants. We recorded calls uttered in the separation context from 20 infants. We digitized the first 50 calls of a given series and subjected them to a Fourier transform. From each frequency–time spectrum, we extracted 65 acoustic parameters using a software program (LMA 5.9). We then used a cluster analysis to separate the ‘coo’ calls from other call types. With increasing age, the ‘coos’ dropped in pitch and became more even. The course of amplitude became more constant and the call duration increased slightly. Nevertheless, we found a high intra‐individual variation throughout the 5 mo. Neither rearing condition nor sex had any apparent influence on age‐related changes in ‘coo’ structure. With one exception, all parameters that correlated with age could be explained by variation in weight. Therefore, we conclude that growth is the main factor accounting for the observed changes.
Consortship and Mating Success in Chacma Baboons (Papio cynocephalus ursinus)
Authors: Weingrill T. , Lycett J. E. , Henzi S. P.
Published: March 2003

Chacma baboons (Papio cynocephalus ursinus) show a lower consortship take‐over rate and longer consortship duration than the other savannah baboons (Bulger 1993). It has been argued that researchers have focused on atypically small troops with few adult males, resulting in low competition for access to oestrous females. Consortship data from two mountain baboon troops containing seven and four males, respectively, were analysed to determine whether the troop with the greater number of males showed a weaker correlation between mating success and rank due to an expected higher consortship take‐over rate. No consort take‐overs were observed in either study troop and mating success in both troops was correlated strongly with male rank. The distribution of days spent in consortship amongst the males could be explained by the priority‐of‐access‐model. The degree of cycle overlap determined the number of males observed consorting oestrous females, whereas the number of males did not influence the relationship between rank and consorting activity.
Insemination Capacity and Dispersal in Relation to Sex Allocation Decisions in Goniozus legneri (Hymenoptera: Bethylidae): Why Are There More Males in Larger Broods?
Authors: Hardy Ian C. W. , Stokkebo Stinne , Bønløkke‐Pedersen Jesper , Sejr Mikael K.
Published: March 2003

Models considering sex ratio optima under single foundress strict local mate competition predict that female bias will be reduced by stochasticity in sex allocation, developmental mortality of males and limited insemination capacity of males. In all three cases the number of males per brood is expected to increase with brood size. Sex ratio optima may also be less female biased when several mothers contribute offspring to local mating groups or if non‐local mating occurs between members of different broods; again more males are expected in larger broods. In the parasitoid wasp Goniozus legneri (Hymenoptera: Bethylidae), sex allocation has only a small stochastic component, developmental mortality is low and non‐siblings are unlikely to develop in the same brood. However, the number of males per brood increases with the size of the brood (produced by a single mother). We investigated the further possibilities of limited insemination capacity and non‐local mating using a naturalistic experimental protocol. We found that limited insemination capacity is an unlikely general explanation for the increase in number of males with brood size. All males and females dispersed from both mixed and single sex broods. Although most females in mixed sex broods mated prior to dispersal, these data suggest that non‐local mating is possible, for instance via male immigration to broods containing virgin females. This may influence sex ratio optima and account for the trend in male number.
Call Intensity and Female Preferences in the European Green Toad
Authors: Castellano Sergio , Rosso Alessandra , Laoretti Francesca , Doglio Stefano , Giacoma Cristina
Published: March 2003

In the present paper we study the pattern of variation in call intensity in a natural population of the European green toad (Bufo viridis), and we analyse females preferences for this property by means of playback experiments. Although call sound pressure level (SPL) shows little within‐bout variation, we found significant positive correlation between call SPL and fundamental frequency: on average, an increase of 6 dB SPL produces a 100‐Hz increase in fundamental frequency. When females were given a choice between two calls differing by 10 and 6 dB SPL, they significantly preferred the loudest call, whereas they did not discriminate between calls differing by 3 dB. To test whether a 3‐dB difference reflects a sensory or behavioural limit, we carried out three experiments where females were given a choice between two calls differing in both duration (4 s and 6 s, respectively) and SPL (3 dB). In all three experiments, the longer call attracted a larger number of females, but the 3‐dB difference did not show any significant effect. Finally, we investigated the relationships between call intensity and frequency on female preferences. Previous experiments showed size‐dependent preferences for calls with lower‐than‐average frequencies (1.3 kHz) over calls with higher‐than‐average frequencies (1.6 kHz). Here, we show that this weak preference is abruptly reversed when the highest‐pitched call is broadcast at an intensity 6 dB higher than the alternative.
Learning Differences between Feral Pigeons and Zenaida Doves: The Role of Neophobia and Human Proximity
Authors: Seferta Angela , Guay Patrick‐Jean , Marzinotto Erika , Lefebvre Louis
Published: March 2003

Learning differences predicted from ecological variables can be confounded with differences in wariness of novel stimuli (neophobia). Previous work on feral pigeons (Columba livia), as well as on group‐feeding and territorial zenaida doves (Zenaida aurita), reported individual and social learning differences predicted from social foraging mode. In the present study, we show that speed of learning a foraging task covaries with neophobia and latency to feed from a familiar dish in the three types of columbids. Pigeons were much faster than either territorial or group‐feeding zenaida doves on all tests conducted in captivity, but showed unexpectedly strong neophobia in some urban flocks during field tests. Human proximity strongly affected performance in group‐feeding doves both in the field and in captivity. They were slightly faster at learning than their territorial conspecifics in cage tests. In multiple regressions, species identity, but not social foraging mode, significantly predicted individual variation in learning, as did individual variation in neophobia. Wariness of novel stimuli and species differences associated with artificial selection appear to be more important than foraging mode and wariness of humans in accounting for learning differences between these columbids.
Motion, not Shape, Facilitates Association of Predation Risk with Novel Objects by Fathead Minnows (Pimephales promelas)
Authors: Wisenden Brian D. , Harter Katherine R.
Published: March 2003

Injury‐released chemical cues are reliable indicators of predation risk among many aquatic taxa. When a novel, neutral stimulus is presented in tandem with chemical cues from an injured conspecific, an association is formed between the novel stimulus and apparent risk. Learned recognition of predation risk is well documented for fathead minnows, Pimephales promelas. When minnows detect alarm cues in nature they are also potentially exposed to multiple environmental stimuli, few of which are likely to be relevant indicators of risk. How do minnows discern among candidate stimuli potentially associated with predation risk? Two possibilities are shape and motion. In this study, individual piscivore‐naïve minnows were presented simultaneously with conspecific chemical alarm cues and two stimulus objects. One object was a darkened tube with its long axis in the horizontal plane (fish‐like). The second object was a black disk. Following introduction of chemical alarm cues, one of the objects was raised and lowered repeatedly. After a single conditioning trial, minnows associated risk significantly more with the previously moving object than the previously stationary object, as indicated by reduced activity. Object shape had no significant effect on response intensity in test trials. Our data suggest that minnows have been selected to form aversive responses to moving objects at a site of recent predation because movement is a more predictable indicator of predator identity than shape.
Food Transfer and Development of Feeding Behavior and Food‐Associated Vocalizations in Cotton‐Top Tamarins
Authors: Roush Rebecca S. , Snowdon Charles T.
Published: March 2003

Food transfer between adults and infants is common in many marmoset and tamarin monkeys, and is often accompanied by vocalizations. We hypothesized that vocalizations by adults in a food transfer context creates an opportunity for infants to learn not only what foods are appropriate but what vocalizations are appropriate in feeding contexts. We studied the development of feeding behavior and food‐associated vocalizations in 10 infant cotton‐top tamarins through the first 20 wks of life. Infants obtained solid food through transfers from older group members, primarily the adult male, beginning at weeks 5–6. Both adults and infants vocalized during food transfers with adults, producing rapid sequences of the call types adults normally give when feeding. Infants were usually successful in obtaining food primarily when the adult was vocalizing. The sooner infants were active participants in food transfers, the sooner they began to feed independently. In the early weeks, infants produced a large number of vocal types during food transfers, but with increasing age there was a steady increase in the number of adult‐form food calls and a reduction in other, non‐food‐associated calls. Infants that fed independently at an early age produced fewer non‐food‐associated calls by the last month of observation. Infants called at higher rates to their most preferred food. Food transfers accompanied by vocalizations may provide an opportunity for infants to learn about appropriate foods as well as the vocalizations that accompany feeding in adults, and may represent a form of ‘coaching’ or information donation by adults.