The formation and execution of sequential plans in pigeons (Columba livia)

The ability to formulate and execute plans is a hallmark of human behaviour. Here we present evidence of planning in pigeons. Subjects were trained to respond to three geometric shapes in a prescribed order. Probe trials were then introduced in which, following a response to the first item, the on screen positions of the second and third item were exchanged. If subjects were planning a sequence of responses at the outset of a trial, we would expect reaction time to the second item to increase, reflecting the updating of a predetermined response plan. This is exactly what was found. Subjects also responded correctly on trials in which, following a response to the first item, stimuli were covered by opaque white squares. Together these results suggest pigeons are able to plan one step ahead on the simultaneous chaining paradigm.     

Response strategies during acquisition of serial learning in pigeons (Columba livia)

Pigeons were exposed on fixed duration sessions to four chromatic stimuli and trained to perform a 2-item sequence. A detailed analysis of incorrect responses performed on each trial prior to completion of the sequence led to distinguish three learning stages. Already on initial sessions animals responded significantly more frequently to relevant stimuli than to irrelevant ones indicating stimulus control by salience. During an intermediary stage, responding to item 2 increased significantly and animals started an increasing number of trials with item 2, suggesting stimulus control by recency. On the final session the correct sequence outnumbered significantly the reverse sequence, suggesting control by order, while recency and salience effects were present to a lesser extent. Repeated pecks, i.e. consecutive pecks on the same cue, occurred on the four cues on the first session and decreased significantly on the last session for irrelevant colours. In addition, when key pecks were followed by a brief sound signal, repeats on relevant stimuli decreased while efficient colour pecks (i.e. when repeats were ignored) on these stimuli increased. These findings are discussed in the light of those obtained in traditional chaining paradigms.     

Some characteristics of spatial associative memory in the pigeon, Columba livia

Willson and Wilkie (1993) developed a novel procedure to assess pigeons' memory for the spatial location of food. Only one of four locations provided food each daily session. Each location consisted of an illuminated pecking key and grain feeder. Over different days different locations, randomly selected, provided food during a 16-min session. The pigeons tended to revisit the location at which food was found on the previous day thereby demonstrating memory for food-spatial location associations over 24 h. Three experiments were conducted to further investigate this phenomenon. In Experiment 1 the session duration was varied between 4 and 32 min. Longer sessions had no detectable effect on their ability to remember the rewarded location 24 h later, a result that suggests that only brief encounters with food at a particular location are necessary for recall. In Experiment 2 the necessity of an active search for the day's rewarded location was removed; a 5-min period in which only the rewarded key was lit preceded the regular 16-min session. Pecks to the lit key in this 5-min period produced grain on the standard schedule. This manipulation facilitated the pigeons' discovery of food but did not affect their ability to remember the rewarded location, suggesting that the process of search and discovery is not essential to the associative memory process. In Experiment 3, food was available during the complete session (non-depleting condition) or was available only during the first half of the session (depleting condition). No detectable differences in the birds' memory of yesterday's profitable location were found. This suggests that non-depletion of food is not a necessary condition for day-to-day recall of food location. Taken together these findings enlarge our understanding of the spatial associative memory process.     

Courtship as a reinforcement for key pecking in the pigeon, Columba livia

This report describes a within-subjects comparison of the reinforcing effects of food and display on a single response, key pecking. Three male pigeons socially isolated and food deprived for 22 hr pecked a key-light when pecks resulted in a brief sighting of their respective mates. Pecks to a second key-light concurrently available resulted in brief food rewards. Responses to the female key had a greater latency than responses to the food key, irrespective of the nature of the preceding reinforcement. The two responses also differed in their form and in the extent to which they were accompanied by other behaviours performed around the key-lights. This is discussed in terms of both response-reinforcer interaction and the intrusion of Pavlovian conditioning effects.     

The peeping response of pigeons (Columba livia) to isolation from conspecifics and exposure to a novel environment

The present study examined the acute behavioral responses of pigeons to separation from conspecifics and exposure to an unfamiliar environment (UE). The effects of (1) repeated exposure to the UE; (2) visual isolation from surroundings, or saline injections; and (3) diazepam treatment (i.p., 0.25, 0.75, 2.5 or 7.5 mg/kg) before the trial were also examined. UE exposure evoked intense ballistic head movements (peeping), gradually replaced with angular head movements (AHM), both associated with immobility of the trunk and legs. These behaviors failed to habituate after three trials (7-day intertrial intervals). Visual isolation from the surroundings and saline injection prior to exposure to the UE increased the AHM and reduced peeping. Doses of diazepam (0.25 and 0.75 mg/kg) that have demonstrated anti-conflict effects in other tests did not affect the behavioral responses to the UE. Diazepam at 2.5 and 7.5 mg/kg doses consistently increased time spent in immobility. These data suggest that peeping, although expressed in potentially threatening or harmful situations appears not to be a fear-motivated behavior or, alternatively, this specific behavioral response is not diazepam sensitive.     

The distribution of mallophaga on the domestic pigeon (Columba livia)

The distribution of Hohorstiella lata, Colpocephalum turbinatum, Campanulotes bidentatus compar, and Comlumbicola columbae on domestic pigeons were determined. Each species laid its eggs on a different part of the body but all fed on the fluffy part of the body feathers. H. lata also fed on blood, and C. turbinatum on its own eggs and nymphs. Reduction of the efficiency of preening led to an increase in the number of lice and more widespread distribution of nymphs and adults but not to a rapid change in the distribution of eggs. It is suggested that preening has played a major selective role, and that the morphological and behavioural adaptions of the lice are to ensure that they and their eggs survive this type of predation.     

Pigeons’ (Columba livia) hierarchical organization of local and global cues in touch screen tasks

Redundant encoding of local and global spatial cues is a common occurrence in many species. However, preferential use of the each type of cue seems to vary across species and tasks. In the current study, pigeons (Columba livia) were trained in three experiments on a touch screen task which included redundant local positional cues and global spatial cues. Specifically, pigeons were required to choose the middle out of three choice squares, such that the position within the array provided local information and the location on the screen provided global information. In Experiment 1, pigeons were trained and tested on vertically aligned arrays. In Experiment 2, pigeons were trained and tested on horizontally aligned arrays, and in Experiment 3, pigeons were trained and tested with vertical, horizontal and diagonally aligned arrays. The results indicate that preference for cue type depends upon the type of spatial information being encoded. Specifically, on vertical and diagonally aligned arrays, pigeons preferred global cues, whereas on horizontally aligned arrays, pigeons preferred local cues.     

Rats (Rattus norvegicus) and pigeons (Columbia livia) are sensitive to the distance to food,but only rats request more food when distance increases

Three experiments investigated foraging by rats and pigeons. In Experiment 1, each response on a manipulandum delivered food to a cup, with the distance between the manipulandum and the cup varying across conditions. The number of responses made before traveling to collect and eat the food increased with distance for rats, but not for pigeons. In Experiment 2, two manipulanda were placed at different distances from a fixed food source; both pigeons and rats preferentially used the manipulandum closest to the food source. Experiment 3 was a systematic replication of Experiment 1 with pigeons. In different conditions, each peck on the left key increased the upcoming hopper duration by 0.5, 1.5 or 2.5 s. Completing a ratio requirement on the right key of 1, 4, 8, 16 or 32 pecks, depending on the condition, then produced the food hopper for a duration that depended on the number of prior left pecks. As the ratio requirement increased on the right key, pigeons responded more on the left key and earned more food. Overall, the results replicate previous research, underlining similarities and differences between these species. The results are discussed in terms of optimal foraging, reinforcer sensitivity and delay discounting.     

Social cognition: imitation, imitation, imitation

Monkeys recognize when they are being imitated, but they seem unable to learn by imitation. These facts make sense if imitation is seen as two different capacities: social mirroring, when actions are matched and have social benefits; and learning by copying, when new behavioural routines are acquired by observation.     

Recent advances in the cryopreservation of shoot-derived germplasm of economically important fruit trees of Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis

This paper presents the advances made over the last decade in cryopreservation of economically important vegetatively propagated fruit trees. Cryopreservation protocols have been established using both dormant buds sampled on field-grown plants and shoot tips sampled on in vitro plantlets. In the case of dormant buds, scions are partially dehydrated by storage at − 5 °C, and then cooled slowly to − 30 °C using low cooling rates (c.a. 1 °C/h) before immersion in liquid nitrogen. After slow rewarming and rehydration of samples, regrowth takes place either through grafting of buds on rootstocks or excision of apices and inoculation in vitro. In the case of shoot tips of in vitro plantlets, the cryopreservation techniques employed are the following: controlled rate cooling procedures involving slow prefreezing followed by immersion in liquid nitrogen or vitrification-based procedures including encapsulation–dehydration, vitrification, encapsulation–vitrification and droplet-vitrification. The current status of cryopreservation for a series of fruit tree species including Actinidia, Diospyros, Malus, Olea, Prunus, Pyrus and Vitis is presented. Routine application of cryopreservation for long-term germplasm storage in genebanks is currently limited to apple and pear, for which large cryopreserved collections have been established at NCGRP, Fort Collins (USA), using dormant buds and in vitro shoot tips, respectively. However, there are a growing number of examples of pilot scale testing experiments under way for different species in various countries. Progress in the further development and application of cryopreservation techniques will be made through a better understanding of the mechanisms involved in the induction of tolerance to dehydration and cryopreservation in frozen explants.     

Iridoid glucosides in Griselinia, Aralidium and Toricellia

From three of five investigated species of Griselinia a new iridoid glucoside, griselinoside, was isolated. It was found to be present also in foliage of Aralidium pinnatifidum and Toricellia angulata, accompanied in the former by aralidioside another novel iridoid glucoside. The structures and absolute configurations of the two iridoids were elucidated by NMR spectroscopy and chemical conversions. From G. littoralis and T. angulata the glucosides magnolioside and syringoside respectively were isolated. ¹³C NMR spectra are given for thirteen iridoid derivatives.     

Extrachromosomal DNA in Bacillus thuringiensis var. kurstaki, var. finitimus, var. sotto, and in Bacillus popilliae

Four entomopathogenic bacteria contained extrachromosomal deoxyribonucleic acid (DNA) molecules of various sizes. Bacillus thuringiensis var. kurstaki contained twelve elements banding on agarose gels that ranged from 0.74 to > 50 × 10⁶ daltons, three of which were giant extrachromosomal DNA elements. B. thuringiensis var. sotto contained one giant extrachromosomal DNA element with a molecular size of about 23.5 × 10⁶ daltons and two lesser elements of 0.80 and 0.62 × 10⁶ daltons. B. thuringiensis var. finitimus harbored two giant DNA elements corresponding to >50 × 10⁶ daltons and two lesser bands with relative small size (0.98 and 0.97 × 10⁶ daltons). B. popilliae contained no giant extrachromosomal DNA elements but did contain two smaller elements corresponding to 4.45 and 0.58 × 10⁶ daltons. The possible use of extrachromosomal DNA elements that prove to be autonomous replicons for recombinant DNA studies is discussed.     

Comparative analysis of GT14/GT14-like gene family in Arabidopsis, Oryza, Populus, Sorghum and Vitis

Glycosyltransferase family14 (GT14) belongs to the glycosyltransferase (GT) superfamily that plays important roles in the biosynthesis of cell walls, the most abundant source of cellulosic biomass for bioethanol production. It has been hypothesized that DUF266 proteins are a new class of GTs related to GT14. In this study, we identified 62 GT14 and 106 DUF266 genes (named GT14-like herein) in Arabidopsis, Oryza, Populus, Sorghum and Vitis. Our phylogenetic analysis separated GT14 and GT14-like genes into two distinct clades, which were further divided into eight and five groups, respectively. Similarities in protein domain, 3D structure and gene expression were uncovered between the two phylogenetic clades, supporting the hypothesis that GT14 and GT14-like genes belong to one family. Therefore, we proposed a new family name, GT14/GT14-like family that combines both subfamilies. Variation in gene expression and protein subcellular localization within the GT14-like subfamily were greater than those within the GT14 subfamily. One-half of the Arabidopsis and Populus GT14/GT14-like genes were found to be preferentially expressed in stem/xylem, indicating that they are likely involved in cell wall biosynthesis. This study provided new insights into the evolution and functional diversification of the GT14/GT14-like family genes.     

First records of flower biology and pollination in African Annonaceae: Isolona, Piptostigma, Uvariodendron, Monodora and Uvariopsis

Seven species from five genera of Annonaceae were studied with regard to their flower biology and pollination in the Southwest Province of Cameroon, West Africa. They have protogynous hermaphroditic flowers, with exception of Uvariopsis species, which are monoecious. Fused petals of Isolona campanulata remain apically spreading and open during anthesis but form a deep basal urceolate tube around the reproductive organs. At anthesis the yellow pendent flowers emit a fruit-like scent and attracted small beetles, the likely pollinators. Piptostigma sp. flowers also emit a fruit-like scent but provide a closed pollination chamber formed by the three inner petals. Small staphylinid beetles attracted during the female stage of anthesis are released from the flowers at the end of the male stage 2-3 days later. Both species have diurnal anthesis, attracting and releasing the flower visitors during daytime. In contrast, Uvariodendron connivens and U. calophyllum have nocturnal anthesis with floral thermogenesis, produce spicy, aromatic and fruity scents and attract large Scarabaeidae beetles, the pollinators, along with many curculionid beetles, which were principally predators of the thick petals. The very large flowers of Monodora tenuifolia have yellowish petals which are spotted with dark red markings. Together with the sweetish, slightly disagreeable scent the flowers attract flies, principally dung flies. The two investigated Uvariopsis species are monoecious with pistillate and staminate flowers being functional at the same time. The violet red flowers of U. bakeriana visually seem to mimic the fruiting body of certain stinkhorn fungi (Phallaceae) although without producing their strong unpleasant carcass stench. Flower-visiting dung flies were rare. Conversely, U. congolana has a strong fungus-like scent, its flowers are presented at litter height and dung flies living in the litter were the flower visitors, albeit sporadic. The 4-5 days lasting anthesis of both Uvariopsis species appears to be an evolutionary consequence of their diffuse pollinator spectra. The studied African Annonaceae therefore have either cantharophilous or myiophilous/sapromyiophilous flowers with, in part, respectively, remarkably long anthesis, thermogenesis, and widely open, large flowers - all attributes unknown or rare in the hitherto better studied Neotropical Annonaceae.     

Interconversion of trans, trans and cis, trans farnesol by enzymes from Andrographis

When trans, trans-farnesol [4,8,12-¹⁴C₃,1-³H₂] is isomerized to cis, trans-farnesol by soluble enzymes from Andrographis paniculata tissue cultures, 50% of the tritium label is lost. The same loss is observed when isomerization occurs in the opposite direction. This is in accordance with the proposed mechanism for isomerization via aldehydes.     

Nitrogen-containing non-steroidal secondary metabolites of Solanum, Cyphomandra, Lycianthes and Margaranthus

Of the 49 species of Solanum studied, cuscohygrine has been detected in 25, solamine and related amines in 17 and solamine-derived amides in 16. Five species of Cyphomandra examined all contained both amines and amides. From roots of Margaranthus solanaceus cuscohygrine has been isolated which probably occurs, too, in roots of Lycianthes rantonnettii. The distribution of these compounds throughout the taxa could be of chemotaxonomic value.     

Learning and imitation as a function of social status in macaque monkeys (Macaca nemestrina)

Learning and imitation were examined in animals selected from two groups of sixteen pigtail monkeys. There were significant differences in performance on a cued-alternation task as a function of both social status within the stable group, and prior exposure to a social model. High status animals responded more frequently, but were less successful in acquiring appropriate response delay. Exposure to the model improved response latencies and acquisition of response delay for all subjects. However, model exposure did not improve alternation performance. Results are discussed in terms of prior social experience of the subjects, general learning strategies, and differential sensitivity to multiple reinforcement contingencies. Findings are related to ethological concepts of imitation, and field reports on primate social learning.