Effects of Passage Through Tamarin Guts on the Germination Potential of Dispersed Seeds

Passage through tamarin guts may have an effect on seed germination potential. To examine these effects, and the variation between 2 sympatric tamarin species, we studied Saguinus mystax and S. fuscicollis in northeastern Peruvian Amazonia. For most of 39 plant species, neither germination success nor latency was modified by gut passage. Neutral effects on seed germination potential suggest that tamarins may fulfill criteria for effective seed dispersal.     

Reactions of wild tamarins,Saguinus mystax andSaguinus fuscicollis to avian predators

During a field study in northeastern Peru, the reactions of a group ofSaguinus mystax on Padre Isla and of a mixed-species troop ofS. mystax andSaguinus fuscicollis at the Río Blanco to raptorial and other birds were observed. Alarms that are specific to flying stimuli were elicited by birds of prey, but other birds that do not represent a threat to the tamarins also caused alarm calls. Alarm events (i.e., instances when one or more alarm calls were given) were observed at rates of 0.3/hr (Padre Isla) and 0.5/hr (Río Blanco). Rates of alarm events significantly increased after the birth of an infant in the Padre Isla group and after the attack of an ornate hawk-eagle (Spizaetus ornatus) on the Río Blanco group. Reactions to alarming stimuli/alarm calls ranged from looking up to falling down from trees. The modification of the tamarins' behavior by the potential presence of aerial predators indicates that raptors represent an important predatory threat to tamarins.     

Effects of support size and orientation on symmetric gaits in free-ranging tamarins of Amazonian Peru: implications for the functional significance of primate gait sequence patterns

The adoption of a specific gait sequence pattern during symmetrical locomotion has been proposed to have been a key advantage for the exploitation of the fine branch niche in early primates. Diverse aspects of primate locomotion have been extensively studied in technically equipped laboratory settings, but evolutionary conclusions derived from these investigations have rarely been verified in wild primates. Bridging the gap from the lab to the field, we conducted an actual performance determination of symmetrical gaits in two free-ranging tamarin species (Saguinus mystax and Saguinus fuscicollis) of Amazonian Peru by analyzing high-speed video recordings of naturally occurring locomotor bouts. Tamarins arguably represent viable models for aspects of early primate locomotion. We tested three specific hypotheses derived from laboratory studies to test for the influence of support size and orientation and to gain further insight into the functional significance of primate gait sequence patterns: (1) The tamarins utilize symmetrical gaits at a higher rate on small supports than on larger ones. (2) During symmetrical locomotion on small supports, diagonal sequences are utilized at a higher rate than on larger supports. (3) On inclines, diagonal sequences are predominantly used and on declines, lateral sequences are predominantly used. Our results corroborated hypotheses 1 and 3. We found no clear support for hypothesis 2. In conclusion, our results add to the notion that primate gait plasticity, rather than uniform adoption of diagonal sequence gaits, enabled early primates to accommodate different support types and effectively exploit the small branch niche.     

An experimental investigation of the pair bond in the callitrichid monkey,Saguinus labiatus

The strength and specificity of attraction between mated pairs of red-bellied tamarins (Saguinus labiatus) were tested in the laboratory. Test individuals were placed in a choice situation in which they could indicate their preference, by proximity and quality of behavior measures, to either their pair mate in an adjoining cage or an alternative in a second adjoining cage (same-sex animal, opposite-sex animal, or an empty cage). The test animals showed a significant preference to be in visual contact and proximity with their pair mates instead of the alternative when it was an animal of the same sex as the test individual or an empty cage. However, when the choice was between their pair mate and an animal of the opposite sex, no preference for their pair mate was apparent. No sex differences were found. It is concluded that attraction to a pair mate is not sufficient to maintain a pair bond, and when pairs ofS. labiatus breed monogamously, the pair relationship is likely to be maintained, at least in part, through aggression between same-sex individuals.     

Social behavior of the emperor tamarin in captivity: Components of agonistic display and the agonistic network

Agonistic behavior was studied longitudinally for 16 months in an intact family groups of captive emperor tamarins (Saguinus imperator subgrisescens) using methods from quantitative ethology and social network analysis. A motivational analysis of the components of agonistic display revealed the relative strength of each component along a continuum from strongly dominant to strongly subordinate. Tabulations of exchanges of strongly dominant and strongly subordinate components in interactions among the tamarins revealed an agonistic network (“dominance hierarchy”) that approached, but did not quite reach, the ideal state of a transitive order (“linear dominance hierarchy”). The frequency with which individual tamarins long called and scent marked was not closely correlated with their position (“dominance rank”) in the agonistic network. Instead, individuals undergoing change in status long called and scent marked frequently, irrespective of their rank.     

Biochemical diversity and genetic distance in two species of the genusSaguinus

A comparative study of 20 blood genetic systems was performed on three populations of genusSaguinus: S. fuscicollis weddelli, S. midas niger, andS. midas midas. Some markers are useful for the characterization of the two species.ADA ⁵, ADA⁶, CA2³, CA2⁴, andES2 ² occur only inS. fuscicollis whileADA ⁴is fixed inS. midas. S. midas midas showed heterozygosity value comparable to those previously obtained for the genusAlouatta. Estimates of genetic distance betweenS. fuscicollis andS. midas species of about 14% are in accordance with those referred to in the literature for interspecific differences. Genetic distances between subspecies ofSaguinus midas were nearly 3%, which is within the range for subspecies.     

Characterization and Social Correlates of Fecal Testosterone and Cortisol Excretion in Wild Male <Emphasis Type="Italic">Saguinus mystax</Emphasis>

Reproductive success in male primates can be influenced by testosterone (T) and cortisol (C). We examined them in wild Saguinus mystax via fecal hormone analysis. Firstly, we wanted to characterize male hormonal status over the course of the year. Further we tested the influence of the reproductive status of the breeding female, social instability, and intergroup encounter rates on T levels, comparing the results with predictions of the challenge hypothesis (Wingfield et al., 1990). We also tested for interindividual differences in hormonal levels, possibly related to social or breeding status. We collected data during a 12-mo study on 2 groups of moustached tamarins at the Estación Biológica Quebrada Blanco in northeastern Peru. We found fairly similar T and C levels over the course of the year for all males. Yet an elevation of T shortly after the birth of infants, during the phase of ovarian inactivity of the groups breeding female, was evident. Hormonal levels were not significantly elevated during a phase of social instability, did not correlate with intergroup encounter rates, and did not differ between breeding and nonbreeding males. Our results confirm the challenge hypothesis (Wingfield et al., 1990). The data suggest that reproductive competition in moustached tamarins is not based on endocrinological, but instead on behavioral mechanisms, possibly combined with sperm competition.     

A field study on the red-bellied tamarin,Saguinus l. labiatus,in Bolivia

A 5-month field study was conducted on red-bellied tamarins,Saguinus labiatus labiatus, in the Pando Department of northern Bolivia. Group sizes ranged from 5 to 10 animals, and each group associated with a group of saddle-backed tamarins,Saguinus fuscicollis weddelli. Members of three groups were trapped and marked and data were collected by radiolocation. The average range size used over 10 days was 19 ha. On average the groups entered about 29% of their range each day and had a mean daily path length of about 1487 m. The groups used a number of different sleeping sites within their ranges. They fed on a variety of different fruits and also on nectar from flowers, resin, and insects. Areas within the home range which were used significantly more than expected were generally those in which one or more of the following existed: a sleeping site, an intergroup encounter site, or a site where the group took shelter during an extended period of heavy rain.     

Social behaviour and infant carrying in a group of moustached tamarins,Saguinus mystax (primates: Platyrrhini: Callitrichidae), on Padre Isla,Peruvian Amazonia

The social behaviour of a group of eight moustached tamarins,Saguinus mystax, (five males, three females) was studied on Padre Isla in northeastern Peru. About 60% of all allogrooming was done by the two adult males in the group, and about 11% by a young adult female. All other group members groomed very little. The adult breeding female received more grooming than any other group member. After the death of the adult female (preyed upon by an anaconda) the amount of active allogrooming remained constant for all group members except for the young adult female, who increased her contribution to about 30%. Her preferred grooming partner was the subadult female, which generally screamed when being groomed by the young adult female and terminated grooming by going away. This kind of grooming relation is termed “forced grooming” and is interpreted as a possible social control mechanism. The young adult female groomed the adult males more often after the death of the adult female than before. This might have had the function of strengthening the social bond with the adult males and in obtaining the breeding position in the group. After the death of the adult female, the vulva of the young adult female grew to full adult size. Agonistic behaviour was less frequent than allogrooming. Most aggressive interactions (50%) originated from the subadult male of the group. The young adult female was the target of most of these aggressions. Extremely little aggression occurred between the three females. The young adult female was the only individual who tried to emigrate from the group during the study period. Her attempt to join a neighbour group failed due to rejection by all four members of this group. All group members participated in carrying an infant, but the adult males and the young adult female carried most frequently. Contribution to infant carrying varied with the infant's age.     

Proposed nutritional importance of plant exudates in the diet of the Panamanian Tamarin,Saguinus oedipus geoffroyi

Data collected on the feeding behavior of Saguinus oedipus geoffroyi(Panamanian tamarin) in Panama show that plant exudates, as well as insects and fruits, are a major component of the diet. During the months of May, June, and July, tamarins were observed clinging to the trunks of Anacardium excelsum(Anacardiaceae) while feeding on exudates. These observations accounted for greater than 14% of the total feeding time of this primate. Nutritional analyses indicate that Anacardiumexudates provide these tamarins with a rich source of the mineral calcium as well as protein, carbohydrates, and water. The seasonal pattern of exudate feeding observed in S. oedipusappears to coincide with certain nutritionally sensitive periods of the reproductive cycle and may serve to offset a potential mineral imbalance incurred during the terminal phase of gestation and lactation.     

A New Subspecies of <Emphasis Type="Italic">Saguinus fuscicollis</Emphasis> (Primates,Callitrichidae)

Saddleback tamarins (Saguinus fuscicollis, S. melanoleucus, and S. tripartitus) occur in the upper Amazon, west of the rios Madeira and Mamoré–Guaporé to the Andes. They currently comprise 13 species and subspecies in Bolivia, Brazil, Colombia, Ecuador, and Peru. Here we report on a previously undescribed subspecies of Saguinus fuscicollis from the interfluvium of the lower rios Madeira and Purus in the central Amazon of Brazil. It is a distinct form with a very pronounced mottling on the back giving the appearance of a saddle, a characteristic shared by the 3 species, and the reason for their collective common name. The lack of a white superciliary chevron and its highly mottled ochraceous-dark brown to black saddle that extends from the scapular region to the base of the tail distinguish the new taxon from Saguinus fuscicollis weddelli. The latter characteristic also distinguishes it from another saddleback tamarin (Saguinus fuscicollis ssp.) that has been reported immediately to the south of its range in the same interfluvium. We compare pelage coloration, external characters and craniometric measurements with its geographically closest relatives, Saguinus fuscicollis weddelli and S. f. avilapiresi, and indicate its probable geographic distribution in a small area between the rios Madeira and Purus, just south of the Rio Amazonas.     

Patterns of range use,range defense,and intergroup spacing in moustached tamarin monkeys (Saguinus mystax)

In this paper we examine patterns of group spacing and habitat utilization in neighboring groups of marked free-ranging moustached tamarin monkeys (Saguinus mystax) inhabiting Padre Isla, a small island in the Amazon Basin of northeastern Peru, and describe the set of behavioral mechanisms used by tamarins to maintain the spatial isolation and social integrity of individual groups. Specifically, we address a series of questions regarding the importance of resource defense, mate defense, and territorial defense in intergroup interactions. From June through November 1990, we recorded 67 intergroup interactions involving members of our two main study groups. These interactions occurred at a rate of .14/observation hour and were of two general types. Vocal battles averaged 18 min in duration and were characterized by a series of high frequency, short syllable, long calls that were exchanged between groups separated by distances of greater than 25 m. Aggressive encounters averaged 26 min in duration and involved visual contact, alarm calls, scent marking, and sequences of chases and retreats. Intergroup confrontations did not cluster around the perimeter of a group's home range, and there was no evidence that moustached tamarins patrolled range borders. Our data indicate that 35% of aggressive encounters occurred in the vicinity of major feeding trees. Priority access to these sites is likely to have an important influence on tamarin foraging success. Mate defense and the exploration of new breeding opportunities also appear to be important functions of intergroup conflicts. Not only did the frequency of aggressive encounters increase during breeding periods, but three-fourths of all observed copulations occurred during or within 30 min of an encounter. Given the high degree of reproductive competition reported among tamarin females and the time and energy group members devote to intergroup aggression, maintaining access to a stable home range and the resources contained within that range appear to be critical functions of moustached tamarin social interactions.     

Urine washing and related behaviour in wild moustached tamarins,Saguinus mystax (callitrichidae)

Urine washing (UW) and urinating onto hand (UH) are reported for the first time for a wild callitrichid monkey, the moustached tamarin,Saguinus mystax. Both patterns are very rare and no sex difference in frequency is apparent. The temporal distribution shows a maximum of UH/UW around midday when ambient temperature is at maximum and humidity at minimum. No seasonal effects were observed, but any seasonal effect might be masked by the low frequency of UH/UW. UH/UW are not linked to a single behavioural context and may have multiple functions in thermoregulation/water conservation, cleaning, improving grip, and as a social signal.     

Endocrine Correlates of Reproductive Status in Breeding and Nonbreeding Wild Female Moustached Tamarins

In callitrichid primates, reproduction is usually restricted to a single female per group. Reproductive rate is high and the occurrence of a postpartum estrus can lead to simultaneous lactation and pregnancy. In contrast, nonreproductive females often show ovarian inactivity. However, most studies on callitrichid reproductive physiology have been conducted in captivity, where conditions differ considerably from those in the wild, so that reproductive conditions may be strongly modified. Using fecal estrogen and progestogen measurements to monitor female reproductive status in 2 groups of wild moustached tamarins (Saguinus mystax), we examined 1) whether reproductive females in free-ranging groups also show postpartum estrus and 2) whether nonreproductive females demonstrate signs of ovarian activity. In both reproductive females, clear changes in the excretion pattern of progestogen and estrogen metabolites over time in combination with information on parturition dates allowed us to differentiate between pregnancy, a period of postpartum ovarian inactivity lasting for 54 and 64–82 days, and a period of ovarian activity before conception. Nonreproductive females demonstrated temporal fluctuations in hormone concentrations and absolute hormone levels that were similar to ones in the breeding females during the phase of ovarian activity. The results suggest that, in contrast to most captive female tamarins, reproductive females in wild groups of moustached tamarins do not have a postpartum estrus and that nonreproductive females show ovarian activity despite the presence of a breeding female. We therefore conclude that findings from captivity should be only carefully compared to the situation in the wild.     

Age effects on intracortical microstructure and cortical thickness in adult saddle-back tamarins

Intracortical bone remodeling and cortical thickness data were collected from middiaphyseal thin sections of the humerus, ulna and tibia for 47 specimens ofSaguinus fuscicollis. Individuals were classified into age cohorts: Young Adult, Mid-adult I, Mid-adult II and Old Adult. Correlation analyses revealed significant relationships between age cohort and the number of osteons for the humerus and ulna, and between age cohort and non-Haversian canals for each of the three long bone elements. Significant relationships between age cohort and dimension of cortex size suggested an age-related pattern of cortical shifting in the ulna and older-age bone loss in the tibia.     

Aspergillus on tree nuts: incidence and associations

California exports tree nuts to countries where they face stringent standards for aflatoxin contamination. Trade concerns have stimulated efforts to eliminate aflatoxins and Aspergillus flavus from almonds, pistachios and walnuts. Incidence of fungi on tree nuts and associations among fungi on tree nuts were studied. Eleven hundred pistachios, almonds, walnuts and brazil nuts without visible insect damage were plated on salt agar and observed for growth of fungi. Samples came both from California nut orchards and from supermarkets. To distinguish internal fungal colonization of nuts from superficial colonization, half the nuts were surface-sterilized before plating. The most common genera found were Aspergillus , Rhizopus and Penicillium . Each species of nut had a distinct mycoflora. Populations of most fungi were reduced by surface sterilization in all except brazil nuts, suggesting that they were present as superficial inoculum on (rather than in) the nuts. In general, strongly positive associations were observed among species of Aspergillus ; nuts infected by one species were likely to be colonized by other species as well. Presence of Penicillium was negatively associated with A. niger and Rhizopus in some cases. Results suggest that harvest or postharvest handling has a major influence on nut mycoflora, and that nuts with fungi are usually colonized by several fungi rather than by single species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Demographic consequences of drought in the herbaceous perennial Cryptantha flava: effects of density,associations with shrubs,and plant size

The demographic consequences of a severe drought year were examined for two experimental plantings of the herbaceous desert perennial Cryptantha flava(Boraginaceae) in northeastern Utah, United States. A total of 6680 nutlets were planted individually or in clusters of four both under shrubs and in open microhabitats within two natural populations. Survival, growth, and flowering as a function of density and microhabitat were followed for 7 years, including 1 year when precipitation just before and during the growing season was 74.5% below normal. The design permitted assessment of how intraspecific density and shrub cover affect demographic response to drought. Mortality increased and flowering decreased dramatically during drought but neither varied with density or between shrub and open microhabitats. For plants growing under shrubs, survival (at Site 1) and growth (at Site 2) varied with shrub species. Average aboveground plant size also decreased during drought. Population size hierarchies were rearranged because larger plants lost leaf rosettes while many smaller plants grew. Density and microhabitat affected plant performance in non-drought years but more often at Site 1 than at Site 2. Individuals growing alone often were more likely to flower and/or produced more inflorescences when they did flower than did individuals growing with at least one other plant. However, for 2 years, survival rates at Site 1 were higher for plants growing in clumps than for single individuals. Shrubs also had mixed effects on plant performance. In some years, survival was higher under shrubs, but at Site 1 plants in the open often were more likely to flower and/or produced more inflorescences. Thus despite severe demographic consequences of drought, the study provided no evidence that intraspecific competition, interference by shrubs, or facilitation by shrubs increases under limited soil water.     

Competition for S and N by associations of three annual range species in lysimeters

Summary Competition for S and N was studied on free draining lysimeters seeded to associations of three annual forages on Josephine loam (Typic Haploxerults), an important soil for revegetation to rangeland production. Forage yields increased and the botanical composition shifted toward subclover (Trifolium subterraneum L.) with added S. Sulfate uptake and plant S concentration were increased as a function of the S applied. Forage yields were related to plant S concentration and N:S ratios. Subclover and filaree (Erodium botrys (Cav.) Bertol.) obtained a larger proportion of their S from fertilizer-S than did soft chess (Bromus mollis L.). Total S uptake was largely from the applied fertilizer, 39% at the intermediate S level and 78% at high S. The replacement series design of the experiment and the use of labeled S and N permitted calculation of competition coefficients for fertilizer S, total S, soil N, and total N uptake for the species in pairwise associations. Sulfur was the factor limiting to subclover where S was not applied, and N was the limiting factor to soft chess and filaree in mixtures with subclover at high S where subclover was able to fix most of its own N. In the mixture of soft chess and filaree competition for S and N was about equally intense for both nutrients at all S levels, and filaree was dominant consistently. Comparison of two methods for estimating the fate of fertilizer S showed that differences in sulfur uptake and leachate losses over the controls provided significantly higher values for sulfur recovery than estimates based on the fate of³⁵S. Contribution of the University of California Hopland Field Station and Dept. of Agronomy and Range Science, Univ. of California, Davis, CA 95616.     

Current status in production and utilization of dihaploids from somatic hybrids between eggplant (Solanum melongena L.) and its wild relatives

The major constrains for practical exploitation of the somatic hybrids between eggplant and its wild relatives have been their sterility and tetraploidy which prevented their incorporation into breeding programs. Here we demonstrate that anther culture was successfully utilized to bring back the ploidy level to the diploid status in tetraploid interspecific hybrids between eggplant and the allied species S. integrifolium and S. aethiopicum gr. gilo. Both the relative species are resistant to Fusarium oxysporum f. sp. melongenae and to some strains of bacterial wilt (Ralstonia solanacearum) which are very destructive diseases of eggplant. Dihaploid androgenetic plants were obtained from the somatic hybrids, from the “double somatic hybrid” obtained by sexual cross of the two somatic hybrids [(eggplant + S. aethiopicum) × (eggplant + S. integrifolium)], and from tetraploid backcrossed plants between the somatic hybrid with S. aethiopicum and eggplant. Phenotypical, molecular, biological and biochemical characterization, and also artificial inoculation with Fusarium oxysporum are consistent with a recombination between the genomes of the species involved in the hybridizations. Dihaploids resistant to Fusarium were successfully backcrossed with eggplant. Besides their utility as potential valuable breeding materials, the introgressed lines obtained may be utilized in genetic and molecular studies about the resistance to Fusarium from S. integrifolium and S. aethiopicum gr. gilo.     

Use of Social and Ecological Information in Tamarin Foraging Decisions

A major consequence of group living is that foragers may rely on social information in addition to ecological information to locate feeding sites. Although conspecifics can provide cues as to the spatial location of food patches, individual foraging decisions also must include some assessment of the likelihood of obtaining access to a resource other group members seek. This likelihood differs in the 2 models generally proposed to explain intragroup social foraging: the information-sharing model and the producer-scrounger model. We conducted an experimental field study on wild groups of emperor (Saguinus imperator) and saddleback (S. fuscicollis) tamarins to determine the foraging strategies adopted by individual group members and their relationship to social rank, food intake, and the ability to use ecological and social information in making intra-patch foraging decisions. Individual tamarins applied different behavioral strategies compatible with a finder-joiner paradigm to solve foraging problems. About half of the individuals in each study group initiated 74%–90% of all food searches and acted as finders. Most alpha individuals adopted a joiner strategy by monitoring the activities of others' to obtain a reward. The individual arriving first at a reward platform enjoyed a finder's advantage. Despite differences in search effort, both finders and joiners presented similar abilities in learning to associate ecological cues with the presence of food rewards at our experimental feeding stations. We conclude that within a group foraging context, tamarins integrate social and ecological information in decision-making.