Modeling Behavior by Coastal River Otter (Lontra Canadensis) in Response to Prey Availability in Prince William Sound,Alaska: A Spatially-Explicit Individual-Based Approach

Effects of climate change on animal behavior and cascading ecosystem responses are rarely evaluated. In coastal Alaska, social river otters (Lontra Canadensis), largely males, cooperatively forage on schooling fish and use latrine sites to communicate group associations and dominance. Conversely, solitary otters, mainly females, feed on intertidal-demersal fish and display mutual avoidance via scent marking. This behavioral variability creates “hotspots” of nutrient deposition and affects plant productivity and diversity on the terrestrial landscape. Because the abundance of schooling pelagic fish is predicted to decline with climate change, we developed a spatially-explicit individual-based model (IBM) of otter behavior and tested six scenarios based on potential shifts to distribution patterns of schooling fish. Emergent patterns from the IBM closely mimicked observed otter behavior and landscape use in the absence of explicit rules of intraspecific attraction or repulsion. Model results were most sensitive to rules regarding spatial memory and activity state following an encounter with a fish school. With declining availability of schooling fish, the number of social groups and the time simulated otters spent in the company of conspecifics declined. Concurrently, model results suggested an elevation of defecation rate, a 25% increase in nitrogen transport to the terrestrial landscape, and significant changes to the spatial distribution of “hotspots” with declines in schooling fish availability. However, reductions in availability of schooling fish could lead to declines in otter density over time.     

Human Collective Intelligence under Dual Exploration-Exploitation Dilemmas

The exploration-exploitation dilemma is a recurrent adaptive problem for humans as well as non-human animals. Given a fixed time/energy budget, every individual faces a fundamental trade-off between exploring for better resources and exploiting known resources to optimize overall performance under uncertainty. Colonies of eusocial insects are known to solve this dilemma successfully via evolved coordination mechanisms that function at the collective level. For humans and other non-eusocial species, however, this dilemma operates within individuals as well as between individuals, because group members may be motivated to take excessive advantage of others'' exploratory findings through social learning. Thus, even though social learning can reduce collective exploration costs, the emergence of disproportionate “information scroungers” may severely undermine its potential benefits. We investigated experimentally whether social learning opportunities might improve the performance of human participants working on a “multi-armed bandit” problem in groups, where they could learn about each other''s past choice behaviors. Results showed that, even though information scroungers emerged frequently in groups, social learning opportunities reduced total group exploration time while increasing harvesting from better options, and consequentially improved collective performance. Surprisingly, enriching social information by allowing participants to observe others'' evaluations of chosen options (e.g., Amazon''s 5-star rating system) in addition to choice-frequency information had a detrimental impact on performance compared to the simpler situation with only the choice-frequency information. These results indicate that humans groups can handle the fundamental “dual exploration-exploitation dilemmas” successfully, and that social learning about simple choice-frequencies can help produce collective intelligence.     

“Candidatus Midichloriaceae” fam. nov. (Rickettsiales), an Ecologically Widespread Clade of Intracellular Alphaproteobacteria

“Candidatus Midichloria mitochondrii” is an intramitochondrial bacterium of the order Rickettsiales associated with the sheep tick Ixodes ricinus. Bacteria phylogenetically related to “Ca. Midichloria mitochondrii” (midichloria and like organisms [MALOs]) have been shown to be associated with a wide range of hosts, from amoebae to a variety of animals, including humans. Despite numerous studies focused on specific members of the MALO group, no comprehensive phylogenetic and statistical analyses have so far been performed on the group as a whole. Here, we present a multidisciplinary investigation based on 16S rRNA gene sequences using both phylogenetic and statistical methods, thereby analyzing MALOs in the overall framework of the Rickettsiales. This study revealed that (i) MALOs form a monophyletic group; (ii) the MALO group is structured into distinct subgroups, verifying current genera as significant evolutionary units and identifying several subclades that could represent novel genera; (iii) the MALO group ranks at the level of described Rickettsiales families, leading to the proposal of the novel family “Candidatus Midichloriaceae.” In addition, based on the phylogenetic trees generated, we present an evolutionary scenario to interpret the distribution and life history transitions of these microorganisms associated with highly divergent eukaryotic hosts: we suggest that aquatic/environmental protista have acted as evolutionary reservoirs for members of this novel family, from which one or more lineages with the capacity of infecting metazoa have evolved.     

The Wallpaper Effect: The Contact Hypothesis Fails for Minority Group Members Who Live in Areas with a High Proportion of Majority Group Members

We aim to provide one explanation for why the link between contact and prejudice is consistently less strong for minority group members than it is for majority group members. Specifically, we propose a “wallpaper effect” such that contact works to increase minority group members'' positivity towards majority groups when they live in areas densely populated with other minority group members. Conversely, we suggest that when minority group members live in neighborhoods patterned with majority group faces (as is so often the case), contact will be less transformative. We test this assumption using a large sample of both New Zealander minority (Māori; N = 925) and majority (European; N = 3805) group members. In line with predictions, Māori who lived in minority dense neighborhoods showed the traditional association between contact and increased warmth towards New Zealander Europeans. This relationship, however, was weak or non-existent when they lived in primarily European neighborhoods. Contact effects in majority group members were unaffected by neighborhood composition. The interaction held when controlling for, and was not explained by: gender, income, experiences of harm, cognitions of race-based rejection, or realistic threat. We provide the first evidence to suggest that when it comes to minority group members'' intergroup attitudes, contact with majority group members may be a relatively ineffective predictor unless the “wallpaper” of their lives is minority-dense.     

Division of Labor Regulates Precision Rescue Behavior in Sand-Dwelling Cataglyphis cursor Ants: To Give Is to Receive

Division of labor, an adaptation in which individuals specialize in performing tasks necessary to the colony, such as nest defense and foraging, is believed key to eusocial insects'' remarkable ecological success. Here we report, for the first time, a completely novel specialization in a eusocial insect, namely the ability of Cataglyphis cursor ants to rescue a trapped nestmate using precisely targeted behavior. Labeled “precision rescue”, this behavior involves the ability of rescuers not only to detect what, exactly, holds the victim in place, but also to direct specific actions to this obstacle. Individual ants, sampled from each of C. cursor''s three castes, namely foragers, nurses and inactives, were experimentally ensnared (the “victim”) and exposed to a caste-specific group of potential “rescuers.” The data reveal that foragers were able to administer, and obtain, the most help while members of the youngest, inactive caste not only failed to respond to victims, but also received virtually no help from potential rescuers, regardless of caste. Nurses performed intermediate levels of aid, mirroring their intermediate caste status. Our results demonstrate that division of labor, which controls foraging, defense and brood care in C. cursor, also regulates a newly discovered behavior in this species, namely a sophisticated form of rescue, a highly adaptive specialization that is finely tuned to a caste member''s probability of becoming, or encountering, a victim in need of rescue.     

Which Single Intervention Would Do the Most to Improve the Health of Those Living on Less Than $1 Per Day?

Background to the debate: PLoS Medicine is participating in the Council of Science Editors'' global theme issue on poverty and human development on October 22, 2007 (http://www.councilscienceeditors.org/globalthemeissue.cfm). Over 200 scientific and medical journals are taking part. For our theme issue, we asked a wide variety of commentators worldwide—including clinicians, medical researchers, health reporters, policy makers, health activists, and development experts—to name the single intervention that they think would improve the health of those living in poverty. We also asked four individuals living in poor, rural agricultural communities in the Santillana district, province of Huanta, Ayacucho, Peru to give us their response to the question, “What do you think would do the most to improve your health and the health of your family?” (The four community members were Severino Rojas Poma, Mercedes Vargas Soto, Julián De La Cruz Chahua, and Martín Rojas Poma). Our October 2007 Editorial discusses this debate further.     

Enterovirus Infections: Etiologic,Epidemiologic and Clinical Aspects

The term enteroviruses was introduced in 1957 to bring together in one large family the polioviruses, Coxsackie A and B and echoviruses, all agents for which the human alimentary tract is the natural habitat. At present more than 60 distinct members are recognized: three polioviruses, 24 Coxsackie A, six Coxsackie B and 30 echoviruses. The list of new members, particularly in the echo-group, grows regularly. The viruses are frequently widely disseminated in the summer and fall of the year, circulating chiefly among young children, causing both apparent and inapparent infection. The enteroviruses are responsible for a wide spectrum of clinical manifestations, including non-specific febrile illness, sometimes with rash, aseptic meningitis, paralytic disease, respiratory infections, pericarditis and myocarditis. There is considerable overlap in biologic behavior, and the same syndrome can be induced by many different agents.In a few instances the clinical pattern is distinct enough to suggest the group of agents involved. Thus, herpangina is associated with the Coxsackie A viruses and epidemic myalgia (devil''s grip) with the Coxsackie B group. Paralytic disease is caused primarily by the polioviruses, but recently it has been found that other members, particularly the Coxsackie B viruses and Coxsackie A7 can also cause “paralytic poliomyelitis.”The ultimate potential of enteroviruses in terms of central nervous system disease and other manifestations is unpredictable. Great variety in terms of clinical and epidemiologic behavior of known and “new” viruses has been the pattern in the past, and is likely to continue.     

A Mesophilic,Autotrophic, Ammonia-Oxidizing Archaeon of Thaumarchaeal Group I.1a Cultivated from a Deep Oligotrophic Soil Horizon

Soil nitrification plays an important role in the reduction of soil fertility and in nitrate enrichment of groundwater. Various ammonia-oxidizing archaea (AOA) are considered to be members of the pool of ammonia-oxidizing microorganisms in soil. This study reports the discovery of a chemolithoautotrophic ammonia oxidizer that belongs to a distinct clade of nonmarine thaumarchaeal group I.1a, which is widespread in terrestrial environments. The archaeal strain MY2 was cultivated from a deep oligotrophic soil horizon. The similarity of the 16S rRNA gene sequence of strain MY2 to those of other cultivated group I.1a thaumarchaeota members, i.e., Nitrosopumilus maritimus and “Candidatus Nitrosoarchaeum koreensis,” is 92.9% for both species. Extensive growth assays showed that strain MY2 is chemolithoautotrophic, mesophilic (optimum temperature, 30°C), and neutrophilic (optimum pH, 7 to 7.5). The accumulation of nitrite above 1 mM inhibited ammonia oxidation, while ammonia oxidation itself was not inhibited in the presence of up to 5 mM ammonia. The genome size of strain MY2 was 1.76 Mb, similar to those of N. maritimus and “Ca. Nitrosoarchaeum koreensis,” and the repertoire of genes required for ammonia oxidation and carbon fixation in thaumarchaeal group I.1a was conserved. A high level of representation of conserved orthologous genes for signal transduction and motility in the noncore genome might be implicated in niche adaptation by strain MY2. On the basis of phenotypic, phylogenetic, and genomic characteristics, we propose the name “Candidatus Nitrosotenuis chungbukensis” for the ammonia-oxidizing archaeal strain MY2.     

Structural Basis for Ligand Regulation of the Fatty Acid-binding Protein 5, Peroxisome Proliferator-activated Receptor β/δ (FABP5-PPARβ/δ) Signaling Pathway

Fatty acid-binding proteins (FABPs) are a widely expressed group of calycins that play a well established role in solubilizing cellular fatty acids. Recent studies, however, have recast FABPs as active participants in vital lipid-signaling pathways. FABP5, like its family members, displays a promiscuous ligand binding profile, capable of interacting with numerous long chain fatty acids of varying degrees of saturation. Certain “activating” fatty acids induce the protein''s cytoplasmic to nuclear translocation, stimulating PPARβ/δ transactivation; however, the rules that govern this process remain unknown. Using a range of structural and biochemical techniques, we show that both linoleic and arachidonic acid elicit FABP5''s translocation by permitting allosteric communication between the ligand-sensing β2 loop and a tertiary nuclear localization signal within the α-helical cap of the protein. Furthermore, we show that more saturated, nonactivating fatty acids inhibit nuclear localization signal formation by destabilizing this activation loop, thus implicating FABP5 specifically in cis-bonded, polyunsaturated fatty acid signaling.     

Demography of the Giant Otter (Pteronura brasiliensis) in Manu National Park,South-Eastern Peru: Implications for Conservation

The giant otter (Pteronura brasiliensis) is an endangered semi-aquatic carnivore of South America. We present findings on the demography of a population inhabiting the floodplain of Manu National Park, south-eastern Peru, arising from 14 annual dry season censuses over a 16 year period. The breeding system of territorial groups, including only a single breeding female with non-reproductive adult ‘helpers’, resulted in a low intrinsic rate of increase (0.03) and a slow recovery from decades of hunting for the pelt trade. This is explained by a combination of factors: (1) physiological traits such as late age at first reproduction and long generation time, (2) a high degree of reproductive skew, (3) small litters produced only once a year, and (4) a 50% mortality between den emergence and age of dispersal, as well as high mortality amongst dispersers (especially males). Female and male giant otters show similar traits with respect to average reproductive life-spans (female 5.4 yrs., male 5.2 yrs.) and average cub productivity (female 6.9, male 6.7 cubs per lifetime); the longest reproductive life spans were 11 and 13 years respectively. Individual reproductive success varied substantially and depended mainly on the duration of dominance tenure in the territory. When breeding females died, the reproductive position in the group was usually occupied by sisters or daughters (n = 11), with immigrant male partners. Male philopatry was not observed. The vulnerability of the Manu giant otter population to anthropogenic disturbance emphasises the importance of effective protection of core lake habitats in particular. Riverine forests are the most endangered ecosystem in the Department of Madre de Dios due to the concentration of gold mining, logging and agricultural activities in floodplains, highlighting the need for a giant otter habitat conservation corridor along the Madre de Dios River.     

Conflict between Fishermen and Giant Otters Pteronura brasiliensis in Western Brazilian Amazon

The recovery of giant otter populations after the hunting prohibition and restriction of the pelt trade resulted in more frequent conflicts with fishermen. In this study, fisherman–giant otter conflicts were analyzed in the Uacari Sustainable Development Reserve, where giant otters are accused of interfering with fisheries by eating the fish (predation), frightening the fish away (local interference), and damaging fishing equipment (direct interference). Interference by predation was analyzed by evaluating overlap in fish species consumption between humans (measured by subsistence and commercial catches) and giant otters. The giant otter diet was assessed from fecal samples, and the human diet through questionnaires. Local and direct interferences were analyzed through fish samples using gillnets and comparing capture efficiency with and without giant otters’ presence. The overlap between human and giant otter diets was low (0.37), varied seasonally, and was smaller in the low water (0.24) than in the high water period (0.60), when both species tend to be more generalists. Overlap between fish species consumed by giant otters and those exploited by commercial fisheries was small (0.34). Giant otter presence during the experimental fishing was low (9.5%), restricted to the high water period, and did not significantly reduce the captures (U = 13, P = 0.61). The low overlap in diet may be a result of differences in preferences and fishing strategies. The conflict between giant otters and fishermen is greater in the high water period, when the income of the fisheries decreases; however, the conflict seems to be mainly motivated by the resident's prejudice against giant otters.     

Basis for Cumulative Cultural Evolution in Chimpanzees: Social Learning of a More Efficient Tool-Use Technique

Background

The evidence for culture in non-human animals has been growing incrementally over the past two decades. However, the ability for cumulative cultural evolution, with successive generations building on earlier achievements, in non-human animals remains debated. Faithful social learning of incremental improvements in technique is considered to be a defining feature of human culture, differentiating human from non-human cultures. This study presents the first experimental evidence for chimpanzees'' social transmission of a more efficient tool-use technique invented by a conspecific group member.

Methodology/Principal Findings

The chimpanzees were provided with a straw-tube, and spontaneously demonstrated two different techniques in obtaining juice through a small hole: “dipping” and “straw-sucking”. Both the “dipping” and “straw-sucking” techniques depended on the use of the same tool (straw-tube) for the same target (juice) accessible from exactly the same location (small hole 1 cm in diameter). Therefore the difference between “dipping” and “straw-sucking” was only in “technique”. Although the two techniques differed significantly in their efficiency, their cognitive and perceptuo-motor complexity were comparable. All five chimpanzees who initially performed the “dipping” technique switched to using the more efficient “straw-sucking” technique upon observing a conspecific or human demonstrate the more proficient alternate “straw-sucking” technique.

Conclusions/Significance

The social learning mechanism involved here was clearly not local or stimulus enhancement, but imitation or emulation of a tool-use technique. When there is no biologically relevant difference in cognitive or perceptuo-motor complexity between two techniques, and when chimpanzees are dissatisfied with their own technique, chimpanzees may socially learn an improved technique upon close observation of a proficient demonstrator. This study provides important insights into the cognitive basis for cumulative culture in chimpanzees, and also suggests possible conditions in which cumulative cultural evolution could arise even in non-human animals.     

Purine Analogue Sensitivity and Lipase Activity of Leptospires

The genus Leptospira can be divided into three groups based on purine analogue sensitivity and lipase (trioleinase) activity. Group 1 contains members of the “parasitic complex” of leptospires which initially cannot grow in media containing 10 μg of 2,6-diaminopurine (DAP) per ml or 200 μg of 8-azaguanine per ml. In addition, leptospires in this group possess lipase activity. Group 2 also contains members of the “parasitic complex” of leptospires. Although these leptospires are similarly sensitive to 8-azaguanine, they differ from group 1 leptospires in that they grow in media containing 10 μg of DAP per ml, and they do not possess detectable lipase activity. Group 3 consists of leptospires belonging to the “biflexa complex.” These leptospires are resistant to both purine analogues and have lipase activity.     

Nitrous Oxide Inhalation as a Fad—Dangers in Uncontrolled Sniffing for Psychedelic Effect

“LAUGHING GAS is the newest thing for kids seeking kicks,” the Stanford Daily reports. “They sniff it.”So begins a news story in the Los Angeles Times of 26 January 1967. The story continues:“It''s the latest way to travel, or so say a growing group of devotees on the campus,” the university student paper said. “It can produce much the same effects as psychedelic drugs, they claim, and it''s cheaper to obtain.”“One student said he buys the gas, nitrous oxide, from a medical supply house. `They think I am anesthetizing rats,'' he explained.“Campus medical authorities said the gas, sniffed `in sufficient amounts... could produce all the states of anesthesia, including the final stage—death.''”     

Microbial Protein-tyrosine Kinases

Microbial ester kinases identified in the past 3 decades came as a surprise, as protein phosphorylation on Ser, Thr, and Tyr amino acids was thought to be unique to eukaryotes. Current analysis of available microbial genomes reveals that “eukaryote-like” protein kinases are prevalent in prokaryotes and can converge in the same signaling pathway with the classical microbial “two-component” systems. Most microbial tyrosine kinases lack the “eukaryotic” Hanks domain signature and are designated tyrosine kinases based upon their biochemical activity. These include the tyrosine kinases termed bacterial tyrosine kinases (BY-kinases), which are responsible for the majority of known bacterial tyrosine phosphorylation events. Although termed generally as bacterial tyrosine kinases, BY-kinases can be considered as one family belonging to the superfamily of prokaryotic protein-tyrosine kinases in bacteria. Other members of this superfamily include atypical “odd” tyrosine kinases with diverse mechanisms of protein phosphorylation and the “eukaryote-like” Hanks-type tyrosine kinases. Here, we discuss the distribution, phylogeny, and function of the various prokaryotic protein-tyrosine kinases, focusing on the recently discovered Mycobacterium tuberculosis PtkA and its relationship with other members of this diverse family of proteins.     

Social and Emotional Values of Sounds Influence Human (Homo sapiens) and Non-Human Primate (Cercopithecus campbelli) Auditory Laterality

The last decades evidenced auditory laterality in vertebrates, offering new important insights for the understanding of the origin of human language. Factors such as the social (e.g. specificity, familiarity) and emotional value of sounds have been proved to influence hemispheric specialization. However, little is known about the crossed effect of these two factors in animals. In addition, human-animal comparative studies, using the same methodology, are rare. In our study, we adapted the head turn paradigm, a widely used non invasive method, on 8–9-year-old schoolgirls and on adult female Campbell''s monkeys, by focusing on head and/or eye orientations in response to sound playbacks. We broadcast communicative signals (monkeys: calls, humans: speech) emitted by familiar individuals presenting distinct degrees of social value (female monkeys: conspecific group members vs heterospecific neighbours, human girls: from the same vs different classroom) and emotional value (monkeys: contact vs threat calls; humans: friendly vs aggressive intonation). We evidenced a crossed-categorical effect of social and emotional values in both species since only “negative” voices from same class/group members elicited a significant auditory laterality (Wilcoxon tests: monkeys, T = 0 p = 0.03; girls: T = 4.5 p = 0.03). Moreover, we found differences between species as a left and right hemisphere preference was found respectively in humans and monkeys. Furthermore while monkeys almost exclusively responded by turning their head, girls sometimes also just moved their eyes. This study supports theories defending differential roles played by the two hemispheres in primates'' auditory laterality and evidenced that more systematic species comparisons are needed before raising evolutionary scenario. Moreover, the choice of sound stimuli and behavioural measures in such studies should be the focus of careful attention.