Juvenile hormone interacts with multiple factors to modulate aggression and dominance in groups of orphan bumble bee (Bombus terrestris) workers.

Juvenile hormone (JH) is a key regulator of insect development and reproduction. Given that JH commonly affects adult insect fertility, it has been hypothesized to also regulate behaviors such as dominance and aggression that are associated with reproduction. We tested this hypothesis in the bumble bee Bombus terrestris for which JH has been shown to be the major gonadotropin. We used the allatoxin Precocene-I (P-I) to reduce hemolymph JH titers and replacement therapy with the natural JH to revert this effect. In small orphan groups of workers with similar body size but mixed treatment, P-I treated bees showed lower aggressiveness, oogenesis, and dominance rank compared with control and replacement therapy treated bees. In similar groups in which all bees were treated similarly, there was a clear dominance hierarchy, even in P-I and replacement therapy treatment groups in which the bees showed similar levels of ovarian activation. In a similar experiment in which bees differed in body size, larger bees were more likely to be dominant despite their similar JH treatment and ovarian state. In the last experiment, we show that JH manipulation does not affect dominance rank in groups that had already established a stable dominance hierarchy. These findings solve previous ambiguities concerning whether or not JH affects dominance in bumble bees. JH positively affects dominance, but bees with similar levels of JH can nevertheless establish dominance hierarchies. Thus, multiple factors including JH, body size, and previous experience affect dominance and aggression in social bumble bees.

The effects of CO2 and nutrient fertilisation on the growth and temperature response of the mangrove Avicennia germinans.

In order to understand plant responses to both the widespread phenomenon of increased nutrient inputs to coastal zones and the concurrent rise in atmospheric CO2 concentrations, CO2-nutrient interactions need to be considered. In addition to its potential stimulating effect on photosynthesis and growth, elevated CO2 affects the temperature response of photosynthesis. The scarcity of experiments testing how elevated CO2 affects the temperature response of tropical trees hinders our ability to model future primary productivity. In a glasshouse study, we examined the effects of elevated CO2 (800 ppm) and nutrient availability on seedlings of the widespread mangrove Avicennia germinans. We assessed photosynthetic performance, the temperature response of photosynthesis, seedling growth and biomass allocation. We found large synergistic gains in both growth (42 %) and photosynthesis (115 %) when seedlings grown under elevated CO2 were supplied with elevated nutrient concentrations relative to their ambient growing conditions. Growth was significantly enhanced under elevated CO2 only under high-nutrient conditions, mainly in above-ground tissues. Under low-nutrient conditions and elevated CO2, root volume was more than double that of seedlings grown under ambient CO2 levels. Elevated CO2 significantly increased the temperature optimum for photosynthesis by ca. 4 °C. Rising CO2 concentrations are likely to have a significant positive effect on the growth rate of A. germinans over the next century, especially in areas where nutrient availability is high.

Evolution of learned strategy choice in a frequency-dependent game.

In frequency-dependent games, strategy choice may be innate or learned. While experimental evidence in the producer-scrounger game suggests that learned strategy choice may be common, a recent theoretical analysis demonstrated that learning by only some individuals prevents learning from evolving in others. Here, however, we model learning explicitly, and demonstrate that learning can easily evolve in the whole population. We used an agent-based evolutionary simulation of the producer-scrounger game to test the success of two general learning rules for strategy choice. We found that learning was eventually acquired by all individuals under a sufficient degree of environmental fluctuation, and when players were phenotypically asymmetric. In the absence of sufficient environmental change or phenotypic asymmetries, the correct target for learning seems to be confounded by game dynamics, and innate strategy choice is likely to be fixed in the population. The results demonstrate that under biologically plausible conditions, learning can easily evolve in the whole population and that phenotypic asymmetry is important for the evolution of learned strategy choice, especially in a stable or mildly changing environment.

Earlier Morning Arrival to Pollen-Rewarding Flowers May Enable Feral Bumble Bees to Successfully Compete with Local Bee Species and Expand Their Distribution Range in a Mediterranean Habitat.

During recent decades, bumble bees (Bombus terrestris) have continuously expanded their range in the Mediterranean climate regions of Israel. To assess their potential effects on local bee communities, we monitored their diurnal and seasonal activity patterns, as well as those of native bee species in the Judean Hills. We found that all bee species tend to visit pollen-providing flowers at earlier times compared to nectar-providing flowers. Bumble bees and honey bees start foraging at earlier times and colder temperatures compared to other species of bees. This means that the two species of commercially managed social bees are potentially depleting much of the pollen, which is typically non-replenished, before most local species arrive to gather it. Taking into consideration the long activity season of bumble bees in the Judean hills, their ability to forage at the low temperatures of the early morning, and their capacity to collect pollen at early hours in the dry Mediterranean climate, feral and range-expanding bumble bees potentially pose a significant competitive pressure on native bee fauna. Their effects on local bees can further modify pollination networks, and lead to changes in the local flora.

Individual-learning ability predicts social-foraging strategy in house sparrows.

Social foragers can use either a 'producer' strategy, which involves searching for food, or a 'scrounger' strategy, which involves joining others' food discoveries. While producers rely on personal information and past experience, we may ask whether the tendency to forage as a producer is related to being a better learner. To answer this question, we hand-raised house sparrow (Passer domesticus) nestlings that upon independence were given an individual-learning task that required them to associate colour signal and food presence. Following the testing phase, all fledglings were released into a shared aviary, and their social-foraging tendencies were measured. We found a significant positive correlation between individual's performance in the individual-learning task and subsequent tendency to use searching (producing) behaviour. Individual-learning score was negatively correlated with initial fear of the test apparatus and with body weight. However, the correlation between individual learning and searching remained significant after controlling for these variables. Since it was measured before the birds entered a social group, individual-learning ability could not be the outcome of being a producer. However, the two traits may be initially associated, or individual learning could facilitate producing behaviour. To our knowledge, this is the first evidence that associates individual-learning abilities with social-foraging strategies in animal groups.

Recombination and the evolution of coordinated phenotypic expression in a frequency-dependent game.

A long standing question in evolutionary biology concerns the maintenance of adaptive combinations of traits in the presence of recombination. This problem may be solved if positive epistasis selects for reducing the rate of recombination between such traits, but this requires sufficiently strong epistasis. Here we use a model that we developed previously to analyze a frequency-dependent strategy game in asexual populations, to study how adaptive combinations of traits may be maintained in the presence of recombination when epistasis is too weak to select for genetic linkage. Previously, in the asexual case, our model demonstrated the evolution of adaptive associations between social foraging strategies and learning rules. We verify that these adaptive associations, which are represented by different two-locus haplotypes, can easily be broken by genetic recombination. We also confirm that a modifier allele that reduces the rate of recombination fails to evolve (due to weak epistasis). However, we find that under the same conditions of weak epistasis, there is an alternative mechanism that allows an association between traits to evolve. This is based on a genetic switch that responds to the presence of one social foraging allele by activating one of the two alternative learning alleles that are carried by all individuals. We suggest that such coordinated phenotypic expression by genetic switches offers a general and robust mechanism for the evolution of adaptive combinations of traits in the presence of recombination.

A star is torn-molecular analysis divides the Mediterranean population of Poli's stellate barnacle, Chthamalus stellatus (Cirripedia, Chtamalidae).

Poli's stellate barnacle, Chthamalus stellatus Poli, populates the Mediterranean Sea, the North-Eastern Atlantic coasts, and the offshore Eastern Atlantic islands. Previous studies have found apparent genetic differences between the Atlantic and the Mediterranean populations of C. stellatus, suggesting possible geological and oceanographic explanations for these differences. We have studied the genetic diversity of 14 populations spanning from the Eastern Atlantic to the Eastern Mediterranean, using two nuclear genes sequences revealing a total of 63 polymorphic sites. Both genotype-based, haplotype-based and the novel SNP distribution population-based methods have found that these populations represent a geographic cline along the west to east localities. The differences in SNP distribution among populations further separates a major western cluster into two smaller clusters, the Eastern Atlantic and the Western Mediterranean. It also separates the major eastern cluster into two smaller clusters, the Mid-Mediterranean and Eastern Mediterranean. We suggested here environmental conditions like surface currents, water salinity and temperature as probable factors that have formed the population structure. We demonstrate that C. stellatus is a suitable model organism for studying how geological events and hydrographic conditions shape the fauna in the Mediterranean Sea.

Co-evolution of learning complexity and social foraging strategies.

Variation in learning abilities within populations suggests that complex learning may not necessarily be more adaptive than simple learning. Yet, the high cost of complex learning cannot fully explain this variation without some understanding of why complex learning is too costly for some individuals but not for others. Here we propose that different social foraging strategies can favor different learning strategies (that learn the environment with high or low resolution), thereby maintaining variable learning abilities within populations. Using a genetic algorithm in an agent-based evolutionary simulation of a social foraging game (the producer-scrounger game) we demonstrate how an association evolves between a strategy based on independent search for food (playing a producer) and a complex (high resolution) learning rule, while a strategy that combines independent search and following others (playing a scrounger) evolves an association with a simple (low resolution) learning rule. The reason for these associations is that for complex learning to have an advantage, a large number of learning steps, normally not achieved by scroungers, are necessary. These results offer a general explanation for persistent variation in cognitive abilities that is based on co-evolution of learning rules and social foraging strategies.

Juvenile hormone affects the development and strength of circadian rhythms in young bumble bee (Bombus terrestris) workers.

The circadian and endocrine systems influence many physiological processes in animals, but little is known on the ways they interact in insects. We tested the hypothesis that juvenile hormone (JH) influences circadian rhythms in the social bumble bee Bombus terrestris. JH is the major gonadotropin in this species coordinating processes such as vitellogenesis, oogenesis, wax production, and behaviors associated with reproduction. It is unknown however, whether it also influences circadian processes. We topically treated newly-emerged bees with the allatoxin Precocene-I (P-I) to reduce circulating JH titers and applied the natural JH (JH-III) for replacement therapy. We repeated this experiment in three trials, each with bees from different source colonies. Measurements of ovarian activity suggest that our JH manipulations were effective; bees treated with P-I had inactive ovaries, and this effect was fully recovered by subsequent JH treatment. We found that JH augments the strength of circadian rhythms and the pace of rhythm development in individually isolated newly emerged worker bees. JH manipulation did not affect the free-running circadian period, overall level of locomotor activity, sleep amount, or sleep structure. Given that acute manipulation at an early age produced relatively long-lasting effects, we propose that JH effects on circadian rhythms are mostly organizational, accelerating the development or integration of the circadian system.

Behavioral changes, stress, and survival following reintroduction of Persian fallow deer from two breeding facilities.

Reintroductions often rely on captive-raised, naïve animals that have not been exposed to the various threats present in natural environments. Wild animals entering new areas are timid and invest much time and effort in antipredator behavior. On the other hand, captive animals reared in predator-free conditions and in close proximity to humans may initially lack this tendency, but can reacquire some antipredator behavior over time. We monitored the changes in antipredator-related behaviors of 16 radio-collared Persian fallow deer (Dama mesopotamica) reintroduced to the Soreq Valley in Israel from 2 breeding facilities: one heavily visited by the public (The Biblical Zoo of Jerusalem, Israel) and the other with reduced human presence (Hai-Bar Carmel, Israel). We monitored each individual for up to 200 days after release, focusing on flush and flight distance, flight mode (running or walking), and use of cover. In addition, we compared fecal corticosterone (a stress-related hormone) from samples collected from known animals in the wild to samples collected in the breeding facilities. Reintroduced individuals from both origins exhibit increased flush distance over time; flush and flight distances were larger in individuals from Hai-Bar; use of cover increased with time, but was greater in Hai-Bar Carmel animals; corticosterone levels were significantly higher in fecal samples from reintroduced animals than in samples from captive animals; and Hai-Bar Carmel animals had an 80% survival rate over the 200 days, whereas no animals from the Biblical Zoo of Jerusalem survived. Reintroduced Persian fallow deer reacquired antipredator behaviors after the release, but the process was slow (months) and differences between conditions at the breeding facilities that were seemingly benign (e.g., number of visitors and other human related activities) influenced this process and consequently affected the success of the reintroduction. Captive breeding facilities for the purpose of reintroduction should minimize anthropogenic disturbances.

Facilitating complex DNA mixture interpretation by sequencing highly polymorphic haplotypes.

Interpretation of complex DNA mixtures is an ongoing challenge in the field of forensic genetics. Commonly used STR markers are quite polymorphic, enabling very high statistical association between a single source DNA profile from a crime scene and a matching suspect. STR typing of low order mixtures with two and three contributors also commonly produces high statistical association for a contributor, using current interpretation software. However higher order mixtures, with four contributors or more, are more challenging. Shared alleles among the many contributors may complicate the correct assessment of the number of contributors to a mixture and decreases the statistical support for inclusion of contributors. Recently, there is a rising use of massively parallel sequencing for forensic applications, and markers such as SNPs and short haplotypes are receiving more attention. However, these markers are even less polymorphic than autosomal STRs and are not suitable for complex mixture interpretation. We propose to use a different panel of haplotype markers, which contain many SNPs and are very polymorphic. These markers can be sequenced either by standard sequencing technologies or by a new instrument called MinION that sequences DNA as it passes through a nanopore. This instrument is very small and can sequence long stretches of DNA, but suffers from high error rate. We present a method for calling haplotype alleles facing high error rate, and use simulation to test its robustness. We also calculate likelihood ratio (LR) between propositions of contribution and non-contribution for individuals that do, and do not, contribute to various complex DNA mixtures. Our results indicate that the correct alleles can be identified in a mixture, despite the high sequencing error rate, and that contributors get high LR (>109) even in complex mixtures with up to five contributors. Non-contributors receive a very small LR, below 1 in most cases (>98%), which support their exclusion as possible donors to the complex DNA mixtures.

Dinoflagellate-cyanobacterium communication may determine the composition of phytoplankton assemblage in a mesotrophic lake.

The reasons for annual variability in the composition of phytoplankton assemblages are poorly understood but may include competition for resources and allelopathic interactions. We show that domination by the patch-forming dinoflagellate, Peridinium gatunense, or, alternatively, a bloom of a toxic cyanobacterium, Microcystis sp., in the Sea of Galilee may be accounted for by mutual density-dependent allelopathic interactions. Over the last 11 years, the abundance of these species in the lake displayed strong negative correlation. Laboratory experiments showed reciprocal, density-dependent, but nutrient-independent, inhibition of growth. Application of spent P. gatunense medium induced sedimentation and, subsequently, massive lysis of Microcystis cells within 24 hr, and sedimentation and lysis were concomitant with a large rise in the level of McyB, which is involved in toxin biosynthesis by Microcystis. P. gatunense responded to the presence of Microcystis by a species-specific pathway that involved a biphasic oxidative burst and activation of certain protein kinases. Blocking this recognition by MAP-kinase inhibitors abolished the biphasic oxidative burst and affected the fate (death or cell division) of the P. gatunense cells. We propose that patchy growth habits may confer enhanced defense capabilities, providing ecological advantages that compensate for the aggravated limitation of resources in the patch. Cross-talk via allelochemicals may explain the phytoplankton assemblage in the Sea of Galilee.

Genome methylation patterns across castes and generations in a parasitoid wasp.

Environmental influences shape phenotypes within and across generations, often through DNA methylations that modify gene expression. Methylations were proposed to mediate caste and task allocation in some eusocial insects, but how an insect's environment affects DNA methylation in its offspring is yet unknown. We characterized parental effects on methylation profiles in the polyembryonic parasitoid wasp Copidosoma koehleri, as well as methylation patterns associated with its simple caste system. We used methylation-sensitive amplified fragment length polymorphism (MS-AFLP) to compare methylation patterns, among (1) reproductive and soldier larvae; and (2) offspring (larvae, pupae, and adults) of wasps that were reared at either high or low larval density and mated in the four possible combinations. Methylation frequencies were similar across castes, but the profiles of methylated fragments differed significantly. Parental rearing density did not affect methylation frequencies in the offspring at any developmental stage. Principal coordinate analysis indicated no significant differences in methylation profiles among the four crossbreeding groups and the three developmental stages. Nevertheless, a clustering analysis, performed on a subset of the fragments, revealed similar methylation patterns in larvae, pupae, and adults in two of the four parental crosses. Nine fragments were methylated at two cytosine sites in all larvae, and five others were methylated at two sites in all adults. Thus, DNA methylations correlate with within-generation phenotypic plasticity due to caste. However, their association with developmental stage and with transgenerational epigenetic effects is not clearly supported.

'The story of Abraham, Isaac and Jacob" or "am I my brother's keeper?".

Presented is a case report of a violent sexual assault where the DNA profile obtained from an item of evidence was compared to a suspect's profile. The profiles did not match, but the sharing of such a large number of alleles raised the suspicion that perhaps the real perpetrator was a blood relative of the suspect. The investigators requested a sample from the suspect's brother, and a match was defined. In an era of technological breakthroughs in the field of forensic DNA analysis, the importance of the scientist's attention to the evidence presented in each case is stressed.

Presentation of a three-banded allele pattern--analysis and interpretation.

The Israel police forensic biology laboratory received as an item of evidence in an attempted murder case, a pair of trousers belonging to a suspect. A bloodstain was observed on the trousers and analyzed by STR typing for nine loci using the Promega GenePrint STR silver stain detection kits. The genetic profile defined was found to be identical to that of the victim's at all nine loci. Within this profile a three-banded allele pattern was observed at the D16S539 locus, both in the bloodstain and in the victim's reference blood sample. Confirmation of this phenomenon was accomplished by amplifying the extracted DNA from both the trousers and the victim's blood sample using the PowerPlex 16 kit by Promega and the AmpFlSTR SGM Plus kit by Perkin Elmer, followed by analysis of the amplification products by capillary electrophoresis on the ABI prism 310 genetic analyzer. The same three-banded allele pattern was observed at the D16S539 locus in both specimen and reference DNA, using each of the three kits. Three additional loci located on chromosome 16 (D16S3407, D16S2617 and D16S3082), not employed for forensic identification, were also analyzed and did not show three-banded allele pattern.

The medico-legal investigation of the El Aqsah Intifada.

BACKGROUND: The majority (n = 445) of the Israeli and Palestinian fatal victims of the El Aqsah Intifada was examined at the National Center of Forensic Medicine in Tel Aviv. Analysis of the trauma sustained and the anthropologic profile of both the victims and the perpetrators elucidates the trends and contrasts them with the phenomenon in the past. OBJECTIVES: The purpose of the forensic investigation of mass casualty incidents is manifold: establishing the minimal number of individuals involved, identifying the victims and perpetrators, collecting material evidence, and determining the modus operandi. METHODS: The postmortem examination includes external description of the bodies and their injuries, photo-documentation, and sampling of tissues. Radiography, dental examination, and a ten-print card of each cadaver are also recorded. RESULTS: The modus operandi of the current Intifada is somewhat different from that of the previous wave of terrorism and includes more road shootings and vehicular terrorism. In addition, three suicide bombers who detonated explosive devices within crowded areas were young women, and the age of the perpetrators has increased from up to 35 years to individuals as old as 47, thus greatly enlarging the potential number of suicide terrorists. Virologic and biologic tests have been introduced to examine the tissues of the suicide bombers since they are possible sources of contagion to the wounded victims. CONCLUSION: The results of the medico-legal investigation of victims and perpetrators of terrorism enable us to establish the modus operandi and the profile of potential perpetrators, which can help in the prevention of similar attacks. Documentation of the different types of injuries in fatal victims of explosion and shooting contributes to improving the awareness of the medical staff treating the wounded of similar attacks. Further investigation into the reliability of virologic and biologic tests conducted on postmortem tissue is recommended.

Can brothers share the same STR profile?

This report demonstrates the limits of DNA identification when siblings are involved. The Israeli DNA database routinely amplifies suspects samples using the PowerPlex(®) ESI16 system (Promega). While uploading a series of suspects into the database software, we found an unusual high number of shared alleles between two suspects 31 out of 32 alleles. Verification of their demographic data identified them as brothers. After confirmation of their paternity affiliation using the AmpFlSTR(®)YFiler™ (Applied Biosystems), we used two other multiplexes kits to improve the differentiation rate. The PowerPlex(®) ESX17 System (Promega) added one locus, SE33, who exhibits four different alleles. The second kit, the AmpFlSTR(®)MiniFiler™ (Applied Biosystems) added three more loci. Only one allele difference was found. In order to increase the discrimination power between related and unrelated individuals, we recommend that the DNA laboratories consider using a larger multiplex typing kit in cases like the one informed here.

The role of beginner's luck in learning to prefer risky patches by socially foraging house sparrows.

Although there has been extensive research on the evolution of individual decision making under risk (when facing variable outcomes), little is known on how the evolution of such decision-making mechanisms has been shaped by social learning and exploitation. We presented socially foraging house sparrows with a choice between scattered feeding wells in which millet seeds were hidden under 2 types of colored sand: green sand offering ~80 seeds with a probability of 0.1 (high risk-high reward) and yellow sand offering 1 seed with certainty (low risk-low reward). Although the expected benefit of choosing variable wells was 8 times higher than that of choosing constant wells, only some sparrows developed a preference for variable wells, whereas others developed a significant preference for constant wells. We found that this dichotomy could be explained by stochastic individual differences in sampling success during foraging, rather than by social foraging strategies (active searching vs. joining others). Moreover, preference for variable or constant wells was related to the sparrows' success during searching, rather than during joining others or when picking exposed seeds (i.e., they learn when actively searching in the sand). Finally, although for many sparrows learning resulted in an apparently maladaptive risk aversion, group living still allowed them to enjoy profitable variable wells by occasionally joining variable-preferring sparrows.

LEARNING TO CHOOSE AMONG SOCIAL FORAGING STRATEGIES IN ADULT HOUSE SPARROWS (Passer domesticus).

Social foragers may be regarded as being engaged in a producer-scrounger game in which they can search for food independently or join others who have discovered food. Research on the producer-scrounger game has focused mainly on the different factors influencing its ESS solution, but very little is known about the actual mechanisms that shape players' decisions. Recent work has shown that early experience can affect producer-scrounger foraging tendencies in young house sparrows, and that in nutmeg mannikins learning is involved in reaching the ESS. Here we show that direct manipulation of the success rate experienced by adult sparrows when following others can change their strategy choice on the following day. We presented to live sparrows an experimental regime, where stuffed adult house sparrows in a feeding position were positioned on a foraging grid that included two reward regimes: a positive one, in which the stuffed models were placed near food, and a negative one, in which the models were placed away from food. There was a significant increase in joining behavior after the positive treatment (exhibited by 84% of the birds), but no change after the negative treatment. Further analysis demonstrated that sparrows more frequently used the strategy with which they were more successful (usually joining), and that differences in strategy use were correlated with differences in success. These results suggest that adult birds can monitor their success and learn to choose among social foraging strategies in the producer-scrounger game.

A search for obligatory paternal alleles in a DNA database to find an alleged rapist in a fatherless paternity case.

A sexual assault case resulted in a pregnancy, which was subsequently aborted. The alleged father of the fetus was unknown. Maternal and fetal types were obtained using the 11-locus AmpFℓSTR(®) SGM Plus(®) kit. The national DNA database was searched for the paternal obligatory alleles and detected two suspects who could not be excluded as father of the male fetus. Additional typing using the AmpFℓSTR(®) Minifiler(™) kit, containing three additional autosomal loci, was not sufficient to exclude either suspect. Subsequent typing using the PowerPlex(®) 16, containing four additional loci, and Y-Filer(™) kits resulted in excluding one suspect. Searching a database for paternal obligatory alleles can be fruitful, but is fraught with possible false positive results so that finding a match must be taken as only preliminary evidence.