Implications of variation in worker body size for the honey bee recruitment system

Honey bee scouts seek food from flowers, return to the colony, and may perform a dance used to recruit dance followers to the flowers. Variation in body size of workers may result in the communication of misinformation because some information acquired by the scout and signaled to recruits is affected by body size. I tested two predictions of this hypothesis. (1) Recruitment communication takes place between bees of similar size despite the withincolony size distribution. (2) There is an inverse relationship between the size variation of foraging honey bees (Apis mellifera)and the rate at which nectar is returned to the colony. A positive relationship was found between the size of a dancer and that of its dance followers, which together comprise a dance group. There was less variation in size within dance groups than among groups. These two factors effectively lower the difference in size between signal sender and signal receiver and may enhance the flow of accurate size-dependent information. Also, an inverse relationship between size variation and rate of nectar intake was detected in each of six colonies using partial correlation analysis. This may be due to communication of misinformation when size variance is higher. The relationship was statistically significant in two colonies and the combined results were significant. The results of the first study suggest the generally weak relationships found in this second study.     

Effect of SERCA Pump Inhibitors on Chemoresponses in Paramecium

ABSTRACT. Inhibitors of SERCA (sarcoplasmic/endoplasmic reticulum Ca²⁺-dependent ATPase) calcium pumps were used to investigate the involvement of internal Ca²⁺ stores in the GTP response in Paramecium . External application of these inhibitors was found to dramatically alter the typical behavioral and electrophysiological responses of Paramecium to extracellular chemical stimulation. In particular, 2.5-di-tert-butylhydroquinone (BHQ) strongly inhibited the backward swimming response of paramecia to externally applied GTP, though it did not inhibit the associated whirling response. BHQ also prolonged the normally brief electrophysiological response of these cells to GTP. BHQ completely blocked the behavioral and electrophysiological responses of Paramecium to extracellular Ba²⁺, but had no measurable effect on the behavioral or electrophysiological responses of these cells to another depolarizing stimulus, elevated external K⁺ concentration. These results suggest the involvement of nonciliary Ca²⁺ ions in the GTP and Ba²⁺ responses.     

Multimodal signalling in estrildid finches: song,dance and colour are associated with different ecological and life‐history traits

Sexual traits (e.g. visual ornaments, acoustic signals, courtship behaviour) are often displayed together as multimodal signals. Some hypotheses predict joint evolution of different sexual signals (e.g. to increase the efficiency of communication) or that different signals trade off with each other (e.g. due to limited resources). Alternatively, multiple signals may evolve independently for different functions, or to communicate different information (multiple message hypothesis). We evaluated these hypotheses with a comparative study in the family Estrildidae, one of the largest songbird radiations, and one that includes many model species for research in sexual selection and communication. We found little evidence for either joint evolution or trade‐offs between song and colour ornamentation. Some negative correlations between dance repertoire and song traits may suggest a functional compromise, but generally courtship dance also evolved independently from other signals. Instead of correlated evolution, we found that song, dance and colour are each related to different socio‐ecological traits. Song complexity evolved together with ecological generalism, song performance with investment in reproduction, dance with commonness and habitat type, whereas colour ornamentation was shown previously to correlate mostly with gregariousness. We conclude that multimodal signals evolve in response to various socio‐ecological traits, suggesting the accumulation of distinct signalling functions.     

Rapid partner switching may facilitate increased broadcast group size in dance compared with conversation groups

Dancing is a universal human activity that involves exertive rhythmic movement to music. It is often conducted in a social environment and often involves synchronization. It has been found to cause dancers to bond socially. Like conversation, it has been suggested that dancing may be an inexpensive form of social bonding, in that both activities facilitate efficient group bonding by allowing multiple individuals to bond simultaneously. However, no previous study has systematically observed the size of naturally occurring dance groups. During unobtrusive observation of natural dance and conversation behavior, we found that the cumulative number of dance partners (cumulative group) was greater than the number of partners at any one moment (instantaneous group), whereas no such difference was found for conversation. Additionally, the length of uninterrupted engagement (bout) was negatively predicted by group size in conversation but not dance groups, and it was significantly longer in conversation groups than dance groups. Finally, instantaneous group size was significantly larger in dance than conversation groups, and also positively related to time spent synchronizing in dance groups. Together, these results suggest that dance may allow a larger number of individuals to simultaneously engage with each other than conversation does because (i) more rapid partner switching increases cumulative broadcast group; and (ii) synchrony facilitates simultaneous interaction with multiple individuals, allowing for larger instantaneous groups. We conclude that the capacity for information transfer provided by language comes at a cost in terms of social bonding, and that dance may have played an important role in bonding large hominin social groups.     

Merging movements: Diverse dance practices in postsecondary education

This article examines students' choices in a postsecondary dance major curriculum where students selected to study one or more of five dance practices (African and Diaspora Movement Practices, Contemporary Ballet, Movement Language Sources, Postmodern Contemporary Dance, and Urban Movement Practices) each semester along with required coursework centered on inquiry, the ability to pose and pursue informed questions, and creativity, the process of making something new. Using a qualitative research approach, the study investigated three main questions: What factors drive students' course selections?; How do students fuse information from diverse dance practices?; and What do students learn through taking courses with peers who study diverse dance practices? The study's findings suggest that the selection and study of diverse dance practices in combination with a curricular emphasis on creativity and inquiry led students to feel empowered in their dance education, develop and articulate individualized movement approaches, and increased awareness of dance and creative problem-solving ability. Postsecondary dance programs prepare future citizens, artists, educators, and administrators who may find themselves in leadership or other positions that require a re-thinking and implementation of arts policies in public schools and other settings. As such, the study's findings also speak to the potential for arts policies and their implementation to evolve in a way that situates dance as a critical component of a comprehensive education.     

Genetic diversity within honeybee colonies increases signal production by waggle-dancing foragers

Recent work has demonstrated considerable benefits of intracolonial genetic diversity for the productivity of honeybee colonies: single-patriline colonies have depressed foraging rates, smaller food stores and slower weight gain relative to multiple-patriline colonies. We explored whether differences in the use of foraging-related communication behaviour (waggle dances and shaking signals) underlie differences in foraging effort of genetically diverse and genetically uniform colonies. We created three pairs of colonies; each pair had one colony headed by a multiply mated queen (inseminated by 15 drones) and one colony headed by a singly mated queen. For each pair, we monitored the production of foraging-related signals over the course of 3 days. Foragers in genetically diverse colonies had substantially more information available to them about food resources than foragers in uniform colonies. On average, in genetically diverse colonies compared with genetically uniform colonies, 36% more waggle dances were identified daily, dancers performed 62% more waggle runs per dance, foragers reported food discoveries that were farther from the nest and 91% more shaking signals were exchanged among workers each morning prior to foraging. Extreme polyandry by honeybee queens enhances the production of worker-worker communication signals that facilitate the swift discovery and exploitation of food resources.     

Cardiovascular system of normal aged subjects. Cardiovascular senescence

The cardiovascular system of the elderly is characterised by (i) an increased characteristic impedance of the big vessels, without hypertension; (ii) a cardiac index unchanged at rest and during submaximal exercising, despite a diminished VO2 max; (iii) a diastolic dysfunction with reduced rapid early filling (E wave at echo) and enhanced atrial systole (A wave); (iv) benign arrhythmias; (v) a reduced coronary reserve and an increased sensitivity to ischemia; (vi) an efficacy of converting enzyme inhibitors remaining unchanged, despite an altered renin-agiotensin system.     

The Elusive Honey Bee Dance “Language” Hypothesis

In the mid-1930s, Karl von Frisch proposed the equivalent of an odor-search hypothesis for honey bee recruitment to food sources. A decade later he switched to the equivalent of a dance language hypothesis (though he apparently did not consider his conclusions as hypotheses in either case). The later and more exotic hypothesis rapidly gained acceptance, but it failed its first experimental tests in the mid-1960s; searching recruits did not behave as von Frisch indicated they should under the language hypothesis. His earlier and more conservative odor-search hypothesis meshed better with results obtained in those test experiments. Language advocates then ignored basic precepts of scientific process, rejected and/or ignored results not in accord with their favored hypothesis, and instead repeatedly sought additional supportive evidence. While so doing, they inadvertently accumulated yet more evidence counter to von Frisch's original intent. By invoking ad hoc modifications and qualifications, advocates weakened, rather than strengthened, the hypothesis they continued to embrace. That strict adherence to the language hypothesis has had an unfortunate result; the exclusive investment in that line of research by various governmental agencies has failed to provide practical help to beekeepers or growers in the past half-century.