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This study investigated the changes in sea ice temperature, microalgae species distribution, shape changes, and photosynthetic activity observed in the first‐year ice that forms in winter in Saroma‐ko Lagoon, Hokkaido, Japan. Temperatures at the bottom of the ice remained constant at −1.7°C, near the freezing point, while they varied between −6 and −1°C with diel fluctuations at the surface layer. Carefully collected algal samples showed high photosynthetic quantum yield and acclimation to the light intensities of individual ice layers; this indicates that the algal photosynthetic activity responds to dynamic changes in the ice environment, such as variations in temperature, salinity, and brine space. The algal communities consisted of more than 95% diatoms. Smaller algal cells were distributed in the upper layer of the sea ice compared to the lower layers. Chaetoceros sp., the dominant small‐cell species, was evenly distributed throughout the layers. In contrast, Detonula confervacea, the dominant large‐cell species, was unevenly distributed in the lower layer, with smaller colony size and cell volume in the upper layer. The shape differences observed in this species were thought to be a response to the changing environment within the first‐year sea ice. [ABSTRACT FROM AUTHOR]

Home range is an ecological concept that affects many aspects of the life of vertebrates and hence understanding how it varies between species is crucial. Mammalian home range size has been linked to body size and diet, but these studies were based predominantly on terrestrial species and most specifically excluded bats. As the only group of flying mammals, bats experience distinctly different constraints on movement, and hence home range. However, despite their diversity, relatively little is known about the home ranges of bats, and this is the first global review assessing correlates of their home range size. Our hypothesis is that home range will be impacted by different ecological conditions experienced by the bats and by the biological traits of the bats themselves. We performed a meta-analysis based on published data for 81 bat species to identify variables that contribute most to home range size. Sex, wing loading, functional group, colony size, dietary class, distance from the equator (latitudinal region), habitat type, and the interaction between habitat type and latitudinal region were all important explanatory variables. Wing loading was positively correlated with home range size—while females, open-air foragers, large colony sizes, and bats in temperate regions consistently had large home ranges. Understanding the correlates of home range has important implications, for example, for bat conservation and for assessing the risk of spillover of zoonotic pathogens from bats to humans and livestock. [ABSTRACT FROM AUTHOR]

Colonial nesting waterbirds in agricultural landscapes have historically received limited research attention, especially in South Asia. For example, the Asian openbill (Anastomus oscitans) is a colonial species that extensively utilizes agricultural landscapes, yet there is a notable lack of substantial studies despite increasing urbanization across these landscapes. We investigated the factors affecting the breeding ecology of Asian openbills in eastern Nepal. We used a grid‐based approach to locate stork colonies and monitored them throughout the breeding season from May to November for three consecutive years (2020–2022). Altogether, we observed a total of 67 active colonies, comprising 4020 active nests, which successfully fledged a total of 7566 chicks. Additionally, most of the colonies were located within areas of human settlements (40%), followed by community forests (33%) and agricultural land (27%). The Asian openbills primarily preferred large trees, such as Bombax ceiba (72%), for nesting. The mean height of nesting trees was approximately 4 m taller, the diameter at breast height was twice as large, and the canopy cover area was three times greater than that of non‐nesting trees. The canopy cover area of trees positively influenced the colony size, while colony size positively influenced the fledgling's success. Our study underscores the significance of large trees in providing sufficient space for accommodating a substantial number of openbill nests and fledglings. These findings have significant implications for conservation efforts to protect large trees along with wetlands and agricultural lands, as crucial measures to ensure the sustainable breeding of this nationally vulnerable species. [ABSTRACT FROM AUTHOR]

Abstract Marine heatwaves are increasing in frequency and duration, threatening tropical reef ecosystems through intensified coral bleaching events. We examined a strikingly variable spatial pattern of bleaching in Moorea, French Polynesia following a heatwave that lasted from November 2018 to July 2019. In July 2019, four months after the onset of bleaching, we surveyed > 5000 individual colonies of the two dominant coral genera, Pocillopora and Acropora, at 10 m and 17 m water depths, at six forereef sites around the island where temperature was measured. We found severe bleaching increased with colony size for both coral genera, but Acropora bleached more severely than Pocillopora overall. Acropora bleached more at 10 m than 17 m, likely due to higher light availability at 10 m compared to 17 m, or greater daily temperature fluctuation at depth. Bleaching in Pocillopora corals did not differ with depth but instead varied with the interaction of colony size and Accumulated Heat Stress (AHS), in that larger colonies (> 30 cm) were more sensitive to AHS than mid-size (10–29 cm) or small colonies (5–9 cm). Our findings provide insight into complex interactions among coral taxa, colony size, and water depth that produce high spatial variation in bleaching and related coral mortality.

Marine heatwaves are increasing in frequency and duration, threatening tropical reef ecosystems through intensified coral bleaching events. We examined a strikingly variable spatial pattern of bleaching in Moorea, French Polynesia following a heatwave that lasted from November 2018 to July 2019. In July 2019, four months after the onset of bleaching, we surveyed > 5000 individual colonies of the two dominant coral genera, Pocillopora and Acropora, at 10 m and 17 m water depths, at six forereef sites around the island where temperature was measured. We found severe bleaching increased with colony size for both coral genera, but Acropora bleached more severely than Pocillopora overall. Acropora bleached more at 10 m than 17 m, likely due to higher light availability at 10 m compared to 17 m, or greater daily temperature fluctuation at depth. Bleaching in Pocillopora corals did not differ with depth but instead varied with the interaction of colony size and Accumulated Heat Stress (AHS), in that larger colonies (> 30 cm) were more sensitive to AHS than mid-size (10–29 cm) or small colonies (5–9 cm). Our findings provide insight into complex interactions among coral taxa, colony size, and water depth that produce high spatial variation in bleaching and related coral mortality. [ABSTRACT FROM AUTHOR]

The size of animal groups has profound effects on individual and collective behavior, particularly in social insect colonies. Larger colonies are predicted to be more complex with more specialization among members. However, the empirical support of this theoretical expectation is limited. Hygienic behavior of honey bees is a complex cooperative behavior of workers detecting, uncapping, and removing unhealthy brood. It is an important defense against brood diseases, including the ectoparasitic mite Varroa destructor. We support the prediction that hygienic behavior increases with group size using a simulation model. To also test this prediction empirically, we performed five experiments, to compare the hygienic performance of small and large honey bee groups at four different scales, roughly representing four orders of magnitude. Hygienic performance qualitatively increased across the different scales, but different methodologies limit quantitative comparisons across experiments. Within experiments, group size was also positively related to hygienic behavior. The strongest effects of group size were measured in groups that were smaller than what honey bees adopt under natural conditions. The group-size effect on hygienic performance decreased with increasing scale and at the full colony scale, group size was unrelated to hygienic assay scores. Therefore, colony size is unlikely to confound the hygienic evaluation of colonies in apicultural practice although we demonstrate clear effects of group size on hygienic behavior. Direct observations of individual behavior that were performed in two small scale experiments did not support our prediction of increased individual specialization in larger groups. Thus, our study supports the notion of performance benefits of larger groups in the context of social immunity, although the mechanisms of how group size enhances hygienic behavior remain to be investigated further. Significance Statement: Social insects owe their ecological success partly to their efficient division of labor and behavioral specialization of colony members. Empirical support for the theoretical argument that group performance increases with group size is insufficient. Hygienic behavior is an important defense against brood pests and diseases that threaten honey bee health. Yet, it has not been investigated with respect to group size. Here, we analyze a simulation model, demonstrating theoretically that group size is predicted to increase hygienic behavior. We then provide experimental support for this prediction across a range of group sizes, though results of some experiments are equivocal and sample sizes are limited, constraining our empirical conclusions. In small groups, we find support for the theoretical idea that hygienic performance increases with group size, but our study also indicates that this effect is not very important under apiculturally relevant group size conditions. We find no support for higher individual specialization in larger groups. Furthermore, our study indicates that beekeepers can disregard deviations in colony size when assessing their stock for hygienic behavior. [ABSTRACT FROM AUTHOR]

Surface blooms of colony-forming Microcystis are increasingly occurring in aquatic ecosystems on a global scale. Recent studies have found that the Microcystis colonial morphology is a crucial factor in the occurrence, persistence, and dominance of Microcystis blooms, yet the mechanism driving its morphological dynamics has remained unknown. This study conducted a laboratory experiment to test the effect of extracellular polymeric substances on the morphological dynamics of Microcystis. Ultrasound was used to disaggregate colonies, isolating the cells and of the Microcystis suspension. The single cells were then re-cultured under three homologous EPS concentrations: group CK, group Low, and group High. The size, morphology, and EPS [including tightly bound EPS (TB-EPS), loosely bound EPS (LB-EPS), bound polysaccharides (B-polysaccharides), and bound proteins (B-proteins)] changes of colonies were closely monitored over a period of 2 months. It was observed that colonies were rapidly formed in group CK, with median colony size (D50) reaching 183 µm on day 12. The proportion of colonies with a size of 150-500 µmincreased from 1% tomore than 50%. Colony formation was also observed in both groups Low and High, but their D50 increased at a slower rate and remained around 130 µm after day 17. Colonies with a size of 50-150 µm account for more than 50%. Groups CK and Low successively recovered the initial Microcystis morphology, which is a ring structure formed of several small colonies with a D50 of 130 µm. During the recovery of the colony morphology, the EPS per cell increased and then decreased, with TB-EPS and B-polysaccharides constituting the primary components. The results suggest that colony formation transitioned from adhesion driven to being division driven over time. It is suggested that the homologous EPS released into the ambient environment due to the disaggregation of the colony is a chemical cue that can affect the formation of a colony. This plays an important but largely ignored role in the dynamics of Microcystis and surface blooms. [ABSTRACT FROM AUTHOR]

Corbiculate bees offer the opportunity to analyse the evolution of differences in body size between sexes in relationship to the social environment, because this group of phylogenetically related taxa have contrasting levels of social organization, ranging from solitary to highly eusocial. Sexual size dimorphism evolves because body size is usually related to reproductive success through different pathways in females and males. Female body size is strongly correlated with fecundity, whereas in males the body size is correlated with mating success. Within a clade, if sexual selection on males has been stronger than selection on female fecundity, a sexual size dimorphism bias to males would be expected (Rensch's rule), or an opposite trend when the fecundity of females has had a stronger effect. We tested these predictions by taking an allometric approach that considered differences in the capacity of a reproductive female to start a nest on her own or not. Phylogenetic analysis of the whole clade and another analysis including only species in which the females start nests on their own showed that the corbiculate bees do not seem to follow Rensch's rule. The males and reproductive females of the species in which the females have lost their capacity to start nests were smaller than the reproductive individuals of species in which the females start nests on their own, suggesting that selective pressures linked to the evolution of sociality might constrain the evolution of a large body size in both males and reproductive females. [ABSTRACT FROM AUTHOR]

Abstract Colonial nesting waterbirds in agricultural landscapes have historically received limited research attention, especially in South Asia. For example, the Asian openbill (Anastomus oscitans) is a colonial species that extensively utilizes agricultural landscapes, yet there is a notable lack of substantial studies despite increasing urbanization across these landscapes. We investigated the factors affecting the breeding ecology of Asian openbills in eastern Nepal. We used a grid‐based approach to locate stork colonies and monitored them throughout the breeding season from May to November for three consecutive years (2020–2022). Altogether, we observed a total of 67 active colonies, comprising 4020 active nests, which successfully fledged a total of 7566 chicks. Additionally, most of the colonies were located within areas of human settlements (40%), followed by community forests (33%) and agricultural land (27%). The Asian openbills primarily preferred large trees, such as Bombax ceiba (72%), for nesting. The mean height of nesting trees was approximately 4 m taller, the diameter at breast height was twice as large, and the canopy cover area was three times greater than that of non‐nesting trees. The canopy cover area of trees positively influenced the colony size, while colony size positively influenced the fledgling's success. Our study underscores the significance of large trees in providing sufficient space for accommodating a substantial number of openbill nests and fledglings. These findings have significant implications for conservation efforts to protect large trees along with wetlands and agricultural lands, as crucial measures to ensure the sustainable breeding of this nationally vulnerable species.

Biological collectives, like honeybee colonies, can make intelligent decisions and robustly adapt to changing conditions via intricate systems of excitatory and inhibitory signals. In this study, we explore the role of behavioural plasticity and its relationship to network size by manipulating honeybee colony exposure to an artificial inhibitory signal. As predicted, inhibition was strongest in large colonies and weakest in small colonies. This is ecologically relevant for honeybees, for which reduced inhibitory effects may increase robustness in small colonies that must maintain a minimum level of foraging and food stores. We discuss evidence for size-dependent plasticity in other types of biological networks.

Rooks Corvus frugilegus are common and widespread in urban and agricultural habitats in Denmark. Large numbers are killed annually by derogation shooting to control population growth to reduce noise near populated areas and prevent agricultural damage. Responding to increasing public complaints about noise nuisance from urban rookeries, we investigated changes in extent of urban and agricultural habitats within 500 m, 1000 m and 2000 m of all known breeding rook colonies (rookeries) in eastern Jutland, Denmark in 1991 compared to 2021 based on open access land cover GIS layers in 1990 and 2019. Numbers of rookeries increased by 40% from 95 (1991) to 133 (2021) but nest abundance increased only by 6% from 10,299 to 10,887 due to more and significantly smaller rookeries, increasingly associated with urban sites. In both years, the proportion of urban area within distance classes of rookeries was significantly higher, and the area of agriculture significantly lower, than at randomly chosen points in the same region. The proportion of urban area around each rookery decreased with increasing distance, whereas the proportion of agricultural land cover increased. The proportional area of urban land use within the distance classes increased between 1991 and 2021 whereas agricultural land cover decreased. Given no simultaneous major change in overall land use, our results indicate an increasing selection by rooks for smaller urban rookeries over agricultural landscapes, where rookeries have declined. We consider these trends, especially the proliferation of smaller rookeries in urban areas, as a potential explanation for the upsurge in public complaints about rookery noise in residential areas. We urge further research to explain the causes behind these trends before we can provide science-based solutions to resolve such conflicts effectively. [ABSTRACT FROM AUTHOR]

Honey bees are key insect pollinators, providing important economic and ecological value for human beings and ecosystems. This has triggered the development of several monitoring methods for assessing the temporal development of colony size, food storage, brood and pathogens. Nonetheless, most of these methods are based on visual assessments that are observer-dependent and prone to bias. Furthermore, the impact on colony development (invasiveness), as well as accuracy, were rarely considered when implementing new methods. In this study, we present and test a novel accurate and observer-independent method for honey bee colony assessment, capable of being fully standardized. Honey bee colony size is quantified by assessing the weight of adult bees, while brood and provision are assessed by taking photos and conducting image analysis of the combs with the image analysis software Deepbee®. The invasiveness and accuracy of the method were investigated using field data from two experimental apiaries in Portugal, comparing results from test and control colonies. At the end of each field experiment, most of the tested colonies had the same colony size, brood levels and honey production as the control colonies. Nonetheless, continuous weight data indicated some disturbance in tested colonies in the first year of monitoring. The overall accuracy of the image analysis software was improved by training, indicating that it is possible to adapt the software to local conditions. We conclude that the use of this fully quantitative method offers a more accurate alternative to classic visual colony assessments, with negligible impact on colony development. [ABSTRACT FROM AUTHOR]

Trigona spinipes is a generalist species of stingless bee that is dominant in many pollination networks and has a wide distribution in the tropics and subtropics of the Neotropics. This eusocial species builds exposed aerial nests in tree branches. Although some studies have been carried out on nest density, there are surprisingly few studies on its bionomy, and especially on the population size of the colonies. To survey the density and spatial patterns of nests of this stingless bee, three sites within the Northeast region in Brazil were studied, which ranged from urban to rural to forest habitats. A high density of nests was found in rural and urban sites, with 0.6 nests/ha and 0.4 nests/ha, respectively. In comparison, a lower density was found in the forest site, with 0.1 nests/ha in the edge and 0.03 nests/ha in the interior. Thus, the highest density of nests occurred in open areas. In the urban site, the nests showed a uniform distribution, while the distribution was aggregated in the rural site. The majority of nests were oriented so that the entrance faced the opposite direction to prevailing winds. Several aspects of the bionomy of 22 nests were sampled. The mean estimated total population size of colonies (immatures plus imagoes) was 38,813 (range 25,581–53,083) individuals, with 13,202 adults. Our results confirm that this species produces some of the largest colonies within the stingless bees, although lower than previously mentioned, emphasizing its importance in ecosystems of open neotropical areas. [ABSTRACT FROM AUTHOR]

Colony size in social insects is one of the most important factors in shaping their self-organized system. It affects a wide variety of traits such as foraging and defense strategies, social immune responses, the degree of polymorphism, and reproductive output. However, colony size estimation of subterranean termites in the field has been challenging, due to their extremely cryptic biology and multiple site–nesting behavior. Since natural selection favors workers that maximize the number of their siblings, the amount of egg production may reflect the number of workers in the colony. Here, we report a method for inferring colony size in the field using total egg production in each colony from a subterranean termite, Reticulitermes speratus. Our investigation of field colonies revealed that the body weight of queens reaches a peak and had the largest variance in June and July and accurately predicts the number of eggs laid by the queen per 24 h. Using laboratory-reared colonies, we found that the total egg production in each colony is proportional to the number of workers. We also estimated the colony size of 198 field colonies and found that the median and maximum colony size was 24,500 and 451,800 workers per colony. The method for inferring colony size presented here may also be applicable to termite species with a clear seasonality in egg production. The colony size estimate will contribute to understanding the life history strategies and social systems of termites. [ABSTRACT FROM AUTHOR]

In urban environments, trace metals are a widespread class of pollutants that represent a major threat to organisms. Contamination levels in insects differ greatly among habitats, and a basic assumption is that individual contamination depends, at least in part, on environmental contamination. Ants are major actors in ecosystems, but surprisingly little information is available on trace metal contamination of ants in urban environments. Ants could be particularly sensitive to their local environment due to sedentary nesting but their social life could limit contamination. In this study, we assessed whether city colonies of the ant Temnothorax nylanderi (Foerster, 1850) differed from forest colonies in their trace metal contamination, and we tested whether larger colonies tolerate pollution better, then showing a lower level of contamination. We collected ant colonies and soil from five city parks in Paris and five forests around Paris, and we quantified the concentration of five trace metals. We found that despite living in a more contaminated habitat for cadmium, copper and zinc, city colonies were not more contaminated than forest colonies. Lead was the only trace metal more present in the city habitat than the forest habitat, for which city colonies were more contaminated than forest colonies. Interestingly, for lead, contamination decreased when colony size increased, suggesting that living in large groups limits pollutant contamination. Our results suggest that city colonies overcome certain trace metal exposure. We argue that analysing whole colonies is important to take into account social life. [ABSTRACT FROM AUTHOR]

Microcystis has been the dominant bloom-forming cyanobacterial population in Lake Taihu over the past two decades. To illustrate the temporal and spatial variation in the main colony characteristics for Microcystis and their key environmental factors in Lake Taihu, an annual investigation of the size, morphospecies and viability (the viable cell rate) of Microcystis colonies was performed in this study from 2020 to 2021. The average colony diameter ranged from 81.12 to 499.54 μm at all sites during this investigation. The average colony diameter of the whole lake in spring and in late autumn to early winter was higher than that in other times. Microcystis flos-quae, Microcystis aeruginosa, Microcystis novacekii and Microcystis wesenbergii were the main dominant morphotypes, which was mainly affected by pH, TDP and temperature. Although no significant correlation was found between colony viability and environmental factors, the temporal difference in colony viability was remarkable. Colony viability in autumn (mainly October and November), spring (March and April), and July was lower than that in other times. [ABSTRACT FROM AUTHOR]

Animals often search for food more efficiently with experience. However, the contribution of experience to foraging success under direct competition has rarely been examined. Here we used colonies of an individually foraging desert ant to investigate the value of spatial experience. First, we trained worker groups of equal numbers to solve either a complex or a simple maze. We then tested pairs of both groups against one another in reaching a food reward. This task required solving the same complex maze that one of the groups had been trained in, to determine which group would exploit better the food reward. The worker groups previously trained in the complex mazes reached the food reward faster and more of these workers fed on the food than those trained in simple mazes, but only in the intermediate size group. To determine the relative importance of group size versus spatial experience in exploiting food patches, we then tested smaller trained worker groups against larger untrained ones. The larger groups outcompeted the smaller ones, despite the latter's advantage of spatial experience. The contribution of spatial experience, as found here, appears to be small, and depends on group size: an advantage of a few workers of the untrained group over the trained group negates its benefits. [ABSTRACT FROM AUTHOR]

Soft corals are zooxanthellate sessile animals supporting various organisms in coral reefs. However, their populations are threatened by the impacts of ocean warming. Under thermal stress conditions, soft corals may experience mild to severe bleaching which may lead to death. Understanding soft coral bleaching responses highlights the importance in predicting how populations and diversity may be affected by changing climate scenarios. In this study, we examined the bleaching responses of the three dominant soft coral genera (Lobophytum, n = 1318; Sarcophyton, n = 116; Sinularia, n = 639 colonies) in the Bolinao-Anda Reef Complex (BARC), Pangasinan, north-western Philippines during the 2020 thermal stress event in terms of genus and colony size susceptibility, and zooxanthellae density. Degree heating week (DHW) data from 1986–2020 were obtained using remotely sensed data to determine thermal anomalies in the study sites. The maximum DHW (6.3) in 2020 occurred between July–August while bleaching surveys were done during October of the same year. The percentage of bleached portions in each colony was used to determine bleaching category: no bleaching (0%), moderately bleached (1–50%) and heavily bleached (>50%). Quantification of bleaching prevalence and susceptibility of colony sizes were determined by colony count and mean diameter measurements taken from quadrat photographs in October 2020. Haphazard tissue collection (∼3 cm) in each colony of three soft coral genera per bleaching category was done to quantify zooxanthellae density. Results showed that Lobophytum colonies had the lowest bleaching prevalence (41%), followed by Sinularia (66%) and Sarcophyton (78%). All colony size classes of the three genera were susceptible to bleaching. However, smaller colonies of Lobophytum (<15 cm), Sarcophyton (<5 cm) and Sinularia (<5 cm) showed less susceptibility than large colonies. Zooxanthellae density was significantly reduced in moderately and heavily bleached colonies. The results of this study highlight that bleaching susceptibility is genus specific, with Sarcophyton and Sinularia being more susceptible to bleaching than Lobophytum. Smaller colonies seemed to be less susceptible to bleaching than large-sized soft corals suggesting a differential thermal stress response. Spatial variations in bleaching prevalence were also found among reef sites with varying environmental conditions and thermal stress histories. This work provided initial observations on how bleaching affects soft corals. Further studies on soft coral community recovery are recommended to fully understand how these organisms perform after thermal stress events. [ABSTRACT FROM AUTHOR]

The homogenization of agricultural landscapes has led to a decrease in pollinator diversity and abundance. In response to this decline, farmers have implemented agroecological measures, which, in meadows, aim at providing more floral resources. These measures are the availability of unmown floral strips, delayed mowing, and discouraging the use of the conditioner, a device known to harm insects. The aim of our study was to investigate the cascade of effects of these agroecological measures on honey bee colony development and winter survival. We (1) determined the effect of these measures on colony size during the nectar and pollen collecting season in spring and summer, (2) evaluated the effect of spring and summer colony sizes on autumn size, and (3) described the effect of colony size in autumn on winter mortality. In this study, 300 honey bee colonies were monitored over three years in three cantons of Switzerland. Colony size was defined by the numbers of brood cells and of adult workers. Honey bee colony size in summer and autumn was improved by agroecological measures on meadows and likely contributed to the increased overwintering success. This study is a first step toward the targeted identification of viable agroecological measures on temporary meadows that can be implemented to promote honey bee colonies health in the agricultural landscape. [ABSTRACT FROM AUTHOR]

Abstract The homogenization of agricultural landscapes has led to a decrease in pollinator diversity and abundance. In response to this decline, farmers have implemented agroecological measures, which, in meadows, aim at providing more floral resources. These measures are the availability of unmown floral strips, delayed mowing, and discouraging the use of the conditioner, a device known to harm insects. The aim of our study was to investigate the cascade of effects of these agroecological measures on honey bee colony development and winter survival. We (1) determined the effect of these measures on colony size during the nectar and pollen collecting season in spring and summer, (2) evaluated the effect of spring and summer colony sizes on autumn size, and (3) described the effect of colony size in autumn on winter mortality. In this study, 300 honey bee colonies were monitored over three years in three cantons of Switzerland. Colony size was defined by the numbers of brood cells and of adult workers. Honey bee colony size in summer and autumn was improved by agroecological measures on meadows and likely contributed to the increased overwintering success. This study is a first step toward the targeted identification of viable agroecological measures on temporary meadows that can be implemented to promote honey bee colonies health in the agricultural landscape.

Mechanoregulation of cell–extracellular matrix (ECM) interactions are crucial for dictating pluripotent stem cell differentiation. However, not all pluripotent cells respond homogeneously which results in heterogeneous cell populations. When cells, such as mouse epiblast stem cells (EpiSCs), are cultured in clusters, the heterogeneity effect during differentiation is even more pronounced. While past studies implicated variations in signaling pathways to be the root cause of heterogeneity, the biophysical aspects of differentiation have not been thoroughly considered. Here, we demonstrate that the heterogeneity of EpiSC differentiation arises from differences in the colony size and varying degrees of interactions between cells within the colonies and the ECM. Confocal imaging demonstrates that cells in the colony periphery established good contact with the surface while the cells in the colony center were separated by an average of 1–2 µm from the surface. Traction force measurements of the cells within the EpiSC colonies show that peripheral cells generate large tractions while the colony center cells do not. A finite element modeling of EpiSC colonies shows that tractions generated by the cells at the colony periphery lift off the colony center preventing the colony center from undergoing differentiation. Together, our results demonstrate a biophysical regulation of heterogeneous EpiSC colony differentiation. [ABSTRACT FROM AUTHOR]

Predation is an important force structuring ecological communities. However, it is still controversial whether larger predator groups are more efficient at exploiting abundant resources. Here, we explored the association between the number of foragers and predation ability in generalist ant species that differ in forager numbers when exploiting resources.We conducted a field experiment by increasing caterpillar density around nests of two abundant Dorymyrmex ant species in the semiarid Patagonian steppe, where D. tener allocates a higher number of foragers to resource exploitation than D. antarcticus. We (1) compared the association between predation effectiveness (success to complete a task) and efficiency (speed of task performance and economy of foragers) with the number of foragers involved between species, and (2) studied how they responded numerically to increasing prey densities, by sequentially adding 3, 6 and 12 larvae in the same foraging arena. Finally, (3) we compared behavioural and morphological traits related to predation between these ant species.Although D. tener discovered a similar number of arenas with larvae than D. antarcticus, it was more effective as it recruited more and removed more larvae. This species was also more efficient than D. antarcticus in all predation subtasks, and the time used to remove one larva depended on prey density, being faster for the high‐larvae density.Besides the number of foragers, ant species did not differ in other behavioural traits, and D. tener's foragers were slightly larger than those of D. antarcticus.This study illustrates how, in social predators, the predator group size and individual behavioural characteristics may act in conjunction, with relevant consequences at ecological, evolutionary, and applied levels, including potential implications for pest control. [ABSTRACT FROM AUTHOR]

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Abstract Nest building can represent an energetically costly activity for a variety of animal taxa. Besides, the determinants of within‐species variation in the design of nests, notably with respect to natural and sexual selection, are still insufficiently documented. Based on an observational study, we examined the influence of nesting conditions (nesting‐support quality, colony, laying date, and year) on male‐built nest volume and also its potential role as a postmating sexually selected display in the whiskered tern Chlidonias hybrida. This tern species is a monogamous colonial bird with obligate biparental care breeding on aquatic vegetation. Hence, large nesting platforms are expected to be a selective advantage because they would better withstand adverse environmental conditions and provide a secure structure for eggs. Nest size may also serve as a postmating sexual trait, and variation in egg production would be positively associated with nest size. We found that nest volume was adjusted to different environmental cues. A positive relationship was found between nest volume and nesting‐support quality, indicating that the leaf density of white waterlily is essential for nest stability. Variation in nest volume was not correlated to colony size but varied among colonies and years. Male‐built nest volume was also positively associated with mean egg volume per clutch but not with clutch size. The fitness consequences of building a large nest are yet to be studied, and additional investigations are recommended to better understand whether the activity of males early during breeding season (e.g., nest building and courtship feeding performance) really serves as postmating sexually selected signals.

Nutrients and hydrodynamic mixing are both important environmental factors affecting the growth of Microcystis. Effects of nutrient combined with hydrodynamic mixing in the dominance of Microcystis in phytoplankton community is unclear. Here we present data on the effects of hydrodynamic mixing (HM), nutrient addition (+ N + P), and hydrodynamic mixing combined nutrient addition (HM + N + P) on dominance of Microcystis in a microcosm experiments. Results showed that the average number of Microcystis in HM + N + P was 10.09, 3.79, and 1.95 times that of the control (9.19 × 106 cells L−1), + N + P, and HM group, respectively. Moreover, the mean colony sizes of Microcystis in HM + N + P group were 2.08, 1.91, and 1.21 times that of the control (24.42 μm), + N + P,HM group, respectively. Pseudanabaena limnetica replaced Microcystis as the dominant species in control, + N + P, and HM group at end of the experiment, with 82.21%, 90.65%, and 50.37% of total algae number, respectively. However, in HM + N + P group, Microcystis dominated throughout the experimental period, accounting for 73.56–94.67% of the total algae abundance. Results demonstrated that N and P combined with hydrodynamic mixing promoted abundance, colony size of Microcystis, which plays an important role in the dominance of Microcystis in phytoplankton community in natural ecosystems. [ABSTRACT FROM AUTHOR]

Colony growth is a common phenomenon of structured populations dispersed in nature; nevertheless, studies on the spatial distribution of colonies are largely insufficient. Here, we performed a systematic survey to address the questions of whether and how the spatial distribution of colonies was influenced by the genome and environment. Six Escherichia coli strains carrying either the wild-type or reduced genomes and eight media of varied nutritional richness were used to evaluate the genomic and environmental impacts, respectively. The genome size and nutritional variation contributed to the mean size and total area but not the variation and shape of size distribution of the colonies formed within the identical space and of equivalent spatial density. The spatial analysis by means of the Voronoi diagram found that the Voronoi correlation remained nearly constant in common, in comparison to the Voronoi response decreasing in correlation to genome reduction and nutritional enrichment. Growth analysis at the single colony level revealed positive correlations of the relative growth rate to both the maximal colony size and the Voronoi area, regardless of the genomic and nutritional variety. This result indicated fast growth for the large space assigned and supported homeostasis in the Voronoi correlation. Taken together, the spatial distribution of colonies might benefit efficient clonal growth. Although the mechanisms remain unclear, the findings provide quantitative insights into the genomic and environmental contributions to the growth and distribution of spatially or geographically isolated populations. [ABSTRACT FROM AUTHOR]

In a much‐cited 1964 paper entitled "Reproductive efficiency in relation to colony size in hymenopterous societies," Charles Michener investigated the correlation between a colony's size and its reproductive efficiency – the ability of its adult females to produce reproductives, measured as per‐capita output. Based on his analysis of published data from destructively sampled colonies in 18 species, he reported that in most of these species efficiency decreased with increasing colony size. His conclusion that efficiency is higher in smaller groups has since gained widespread acceptance. But it created a seeming paradox: how can natural selection maintain social behaviour when a female apparently enjoys her highest per‐capita output by working alone? Here we treat Michener's pattern as a hypothesis and perform the first large‐scale test of its prediction across the eusocial Hymenoptera. Because data on actual output of reproductives were not available for most species, Michener used various proxies, such as nest size, numbers of brood, or amounts of stored food. We show that for each of Michener's data sets the reported decline in per‐capita productivity can be explained by factors other than decreasing efficiency, calling into question his conclusion that declining efficiency is the cause of the pattern. The most prominent cause of bias is the failure of the proxy to capture all forms of output in which the colony invests during the course of its ontogeny. Other biasing factors include seasonal effects and a variety of methodological flaws in the data sets he used. We then summarize the results of 215 data sets drawn from post‐1964 studies of 80 species in 33 genera that better control for these factors. Of these, 163 data sets are included in two meta‐analyses that statistically synthesize the available data on the relationship between colony size and efficiency, accounting for variable sample sizes and non‐independence among the data sets. The overall effect, and those for most taxonomic subgroups, indicates no loss of efficiency with increasing colony size. Two exceptional taxa, the halictid bees and independent‐founding paper wasps, show negative trends consistent with the Michener hypothesis in some species. We conclude that in most species, particularly those with large colony sizes, the hypothesis of decreasing efficiency with increasing colony size is not supported. Finally, we explore potential mechanisms through which the level of efficiency can decrease, be maintained, or even increase, as colonies increase in size. [ABSTRACT FROM AUTHOR]

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Larger numbers of germline cell divisions can increase the number of mutations inherited by offspring. Therefore, in systems where the number of offspring is dependent on the number of germline cell divisions, a higher overall rate of molecular evolution may be expected. Here, I examine whether colony size in social insects, which varies from tens to millions, influences molecular evolutionary rates via this mechanism. Comparative analyses of whole genomes from three clades of social insects, including eight species in the ant genus Pseudomyrmex, seven fungus-growing ants, and 11 bees, reveal that rates of molecular evolution are positively correlated with colony size. The additional germline cell divisions necessary to maintain large colony sizes may lead to mutation accumulation in the germlines of queens of these species, a process similar to that which occurs in aging human males. Among species with large colonies, I also find a weak signal of intensified constraint on DNA repair genes. This pattern suggests the intriguing possibility that the additional mutations that occur in these taxa may increase selective pressure for replication fidelity. Finally, I find that colony size is negatively associated with GC-content in five highly conserved genes across 115 ant genera, a pattern consistent with a positive relationship between substitution rate and colony size. Colony size, a fundamental facet of eusociality, appears to play a previously unappreciated role in genome evolution. [ABSTRACT FROM AUTHOR]

Harmful cyanobacterial blooms in eutrophic water bodies pose a major threat to the environment and to human health. The morphological functional traits of cyanobacteria play important roles in maintaining their competitive advantages. To explore the regulatory mechanisms of the morphological functional traits of different bloom-forming cyanobacteria, we performed a one-year-long phytoplankton survey from November 2016 to October 2017 in Lake Chaohu, China. The colony size and cell diameter of the dominant cyanobacteria were measured, and their relationships were analyzed. The results showed that Dolichospermum flos-aquae and Microcystis aeruginosa were the dominant cyanobacteria in the lake. Microcystis was the dominant species during the summer; the growth of Dolichospermum growth surpassed that of Microcystis, and Dolichospermum became the dominant species in the late autumn, winter and spring. From winter to spring, the colony size of Dolichospermum decreased from 222.25 μm to 10.51 μm, and the individual cell diameter increased from 6.5 μm to 7.4 μm. From summer to autumn, Dolichospermum showed enlarged colony sizes and reduced cell diameters. The Microcystis colony size increased from 83.71 μm in the spring to 196.71 μm in the summer and autumn, while cells diameter remained essentially at 3–4 μm from March to October in Lake Chaohu. The relationship between colony size and cell diameter in Dolichospermum was significantly positive, while that of Microcystis was not significant. These results suggest that Dolichospermum may maintain biomass through a trade-off between cell diameter and colony size, and that a flexible morphological regulatory mechanism exists. This study seeks to improve our understanding of how bloom-forming cyanobacteria maintain their dominance by regulating their morphological traits. [ABSTRACT FROM AUTHOR]

The rusty patched bumble bee, Bombus affinis, is federally endangered in the United States and Canada. Information on natural history is crucial to conservation planning, but little is known about B. affinis nesting biology, habitat, overwintering, and mating behaviours. We report observations on three B. affinis nests in Minnesota and Wisconsin found in 2020. Previous to this report, there were only four published descriptions of B. affinis nests, with the last nest recorded nearly 30 years ago. Here, we share findings on nesting habitat, nest size, mating behaviours, and nest parasites.The nests were located in between the foundation and a layer of insulation in an urban residence, in an urban backyard near a house foundation, and in a degraded semi‐wooded, riparian natural area.Colony size estimates ranged from 251 to 1341 bees.We observed males chasing gynes near a nest entrance and one mating event approximately 5 m from the nest.We documented the chalcid wasp, Melittobia acasta, as a new host association.These observations increased the known colony size range, documented a new host association, and indicate the potential importance of urban and degraded habitats for recovery of the endangered rusty patched bumble bee. [ABSTRACT FROM AUTHOR]

Most seabirds forage far from land, making them hard to observe when foraging. Satellite tracking of seabirds shows where they come into conflict with human uses of the ocean, and whether they use protected areas. Because tracking data are expensive, data from one colony and/or year are sometimes used to design marine protection for a species across its range. Two assumptions commonly made are that foraging distance increases with colony size and individuals are uniformly distributed around colonies. We tested these assumptions using Magellanic penguins Spheniscus magellanicus as an example. We used a large tracking dataset of 338 penguins foraging for chicks at 10 colonies in Argentina from 1996 to 2019. Foraging distance increased with population size among colonies, but predicted distances would not cover foraging areas for all colonies. There was no relationship between population size and foraging distance within colony among years for colonies with ten and 23 years of data. Penguins were not uniformly distributed around colonies. Penguins used ~24% (12-40%) of the ocean available within the colony’s maximum foraging distance. We also show that overlap between penguin foraging areas and marine protected areas (MPA) and hydrocarbon concessions varied among colonies partly because of variation in how far offshore penguins forage. Overlap with MPAs was low (0% – 20%) for seven of the ten colonies and high (23% – 100%) for the other three. Overlap with a large area permitted for hydrocarbon exploration (seismic surveys) was relatively high (23% – 81%) for seven colonies where penguins forage offshore. Data from one colony are unlikely to indicate the most effective marine spatial planning for all colonies. Our data show that to be effective, marine planning should consider the temporal and spatial dynamics of ocean conditions and the response of marine wildlife to these changes. Climate variability is predicted to increase, making knowledge of foraging-location variation among colonies and years critical to conservation planning.

Abstract Background Geographically separated population growth of microbes is a common phenomenon in microbial ecology. Colonies are representative of the morphological characteristics of this structured population growth. Pattern formation by single colonies has been intensively studied, whereas the spatial distribution of colonies is poorly investigated. Results The present study describes a first trial to address the questions of whether and how the spatial distribution of colonies determines the final colony size using the model microorganism Escherichia coli, colonies of which can be grown under well-controlled laboratory conditions. A computational tool for image processing was developed to evaluate colony density, colony size and size variation, and the Voronoi diagram was applied for spatial analysis of colonies with identical space resources. A positive correlation between the final colony size and the Voronoi area was commonly identified, independent of genomic and nutritional differences, which disturbed the colony size and size variation. Conclusions This novel finding of a universal correlation between the spatial distribution and colony size not only indicated the fair distribution of spatial resources for monogenetic colonies growing with identical space resources but also indicated that the initial localization of the microbial colonies decided by chance determined the fate of the subsequent population growth. This study provides a valuable example for quantitative analysis of the complex microbial ecosystems by means of experimental ecology.

A recent study showed that, in the ant Temnothorax nylanderi, city colonies are more tolerant to cadmium than forest colonies. However, because of annual variation in biological factors (e.g. body size, anti-stress protein production or trace metal accumulation rate), trace metal tolerance may vary over the year. We aimed at testing whether tolerance to cadmium of colonies of T. nylanderi differs between two different seasons within the same year (winter and spring). We also assessed whether the better cadmium tolerance of city colonies was constant over these two different time points. We collected colonies at the end of their hibernation period (winter colonies) and several weeks after (spring colonies) from two different habitats (forest and city) to assess whether response to cadmium was consistent regardless of the environment. We exposed colonies to a cadmium or a control treatment for 61 days. We compared tolerance to cadmium between spring/winter and city/forest colonies by measuring several life history traits. We found that spring colonies tolerates cadmium better than winter colonies, and that city colonies have a higher tolerance to cadmium but only in spring. Although further studies with replicated pairs of city/forest habitats and different years will be necessary to confirm those results, our study suggests that tolerance to trace metals can fluctuate along the yearly cycle. [ABSTRACT FROM AUTHOR]

Hydrodynamic mixing is one of the important environment factors in determining phytoplankton community compositions. Here the influences of continuous hydrodynamic mixing on abundance, morphology, and dominance of Microcystis were investigated in microcosm and lab experiments. Our research results showed that Cyanophyta contributed 57.16% to the total biomass in control, but Chlorophyta was the dominant group in continuous hydrodynamic mixing (CHM) group, contributing 76.54% to the total biomass in the microcosm experiment. The average number of Microcystis in control was 1.95 folds in CHM group. However, the mean abundance of Scenedesmus quadricauda and Pseudanabaena limnetica in CHM was 2.47 and 2.97 folds in control. In the lab experiment, the average number of Microcystis flos-aquae in control was 2.97 folds in CHM group. The mean size of M. flos-aquae colony in control (34.65 μm) group were significantly bigger than that in the CHM (26.78 μm) group. This research results demonstrated that continuous hydrodynamic mixing weakened the dominance of Microcystis, but was beneficial for the others algae (S. quadricauda and P. limnetica) and is helpful in understanding the effect of hydrodynamic mixing on Microcystis blooms in freshwater ecosystem. [ABSTRACT FROM AUTHOR]

Urbanized ecosystems are suitable for the habitat of only a few species of ants, due to conditions caused by human activities. Invasive species of ants have adapted to urbanized ecosystems most successfully. The study of the ant colonies sizes started in Crimea in 2013-2014. In 2019-2021 it was carried out in Ukraine (the Carpathians, Kyiv city, and Kyiv region), in Russia (Rostov-on-Don city and region, and the Urals), and in Uzbekistan (Tashkent city, and tugai forests). The study covers natural (forest, meadow, steppe), suburban (alleys and tree planting) and urban habitats (tree planting along streets and roads, botanical gardens). Our study covers 21 species of ants with trails on forage areas. Nine species were sampled for interspecific comparison of colony sizes. They were collected in at least 2 habitat types within the same geographic region. According to the activity parameter on the trails, the number of foragers and the population of the colony were calculated (using the formula of A. Zakharov). According to our calculations, the maximum colony sizes are typical for invasive species (Crematogaster subdentata, Lasius neglectus, 100-7500 thousand workers) in the urban habitats. Some native species (Dolichoderus quadripunctatus, Formica cinerea) in the urban areas have colonies with 120-350 thousand workers. These values may exceed those for ant species inhabiting natural habitats (30-250 thousand workers). High rates of colony size in the urbanized habitats can be achieved due to availability of food, nesting resources, and the absence of competing ant species. [ABSTRACT FROM AUTHOR]

Large body sizes have evolved structures to facilitate resource transport. Like unitary organisms, social insect colonies must transport information and resources. Colonies with more individuals may experience transport challenges similar to large‐bodied organisms. In ant colonies, transport occurs in the nest, which may consist of structures that facilitate movement. We examine three attributes of nests that might have evolved to mitigate transport challenges related to colony size: (1) subdivision—nests of species with large colonies are more subdivided to reduce crowd viscosity; (2) branching—nest tunnels increase branching in species with large colonies to reduce travel distances; and (3) shortcuts—nests of species with large colonies have cross‐linking tunnels to connect distant parts of the nest and create alternative routes. We test these hypotheses by comparing nest structures of species with different colony sizes in phylogenetically controlled meta‐analyses. Our findings support the hypothesis that nest subdivision and branching evolved to mitigate transport challenges related to colony size. Nests of species with large colonies contain more chambers and branching tunnels. The similarity in how ant nests and bodies of unitary organisms have evolved in response to increasing size suggests common solutions across taxa and levels of biological organization. [ABSTRACT FROM AUTHOR]

Urbanization brings new pressures for individuals. Among them, trace elements, such as cadmium, are important stressors. A recent study highlights a weaker negative effect of cadmium on city colonies relative to their forest counterparts in the ant Temnothorax nylanderi. Here, we aim to test whether the better tolerance of city colonies in this species results from a better ability of workers to rear larvae despite stressful conditions and/or a better ability of larvae to develop properly despite stressful conditions. We performed a cross-fostering experiment of workers and larvae from city and forest colonies, in common garden conditions in the laboratory. Colonies were fed using cadmium-enriched or cadmium-free food for 2 months, and we measured four life-history traits. As expected, cadmium had a negative impact on all traits. Unexpectedly, we did not observe a better tolerance of city colonies to cadmium, contrary to our previous study, which prevented us from disentangling the respective contributions of workers and larvae to cadmium tolerance. Interestingly, forest colonies seemed to be of better quality in our laboratory conditions. Finally, colony size increased adult survival, but only in the absence of cadmium, suggesting that social buffering could collapse with strong external disturbances. [ABSTRACT FROM AUTHOR]

The overall population size and trend of the Magellanic Penguin (Spheniscus magellanicus) is uncertain and population estimates are available only for few locations. The last complete census along its central-southern distribution range in Argentina, province of Santa Cruz, was made in the 1990s. This study updates the breeding population size along Santa Cruz. Population estimates were compared with the last complete census, and trends were studied when it was possible. With 353,256 estimated breeding pairs, the overall population in Santa Cruz remained relatively stable after 25 years. The Santa Cruz population represents 31% of the Argentine Patagonian coast population and could represent between 22 and 30% of the species' global population. Colony sizes varied between 9 and 127,492 breeding pairs. Changes in abundance differed among locations, with individual colonies showing increasing, decreasing, or stable trends, which suggests that local factors determine population dynamics. The most significant increases (> 40%) were observed in the southern sector of Santa Cruz. Contrary to what was observed at the north of the distribution range in the province of Chubut, where trends of several colonies were inversely related to colony size, in Santa Cruz most of the largest colonies remained stable or even increased from the 1990s onwards. [ABSTRACT FROM AUTHOR]

Nest building can represent an energetically costly activity for a variety of animal taxa. Besides, the determinants of within-species variation in the design of nests, notably with respect to natural and sexual selection, are still insufficiently documented. Based on an observational study, we examined the influence of nesting conditions (nesting-support quality, colony, laying date, and year) on male-built nest volume and also its potential role as a postmating sexually selected display in the whiskered tern Chlidonias hybrida. This tern species is a monogamous colonial bird with obligate biparental care breeding on aquatic vegetation. Hence, large nesting platforms are expected to be a selective advantage because they would better withstand adverse environmental conditions and provide a secure structure for eggs. Nest size may also serve as a postmating sexual trait, and variation in egg production would be positively associated with nest size. We found that nest volume was adjusted to different environmental cues. A positive relationship was found between nest volume and nesting-support quality, indicating that the leaf density of white waterlily is essential for nest stability. Variation in nest volume was not correlated to colony size but varied among colonies and years. Male-built nest volume was also positively associated with mean egg volume per clutch but not with clutch size. The fitness consequences of building a large nest are yet to be studied, and additional investigations are recommended to better understand whether the activity of males early during breeding season (e.g., nest building and courtship feeding performance) really serves as postmating sexually selected signals. [ABSTRACT FROM AUTHOR]

In a society, several individuals can help to execute a task otherwise impossible to achieve individually. However, the unnecessary interference of another individual in a solitary task could delay task execution. We studied task interference in acacia ants (Pseudomyrmex spinicola) performing a foraging task. Foraging is solitary: a single worker carries a plant-produced food body and typically stores it inside the plant domatia, but sometimes workers discard them off the tree. Acacia ants have behavioural subcastes among workers with pronounced differences in task execution. Also, task specialization increases with colony size, hence smaller colonies have less specialized individuals. Here, we first assessed whether interferences on a solitary task provided any benefit to the colony, to counteract the delay in performing the task. We found that when nestmates interfered, food items were more likely to be stored rather than discarded. Second, we tested the role of the worker's task specialization on the occurrence of interferences. Specifically, we tested whether interferences (1) are a by-product of lacking workers specialized in foraging ('Jack-of-all-trades' effect), or (2) depend on having experts trying to take over the task ('expert effect'). We found partial support for the Jack-of-all-trades effect, because workers in smaller colonies were more often interfered with, but interferences lasted longer in medium-sized colonies; in larger colonies, workers had fewer interferences that resolved faster. Our evidence supports the 'expert effect', as experienced foragers had fewer and shorter interferences than workers not regularly foraging. Interfering in a solitary task in social insects parallels task conflicts and managerial issues in human organizations and may function as a quality control mechanism in a leaderless organization. • Interference happens when several individuals attempt to execute a task at once. • In acacia ants, interferences were influenced by colony size and task specialization. • In larger colonies, interferences resolved faster than in small or mid-size colonies. • Task experts had fewer and shorter interferences compared to nonexperts. • Interferences in insects parallel task conflicts in human organizations. [ABSTRACT FROM AUTHOR]

• More species forage at canopy than at ground level. • The understorey is largely home to a mixed fauna. • The horizontal species turnover was similar between the three strata. • Generalist species with mid-sized colonies are the most common. • Multi-strata studies can benefit from using aerial flight interception traps. Ants are a major ecological group in tropical rainforests. Few studies in the Neotropics have documented the distribution of ants from the ground to the canopy, and none have included the understorey. A previous analysis of an intensive arthropod study in Panama, involving 11 sampling methods, showed that the factors influencing ant β diversity (i.e., changes in assemblage composition) were, in decreasing order of importance, the vertical (height), temporal (season), and horizontal (geographic distance) dimensions. In the present study, we went one step further and aimed (1) to identify the best sampling methods to study the entire ant assemblage across the three strata, (2) to test if all strata show a similar horizontal β diversity and (3) to analyze the functional structure of the entire ant assemblage. We identified 405 ant species from 11 subfamilies and 68 genera. Slightly more species were sampled in the canopy than on the ground; they belonged to distinct sub-assemblages. The understorey fauna was mainly a mixture of species found in the other two strata. The horizontal β diversity between sites was similar for the three strata. About half of the ant species foraged in two (29%) or three (25%) strata. A single method, aerial flight interception traps placed alongside tree trunks, acting as arboreal pitfall traps, collected half of the species and reflected the vertical stratification. Using the functional traits approach, we observed that generalist species with mid-sized colonies were by far the most numerous (31%), followed by ground- or litter-dwelling species, either specialists (20%), or generalists (16%), and arboreal species, either generalists (19%) or territorially dominant (8%), and finally army ants (5%). Our results reinforce the idea that a proper understanding of the functioning of ant assemblages requires the inclusion of arboreal ants in survey programs. Eleven sampling methods were used to study an entire rainforest ant assemblage at ground, canopy and understorey levels. Ant species composition differed between strata. Horizontal species turnover (β diversity) within forest strata was similar between sites. A functional traits approach revealed that the ant assemblage was mainly composed of generalist species with mid-sized colonies (group #3, 31% of the 405 species). However, ground- or litter-dwelling species were also species-rich (#1 & 2), followed by arboreal ants (#4) including ecologically important territorially dominant arboreal ants (#5), and typical army ants (#6). Of the 11 sampling methods used, aerial flight interception traps placed alongside tree trunks (red triangles in the figure below) collected half of the ant species and reflected the vertical stratification of the ant species, demonstrating an interesting possibility for ant monitoring programs [Display omitted]. [ABSTRACT FROM AUTHOR]

Mechanoregulation of cell–extracellular matrix (ECM) interactions are crucial for dictating pluripotent stem cell differentiation. However, not all pluripotent cells respond homogeneously which results in heterogeneous cell populations. When cells, such as mouse epiblast stem cells (EpiSCs), are cultured in clusters, the heterogeneity effect during differentiation is even more pronounced. While past studies implicated variations in signaling pathways to be the root cause of heterogeneity, the biophysical aspects of differentiation have not been thoroughly considered. Here, we demonstrate that the heterogeneity of EpiSC differentiation arises from differences in the colony size and varying degrees of interactions between cells within the colonies and the ECM. Confocal imaging demonstrates that cells in the colony periphery established good contact with the surface while the cells in the colony center were separated by an average of 1–2 µm from the surface. Traction force measurements of the cells within the EpiSC colonies show that peripheral cells generate large tractions while the colony center cells do not. A finite element modeling of EpiSC colonies shows that tractions generated by the cells at the colony periphery lift off the colony center preventing the colony center from undergoing differentiation. Together, our results demonstrate a biophysical regulation of heterogeneous EpiSC colony differentiation.

Many threatened birds use the mosaic of agricultural landscapes for foraging and breeding. Despite the reliance of many species on these habitats, few studies have investigated factors influencing the breeding ecology of storks in agricultural landscapes. We assessed site-level variables (tree height and location of nest tree; human habitation or non-human habitation), colony-level variables (colony size and chicks per nest), and landscape-level variables (area of human habitation, wetland area, and distance to the nearest wetland) to understand the factors influencing the breeding ecology of the globally threatened Lesser Adjutant (Leptoptilos javanicus) across multiple locations in the agricultural landscape of lowland Nepal during 2019–2020. We monitored 65 active colonies that had 206 active nests in five study sites. Two hundred eighty chicks fledged from these colonies, with 13% (n = 41) chick mortality. Most colonies were in agricultural land (51%) and human habitation (28%). Lesser Adjutant colonies located on tall trees such as Bombax ceiba (57%), Haldina cordifolia (11%), and Ficus religiosa (11%); however, these tree species were used much more than their availability on the landscape. Tree height had a significant positive influence on colony site selection and colony size, whereas colony size positively influenced fledgling success. Measured landscape variables did not have significant relationships with breeding success metrics. The agricultural landscapes of lowland Nepal provided important breeding habitat for Lesser Adjutants, and the suitability of sites with colonies related more to site-level and colony-level than landscape-level variables. Increasing urban development of agricultural landscapes is likely the greatest threat to breeding Lesser Adjutants, with the decline of suitable nesting trees being a potential additional threat. Lowland Nepal's agricultural landscapes support significant breeding populations of Lesser Adjutants that had considerable breeding success, underscoring the urgent need to support traditional agriculture that favors large waterbirds.

Optimal size of social groups may vary between individuals, depending on their phenotypic traits, such as dominance status, age or personality. Larger social groups often enhance transmission rates of pathogens and should be avoided by individuals with poor immune defences. In contrast, more immunocompetent individuals are expected to take advantage of larger group sizes (e.g. better protection, information transfer) with smaller extra costs from pathogen or parasite pressure.Here, we hypothesized that immunocompetence may be a key determinant of group size choice and tested this hypothesis in a colonial waterbird, the common tern Sternahirundo. We used a unique experimental framework, where formation of breeding colonies of different sizes was induced under uniform environmental conditions. For this purpose, different‐size patches of attractive nesting substrate (artificial floating rafts) were provided at a single site with limited availability of natural nesting habitat.Colony size was identified as the only significant predictor of both innate (natural antibody‐mediated complement activation) and adaptive (immunoglobulin concentrations) immunological traits in the common terns, as more immunocompetent birds settled in larger experimental colonies. In contrast, we found no significant associations between colony size and genetic diversity of key pathogen‐recognition receptors, toll‐like receptors (TLRs) and the Major Histocompatibility Complex (MHC) or genome‐wide heterozygosity.We conclude that settlement decisions may be flexible within individuals and, thus, are likely to be primarily determined by the current immunological status, rather than fixed immunogenetic traits. Our study sheds new light on the complex interface between immunity and sociality in animals. [ABSTRACT FROM AUTHOR]

The ant Anonychomyrma inclinatasp. nov. is described. It is an arboreal species, nesting in hollows of living mature trees including Allocasuarina luehmannii, Angophora leiocarpa and various Eucalyptus species. Anonychomyrma inclinata can form colonies which are among the most populous recorded for an ant species in Australia, with over 10 000 workers and a total population of 170 000, including all castes. The ant forms extensive trails, forages for insects, collects nectar from a range of flowering plants including many mistletoes and collects honeydew from Hemiptera. The ant's distribution extends from northern inland New South Wales and south central inland Queensland, as far north‐east as Home Hill, on the Burdekin River. The ant is an obligate attendant of the immature stages of the endangered bulloak jewel butterfly, Hypochrysops piceatus Kerr, Macqueen & Sands, 1969, and the southern population of the sapphire azure, Ogyris aenone Waterhouse, 1902. The distribution of A. inclinata is much wider than that currently known for H. piceatus, suggesting that suitable breeding sites may exist for this rare butterfly in areas not previously surveyed. While A. inclinata appears relatively widespread and is able to utilise a wide range of tree species, it is reliant, like H. piceatus, on mature live trees and so is subject to threats including vegetation clearance, timber‐getting, grazing, and increased drought and fire frequency. Due to its critical importance in the life cycle of H. piceatus, any action taken to conserve the butterfly must also consider the importance of preserving healthy populations of A. inclinata. [ABSTRACT FROM AUTHOR]

In eusocial insects, worker polymorphism is shaped by several factors, including colony size, queen mating frequency, and the timing of queen-worker differentiation during larval development. In a comparative study of 18 species of Cataglyphis desert ants representing a wide range of worker sizes, we used phylogenetically controlled analyses to examine correlations between worker head width variation (i.e., worker polymorphism) and multiple social traits, namely, mature colony size, mean worker head width, queen head width, queen-worker head width dimorphism, and within-colony genetic relatedness, resulting from multiple mating by queens. We found that worker polymorphism was positively correlated with mature colony size, mean worker head width, and queen head width. In contrast, worker polymorphism was not correlated with queen-worker dimorphism and within-colony genetic relatedness. These results underscore that evolution of worker polymorphism and social traits are correlated. They also illustrate that additional research using multivariate approaches is needed to further clarify the evolution of insect societies. Significance statement: In eusocial insects, worker morphological variation (i.e., worker polymorphism) is tightly linked to division of labor. Multiple factors are supposed to shape the evolution of worker polymorphism. Using phylogenetically controlled analyses of worker head width variation from 18 species of Cataglyphis desert ants, we show that worker polymorphism positively correlates with mature colony size, mean worker head width, and queen size. These results highlight that the evolution of worker polymorphism and social traits are correlated. Identifying the mechanisms underlying these relationships could provide major insights into the development and evolution of insect societies. [ABSTRACT FROM AUTHOR]