Characterization of pollen and bacterial community composition in brood provisions of a small carpenter bee

Many insects obtain gut microbes from their diet, but how a mother's foraging patterns influence the microbes found in her offspring's food remains an open question. To address this gap, we studied a bee that forages for pollen from multiple species of plants and may therefore acquire diverse bacteria from different plants. We tested the hypothesis that pollen diversity correlates with bacterial diversity by simultaneously characterizing these two communities in bee brood provisions for the first time. We used deep sequencing of the plant RBCL gene and the bacterial 16S rRNA gene to characterize pollen and bacterial diversity. We then tested for associations between pollen and bacterial species richness and community composition, as well as co‐occurrence of specific bacteria and pollen types. We found that both pollen and bacterial communities were extremely diverse, indicating that mother bees visit a wide variety of flowers for pollen and nectar and subsequently bring a diversity of microbes back into their nests. Pollen and bacterial species richness and community composition, however, were not correlated. Certain pollen types significantly co‐occurred with the most proportionally abundant bacteria, indicating that the plants these pollen types came from may serve as reservoirs for these bacteria. Even so, the overall diversity of these communities appears to mask these associations at a broader scale. Further study of these pollen and bacteria associations will be important for understanding the complicated relationship between bacteria and wild bees.     

Proliferation and copy number variation of BEL-like long terminal repeat retrotransposons within the Diabrotica virgifera virgifera genome

The proliferation of retrotransposons within a genome can contribute to increased size and affect the function of eukaryotic genes. BEL/Pao-like long-terminal repeat (LTR) retrotransposons were annotated from the highly adaptable insect species Diabrotica virgifera virgifera, the Western corn rootworm, using survey sequences from bacterial artificial chromosome (BAC) inserts and contigs derived from a low coverage next-generation genome sequence assembly. Eleven unique D. v. virgifera BEL elements were identified that contained full-length gag–pol coding sequences, whereas 88 different partial coding regions were characterized from partially assembled elements. Estimated genome copy number for full and partial BEL-like elements ranged from ~ 8 to 1582 among individual contigs using a normalized depth of coverage (DOC) among Illumina HiSeq reads (total genome copy number ~ 8821). BEL element copy number was correlated among different D. v. virgifera populations (R² = 0.9846), but individual element numbers varied ≤ 1.68-fold and the total number varied by ~ 527 copies. These data indicate that BEL element proliferation likely contributed to a large genome size, and suggest that differences in copy number are a source of genetic variability among D. v. virgifera.     

Foraging and farming as niche construction: stable and unstable adaptations

All forager (or hunter-gatherer) societies construct niches, many of them actively by the concentration of wild plants into useful stands, small-scale cultivation, burning of natural vegetation to encourage useful species, and various forms of hunting, collectively termed 'low-level food production'. Many such niches are stable and can continue indefinitely, because forager populations are usually stable. Some are unstable, but these usually transform into other foraging niches, not geographically expansive farming niches. The Epipalaeolithic (final hunter-gatherer) niche in the Near East was complex but stable, with a relatively high population density, until destabilized by an abrupt climatic change. The niche was unintentionally transformed into an agricultural one, due to chance genetic and behavioural attributes of some wild plant and animal species. The agricultural niche could be exported with modifications over much of the Old World. This was driven by massive population increase and had huge impacts on local people, animals and plants wherever the farming niche was carried. Farming niches in some areas may temporarily come close to stability, but the history of the last 11,000 years does not suggest that agriculture is an effective strategy for achieving demographic and political stability in the world's farming populations.     

Do solitary foraging nocturnal mammals plan their routes?

Large-brained diurnal mammals with complex social systems are known to plan where and how to reach a resource, as shown by a systematic movement pattern analysis. We examined for the first time large-scale movement patterns of a solitary-ranging and small-brained mammal, the mouse lemur (Microcebus murinus), by using the change-point test and a heuristic random travel model to get insight into foraging strategies and potential route-planning abilities. Mouse lemurs are small nocturnal primates inhabiting the seasonal dry deciduous forest in Madagascar. During the lean season with limited food availability, these lemurs rely on few stationary food resources. We radio-tracked seven lemurs and analysed their foraging patterns. First change-points coincided with out-of-sight keystone food resources. Travel paths were more efficient in detecting these resources than a heuristic random travel model within limits of estimated detection distance. Findings suggest that even nocturnal, solitary-ranging mammals with small brains plan their route to an out-of-sight target. Thus, similar ecological pressures may lead to comparable spatial cognitive skills irrespective of the degree of sociality or relative brain size.     

Foraging movements of emperor penguins at Pointe Géologie, Antarctica

The foraging distributions of 20 breeding emperor penguins were investigated at Pointe Géologie, Terre Adélie, Antarctica by using satellite telemetry in 2005 and 2006 during early and late winter, as well as during late spring and summer, corresponding to incubation, early chick-brooding, late chick-rearing and the adult pre-moult period, respectively. Dive depth records of three post-egg-laying females, two post-incubating males and four late chick-rearing adults were examined, as well as the horizontal space use by these birds. Foraging ranges of chick-provisioning penguins extended over the Antarctic shelf and were constricted by winter pack-ice. During spring ice break-up, the foraging ranges rarely exceeded the shelf slope, although seawater access was apparently almost unlimited. Winter females appeared constrained in their access to open water but used fissures in the sea ice and expanded their prey search effort by expanding the horizontal search component underwater. Birds in spring however, showed higher area-restricted-search than did birds in winter. Despite different seasonal foraging strategies, chick-rearing penguins exploited similar areas as indicated by both a high ‘Area-Restricted-Search Index’ and high ‘Catch Per Unit Effort’. During pre-moult trips, emperor penguins ranged much farther offshore than breeding birds, which argues for particularly profitable oceanic feeding areas which can be exploited when the time constraints imposed by having to return to a central place to provision the chick no longer apply.     

Effects of fasting and feeding on the fast‐start swimming performance of southern catfish Silurus meridionalis

This study investigated the effects of fasting and feeding on the fast‐start escape swimming performance of juvenile southern catfish Silurus meridionalis, a sit‐and‐wait forager that encounters extreme fasting and famine frequently during its lifespan. Ten to 30 days of fasting resulted in no significant change in most of the variables measured in the fast‐start response except a 20–30% decrease in the escape distance during the first 120 ms (D_120ms) relative to the control group (48 h after feeding). The ratio of the single‐bend (SB) response (lower energetic expenditure) to the double‐bend (DB) response increased significantly from 0% in the control group to 75 and 82·5% in the 20 and 30 day fasting groups, respectively. Satiated feeding (25% of body mass) resulted in a significantly lower (36·6%) maximum linear velocity (V_max) and a significantly lower (43·3%) D_120ms than in non‐fed fish (control group, 48 h after feeding). Half‐satiated feeding (12·5% of body mass), however, showed no significant effects on any of the measured variables of the fast‐start response relative to control fish. It is suggested that the increase in the ratio of SB:DB responses with fasting in S. meridionalis may reflect a trade‐off between energy conservation and maintaining high V_max, while variables of fast‐start performance were more sensitive to feeding than fasting might be an adaptive strategy to their foraging mode and food availability in their habitat.     

Osteoarthritis in Siberia's Cis-Baikal: Skeletal indicators of hunter-gatherer adaptation and cultural change

This examination of osteoarthritis in Siberia's Cis-Baikal region focuses on the reconstruction of mid-Holocene mobility and activity patterns with particular interest in an alleged fifth millennium BC biocultural hiatus. Five cemetery populations--two representing the pre-hiatus Kitoi culture (6800-4900 BC) and three the post-hiatus Serovo-Glaskovo (4200-1000 BC)-are considered. The objective is to investigate osteoarthritic prevalence and distribution (patterning) within and among these populations in order to reconstruct mobility and activity patterns among the Cis-Baikal foragers, and to test for possible disparities that may reflect differing adaptive strategies. The data reveal that levels of activity remained relatively constant throughout the mid-Holocene but that mobility and specific activity patterns did not. Although results are consistent with the current understanding of distinct Kitoi and Serovo-Glaskovo subsistence regimes, specifically the lower residential mobility and narrower resource base of the former, they also draw attention to adaptive characteristics shared by all occupants of the Cis-Baikal.     

Evolutionary consequences of a search image

Many predators are able to become better at spotting cryptic prey by recognising specific clues, but by concentrating on one prey type they will become worse at spotting other prey types. This phenomenon is known as the formation of a search image for a certain prey by a predator and is related to apostatic selection. Here, we study the evolution of a search image in the predator by formulating and analysing a mathematical model. The predator forages for two prey types and is able to form an independent search image for both prey. The results show that the evolutionary dynamics can be divided into two parts: a fast and a slow part. At first selection pressure will be strong towards a stable ratio of prey, which is the same as the ratio found for the unbeatable prey choice for predators with a Holling type II functional response. Following this, the slow dynamics will keep this ratio constant independent of the trait values, but the predator will slowly evolve towards a stronger search image and ultimately become a specialist predator or slowly evolve towards generalist with a weak search image. In conclusion, the formation of a search image causes the predator to control the prey densities such that the ratio of available prey is kept constant by the predator.     

Effect of fasting on resting metabolic rate and postprandial metabolic response in Silurus meridionalis

Resting metabolic rate in southern catfish of 2 and 5 day fasting groups were significantly higher than that of the 15 day fasting group ( P  < 0·05). After feeding, peak metabolic rate of specific dynamic action (SDA) of the 15 day fasting group was significantly lower than that of the 2 and 5 day fasting groups ( P  < 0·05). The duration of the SDA of the 15 day fasting group was significantly longer than that of the 2 day fasting group ( P  < 0·05) and the SDA coefficient of the 15 day fasting group was significantly lower than that of the 2 day fasting group ( P  < 0·05).     

Octopamine influences honey bee foraging preference

Colony condition and differences in individual preferences influence forage type collected by bees. Physiological bases for the changing preferences of individual foragers are just beginning to be examined. Recently, for honey bees octopamine is shown to influence age at onset of foraging and probability of dance for rewards. However, octopamine has not been causally linked with foraging preference in the field. We tested the hypothesis that changes in octopamine may alter forage type (preference hypothesis). We treated identified foragers orally with octopamine or its immediate precursor, tyramine, or sucrose syrup (control). Octopamine-treated foragers switched type of material collected; control bees did not. Tyramine group results were not different from the control group. In addition, sugar concentrations of nectar collected by foragers after octopamine treatment were lower than before treatment, indicating change in preference. In contrast, before and after nectar concentrations for bees in the control group were similar. These results, taken together, support the preference hypothesis.