Bystanders, parcelling, and an absence of trust in the grooming interactions of wild male chimpanzees

The evolution of cooperation remains a central issue in socio-biology with the fundamental problem of how individuals minimize the risks of being short-changed (‘cheated’) should their behavioural investment in another not be returned. Economic decisions that individuals make during interactions may depend upon the presence of potential partners nearby, which o ers co operators a temptation to defect from the current partner. The parcelling model posits that donors subdivide services into parcels to force cooperation, and that this is contingent on opportunities for defection; that is, the presence of bystanders. Here we test this model and the e ect of bystander presence using grooming interactions of wild chimpanzees. We found that with more bystanders, initiators gave less grooming at the beginning of the bout and were more likely to abandon a grooming bout, while bouts were less likely to be reciprocated. We also found that the groomer’s initial investment was not higher among frequent groomers or stronger reciprocators, suggesting that contrary to current assumptions, grooming decisions are not based on trust, or bonds, within dyads. Our work highlights the importance of considering immediate social context and the in uence of bystanders for understanding the evolution of the behavioural strategies that produce cooperation

Release rates of trace elements and protein from decomposing planktonic debris. 1. Phytoplankton debris

The release rates of Ag, Am, Cd, Ce, Co, Pb, Se and Zn from decomposing diatom cells were determined using gamma-emitting radiotracers; rates were compared with C and protein loss rates over time. Additionally, experiments were designed to evaluate various artifacts involved in the experimental use of radioisotopes, handling of biogenic debris, and the use of poisons. The release rates of C at 18°C exponentially decreased with time from 17.5% d−1 at 1 d to 2.7% d−1 at 6 d; those of protein slowed from 9.2% d−1 at 1 d to 2.0% d−1 at 6 d. Rates at 18°C were 2–4 times faster than rates at 4°C. Rate changes at both temperatures were much less pronounced from 6–25 d. Retention half-times (tr1/2s) of Ag, Am, Ce, Co and Pb in diatom debris were significantly greater than those of Cd, Se and Zn under the same conditions; tr1/2 values decreased inversely with temperature. The tr1/2 values of C and protein were generally comparable to those of Cd, Se and Zn, whereas the ratios of the other metals to C and protein increased significantly over time. Microbial activity very strongly enhanced Co scavenging onto decaying particles in the dark. The elemental loss rate data suggest that Cd, Se and Zn should generally follow the fate of organic C and protein in decomposing planktonic debris. These elements should be biologically recycled and have longer residence times in surface waters than the other metals which are more particle-reactive and which do not follow organic C and protein release

Data for paper Microbial generation of elemental mercury from dissolved methylmercury in seawater

Elemental mercury (Hg0) formation from other mercury species in seawater results from photoreduction and microbial activity, leading to possible evasion from seawater to overlying air. Microbial conversion of monomethylmercury (MeHg) to Hg0 in seawater remains unquantified. A rapid radioassay method was developed using gamma-emitting 203Hg as a tracer to evaluate Hg0 production from Hg(II) and MeHg in the low pM range. Bacterioplankton assemblages in Atlantic surface seawater and Long Island Sound water were found to rapidly produce Hg0, with production rate constants being directly related to bacterial biomass and independent of dissolved Hg(II) and MeHg concentrations. About 32% of Hg(II) and 19% of MeHg were converted to Hg0 in 4 d in Atlantic surface seawater containing low-bacterial biomass, and in Long Island Sound water with higher bacterial biomass, 54% of Hg(II) and 8% of MeHg were transformed to Hg0. Decreasing temperatures from 24C to 4C reduced Hg0 production rates cell−1 from Hg(II) 3.3 times as much as from a MeHg source. Because Hg0 production rates were linearly related to microbial biomass and temperature, and microbial mercuric reductase was detected in our field samples, we inferred that microbial metabolic activities and enzymatic reactions primarily govern Hg0 formation in subsurface waters where light penetration is diminished

Copepod feeding strategy determines response to seawater viscosity: videography study of two calanoid copepod species

Author Posting. © Company of Biologists, 2020. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology (2020): jeb.220830, doi: 10.1242/jeb.220830.Calanoid copepods, depending on feeding strategy, have different behavioral and biological controls on their movements, thereby responding differently to environmental conditions such as changes in seawater viscosity. To understand how copepod responses to environmental conditions are mediated through physical, physiological, and/or behavioral pathways, we used high-speed microvideography to compare two copepod species, Acartia hudsonica and Parvocalanus crassirostris, under different temperature, viscosity, and dietary conditions. Acartia hudsonica exhibited “sink and wait” feeding behavior and typically responded to changes in seawater viscosity; increased seawater viscosity reduced particle-capture behavior and decreased the size of the feeding current. In contrast, P. crassirostris continuously swam and did not show any behavioral or physical responses to changes in viscosity. Both species showed a physiological response to temperature, with reduced appendage beating frequency at cold temperatures, but this did not generally translate into effects on swimming speed, feeding flux, or active time. Both copepod species swam slower when feeding on diatom rather than dinoflagellate prey, showing that prey type mediates copepod behavior. These results differentiate species-specific behaviors and responses to environmental conditions, which may lead to better understanding of niche separation and latitudinal patterns in copepod feeding and movement strategies.This study was supported by the National Science Foundation [OCE1634024 to N.F.; OCE-1433979 and OCE-1559062 to H.J.]; and by Stony Brook University [Graduate Council Fellowship and Turner Fellowship to A.S.T].2021-06-1

The accumulation of barium by marine phytoplankton grown in culture

Marine phytoplankton have been implicated as potentially important vectors for the vertical transport of barium in the oceans. To better assess the extent to which phytoplankton can influence the geochemical cycling of barium, its bioconcentration was studied in 21 clones of 19 species of marine phytoplankters belonging to 9 algal classes. Barium levels in the ash ranged from less than 2 μg g–1 for the coccolithophore Emiliania huxleyi and the red alga Porphyridium cruenturn to 589 μg g–1 for the flagellate Tetraselmis levis. Concentrations ≥4000 μg g–1, previously reported for certain samples of diatom ash were not encountered in this study. Concentration factors on a volume basis (VCF) ranged from 0 to 3.2 × 104; the geometric mean VCF for all species was 225. Diatoms and coccolithophores generally had lower VCFs (geometric means of 90 and 12, respectively) than did other species; dinoflagellates had a geometric mean VCF of 490. Experiments with the diatom Thalassiosira pseudonana indicated that Ba cell–1 increased linearly with ambient Ba concentration. Experiments to localize the site of Ba deposition in diatom cells indicated that most of the Ba was associated with the frustules rather than with the organic fraction. Dinoflagellates and several other algae not only concentrated Ba to relatively high levels, but also accumulated Si when grown in Si-enriched medium, although they grew at least as well without added Si as with it. Ba and Si accumulation were generally negatively correlated

Invisible water, visible impact: How unsustainable groundwater use challenges sustainability of Indian agriculture under climate change

India is one of the world’s largest food producers, making the sustainability of its agricultural system of global significance. Groundwater irrigation underpins India’s agriculture, currently boosting crop production by enough to feed 170 million people. Groundwater overexploitation has led to drastic declines in groundwater levels, threatening to push this vital resource out of reach for millions of small-scale farmers who are the backbone of India’s food security. Historically, losing access to groundwater has decreased agricultural production and increased poverty. We take a multidisciplinary approach to assess climate change challenges facing India’s agricultural system, and to assess the effectiveness of large-scale water infrastructure projects designed to meet these challenges. We find that even in areas that experience climate change induced precipitation increases, expansion of irrigated agriculture will require increasing amounts of unsustainable groundwater. The large proposed national river linking project has limited capacity to alleviate groundwater stress. Thus, without intervention, poverty and food insecurity in rural India is likely to worsen

Release rates of trace elements and protein from decomposing planktonic debris. 2. Copepod carcasses and sediment trap particulate matter

In experiments designed to relate the release kinetics of various elements with that of protein from biogenic particles, 110mAg, 241Am, 109Cd, 60Co, 75Se and protein were measured over time in radiolabeled copepod carcasses and particles caught in unpoisoned sediment traps (mostly zooplankton fecal pellets and amorphous marine snow). Log-linear release rate constants (k) of 110mAg, 241Am, 109Cd, and 60Co from carcasses ranged from 0.079 d−1 for 60Co at 2°C to 0.130 d−1 for 109Cd at 15°C, and did not vary significantly with temperature. 75Se was lost most rapidly from copepod carcasses at 2°C, with k = 0.168 d−1; however, at 15°C, 75Se was in two compartments, with 56% in a rapidly exchanging pool (k = 0.391 d−1) and 44% in a slowly exchanging pool (k = 0.107 d−1). Protein displayed loss from two compartments at both temperatures. At 2°C, protein was lost slowly (k = 0.065 d−1) for 1 wk, after which it was released from the carcasses very rapidly (k = 0.245 d−1). At 15°C, however, the loss of protein from carcasses was more rapid over the first 2 d (k = 0.627 d−1) than thereafter (k = 0.127 d−1). The k values of 110mAg, 241Am, and 60Co from sediment trap particles (15°C) ranged from 0.008 to 0.011 d−1. Protein was lost twice as fast as 110mAg, 241Am, and 60Co, more slowly than half of the particulate 109Cd and 75Se in rapidly exchanging pools (k = 0.168 and 0.237 d−1, respectively), and at rates comparable to 109Cd and 75Se in slowly exchanging pools. Overall, copepod carcasses and fecal pellets could act as vectors of these five elements and protein to the deep ocean, the vertical flux being dependent on settling velocity and water column temperature structure. Of the elements considered here, Se follows the cycling of protein most closely

Effects of gut chemistry in marine bivalves on the assimilation of metals from ingested sediment particles

Bioavailability and uptake of trace metals by benthic animals are often assumed to be limited by authigenic sulfide minerals because of their low metal solubilities and reactivities under sedimentary conditions. However, digestive processes and gut conditions such as Eh, pH, and enzyme or surfactant activity, can affect the release of ingested metals in the gut and control uptake. In a series of laboratory experiments with the deposit-feeding clam, Macoma balthica and the suspension-feeding mussel, Mytilus edulis, we assessed assimilation efficiencies (AE) of radioisotopes of Ag, Cd and Co associated with acid-volatile sulfide (AVS), iron oxide (re-oxidized AVS), and reduced and oxidized natural sediment. To evaluate controls on AE, we measured the gut passage time (GPT) of ingested particles, gut Eh, pH, and extraction of Ag, Cd, and Co from particles into gut juice. In general, the overall trends of AEs and metal extraction were Co \u3e Cd ≥ Ag. AEs, metal extraction, and GPTs were higher in M. balthica than in M. edulis in most cases. M. balthica tended overall to take up metals more readily from oxidized than reduced natural sediment, whereas M. edulis did the opposite for Co and Cd. AEs of metals in reoxidized AVS (Fe-oxides) were generally similar to oxic sediment (Ag being the exception for M. edulis). In M. balthica, there was no significant difference in AEs from AVS and Fe-oxide particles for Cd (14 -20%) or Co (27-35%), but AEs for Ag from AVS particles were greater in large clams (28%) than small clams (15%). There were generally poor correlations between AEs of metals and metal release in gut juice. Low pH and moderate reducing conditions facilitated dissolution of AVS- and iron oxide-bound metal in the guts of both animals. The GPTs (64 h) for Co associated with AVS particles in M. edulis were an order of magnitude greater than for Ag and Cd, or for Co associated with other particle types. Overall, no single mechanism appears to control metal AE in marine bivalves and in vitro studies of metal dissolution in gut juice do not completely mimic the complex digestive processes operating in vivo, and thus cannot fully explain metal assimilation in these animals

A systematic review of factors influencing habitat connectivity and biodiversity along road and rail routes in temperate zones

This systematic review, part funded by Network Rail Ltd (UK), considers the role of transportation corridors in habitat connectivity within temperate climates, through verge habitat, surrounding matrix, movement along and across the corridor, the wider landscape context and management practices. PICO terms were developed for the bibliographic search on 15/11/22 using Web of Science (all databases), yielding 168 studies for review. The risk of bias was minimised by excluding non-peer reviewed papers. Large and exotic taxa were excluded due to a focus on temperate zones, as were studies on invasive species and climate change where the primary focus was not ecological connectivity. Emergent themes were used to structure the paper. Results indicate that transportation corridors have significant potential for habitat connectivity, especially for generalist and open-specialist species, which favour early to mid-successional habitats. However, physiology is a key determinant in dispersal ability. Vegetation management should consider representative communities rather than individual species. Gaps exist in the range of taxa studied, understanding of seasonal variations and lifecycle stages supported in verges, survival factors such as predation and disease and changes to community structure. Rail environments are under-represented and there is limited knowledge on the relative impacts of vegetation management regimes

Classification of neurons in the primate reticular formation and changes after recovery from pyramidal tract lesion

The reticular formation is important in primate motor control, both in health and during recovery after brain damage. Little is known about the different neurons present in the reticular nuclei. Here we recorded extracellular spikes from the reticular formation in five healthy female awake behaving monkeys (193 cells), and in two female monkeys 1 year after recovery from a unilateral pyramidal tract lesion (125 cells). Analysis of spike shape and four measures derived from the interspike interval distribution identified four clusters of neurons in control animals. Cluster 1 cellshadaslowfiringrate. Cluster 2 cell shad narrow spikes and irregular firing, which of ten included high-frequencybursts. Cluster3cellswere highly rhythmic and fast firing. Cluster 4 cells showed negative spikes. A separate population of 42 cells was antidromically identified as reticulospinal neurons in five anesthetized female monkeys. The distribution of spike width in these cells closely overlaid the distribution for cluster 2, leading us tentatively to suggest that cluster 2 included neurons with reticulospinal projections. In animals after corticospinal lesion, cells could be identified in all four clusters. The firing rate of cells in clusters 1 and 2 was increased in lesioned animals relative to control animals (by 52% and 60%, respectively); cells in cluster 2 were also more regular and more bursting in the lesioned animals. We suggest that changes in both membrane properties and local circuits within the reticular formation occur following lesioning, potentially increasing reticulospinal output to help compensate for lost corticospinal descending drive