Warming experiments elucidate the drivers of observed directional changes in tundra vegetation

Few studies have clearly linked long-term monitoring with insitu experiments to clarify potential drivers of observed change at a given site. This is especially necessary when findings from a site are applied to a much broader geographic area. Here, we document vegetation change at Barrow and Atqasuk, Alaska, occurring naturally and due to experimental warming over nearly two decades. An examination of plant cover, canopy height, and community indices showed more significant differences between years than due to experimental warming. However, changes with warming were more consistent than changes between years and were cumulative in many cases. Most cases of directional change observed in the control plots over time corresponded with a directional change in response to experimental warming. These included increases in canopy height and decreases in lichen cover. Experimental warming resulted in additional increases in evergreen shrub cover and decreases in diversity and bryophyte cover. This study suggests that the directional changes occurring at the sites are primarily due to warming and indicates that further changes are likely in the next two decades if the regional warming trend continues. These findings provide an example of the utility of coupling insitu experiments with long-term monitoring to accurately document vegetation change in response to global change and to identify the underlying mechanisms driving observed changes

An investigation of biases in social learning and social attention in wild vervet monkeys (Chlorocebus aethiops pygerythrus) and captive tufted capuchins (Sapajus apella)

Researchers in the field of social learning have suggested that certain biases may exist in whom animals learn from, creating a non-random flow of social information. A number of potential biases have been proposed based upon theoretical models, including biases to copy more dominant individuals or individuals who receive the best payoff from their behaviour, but empirical evidence for these biases is lacking. This thesis presents the first examination of dominance-based bias in a wild population of primates and of a payoff-based bias in captive capuchins. In two field experiments, dominant and low-ranking females from each of three wild groups of vervet monkeys (Chlorocebus aethiops pygerythrus) in KwaZulu-Natal, South Africa were trained to demonstrate contrasting behaviours to their group before observers were provided with a choice between the two modelled preferences. No evidence was found for a consistent bias to copy the behaviour of the dominant female in either experiment. Instead, in both experiments, a preference for one behaviour emerged, regardless of model rank. In the latter experiment, higher-ranking females were significantly more likely to match the dominant model’s action than were low-ranking females. The low-ranking models were more likely than their high-ranking counterparts to switch behaviours, despite their trained behaviour continuing to be productive. An analyses of the observations revealed that observers were biased towards attending to kin, and observer age appeared to influence access to the dominant models, but no overall preference to attend to the dominant female was found. Together these findings indicate that kinship, sex, age and preferences for specific behaviours are more important factors than model rank in vervet monkey social learning. Finally, I examined whether captive tufted capuchins (Sapajus apella) utilized a payoff-based social learning bias in their foraging decisions. Subjects did not utilize public information when choosing between demonstrated resource-rich and resource-poor sites, suggesting that the social learning abilities of capuchins may not extend to determining the profitability of feeding sites, although limitations of the study are discussed.  Work supported by a grant from the John Templeton Foundatio

Dynamics of Intersexual Dominance and Adult Sex- Ratio in Wild Vervet Monkeys

Intersexual dominance relations are important for female mammals, because of their consequences for accessing food and for the degree of sexual control females experience from males. Female mammals are usually considered to rank below males in the dominance hierarchy, because of their typical physical inferiority. Yet, in some groups or species, females are nonetheless dominant over some males (partial female dominance). Intersexual dominance, therefore, also depends on traits other than sexual dimorphism, such as social support, social exchange, group adult sex-ratio, and the widespread self-reinforcing effects of winning and losing fights, the “winner-loser effect.” The importance of sex-ratio and the winner-loser effect remains poorly understood. A theoretical model, DomWorld, predicts that in groups with a higher proportion of males, females are dominant over more males when aggression is fierce (not mild). The model is based on a small number of general processes in mammals, such as grouping, aggression, the winner-loser effect, the initially greater fighting capacity of males than females, and sex ratio. We expect its predictions to be general and suggest they be examined in a great number of species and taxa. Here, we test these predictions in four groups of wild vervet monkeys (Chlorocebus pygerythrus) in Mawana game reserve in Africa, using 7 years of data. We confirm that a higher proportion of males in the group is associated with greater dominance of females over males; a result that remains when combining these data with those of two other sites (Amboseli and Samara). We additionally confirm that in groups with a higher fraction of males there is a relatively higher (a) proportion of fights of males with other males, and (b) proportion of fights won by females against males from the fights of females with any adults. We reject alternative hypotheses that more dominance of females over males could be attributed to females receiving more coalitions from males, or females receiving lowered male aggression in exchange for sexual access (the docile male hypothesis). We conclude that female dominance relative to males is dynamic and that future empirical studies of inter-sexual dominance will benefit by considering the adult sex-ratio of groups.</p

The two phases of the Cambrian Explosion

Abstract The dynamics of how metazoan phyla appeared and evolved – known as the Cambrian Explosion – remains elusive. We present a quantitative analysis of the temporal distribution (based on occurrence data of fossil species sampled in each time interval) of lophotrochozoan skeletal species (n = 430) from the terminal Ediacaran to Cambrian Stage 5 (~545 – ~505 Million years ago (Ma)) of the Siberian Platform, Russia. We use morphological traits to distinguish between stem and crown groups. Possible skeletal stem group lophophorates, brachiopods, and molluscs (n = 354) appear in the terminal Ediacaran (~542 Ma) and diversify during the early Cambrian Terreneuvian and again in Stage 2, but were devastated during the early Cambrian Stage 4 Sinsk extinction event (~513 Ma) never to recover previous diversity. Inferred crown group brachiopod and mollusc species (n = 76) do not appear until the Fortunian, ~537 Ma, radiate in the early Cambrian Stage 3 (~522 Ma), and with minimal loss of diversity at the Sinsk Event, continued to diversify into the Ordovician. The Sinsk Event also removed other probable stem groups, such as archaeocyath sponges. Notably, this diversification starts before, and extends across the Ediacaran/Cambrian boundary and the Basal Cambrian Carbon Isotope Excursion (BACE) interval (~541 to ~540 Ma), ascribed to a possible global perturbation of the carbon cycle. We therefore propose two phases of the Cambrian Explosion separated by the Sinsk extinction event, the first dominated by stem groups of phyla from the late Ediacaran, ~542 Ma, to early Cambrian stage 4, ~513 Ma, and the second marked by radiating bilaterian crown group species of phyla from ~513 Ma and extending to the Ordovician Radiation

Single-cell multi-omics analysis of the immune response in COVID-19

Funder: Lister Institute of Preventive Medicine; doi: https://doi.org/10.13039/501100001255Funder: University College London, Birkbeck MRC Doctoral Training ProgrammeFunder: The Jikei University School of MedicineFunder: Action Medical Research (GN2779)Funder: NIHR Clinical Lectureship (CL-2017-01-004)Funder: NIHR (ACF-2018-01-004) and the BMA FoundationFunder: Chan Zuckerberg Initiative (grant 2017-174169) and from Wellcome (WT211276/Z/18/Z and Sanger core grant WT206194)Funder: UKRI Innovation/Rutherford Fund Fellowship allocated by the MRC and the UK Regenerative Medicine Platform (MR/5005579/1 to M.Z.N.). M.Z.N. and K.B.M. have been funded by the Rosetrees Trust (M944)Funder: Barbour FoundationFunder: ERC Consolidator and EU MRG-Grammar awardsFunder: Versus Arthritis Cure Challenge Research Grant (21777), and an NIHR Research Professorship (RP-2017-08-ST2-002)Funder: European Molecular Biology Laboratory (EMBL)Abstract: Analysis of human blood immune cells provides insights into the coordinated response to viral infections such as severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). We performed single-cell transcriptome, surface proteome and T and B lymphocyte antigen receptor analyses of over 780,000 peripheral blood mononuclear cells from a cross-sectional cohort of 130 patients with varying severities of COVID-19. We identified expansion of nonclassical monocytes expressing complement transcripts (CD16+C1QA/B/C+) that sequester platelets and were predicted to replenish the alveolar macrophage pool in COVID-19. Early, uncommitted CD34+ hematopoietic stem/progenitor cells were primed toward megakaryopoiesis, accompanied by expanded megakaryocyte-committed progenitors and increased platelet activation. Clonally expanded CD8+ T cells and an increased ratio of CD8+ effector T cells to effector memory T cells characterized severe disease, while circulating follicular helper T cells accompanied mild disease. We observed a relative loss of IgA2 in symptomatic disease despite an overall expansion of plasmablasts and plasma cells. Our study highlights the coordinated immune response that contributes to COVID-19 pathogenesis and reveals discrete cellular components that can be targeted for therapy

Examining the use of auditory signals as “attention-getters” in Zoo-housed gorillas and orangutans

An empirical study of the use of auditory "attention-getters" in gorillas and orangutan

Examining the use of auditory signals as “attention-getters” in Zoo-housed gorillas and orangutans

An empirical study of the use of auditory "attention-getters" in gorillas and orangutan

Use of communicative behaviors by captive gorillas and orangutans

Funded by the David Bohnett Foundation, an examination of how human attention state affects the use of visual and auditory communicative signals by gorillas and orangutan