THE ECOLOGY OF MUTUALISM

Elementary ecology texts tell us that organisms interact in three fundamen­ tal ways, generally given the names competition, predation, and mutualism. The third member has gotten short shrift (264), and even its name is not generally agreed on. Terms that may be considered synonyms, in whole or part, are symbiosis, commensalism, cooperation, protocooperation, mutual aid, facilitation, reciprocal altruism, and entraide. We use the term mutual­ism, defined as an interaction between species that is beneficial to both, since it has both historical priority (311) and general currency. Symbiosis is the living together of two organisms in close association, and modifiers are used to specify dependence on the interaction (facultative or obligate) and the range of species that can take part (oligophilic or polyphilic). We make the normal apologies concerning forcing continuous variation and diverse interactions into simple dichotomous classifications, for these and all subsequent definitions

THE ECOLOGY OF MUTUALISM

Elementary ecology texts tell us that organisms interact in three fundamen­ tal ways, generally given the names competition, predation, and mutualism. The third member has gotten short shrift (264), and even its name is not generally agreed on. Terms that may be considered synonyms, in whole or part, are symbiosis, commensalism, cooperation, protocooperation, mutual aid, facilitation, reciprocal altruism, and entraide. We use the term mutual­ism, defined as an interaction between species that is beneficial to both, since it has both historical priority (311) and general currency. Symbiosis is the living together of two organisms in close association, and modifiers are used to specify dependence on the interaction (facultative or obligate) and the range of species that can take part (oligophilic or polyphilic). We make the normal apologies concerning forcing continuous variation and diverse interactions into simple dichotomous classifications, for these and all subsequent definitions

Dispersal of sweet pignut hickory in a year of low fruit production, and the influence of predation by a curculionid beetle

The rate at which fallen hickory nuts are removed from beneath the parent tree, and the effect on this rate of the seed predator Conotrachelus affinis , was studied in an oak-hickory forest in southeastern Michigan, USA, during a year in which few nuts were produced. The trees responded to Conotrachelus , which destroyed half the nut crop, by aborting inviable nuts during the summer. The seed dispersers, mostly gray squirrels, removed fallen nuts rapidly, showing the ability to distinguish viable nuts and remove them preferentially. The number of nuts removed in a week varies directly with the number available, and removal rate increases when many viable nuts are falling. The death of most seeds before dispersal, and the squirrels' efficiency at foraging on nuts and recovering them after burial, imply that successful hickory reproduction takes place only in years of heavy nut production.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47717/1/442_2004_Article_BF00751606.pd

The ecology of mutualism

Elementary ecology texts tell us that organisms interact in three fundamen­ tal ways, generally given the names competition, predation, and mutualism. The third member has gotten short shrift (264), and even its name is not generally agreed on. Terms that may be considered synonyms, in whole or part, are symbiosis, commensalism, cooperation, protocooperation, mutual aid, facilitation, reciprocal altruism, and entraide. We use the term mutual­ism, defined as an interaction between species that is beneficial to both, since it has both historical priority (311) and general currency. Symbiosis is the living together of two organisms in close association, and modifiers are used to specify dependence on the interaction (facultative or obligate) and the range of species that can take part (oligophilic or polyphilic). We make the normal apologies concerning forcing continuous variation and diverse interactions into simple dichotomous classifications, for these and all subsequent definitions

Resistance and resilience in a directly regenerating rainforest: Nicaraguan trees of the Vochysiaceae after Hurricane Joan

Two trees of the family Vochysiaceae, Vochysia ferruginea and Qualea paraensis, were abundant in a Nicaraguan rainforest which was heavily damaged by Hurricane Joan in 1988, and both had recovered their previous densities by 1993. However, their regeneration followed quite different paths. Vochysia suffered complete mortality of adult trees in the hurricane, but rapid growth and high survivorship of its abundant seedlings and sprouts of saplings, restored its population density (though not yet its mean diameter at breast height) and indeed led to spatial expansion. Qualea, however, showed 100% survival of trees during the hurricane but substantial mortality in the following years. Although seedlings and sprouts of Qualea are quite rare, ingrowth is sufficient to maintain the population so far. However, vine growth on Qualea (unlike Vochysia) is substantial.These two species are thus contrasting elements of the `direct regeneration' which has been observed in this rainforest. The Vochysia pattern of death and recovery can be described as `resilience', while the Qualea pattern of survival can be called `resistance'. The regenerating Vochysia population is mostly seedlings and saplings, while that of Qualea is mostly adult trees. Depending on the pattern of regeneration, different management strategies will be appropriate for maintaining tree species subject to natural disturbances such as hurricanes and/or artificial ones such as logging.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31279/1/0000185.pd

Post-agriculture versus post-hurricane succession in southeastern Nicaraguan rain forest

Wecompared five-year old forests developing after agriculture to those recoveringfrom Hurricane Joan (1988) and to the pre-hurricane forest, at two sites intropical rain forest in southeastern Nicaragua. We used non-parametric clusteranalysis to group transects by their species compositions, and compared theirspecies richness, estimated total species richness, dominance, density andbasalarea. Post-agriculture transects showed distinctive species compositions andlower diversity than post-hurricane transects, which were in turn more similarto the pre-hurricane forest. These results are similar to those found by otherresearchers in the Amazon and in Puerto Rico. Land use history was moreimportant than proximity in the landscape in determining the composition andstructure of post-disturbance forests in this region.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43884/1/11258_2004_Article_266487.pd

Weekly SARS-CoV-2 screening of asymptomatic kindergarten to grade 12 students and staff helps inform strategies for safer in-person learning

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in K-12 schools was rare during in 2020-2021; few studies included Centers for Disease Control and Prevention (CDC)-recommended screening of asymptomatic individuals. We conduct a prospective observational study of SARS-CoV-2 screening in a mid-sized suburban public school district to evaluate the incidence of asymptomatic coronavirus disease 2019 (COVID-19), document frequency of in-school transmission, and characterize barriers and facilitators to asymptomatic screening in schools. Staff and students undergo weekly pooled testing using home-collected saliva samples. Identification of \u3e 1 case in a school prompts investigation for in-school transmission and enhancement of safety strategies. With layered mitigation measures, in-school transmission even before student or staff vaccination is rare. Screening identifies a single cluster with in-school staff-to-staff transmission, informing decisions about in-person learning. The proportion of survey respondents self-reporting comfort with in-person learning before versus after implementation of screening increases. Costs exceed $260,000 for assays alone; staff and volunteers spend 135-145 h per week implementing screening

Of, By, and For Which People? Government and Contested Heritage in the American Midwest

Two government-owned and managed heritage sites in Indiana, USA, offer an opportunity to explore the role of governments in adjudicating the competing paradigms of value and contested uses. Strawtown Koteewi is a Hamilton County park and Mounds State Park is part of the Indiana Department of Natural Resources statewide park system. Each site has come under scrutiny in recent years. Strawtown Koteewi is one of the most significant sites in the area for understanding the history of Native peoples. After almost a decade of archaeological excavations, several Native American groups, under the auspices of the Native American Graves Protection and Repatriation Act (NAGPRA), initiated repatriation processes for the recovery of human remains, and some objected to the ongoing archaeological research. At Mounds State Park a coalition of citizens opposed a planned dam project intended to ensure a safe and plentiful water supply and to spur economic development in the area. In each case, the government entities have had to navigate the political landscapes of competing claims about the sites. These case studies expose the fissures between authorized heritage discourse and the paradigms of meaning among the diverse constituencies of the sites, and they highlight the tenuous position of public governance in privileging competing cultural, economic, and social interests. While not unique, the state and county agencies’ positions within these fields of power and their strategic choices reveal some of the barriers and constraints that limit their actions as well as the deep-seated ideologies of policies that perpetuate settler colonial politics in the control and interpretation of indigenous heritage

Dimensionless cosmology

Although it is well known that any consideration of the variations of fundamental constants should be restricted to their dimensionless combinations, the literature on variations of the gravitational constant $G$ is entirely dimensionful. To illustrate applications of this to cosmology, we explicitly give a dimensionless version of the parameters of the standard cosmological model, and describe the physics of Big Bang Neucleosynthesis and recombination in a dimensionless manner. The issue that appears to have been missed in many studies is that in cosmology the strength of gravity is bound up in the cosmological equations, and the epoch at which we live is a crucial part of the model. We argue that it is useful to consider the hypothetical situation of communicating with another civilization (with entirely different units), comparing only dimensionless constants, in order to decide if we live in a Universe governed by precisely the same physical laws. In this thought experiment, we would also have to compare epochs, which can be defined by giving the value of any {\it one} of the evolving cosmological parameters. By setting things up carefully in this way one can avoid inconsistent results when considering variable constants, caused by effectively fixing more than one parameter today. We show examples of this effect by considering microwave background anisotropies, being careful to maintain dimensionlessness throughout. We present Fisher matrix calculations to estimate how well the fine structure constants for electromagnetism and gravity can be determined with future microwave background experiments. We highlight how one can be misled by simply adding $G$ to the usual cosmological parameter set

Extracting causal relations on HIV drug resistance from literature

<p>Abstract</p> <p>Background</p> <p>In HIV treatment it is critical to have up-to-date resistance data of applicable drugs since HIV has a very high rate of mutation. These data are made available through scientific publications and must be extracted manually by experts in order to be used by virologists and medical doctors. Therefore there is an urgent need for a tool that partially automates this process and is able to retrieve relations between drugs and virus mutations from literature.</p> <p>Results</p> <p>In this work we present a novel method to extract and combine relationships between HIV drugs and mutations in viral genomes. Our extraction method is based on natural language processing (NLP) which produces grammatical relations and applies a set of rules to these relations. We applied our method to a relevant set of PubMed abstracts and obtained 2,434 extracted relations with an estimated performance of 84% for F-score. We then combined the extracted relations using logistic regression to generate resistance values for each <drug, mutation> pair. The results of this relation combination show more than 85% agreement with the Stanford HIVDB for the ten most frequently occurring mutations. The system is used in 5 hospitals from the Virolab project <url>http://www.virolab.org</url> to preselect the most relevant novel resistance data from literature and present those to virologists and medical doctors for further evaluation.</p> <p>Conclusions</p> <p>The proposed relation extraction and combination method has a good performance on extracting HIV drug resistance data. It can be used in large-scale relation extraction experiments. The developed methods can also be applied to extract other type of relations such as gene-protein, gene-disease, and disease-mutation.</p