Aim: The island rule has been widely applied to a range of taxonomic groups, with some studies reporting supporting evidence but others questioning this hypothesis.To bring more clarity to this debate, we conducted a comparative analysis of the available literature, focussing on potential biases. Location: Worldwide.Methods: We performed a systematic review to identify studies testing the island rule and translated these studies' outcomes, so that they follow a consistent approach.The studies were assessed for differences in their analysis of the island rule. We created an authorship network showing who published studies with whom on the topic and weighted the data based on co-authorship and number of publications.Results: We identified 143 relevant studies, finding a significantly lower frequency of supporting studies according to our consistent approach (50%) than the authors' own statements (59%). Two core-author groups could be identified with a strong publication record on the island rule. The first group has predominately published studies supporting the rule, whereas the other group has mainly published studies questioning it. According to a subsequent analysis excluding studies with a high risk of HARKing (hypothesizing after the results are known), the frequency of studies supporting the rule further dropped to 42%.Main conclusions: Empirical support for the island rule is low, especially for nonmammalian taxa and when using a consistent evaluation approach. Differences among studies in supporting versus questioning this hypothesis seem to be partly due to author-related biases. Methods to address potential biases in studying ecological hypotheses are urgently needed. We offer such a method here. K E Y W O R D Sauthor biases, author groups, hierarchy of hypotheses, island biogeography, island dwarfism, island gigantism, island rule | INTRODUCTIONThe observation that species on islands are smaller or larger than their mainland counterparts has led to the formulation of the island rule which describes "the tendency for a graded series of changes in the size of island vertebrate species in relation to mainland congeners, such that small-bodied species tend to get larger, and vice versa"-definition from a standard textbook on Island Biogeography (Whittaker & Fern andez-Palacios, 2007, p. 346). The island rule was first formulated by Leigh van Valen (1973) who stated that "the regular evolution of mammalian body size on islands is an extraordinary phenomenon which seems to have fewer exceptions than any other ecotypic rule in animals" (p. 35). These findings were based on a study by Foster (1964), who had described the tendency of several mammalian orders to be either larger (Rodentia) or smaller (Carnivora, Artiodactyla, Lagomorpha) when isolated on marine islandsThe dataset underlying this analysis will be included in the expanded online edition. compared to related mainland populations. The island rule was fundamentally reshaped by Lomolino (1985) (see also Heaney, 1978), who had reviewed a simil...
The importance of soldiers to termite society defence has long been recognized, but the contribution of soldiers to other societal functions, such as colony immunity, is less well understood. We explore this issue by examining the role of soldiers in protecting nestmates against pathogen infection. Even though they are unable to engage in grooming behaviour, we find that the presence of soldiers of the Darwin termite, Mastotermes darwiniensis, significantly improves the survival of nestmates following entomopathogenic infection. We also show that the copious exocrine oral secretions produced by Darwin termite soldiers contain a high concentration of proteins involved in digestion, chemical biosynthesis, and immunity. The oral secretions produced by soldiers are sufficient to protect nestmates against infection, and they have potent inhibitory activity against a broad spectrum of microbes. Our findings support the view that soldiers may play an important role in colony immunity, and broaden our understanding of the possible function of soldiers during the origin of soldier-first societies.
A key dimension of our current era is Big Data, the rapid rise in produced data and information; a key frustration is that we are nonetheless living in an age of ignorance, as the real knowledge and understanding of people does not seem to be substantially increasing. This development has critical consequences, for example it limits the ability to find and apply effective solutions to pressing environmental and socioeconomic challenges. Here, we propose the concept of “knowledge in the dark”—or short: dark knowledge—and outline how it can help clarify key reasons for this development: ( i) production of biased, erroneous, or fabricated data and information; ( ii) inaccessibility and ( iii) incomprehensibility of data and information; and ( iv) loss of previous knowledge. Even in the academic realm, where financial interests are less pronounced than in the private sector, several factors lead to dark knowledge, that is they inhibit a more substantial increase in knowledge and understanding. We highlight four of these factors—loss of academic freedom, research biases, lack of reproducibility, and the Scientific tower of Babel—and offer ways to tackle them, for example establishing an international court of arbitration for research and developing advanced tools for research synthesis.
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