Why are some people bitten more than others?

Much progress has been made in describing how it is, in a mechanistic sense, that some vertebrate hosts (species or individuals) are bitten more than others, principally because of their odour or appearance. Little attention has been paid to why, in an evolutionary sense, these particular animals are bitten. Irrespective of the proximate mechanisms of host choice, there must be an intense selection pressure on insects to feed on those hosts that are most amenable to being bitten. We should be better able to predict host choice by understanding the evolutionary processes at work.     

Why are some people more jealous than others? Genetic and environmental factors

Research on romantic jealousy has traditionally focused on sex differences. We investigated why individuals vary in romantic jealousy, even within the sexes, using a genetically informed design of ~7700 Finnish twins and their siblings. First, we estimated genetic, shared environmental and nonshared environmental influences on jealousy, Second, we examined relations between jealousy and several variables that have been hypothesized to relate to jealousy because they increase the risk (e.g., mate-value discrepancy) or costs (e.g., restricted sociosexuality) of infidelity. Jealousy was 29% heritable, and non-shared environmental influences explained the remaining variance. The magnitude and sources of genetic influences did not differ between the sexes. Jealousy was associated with: having a lower mate value relative to one's partner; having less trust in one's current partner; having been cheated by a previous or current partner; and having more restricted sociosexual attitude and desire. Within monozygotic twin pairs, the twin with more restricted sociosexual desire and less trust in their partner than his or her co-twin experienced significantly more jealousy, showing that these associations were not merely due to the same genes or family environment giving rise to both sociosexual desire or trust and jealousy. The association between sociosexual attitude and jealousy was predominantly explained by genetic factors (74%), whereas all other associations with jealousy were mostly influenced by nonshared environmental (non-familial) factors (estimates >71%). Overall, our findings provide some of the most robust support to date on the importance of variables predicted by mate-guarding accounts to explain why people vary in jealousy.     

Indices for monitoring biodiversity change: Are some more effective than others?

Statistically rigorous methods for summarizing and reporting trends in the intactness of biodiversity are a key element of effective biodiversity monitoring programs. There are four major approaches for translating complex monitoring data into easily communicated summary statistics: (1) traditional diversity indices such as species richness and Simpson's diversity, (2) species intactness indices based on occurrence, (3) species intactness indices based on abundance, and (4) multivariate community indices. We use simulated data to evaluate the effectiveness of 13 indices from these four categories based on statistical robustness, sensitivity to errors and noise in the data, ecological relevance, and ease of communication. We show that indices that calculate species intactness using equations like Buckland's arithmetic mean index are the most effective for use in large-scale biodiversity intactness monitoring programs. Traditional diversity indices are unsuitable for monitoring of biodiversity intactness, and multivariate indices can be highly sensitive to errors and noise in the data. Finally, we provide guidelines for the application of these indices in biodiversity intactness monitoring.     

Why are some microbes more ubiquitous than others? Predicting the habitat breadth of soil bacteria

Identifying the traits that determine spatial distributions can be challenging when studying organisms, like bacteria, for which phenotypic information is limited or non‐existent. However, genomic data provide another means to infer traits and determine the ecological attributes that account for differences in distributions. We determined the spatial distributions of ~124 000 soil bacterial taxa across a 3.41 km² area to determine whether we could use phylogeny and/or genomic traits to explain differences in habitat breadth. We found that occupancy was strongly correlated with environmental range; taxa that were more ubiquitous were found across a broader range of soil conditions. Across the ~500 taxa for which genomic information was available, genomic traits were more useful than phylogeny alone in explaining the variation in habitat breadth; bacteria with larger genomes and more metabolic versatility were more likely to have larger environmental and geographical distributions. Just as trait‐based approaches have proven to be so useful for understanding the distributions of animals and plants, we demonstrate that we can use genomic information to infer microbial traits that are difficult to measure directly and build trait‐based predictions of the biogeographical patterns exhibited by microbes.     

Fungal pathogen species richness: why do some plant species have more pathogens than others?

Variation among plant species in the number of associated herbivore and pathogen species is predicted to fit a species-area relationship in which the area or biomass embodied by a plant species is a function of individual size and geographic range size. This hypothesis is tested using published estimates of geographic range, individual size, and species richness of fungal pathogens for 490 plant species occurring in the United States and controlling for sampling intensity and phylogenetic effects. The number of pathogens found on a plant species increases with the metrics of area and/or habitat diversity of plant species, and their effects are similar between gymnosperm and angiosperm lineages. The strength of this pattern across a diverse set of plant lineages suggests that accumulation and persistence of pathogen species on plant species are governed by similar processes among temperate plants.     

What makes some species of milk snakes more attractive to humans than others?

Animals are ancestrally important stimuli for humans who pay disproportional attention to animal objects and exhibit an outstanding ability to categorize animal species, especially those most relevant to them. Humans as well as other primates perceive snakes as ambivalent stimuli that elicit unspecific arousal and attention. We assessed human aesthetic preferences toward milk snakes, the traditional model for studies of Batesian mimicry. The genus is fairly uniform in size and shape, but includes a great variety of color forms; some possessing aposematic patterns while others being rather cryptic. This provides an opportunity to test which features are responsible for positive aesthetic evaluation of the species. We asked the respondents to rank 34 pictures of milk snakes according to perceived beauty. The sets (whole bodies, heads, and skin fragments) covered most of naturally occurring variation in milk snake appearance. While ranking the beauty, the respondents spontaneously classified the species according to two dimensions. In each set, one of the dimensions corresponds to perceived beauty. The respondents’ ranking revealed several distinct clusters of species instead of a continuous gradient. The species clustered in a similar way irrespective of evaluated set. One dimension of the ranking associated with the relative representation of red color and the number of transversal stripes, the other corresponded to a low proportion of red and a high proportion of black color. When the whole body of the snake is evaluated, aposematic coloration contributes to its perceived beauty. In conclusion, humans showed a surprising ability to classify milk snake patterns; they repeatedly formed the same distinct groups of species, thus completing a process that resembles unsupervised categorization.     

Are some plant life forms more effective than others in screening out ultraviolet-B radiation?

Summary The unprecedented rate of depletion of the stratospheric ozone layer will likely lead to appreciable increases in the amount of ultraviolet-B radiation (UV-B, 280–320 nm) reaching the earth's surface. In plants, photosynthetic reactions and nucleic acids in the mesophyll of leaves are deleteriously affected by UV-B. We used a fiber-optic microprobe to make direct measurements of the amount of UV-B reaching these potential targets in the mesophyll of intact foliage. A comparison of foliage from a diverse group of Rocky Mountain plants enabled us to assess whether the foliage of some plant life forms appeared more effective at screening UV-B radiation. The leaf epidermis of herbaceous dicots was particularly ineffective at attenuating UV-B; epidermal transmittance ranged from 18–41% and UV-B reached 40–145 m into the mesophyll or photosynthetic tissue. In contrast to herbaceous dicots, the epidermis of 1-year old conifer needles attenuated essentially all incident UV-B and virtually none of this radiation reached the mesophyll. Although the epidermal layer was appreciably thinner in older needles (7 y) at high elevations (Krumholtz), essentially all incident UV-B was attenuated by the epidermis in these needles. The same epidermal screening effectiveness was observed after removal of epicuticular waxes with chloroform. Leaves of woody dicots and grasses appeared intermediate between herbaceous dicots and conifers in their UV-B screening abilities with 3–12% of the incident UV-B reaching the mesophyll. These large differences in UV-B screening effectiveness suggest that certain plant life forms may be more predisposed than others to meet the challenge of higher UV-B levels resulting from stratospheric ozone depletion.     

Do bonobos copulate more frequently and promiscuously than chimpanzees?

The copulatory activities of bonobos (Pan paniscus) of Wamba, Zaire, were compared with those of chimpanzees (P. troglodytes schweinfurthii) of Mahale, Tanzania. The copulation rates of adult male bonobos were equal to or lower than those of adult male chimpanzees. The copulation rates of adult female bonobos were approximately equal to those of adult female chimpanzees who were in maximal genital swelling, but it should be much higher than those of the adult female chimpanzees throughout the birth interval. The copulation rates of adolescent male bonobos were lower than those of adolescent male chimpanzees, whereas the copulation rates of adolescent female bonobos were much higher than those of adolescent female chimpanzees. It was suggested that the bonobos of Wamba did not copulate more promiscuously than did the chimpanzees of Mahale. The female bonobos may show “receptivity”, whereas female chimpanzees may show rather “proceptivity”.     

Do invasive alien plants benefit more from global environmental change than native plants?

Invasive alien plant species threaten native biodiversity, disrupt ecosystem functions and can cause large economic damage. Plant invasions have been predicted to further increase under ongoing global environmental change. Numerous case studies have compared the performance of invasive and native plant species in response to global environmental change components (i.e. changes in mean levels of precipitation, temperature, atmospheric CO₂ concentration or nitrogen deposition). Individually, these studies usually involve low numbers of species and therefore the results cannot be generalized. Therefore, we performed a phylogenetically controlled meta‐analysis to assess whether there is a general pattern of differences in invasive and native plant performance under each component of global environmental change. We compiled a database of studies that reported performance measures for 74 invasive alien plant species and 117 native plant species in response to one of the above‐mentioned global environmental change components. We found that elevated temperature and CO₂ enrichment increased the performance of invasive alien plants more strongly than was the case for native plants. Invasive alien plants tended to also have a slightly stronger positive response to increased N deposition and increased precipitation than native plants, but these differences were not significant (N deposition: P = 0.051; increased precipitation: P = 0.679). Invasive alien plants tended to have a slightly stronger negative response to decreased precipitation than native plants, although this difference was also not significant (P = 0.060). So while drought could potentially reduce plant invasion, increases in the four other components of global environmental change considered, particularly global warming and atmospheric CO₂ enrichment, may further increase the spread of invasive plants in the future.     

The technical efficiency of transhumance sheep and goat farms and the effect of EU subsidies: Do small farms benefit more than large farms?

Transhumance sheep and goat production have been a common and traditional practice in Greece, with its origins dating back to ancient times. Despite the diminishing number of transhumance farms, it remains an essential activity in less-favoured and mountainous areas of the country. This article applies DEA (Data Envelopment Analysis) in a sample of transhumance farms in Greece in order to assess the technical efficiency of sheep and goat transhumance flocks and determine the factors that affect their performance. The effect of EU subsidies on the technical efficiency of transhumance farms is assessed and the type of farms that benefit most is investigated. Results accrued reveal that the overall technical efficiency of transhumance farms in Greece is quite low and it is affected by herd size. EU subsidies have a significant impact on the technical efficiency of only the low-efficiency, small-sized farms.     

Do the Japanese feel more suspicious about cancer registration than the British?

Background: Cancer registration is indispensable, providing useful statistical measures for the appropriate evaluation of cancer control programs and medical treatment or screening. Methods: Following the British national survey on attitudes toward cancer registration, we conducted an investigation to correctly evaluate the general opinion of the Japanese population in this regard. We randomly recruited 3000 men and women aged 20–69 years from a research database. Results: Only 4% of all respondents had heard about the cancer registry system before the investigation. However, 77% of respondents thought that cancer registration was useful. Forty-three percent of respondents answered, regardless of the strictness of the data protection, that privacy had been violated if the registration occurred without an individual explanation. Compared with the British survey results, Japanese people seemed to be more suspicious about the largely unknown system of cancer registry. Nonetheless, it is noteworthy that Japanese respondents did not show active opposition to cancer registration; they tended to choose “I don’t know” instead of “no” to questions asking if they supported the registry system. Multivariate analysis showed that male sex, older age, and living in the southern region were the factors significantly associated with support for cancer registration. Conclusions: We can seek society's understanding toward cancer registration by actively utilizing information from cancer registries, by using examples of how data are actually used that have wide appeal, and by educating the public on how the data are treated under the complete privacy policy.     

When and why do some social cleavages become politically salient rather than others?

ABSTRACT

Building on Posner (Posner, Daniel N. 2005. Institutions and Ethnic Politics in Africa. New York: Cambridge University Press), this article describes a framework for organizing the information about a community’s social cleavage structure so as to identify the incentives that individuals face to adopt particular social identities. The framework is parsimonious but powerful: it generates predictions about the social cleavages that will emerge as salient in politics, the lobbying we can expect to see regarding the social categories with which community members should identify, and the attempts that will be made to assimilate or engage in “identity entrepreneurship” to fashion entirely new social identities. The framework also clarifies why partition is unlikely to be a remedy for intractable ethnic conflicts.     

Why are some species more commonly afflicted by arthritis than others? A comparative study of spondyloarthropathy in primates and carnivores

Spondyloarthropathy is a painful arthritic affliction of humans that also occurs in wild mammals. Important questions remain concerning the underlying causes of spondyloarthropathy in mammals, particularly regarding whether it is infectious in origin or driven by genetic predisposition and environmental stressors. Moreover, spondyloarthropathy has negative effects on host fitness, leading to potential conservation concerns if it impacts threatened species. Using a comparative data set on the prevalence of joint disease in 34 primate species and 100 carnivore species, we tested predictions involving the epidemiological correlates of spondyloarthropathy in wild mammals. Analyses revealed that 5.6% of primates and 3.6% of carnivores exhibited signs of spondyloarthropathy, with maximum incidence as high as 22% in great apes and 27% in bears. We tested whether prevalence of spondyloarthropathy increases with population density and group size, greater contact with soil, a slower host life history, increased ranging, dietary factors and body mass. We found general support for an effect of body mass, with larger bodied primates and carnivores exhibiting a higher prevalence of spondyloarthropathy. In addition, more threatened species experienced higher rates of spondyloarthropathy, with this association influenced by body mass and phylogeny. The effect of body mass could reflect that larger animals are exposed to more pathogens through greater consumption of resources, or that joints of larger bodied mammals experience greater biomechanical stresses, resulting in inflammation and activation of local joint infections.     

Do molecules matter more than morphology? Promises and pitfalls in parasites

Systematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences--morphological and molecular data--as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.     

ER targeting signals: more than meets the eye?

The signal sequences that target newly synthesized proteins to the endoplasmic reticulum are highly variable; however, the functional significance of this diversity has remained obscure. In this issue, Kang et al. (2006) report that variability in signal sequences allows the cell to selectively regulate the translocation of proteins into the endoplasmic reticulum in a substrate-specific manner.     

Brain and testis: more alike than previously thought?

Several strands of evidence indicate the presence of marked similarities between human brain and testis. Understanding these similarities and their implications has become a topic of interest among the scientific community. Indeed, an association of intelligence with some semen quality parameters has been reported and a relation between dysfunctions of the human brain and testis has also been evident. Numerous common molecular features are evident when these tissues are compared, which is reflected in the huge number of common proteins. At the functional level, human neurons and sperm share a number of characteristics, including the importance of the exocytotic process and the presence of similar receptors and signalling pathways. The common proteins are mainly involved in exocytosis, tissue development and neuron/brain-associated biological processes. With this analysis, we conclude that human brain and testis share several biochemical characteristics which, in addition to their involvement in the speciation process, could, at least in part, be responsible for the expression of a huge number of common proteins. Nonetheless, this is an underexplored topic, and the connection between these tissues needs to be clarified, which could help to understand the dysfunctions affecting brain and testis, as well as to develop improved therapeutic strategies.     

Inconsistent use of multiple comparison corrections in studies of population genetic structure: Are some type I errors more tolerable than others?

Studies of genetic population structure often involve numerous tests of Hardy–Weinberg equilibrium (HWE), linkage disequilibrium (LD) and genetic differentiation. Tests of HWE or LD are important precursors to population structure assessments. When conducting multiple related statistical tests, type I error increases, e.g., familywise error rate (FWER) inflation. FWER inflation can alter the results of statistical tests and thus the conclusions. We surveyed literature from 2011 to 2013 to determine if studies of population structure assess LD and HWE and if FWER corrections were applied consistently across different types of tests. We found significantly inconsistent FWER corrections, with a bias towards less restrictive correction on genetic differentiation and more restrictive corrections with LD and HWE. While varied adjustments of FWER for different types of analyses might be justified, papers with inconsistent usage across tests of HWE, LD and genetic differentiation did not present rationale for their FWER corrections. We also found a lack of documentation of HWE, LD and FWER corrections in studies. We encourage the authors to report statistical tests and related FWER corrections, use FWER corrections consistently or justify their different methods in the same study.