Sex differences in the anatomical locations of human body scarification and tattooing as a function of pathogen prevalence

Pathogen prevalence can affect human mate selection because pathogen severity limits the number of high-quality pathogen-resistant mates. This creates a selection pressure to fashion mechanisms to identify and select pathogen-resistant mates. Gangestad and Buss have suggested that attractiveness indicates pathogen resistance. Humans in many instances enhance their attractiveness by using permanent body markings, such as tattooing and scarification. We hypothesized that as pathogen severity increases, so should permanent marking of body areas that are attended to for evaluating attractiveness and mate quality. Females were predicted to scarify their breasts and stomachs (due to the stomach being a component of waist-to-hip ratio), both indicative of youthfulness and fertility. Males were predicted to scarify those body parts indicative of sexual maturity and strength, such as the face, shoulders, and arms. Cross-cultural data revealed that pathogen prevalence predicts female stomach scarification independent of polygyny, famine, and social class stratification. The relationship between scarification of body parts and pathogen prevalence was not evident for males. These findings, based upon between-society comparisons, suggest that stomach scarification could act as a signal of female mate quality in societies that encounter a high prevalence of pathogens.     

Human parental effort and environmental risk

Parental investment decisions depend on multiple factors, including the extent that parental care benefits offspring. Humans should show reduced parental effort in environments where parenting cannot improve offspring survival. Data from the standard cross-cultural sample are used to test this prediction. The results show that maternal care was inversely associated with famine and warfare, and also showed a quadratic association with pathogen stress, increasing as pathogen stress increased to moderate levels, but decreasing at higher levels. Age at weaning showed a similar quadratic relation with pathogens. The curvilinear associations between parental effort and pathogen stress may reflect that the saturation point of parental care is a function of environmental hazards. Paternal involvement was also inversely related to pathogen stress. The association between pathogens and paternal involvement was partially mediated by polygyny. In sum, maternal and paternal care appears to have somewhat different relations with environmental hazards, presumably owing to sex-specific tradeoffs in reproductive effort.     

Disgust sensitivity relates to affective responses to – but not ability to detect – olfactory cues to pathogens

Hundreds of studies have assessed variation in the degree to which people experience disgust toward substances associated with pathogens, but little is known about the mechanistic sources of this variation. The current investigation uses olfactory perception and threshold methods to test whether it is apparent at the cue-detection level, at the cue-interpretation level, or both. It further tests whether relations between disgust sensitivity and olfactory perception are specific to odors associated with pathogens. Two studies (N's = 119 and 160) of individuals sampled from a Dutch university each revealed that pathogen disgust sensitivity relates to valence perceptions of odors found in pathogen sources, but not to valence perceptions of odors not associated with pathogens, nor to intensity perceptions of odors of either type. Study 2, which also assessed olfactory thresholds via a three-alternative forced-choice staircase method, did not reveal a relation between pathogen disgust sensitivity and the ability to detect an odor associated with pathogens, nor an odor not associated with pathogens. In total, results are consistent with the idea that pathogen disgust sensitivity relates to how olfactory pathogen cues are interpreted after detection, but not necessarily to the ability to detect such cues.     

On the evolution of polygyny: a theoretical examination of the polygyny threshold model

The polygyny threshold model states that if costs incurred areless than the benefits gained from mating polygynously in termsof breeding-situation quality, then polygyny is favored andcould evolve. We constructed mathematical models and computersimulations to evaluate this hypothesis. In the basic model,there is a single locus with two alleles, which regulates whetherthe female is receptive to polygyny. There are two breedingsituations of differing quality on which males randomly assort.Females then select a mate based on the associated breedingsituation and whether the male already has mates. This basicmodel is extended mathematically to include a cost for the initialfemale of a male with multiple mates and again to include geneexpression in males. The computer simulations extend the basicmodel to multiple loci and alleles and to multiple breedingsituations. The results presented here suggest that the polygynythreshold model is valid in a population genetic context: ifthe fitness of females that actually mate polygynously is greaterthan the fitness of monogamous females on poorer breeding situations,polygyny evolves. However, this approach reveals interestingdynamics not apparent from the verbal model. If the trait isexpressed in males and females, then polygyny can evolve evenif females mating polygynously have a lower fitness than femalesmating monogamously. In the multiple breeding-situations model,the polygyny allele increases to some equilibrium value abovewhich it experiences no selection. Surprisingly, as the costof polygyny increases, the equilibrium frequency of the polygynyallele also increases. The difference between this evolutionarymodel and the ideal free distribution is discussed.     

Inverse relationship between systemic resistance of plants to microorganisms and to insect herbivory

Pre-inoculation of plants with a pathogen that induces necrosis leads to the development of systemic acquired resistance (SAR) to subsequent pathogen attack [1]. The phenylpropanoid-derived compound salicylic acid (SA) is necessary for the full expression of both local resistance and SAR [2] [3]. A separate signaling pathway involving jasmonic acid (JA) is involved in systemic responses to wounding and insect herbivory [4] [5]. There is evidence both supporting and opposing the idea of cross-protection against microbial pathogens and insect herbivores [6] [7]. This is a controversial area because pharmacological experiments point to negative cross-talk between responses to systemic pathogens and responses to wounding [8] [9] [10], although this has not been demonstrated functionally in vivo. Here, we report that reducing phenylpropanoid biosynthesis by silencing the expression of phenylalanine ammonialyase (PAL) reduces SAR to tobacco mosaic virus (TMV), whereas overexpression of PAL enhances SAR. Tobacco plants with reduced SAR exhibited more effective grazing-induced systemic resistance to larvae of Heliothis virescens, but larval resistance was reduced in plants with elevated phenylpropanoid levels. Furthermore, genetic modification of components involved in phenylpropanoid synthesis revealed an inverse relationship between SA and JA levels. These results demonstrate phenylpropanoid-mediated cross-talk in vivo between microbially induced and herbivore-induced pathways of systemic resistance.     

Compatible rhizosphere microbes mediated alleviation of biotic stress in chickpea through enhanced antioxidant and phenylpropanoid activities

The study was conducted to examine efficacy of a rhizospheric microbial consortium comprising of a fluorescent Pseudomonas (PHU094), Trichoderma (THU0816) and Rhizobium (RL091) strain on activation of physiological defense responses in chickpea against biotic stress caused by the collar rot pathogen Sclerotium rolfsii. Results of individual microbes were compared with dual and triple strain mixture treatments with reduced microbial load (1/2 and 1/3rd, respectively, of individual microbial load compared to single microbe application) in the mixtures. Periodical studies revealed maximum activities of phenylalanine ammonia lyase [E.C. 4.1.3.5] and polyphenol oxidase [E.C. 1.14.18.1] and accumulation of total phenol content in chickpea in the triple microbe consortium treated plants challenged with the pathogen compared to the single microbe and dual microbial consortia. Similarly, the expression of the antioxidant enzymes superoxide dismutase [E.C.1.15.1.1] and peroxidase [E.C.1.11.1.7] was also highest in the triple microbial consortium which was correlated with lesser lipid peroxidation in chickpea under the biotic stress. Histochemical staining clearly showed maximum and uniform lignification in vascular bundles of chickpea stem sections treated with the triple microbes. The physiological responses were directly correlated with the mortality rate as least plant mortality was recorded in the triple microbe consortium treated plants. The results thus suggest an augmented elicitation of stress response in chickpea under S. rolfsii stress by the triple microbial consortium in a synergistic manner under reduced microbial load.     

A mixed model of the evolution of polygyny and sexual size dimorphism in mammals

The theory of sexual selection is the most widely accepted theory explaining the evolution of mating systems and secondary sexual characters. Polygyny is the most common mating system in mammals, and there is a strong correlation between the degree of polygyny and the degree of sexual size dimorphism skewed towards males. Sexual selection theory posits that polygyny in mammals has evolved through direct, precopulatory, intrasexual selection in males, and that sexual size dimorphism is a result of male competition for mates. New results that are being obtained with the use of molecular techniques and with comparative phylogenetic methods do not appear to support predictions from this classical model in full. In this article, an expansion of the classical model is presented that combines the effects of at least four forms of selection: natural, precopulatory intrasexual, postcopulatory intrasexual, and intersexual selection. This mixed model consists of an initial phase in which natural selection operates on body size, followed by a second phase dominated by sexual selection and involving increases in sexual dimorphism and coercive behaviour of males towards females. Sexual harassment induces female aggregation, thus creating social potential for polygyny. Males compete for access to the groups of females, following two possible evolutionary scenarios, directional or equilibrium sexual selection, both producing similar behavioural polygyny, but with differences in the intensity of intra-male precopulatory sexual selection. Predictions of the mixed model are as follows: 1) polygyny can exist without high variance in male reproductive success (a fundamental requirement in the classical model); 2) extra-group fertilisation can be common; 3) sexual size dimorphism evolved prior to polygyny; 4) sexual coercion is widespread; and 5) females reduce levels of sexual coercion by joining groups.     

The origin of human pathogens: evaluating the role of agriculture and domestic animals in the evolution of human disease

Many significant diseases of human civilization are thought to have arisen concurrently with the advent of agriculture in human society. It has been hypothesised that the food produced by farming increased population sizes to allow the maintenance of virulent pathogens, i.e. civilization pathogens, while domestic animals provided sources of disease to humans. To determine the relationship between pathogens in humans and domestic animals, I examined phylogenetic data for several human pathogens that are commonly evolutionarily linked to domestic animals: measles, pertussis, smallpox, tuberculosis, taenid worms, and falciparal malaria. The majority are civilization pathogens, although I have included others whose evolutionary origins have traditionally been ascribed to domestic animals. The strongest evidence for a domestic-animal origin exists for measles and pertussis, although the data do not exclude a non-domestic origin. As for the other pathogens, the evidence currently available makes it difficult to determine if the domestic-origin hypothesis is supported or refuted; in fact, intriguing data for tuberculosis and taenid worms suggests that transmission may occur as easily from humans to domestic animals. These findings do not abrogate the importance of agriculture in disease transmission; rather, if anything, they suggest an alternative, more complex series of effects than previously elucidated. Rather than domestication, the broader force for human pathogen evolution could be ecological change, namely anthropogenic modification of the environment. This is supported by evidence that many current emerging infectious diseases are associated with human modification of the environment. Agriculture may have changed the transmission ecology of pre-existing human pathogens, increased the success of pre-existing pathogen vectors, resulted in novel interactions between humans and wildlife, and, through the domestication of animals, provided a stable conduit for human infection by wildlife diseases.     

Lifetime offspring production in relation to breeding lifespan, attractiveness, and mating status in male collared flycatchers

As a comprehensive fitness parameter, lifetime reproductive success (LRS) is influenced by many different environmental and genetic factors, among which longevity is one of the most important. These factors can be reflected in secondary sexual characters, which may affect the life histories of individuals via social relations with conspecifics. Facultative polygyny in birds is another conspicuous reproductive trait that potentially increases male reproductive success, but lifetime success data in relation to polygyny are scarce. Here, we used 17?years of breeding data to quantify the LRS of male collared flycatchers (Ficedula albicollis) on the basis of lifetime recruitment of offspring. Breeding lifespan showed a positive relationship with LRS, and it was also significantly associated with mean recruitment of offspring per breeding year. Body size and sexually selected forehead patch size did not predict the number of recruits. Polygyny was positively associated with LRS, but when we corrected for lifespan, this relationship disappeared. Our results demonstrate that the relationship between longevity and LRS is not explained by the higher number of reproductive attempts when living longer, and question the adaptive value of polygyny in this population. The lack of association between forehead patch size and recruitment suggests that forehead patch is a poor indicator of phenotypic quality in our birds.     

Proteomic Analysis of Mn-induced Resistance to Powdery Mildew in Grapevine

Previous studies documented that metal hyperaccumulation armours plants with direct defences against pathogens. In the present study, it was found that high leaf Mn concentrations (<2500 μg g(-1)) induced grapevine resistance to powdery mildew [Uncinula necator (Schw.) Burr]. Manganese delayed pathogen spreading after powdery mildew (PM) inoculation, but did not directly inhibit pathogen growth on a long-term basis. It was postulated that the grapevine resistance resulted from the induction of protective mechanisms in planta. To test this hypothesis, the proteome profile was analysed by Difference Gel Electrophoresis (DIGE) methods to identify proteins that are putatively involved in pathogen resistance. A high Mn concentration caused little oxidative pressure in grapevine, but oxidative stress was deeply enhanced by PM stress. Except for a few proteins that were related to oxidative pressure and proteins specially regulated by Mn or PM, most of the detected proteins exhibited similar changes under excess Mn stress and under PM stress, suggesting that similar signalling processes mediate the responses to the two stresses. As well as PM stress, high leaf Mn concentration significantly enhanced salicylic acid concentration and increased the expression of proteins involved in ethylene and jasmonic acid synthesis. The proteins related to pathogen resistance were also enhanced by excess Mn, including a PR-like protein, an NBS-LRR analogue, and a JOSL protein, and this was accompanied by the increased activity of phenylalanine ammonia lyase. It was concluded that high leaf Mn concentration triggered protective mechanisms against pathogens in grapevine.     

Beta-endorphin, adrenocorticotropic hormone, cortisol and catecholamines during aerobic and anaerobic exercise

Twelve non-specifically trained volunteers (aged 26.5 years, SD 3.6) performed exhausting incremental graded exercise (ST) and 1-min anaerobic cycle ergometer exercise (AnT) at 2-h intervals for the purpose of investigating beta-endorphin (beta-E) behaviour dependent on exercise intensity and anaerobic metabolism. In order to determine [beta-E], adrenocorticotropic hormone [ACTH], cortisol [C], adrenaline [A] and noradrenaline [NA] concentrations, venous blood samples were collected prior and subsequent to exercise until the 20th min of the recovery period, as well as in ST before and after exceeding the individual anaerobic threshold (THan,i). Before, during and after ST, lactate concentration, heart rate and perceived degree of exertion were also determined; after AnT maximum lactate concentration was measured. Both types of exercise led to significant increases in [beta-E], [ACTH], [A] and [NA], with levels of [beta-E] and [ACTH] approximately twice as high after ST as after AnT. The [C] increased significantly only after ST. During ST significant changes in [beta-E] and [ACTH] were measured only after exceeding THan,i. At all measuring times before and after ST and AnT both hormones correlated positively. In AnT the increases of [beta-E] and [A] demonstrated a correlation (r = 0.65; P less than 0.05). Both in AnT and ST there was a relationship between the maximum concentrations of beta-E and lactate (r = 0.63 and 0.71; each P less than 0.05). We therefore conclude that physical exercise with increasing or mostly anaerobic components leads to an increase in [beta-E], the extent correlating with the degree of lactate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Elemental allelopathy by an arsenic hyperaccumulating fern,Pteris vittata L.

Aims The functional advantages of arsenic (As) hyperaccumulation by plants are poorly understood. One proposed benefit, termed elemental allelopathy, occurs when hyperaccumulated As is cycled from the plant back into the top layer of soil, allowing As hyperaccumulators to gain an advantage over intolerant species by increasing soil As concentrations ([ As]) underneath their canopy. To date, there are no studies that detail the presence of increased soil [ As] associated with As hyperaccumulators. In this study, we documented variation in the soil [ As] associated with the Chinese brake fern, Pteris vittata L. and also compared the effects of environmentally relevant soil and solution [ As] on competitor plant growth.Methods Four populations of P. vittata were identified in central Florida, USA. P. vittata tissue samples and soil samples were collected at the base of and at 3 m away from ferns in each population (n = 36). Five sample locations were randomly selected from each site, and soils from the base and 3 m away from each fern were collected to examine the effects of naturally occurring soil [ As] on the germination and growth of a potential competitor plant (Oxalis stricta). Solutions with increasing [ As] were also used to examine the threshold for negative effects of [ As] on O. stricta growth. [ As] were measured using inductively coupled plasma mass spectrometry (ICP-MS).Important findings Overall, soil [ As] from the base of ferns was nearly twice that of soil 3 m away indicating that ferns hyperaccumulate As. However, ferns and their associated soil, contained different [ As] depending on their collection site, indicating that these populations accumulate and use [ As] differently. O. stricta growth decreased and germination was delayed as solution and soil [ As] increased. However, the relative distance from the fern that the soil was collected from did not affect growth, which would be expected with elemental allelopathy. Our results show that P. vittata is associated with higher soil [ As] and these concentrations are sufficient to inhibit growth of competitors. However, the absence of a strong inhibitory relationship associated with proximity to the fern across all locations suggests that the possible functional advantages of elemental allelopathy may depend on site specific characteristics.     

Experimental confirmation of the polygyny threshold model for red-winged blackbirds

The polygyny threshold model assumes that polygynous mating is costly to females and proposes that females pay the cost of polygyny only when compensated by obtaining a superior territory or male. We present, to the authors' knowledge, the first experimental field test to demonstrate that females trade mating status against territory quality as proposed by this hypothesis. Previous work has shown that female red-winged blackbirds (Agelaius phoeniceus) in Ontario prefer settling with unmated males and that this preference is adaptive because polygynous mating status lowers female reproductive success. Other evidence suggests that nesting over water increases the reproductive success of female red-winged blackbirds. Here we describe an experiment in which females were given choices between two adjacent territories, one owned by an unmated male without any over-water nesting sites and the other by an already-mated male with over-water sites. Females overwhelmingly preferred the already-mated males, demonstrating that superior territory quality can reverse preferences based on mating status and supporting the polygyny threshold model as the explanation for polygyny in this population.     

Vaccination and the population structure of antigenically diverse pathogens that exchange genetic material.

Populations of antigenically diverse pathogens undergoing genetic exchange may be categorized into strains on the basis of a set of principal protective antigens. The extent to which polyvalent vaccines based on these protective antigens can alter the population structure of the pathogen is determined by the degree of cross-protection between strains. In the case where there is no cross-protection, vaccinating against a particular strain will have no effect on the others. As cross-protection increases, the strains containing the antigenic variants included in the vaccine will be diminished in prevalence, and those that do not will increase in prevalence. The rise in prevalence of the latter will become more and more exaggerated as cross-protection increases. However, beyond a critical level of cross-protection, in the absence of vaccination, the steady state of the system is asymmetric in that a certain subset of strains (with non-overlapping repertoires of antigenic variants) will dominate over the others in terms of prevalence. Under these circumstances, a vaccine consisting of the most immunogenic combinations of antigenic variants can cause a dramatic increase in frequency of a subset of rare strains.     

Polygyny and fertility in Morocco: the effect of marital instability

This paper analyses the relationship between polygyny and female fertility in the province of Marrakech (Morocco) taking into account the effect of the previous marital instability (number of marriages) and the possible association between female sterility and type of marriage. In the analysed population, polygyny increases in the small towns. Polygynously married women have a higher level of education and show a higher percentage of use of contraceptive methods than the monogamously married ones. Although polygynously married women initially show lower fertility, multivariate analysis carried out on the group of women between 35 and 49 years old show that there are no significant differences in fertility between monogamously and polygynously married women when the effect of the previous marital instability is considerer. Female sterility does not determine marital instability, although it does determine a significant increase in polygynous marriages among the women without children.     

Abundance,origin, and phylogeny of plants do not predict community‐level patterns of pathogen diversity and infection

Pathogens have the potential to shape plant community structure, and thus, it is important to understand the factors that determine pathogen diversity and infection in communities. The abundance, origin, and evolutionary relationships of plant hosts are all known to influence pathogen patterns and are typically studied separately. We present an observational study that examined the influence of all three factors and their interactions on the diversity of and infection of several broad taxonomic groups of foliar, floral, and stem pathogens across three sites in a temperate grassland in the central United States. Despite that pathogens are known to respond positively to increases in their host abundances in other systems, we found no relationship between host abundance and either pathogen diversity or infection. Native and exotic plants did not differ in their infection levels, but exotic plants hosted a more generalist pathogen community compared to native plants. There was no phylogenetic signal across plants in pathogen diversity or infection. The lack of evidence for a role of abundance, origin, and evolutionary relationships in shaping patterns of pathogens in our study might be explained by the high generalization and global distributions of our focal pathogen community, as well as the high diversity of our plant host community. In general, the community‐level patterns of aboveground pathogen infections have received less attention than belowground pathogens, and our results suggest that their patterns might not be explained by the same drivers.     

Human sexual dimorphism in size may be triggered by environmental cues

Evolutionary biologists mostly assume that polygyny increases sexual dimorphism in size because, under polygyny, larger males monopolize mating opportunities and pass on their 'large male' genes to their sons. Available data on parent-child correlations in height among humans (Homo sapiens) do not support the crucial assumption that height is transmitted along sex lines. This paper instead suggests that human sexual dimorphism in size emerged, not because men got taller, but because women got shorter by undergoing early menarche in response to polygyny. It further speculates that, rather than genetically transmitted, the sexual dimorphism may emerge anew in each generation in response to the degree of polygyny in society. The analysis of comparative data supports the prediction that polygyny reduces women's height, but has no effect on men's, and is consistent with the speculation that the origin of human sexual dimorphism in size may be cultural, not genetic.     

Fine-root system development and susceptibility to pathogen colonization

Root development may exert control on plant–pathogen interactions with soil-borne pathogens by shaping the spatial and temporal availability of susceptible tissues and in turn the impact of pathogen colonization on root function. To evaluate the relationship between root development and resistance to apple replant disease (ARD) pathogens, pathogen abundance was compared across root branching orders in a bioassay with two rootstock genotypes, M.26 (highly susceptible) and CG.210 (less susceptible). Root growth, anatomical development and secondary metabolite production were evaluated as tissue resistance mechanisms. ARD pathogens primarily colonized first and second order roots, which corresponded with cortical tissue senescence and loss in second and third order roots. Defense compounds were differentially allocated across root branching orders, while defense induction or stress response was only detected in first order and pioneer roots. Our results suggest disease development is based largely on fine-root tip attrition. In accordance, the less susceptible rootstock supported lower ARD pathogen abundance and altered defense compound production in first order and pioneer roots and maintained higher rates of root growth in both the ARD soil and pasteurized control compared to the more susceptible. Thus, this rootstock’s ability to maintain shoot growth in replant soil may be attributable to relative replant pathogen resistance in distal root branches as well as tolerance of infection based on rates of root growth.     

Turning up the heat: immune brinksmanship in the acute-phase response

The acutephase response (APR) is a systemic response to severe trauma, infection, and cancer, although many of the numerous cytokine-mediated components of the APR are incompletely understood. Some of these components, such as fever, reduced availability of iron and zinc, and nutritional restriction due to anorexia, appear to be stressors capable of causing harm to both the pathogen and the host. We review how the host benefits from differences in susceptibility to stress between pathogens and the host. Pathogens, infected host cells, and neoplastic cells are generally more stressed or vulnerable to additional stress than the host because: (a) targeted local inflammation works in synergy with APR stressors; (b) proliferation/growth increases vulnerability to stress; (c) altered pathogen physiology results in pathogen stress or vulnerability; and (d) protective heat shock responses are partially abrogated in pathogens since their responses are utilized by the host to enhance immune responses. Therefore, the host utilizes a coordinated system of endogenous stressors to provide additional levels of defense against pathogens. This model of immune brinksmanship can explain the evolutionary basis for the mutually stressful components of the APR.