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Colour is an important component of many different defensive strategies, but signal efficacy and detectability will also depend on the size of the coloured structures, and how pattern size interacts with the background. Consequently, size-dependent changes in colouration are common among many different species as juveniles and adults frequently use colour for different purposes in different environmental contexts. A widespread strategy in many species is switching from crypsis to conspicuous aposematic signalling as increasing body size can reduce the efficacy of camouflage, while other antipredator defences may strengthen. Curiously, despite being chemically defended, the gold-striped frog (Lithodytes lineatus, Leptodactylidae) appears to do the opposite, with bright yellow stripes found in smaller individuals, whereas larger frogs exhibit dull brown stripes. Here, we investigated whether size-dependent differences in colour support distinct defensive strategies. We first used visual modelling of potential predators to assess how colour contrast varied among frogs of different sizes. We found that contrast peaked in mid-sized individuals while the largest individuals had the least contrasting patterns. We then used two detection experiments with human participants to evaluate how colour and body size affected overall detectability. These experiments revealed that larger body sizes were easier to detect, but that the colours of smaller frogs were more detectable than those of larger frogs. Taken together our data support the hypothesis that the primary defensive strategy changes from conspicuous aposematism to camouflage with increasing size, implying size-dependent differences in the efficacy of defensive colouration. We discuss our data in relation to theories of size-dependent aposematism and evaluate the evidence for and against a possible size-dependent mimicry complex with sympatric poison frogs (Dendrobatidae)., (© 2022 European Society for Evolutionary Biology.)

Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such "defence portfolios" that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of specific sensory systems (e.g., visual) or specific types of defences (especially aposematism). In this review, we aim to build a comprehensive framework for conceptualizing the evolution of multiple prey defences, beginning with hypotheses for the evolution of multiple defences in general, and defence portfolios in particular. We then examine idealized models of resource trade-offs and functional interactions between traits, along with evidence supporting them. We find that defence portfolios are constrained by resource allocation to other aspects of life history, as well as functional incompatibilities between different defences. We also find that selection is likely to favour combinations of defences that have synergistic effects on predator behaviour and prey survival. Next, we examine specific aspects of prey ecology, genetics and development, and predator cognition that modify the predictions of current hypotheses or introduce competing hypotheses. We outline schema for gathering data on the distribution of prey defences across species and geography, determining how multiple defences are produced, and testing the proximate mechanisms by which multiple prey defences impact predator behaviour. Adopting these approaches will strengthen our understanding of multiple defensive strategies., (© 2023 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology.)

Understanding the relative importance of sexual and natural selection in shaping morphological traits is a long-standing goal of evolutionary ecology. Male-biased sexual size dimorphism (SSD) is typically associated with male-male competition. Similarly, male polymorphisms are considered a consequence of competitive social interactions. This classic paradigm overlooks the fact that environmental factors mediate social interactions and can lead to ecological adaptations. Common side-blotched lizards, Uta stansburiana, are a model system for this paradigm due to well-known rock-paper-scissors social dynamics between male morphs. SSD in this species has been considered primarily a consequence of social interactions, with male size resulting from the number of morphs in each population and female size being constrained through fecundity benefits. We test if the environment explains intraspecific variation in SSD and number of male morphs in U. stansburiana. By compiling data from 49 populations, we show that environmental variables are stronger predictors of SSD than the number of male morphs. Similarly, we show that the environment mediates SSD and potentially contributes to morph loss in colder environments. We propose that the environment favours smaller males in areas of high seasonality. Our results demonstrate the importance of the environment as a mediator of SSD., (© 2021 European Society for Evolutionary Biology.)

Groups of animals possess phenotypes such as collective behaviour, which may determine the fitness of group members. However, the stability and robustness to perturbations of collective phenotypes in natural conditions is not established. Furthermore, whether group phenotypes are transmitted from parent to offspring groups with fidelity is required for understanding how selection on group phenotypes contributes to evolution, but parent-offspring resemblance at the group level is rarely estimated. We evaluated the repeatability, robustness to perturbation and parent-offspring resemblance of collective foraging aggressiveness in colonies of the social spider Anelosimus eximius. Among-colony differences in foraging aggressiveness were consistent over time but changed if the colony was perturbed through the removal of individuals or via individuals' removal and subsequent return. Offspring and parent colony behaviour were correlated at the phenotypic level, but only once the offspring colony had settled after being translocated, and the correlation overlapped with zero at the among-colony level. The parent-offspring resemblance was not driven by a shared elevation but could be due to other environmental factors. The behaviour of offspring colonies in a common garden laboratory setting was not correlated with the behaviour of the parent colony nor with the same colony's behaviour once it was returned to the field. The phenotypes of groups represent a potentially important tier of biological organization, and assessing the stability and heritability of such phenotypes helps us better understand their role in evolution., (© 2020 European Society For Evolutionary Biology.)

Background: Bacterial infections can occur in lesions of pustular psoriasis (PP). The objective of this study was to establish the aerobic and anaerobic microbiology of secondarily infected PP., Methods: A retrospective 10-year review was carried out of clinical and microbiology laboratory records from patients with secondarily infected PP lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria., Results: Bacterial growth was noted in 23 specimens. Aerobic or facultative anaerobic bacteria only were present in 12 patients (52%), anaerobic bacteria only in four (17%), and mixed anaerobic-aerobic flora was present in seven (30%). Thirty-six isolates were recovered (1.6 per specimen), 23 aerobic or facultative bacteria and 13 strict anaerobes. The predominant aerobic and facultative bacteria were Staphylococcus aureus (15 isolates), Group D Enterococcus (two isolates), and Escherichia coli (two isolates). The predominant anaerobes were Peptostreptococcus spp. (six isolates) and Bacteroides fragilis group, Propionibacterium acnes, and pigmented Prevotella spp. in two each. Single bacterial isolates were recovered in 14 patients (61%), 11 of which were S. aureus. Nineteen of the organisms isolated from 18 patients (78%) produced the enzyme beta-lactamase. S. aureus was isolated from all body sites. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric Gram-negative rods and Bacteroides fragilis group predominated in lesions on the legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Fusobacterium spp. were most frequently recovered in lesions of the hand., Conclusions: The polymicrobial etiology of secondarily infected PP lesions and the association of bacterial flora with the anatomic site of the lesions were demonstrated.

Background: There are reports of increased reactions in HIV-1+ patients to ultraviolet light sometimes in association with medication. In addition, there are also reports of increased morbidity associated with radiation therapy in HIV-1+ patients., Methods: Three HIV-1+ patients developed cutaneous toxic reactions to radiation therapy; two with Kaposi's sarcoma (KS) and one with non-Hodgkin's lymphoma., Conclusions: Although the mechanisms which resulted in these reactions are not clear, they may be related to depletion of endogenous scavengers and may be accentuated by the pattern of immune dysregulation present in HIV-1 disease.

Background: There have been scattered reports of HIV+ patients with increased reactions to light as well as anecdotal reports of HIV+ patients with increased morbidity secondary to radiation therapy., Methods: As a part of a military study of HIV+ patients, we followed 987 patients for cutaneous disease for 4 years. All patients were questioned on a periodic basis about increased sensitivity to light. These patients received a physical examination at each protocol visit, and they were given the opportunity to receive all their dermatologic care within the HIV clinic. Fourteen of the patients with photo-induced eruptions were evaluated clinically at the time of the eruption, and 11 of these were biopsied., Results: Thirty-three of the patients reported photo-induced reactions unrelated to oral medications. Although sensitivity to light often began in the early stages of HIV disease, reactions became more severe and more chronic with disease progression. Histologic features varied from few to numerous apoptotic/necrotic keratinocytes within the mid to upper levels of the epidermis associated with a perivascular inflammatory infiltrate, to apoptotic/necrotic keratinocytes throughout an acanthotic epidermis with a lichenoid/interface infiltrate., Conclusions: Although the pathogenesis of these light reactions is not known, these reactions may be related to depletion of endogenous scavengers which results in increased oxidative stress and is modulated by the pattern of immune dysregulation and metabolic dysregulation induced by HIV disease.

Background: The high incidence of cutaneous disease in HIV-1+ patients may be a marker of the chronic state of immune activation. In addition, specific cutaneous diseases may be related to the pattern and degree of immune dysregulation present in the patients at the time of the eruption. We have observed that HIV-1+ patients with pityriasis lichenoides et varioliformis acuta (PLEVA) were in the early to midstage of HIV-1 disease., Materials and Methods: To determine if there was a correlation between the phenotype of the lymphoid infiltrate and surface markers of the epidermis and the known changes in early or late-stage HIV-1 disease, we studied five HIV-1+ patients with PLEVA. Cutaneous biopsy specimens were obtained and immunohistochemical stains were used to determine the expression of ELAM-1, ICAM-1, and HLA-DR and the phenotype of the lymphoid infiltrate., Results: The HIV-1+ patients showed increased expression of HLA-DR on keratinocytes as well as on the mononuclear and dendritic cell populations in the epidermis and dermis. The majority of T cells were activated CD8+ cells., Conclusions: Immunophenotyping of the inflammatory infiltrate in these patients is consistent with a pattern of immune dysregulation seen only in earlier stages of HIV-1 disease. Thus, PLEVA may be useful as a marker of early to midstages of HIV-1 disease.

Background: Bacterial infections occur frequently in lesions of atopic dermatitis (AD). The objectives of the study were to establish the aerobic and anaerobic microbiology of secondarily infected AD., Methods: A retrospective review was carried out of clinical and microbiology laboratory records and of data obtained from patients with secondarily infected AD lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria., Results: Bacterial growth was noted in 41 specimens. Aerobic or facultative anaerobic bacteria only were present in 15 patients (36%), anaerobic bacteria only in eight (20%), and mixed anaerobic-aerobic flora was present in 18 (44%). Seventy-two isolates were recovered (1.8 per specimen), 34 aerobic or facultative bacteria, 35 strict anaerobes, and three Candida sp. The predominant aerobic and facultative bacteria were Staphylococcus aureus (12 isolates), Group A beta hemolytic streptococcus in five isolates, and Escherichia coli in four. The predominant anaerobes were Peptostreptococcus spp. (13 isolates), pigmented Prevotella and Porphyromonas spp. in eight, and Fusobacterium spp. in four isolates. Single bacterial isolates were recovered in 14 patients (34%), seven of which were S. aureus. Twenty-one of the organisms isolated from 16 patients (39%) produced the enzyme beta-lactamase. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric gram-negative rods and Bacteroides fragilis group predominated in lesions on legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Porphyromonas and Fusobacterium spp. were most frequently recovered in lesions of the finger, scalp, face, and neck., Conclusions: The polymicrobial etiology of secondarily infected AD lesions and the association of bacterial flora with the anatomic site of the lesions are demonstrated.

Background: While biopsies are often required for adequate diagnosis of skin lesions in HIV-1 infected patients, these procedures result in the possible exposure of medical personnel to blood and contaminated instruments. To reduce exposure of medical personnel to contaminated needles we have used collagen sponges instead of sutures to control bleeding from punch biopsy sites in HIV-1 infected patients., Methods: A collagen sponge was placed in all punch biopsy sites in HIV-1 infected patients. In cases where there was clinical evidence of local infection the sponges were removed 5-6 minutes after hemostasis was obtained., Results: In over 500 biopsies in which Helistat collagen sponges were used, there have been no cases of secondary infection, and there have been no delays in healing., Conclusions: We believe that the use of these sponges provides a high degree of safety for the physician, which may assure that the commonly atypical clinical lesions seen in HIV-1 disease are biopsied. In addition, these sponges provide hemostasis, particularly significant in this patient population, and convenience, without a significant risk of secondary infection, and may provide some benefit in healing.

Background: In patients with HIV-1 disease there has been an increasing association with human papilloma virus (HPV) infections in multiple locations as well as an increase in associated tumors. In addition, there has been increased recovery of HPV in individuals with decreasing T4 cell counts., Case Report: Recently we have seen an HIV-1+ patient with a cutaneous lesion on the nipple, as well as multiple perianal lesions in which HPV-16 was demonstrated by in-situ hybridization. Although these lesions contained the same subtype of HPV virus, they had very different clinical and histopathologic morphologies, and this represents the first reported association of HPV-16 in a nipple lesion., Discussion: Our patient illustrates that in HIV-1 disease, HPV infections may present in more diffuse and atypical locations. In addition, the diffuse staining with the in-situ probe for HIV-16 within the lesions, tends to support the findings of others, that viral recovery increases with the immune suppression induced by HIV-1.