A probable case of an "Hourglass" epidermoid cyst located in the posterior fossa in an individual from Ibi, Alicante, Spain (12th-13th centuries AD).

Epidermoid bone cysts are rare, unilocular, and slow growing. They develop by the accumulation of ectodermal remnants, and they may be congenital or acquired. The most common locations for these bone cysts are the distal phalanges, followed by the skull. This paper documents an adult male from the Islamic (twelfth and thirteen centuries CE) burial site of Ibi in the Province of Alicante, southeast Spain. This individual had a cranial lesion in the form of a roughly elliptical hole in the posterior fossa (left occipital region). The lesion was examined macroscopically and using X-ray photography. Based on the shape of the lesion, the most likely diagnosis would appear to be a benign tumour, a so-called "hourglass" epidermoid cyst. No direct link between this tumour and the cause of death can be established.

Widespread synchronous decline of Mediterranean-type forest driven by accelerated aridity.

Large-scale, abrupt ecosystem change in direct response to climate extremes is a critical but poorly documented phenomenon1. Yet, recent increases in climate-induced tree mortality raise concern that some forest ecosystems are on the brink of collapse across wide environmental gradients2,3. Here we assessed climatic and productivity trends across the world's five Mediterranean forest ecosystems from 2000 to 2021 and detected a large-scale, abrupt forest browning and productivity decline in Chile (>90% of the forest in <100 days), responding to a sustained, acute drought. The extreme dry and warm conditions in Chile, unprecedented in the recent history of all Mediterranean-type ecosystems, are akin to those projected to arise in the second half of the century4. Long-term recovery of this forest is uncertain given an ongoing decline in regional water balance. This dramatic plummet of forest productivity may be a spyglass to the future for other Mediterranean ecosystems.

Moving towards the ecological intensification of tree plantations.

The growing demand for timber and the boom in massive tree-planting programs could mean the spreading of mismanaged tree plantations worldwide. Here, we apply the concept of ecological intensification to forestry systems as a viable biodiversity-focused strategy that could be critical to develop productive, yet sustainable, tree plantations. Tree plantations can be highly productive if tree species are properly combined to complement their ecological functions. Simultaneously considering soil biodiversity and animal-mediated biocontrol will be critical to minimize the reliance on external inputs. Integrating genetic, functional, and demographic diversity across heterogeneous landscapes should improve resilience under climate change. Designing ecologically intensified plantations will mean breaking the timber productivity versus conservation dichotomy and assuring the maintenance of key ecosystem services at safe levels.

Multi-headed (bifid and trifid) mandibular condyles in archaeological contexts: Two posttraumatic cases.

OBJECTIVE: Bifid and trifid mandibular condyles are infrequent morphological alterations of the mandibular condyle. With the aim of better identifying its possible causing factors in the past and provide clues on the potential types and severities of joint dysfunction that may occur if clinical intervention is not undertaken, two archaeological cases of multi-headed mandibular condyles are presented, and their possible aetiology and pathogenesis are discussed. DESIGN: In this study, 143 adult mandibles recovered in the northwest of Spain were examined: 91 exhumed from San Juan Bautista church (Guardo, Palencia; 16th-19th centuries), and 52 from San Salvador de Palat de Rey church (León, 13th-19th centuries). All mandibles were observed macroscopically for the presence of any morphological and/or pathological alterations. When justified, the mandibles were also scrutinized through computed tomography. RESULTS: Two isolated mandibles (n = 1, Palencia; n = 1, León) with multi-headed mandibular condyles (bifid and trifid) were identified. The computed tomography scan of the affected mandibles revealed alterations compatible with traumatic events, namely line fractures and deformations at the angle of the mandible. CONCLUSIONS: Both the bifid and trifid mandibular condyles here described probably result from traumatic events during childhood leading to a posttraumatic deformation. Although no severe impairment of mandibular use was identified, some asymmetries probably resulted in some sort of malfunction, with TMJ-OA and gonial angle eversion as supporting evidence. Nevertheless, the degree of bone remodelling observed indicates that both individuals lived long after the traumatic occurrence.

Stafne's bone defects from Spain: report of four cases and brief archaeological literature review.

OBJECTIVE: To present for the first time in the north-western Spanish osteological record prevalence data on Stafne's bone defect, to compare the results with those reported by other studies, and to increase the dataset for future inter-population comparisons. MATERIAL: In all, 143 complete adult mandibles recovered from two necropolises were analyzed (n = 118, San Juan Bautista of Guardo, Palencia province, 16th-19th centuries; n = 25, Plaza del Grano, city of León, 12th-15th centuries). METHODS: Differential diagnosis of the lesions was made through macroscopic and Computed Tomography (CT) analyses. RESULTS: Four mandibles (n = 3, Guardo, Palencia; n = 1, León) presented bone cavities on the lingual aspect of the mandible below the mylohyoid channel, between the first molar and the angle of the mandible. CT scan showed unilateral well-defined unilocular oval/round concavities in the lingual mandibular cortex below the inferior alveolar canal. Neither the macroscopic nor the radiological characteristics are compatible with inflammatory or malignant pathology, favoring instead a diagnosis of Stafne's bone defect. CONCLUSIONS: Four cases of Stafne's defects are added to the bioarchaeological inventory. The calculated prevalence is 2.54% for San Juan Bautista and 4% for Plaza del Grano, values in close agreement to those presented in other osteoarchaeological studies. SIGNIFICANCE: The identification of all examples of Stafne's bone defects in past populations will contribute to elucidate which factors may be responsible for this trait's cultural, ecological, temporal, and geographical patterning. LIMITATIONS: The skeletal samples are relatively small. SUGGESTIONS FOR FURTHER RESEARCH: In future investigations of Stafne's bone defects, CT analysis of dry bone specimens is recommended, whenever possible.

Congenital syphilis or mercury treatment: dental alterations in a twelfth- or thirteenth-century child from Medinaceli, Soria, Spain.

Syphilis, together with its variant congenital syphilis, is a disease caused by Treponema pallidum subsp. pallidum. This paper documents possible new skeletal evidence for congenital syphilis from the Medieval Era (twelfth and thirteenth centuries CE) burial site of Medinaceli in the Province of Soria in North-Central Spain. What is involved is dental alteration due to congenital syphilis, mercury treatment, or a combination of both. This study focuses on the hypoplastic dental changes observed in a child approximately eight years of age. Only a fragmented skull with left maxilla and the left side of the mandible were preserved. Macroscopic analysis, X-rays, computerized tomography (CT) and mercury detection analysis by inductively coupled plasma mass spectrometry (ICP-MS) techniques were used to observe dental abnormalities. In addition to extensive caries in the upper second deciduous molar, pulpo-alveolar lesions and facial alterations were observed. The absence of the rest of the skeleton tends to make a diagnosis of congenital syphilis difficult. However, the dental stigmata observed do permit a reasonable diagnosis.

Postfire responses of the woody flora of Central Chile: Insights from a germination experiment.

Fire is a selective agent shaping plant traits and community assembly in fire-prone ecosystems. However, in ecosystems with no fire history, it can be a cause of land degradation when it is suddenly introduced by humans, as plant species may not be able to respond to such novel disturbance. Unlike other Mediterranean-type ecosystems (MTE) of the world, natural fires have not been frequent during the Quaternary in the matorral of Central Chile, and thus, plant adaptive responses are expected to be uncommon. We evaluated the effect of heat shock on seed survival and germination of 21 native woody plants of the Chilean matorral and compiled information on smoke-stimulation and resprouting, to evaluate the importance of fire-adaptive responses in the context of the other MTE. We found that in the Chilean woody flora negative seed responses to fire cues were more frequent than positive responses. Although resprouting is a relatively widespread trait, fire-stimulated germination is not as common in the Chilean matorral as in other MTE. The seeds of seven endemic species were strongly damaged by fire cues and this should be considered in post-fire restoration planning. However, our results also showed that many species were resistant to elevated doses of heat shock and in some, germination was even stimulated. Thus, future research should focus on the evolutionary causes of these responses. These findings could help to develop strategies for fire management in the Chilean matorral. In addition, they will improve our understanding of the evolutionary forces that shaped this plant community and to better frame this region among the other MTE worldwide.

Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene.

Climate and soil attributes determine plant species turnover in global drylands.

AIM: Geographic, climatic, and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. This study aims to: i) characterize patterns of beta diversity in global drylands, ii) detect common environmental drivers of beta diversity, and iii) test for thresholds in environmental conditions driving potential shifts in plant species composition. LOCATION: 224 sites in diverse dryland plant communities from 22 geographical regions in six continents. METHODS: Beta diversity was quantified with four complementary measures: the percentage of singletons (species occurring at only one site), Whittake's beta diversity (ß(W)), a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites (ß(R2)), and a multivariate abundance-based metric (ß(MV)). We used linear modelling to quantify the relationships between these metrics of beta diversity and geographic, climatic, and soil variables. RESULTS: Soil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity (percentage of singletons and ß(W)) were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance ((ß(R2)) and ß(MV)) were more associated with climate variability. Interactions among soil variables, climatic factors, and plant cover were not important determinants of beta diversity. Sites receiving less than 178 mm of annual rainfall differed sharply in species composition from more mesic sites (> 200 mm). MAIN CONCLUSIONS: Soil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving ~ 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation.

Decoupling of soil nutrient cycles as a function of aridity in global drylands.

The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. We find a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems.

Plant species richness and ecosystem multifunctionality in global drylands.

Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.

Anthropogenic fire drives the evolution of seed traits.

Fire is a major disturbance affecting ecosystems worldwide. Phylogenetic studies have shown that the evolution of seed persistence (fire resistance) is associated with fire frequency or severity. However, the existence of specific seed traits resulting from natural selection mediated by fire remains a key question in plant evolution. We evaluated the role of fire in the evolution of seed traits from a microevolutionary perspective, using as a study system a native forb from the Chilean matorral, where fire is a novel, anthropogenic disturbance. We show that anthropogenic fires are shaping the evolution of seed traits such as pubescence and shape. Among-population variation in seed pubescence, shape, and pericarp thickness was strongly associated with fire frequency, and within a population, fire selected those plants with more pubescent seeds, thicker pericarps, and less rounded seeds. Seed pubescence and shape were shown to be heritable traits. Our findings provide insights into the understanding of the evolution of seed traits in fire-prone environments and demonstrate that human-made fires can be driving evolutionary changes in plant species from ecosystems where fires do not occur naturally.

Extremely long-lived stigmas allow extended cross-pollination opportunities in a high Andean plant.

High-elevation ecosystems are traditionally viewed as environments in which predominantly autogamous breeding systems should be selected because of the limited pollinator availability. Chaetanthera renifolia (Asteraceae) is an endemic monocarpic triennial herb restricted to a narrow altitudinal range within the high Andes of central Chile (3300-3500 m a.s.l.), just below the vegetation limit. This species displays one of the larger capitulum within the genus. Under the reproductive assurance hypothesis, and considering its short longevity (monocarpic triennial), an autogamous breeding system and low levels of pollen limitation would be predicted for C. renifolia. In contrast, considering its large floral size, a xenogamous breeding system, and significant levels of pollen limitation could be expected. In addition, the increased pollination probability hypothesis predicts prolonged stigma longevity for high alpine plants. We tested these alternative predictions by performing experimental crossings in the field to establish the breeding system and to measure the magnitude of pollen limitation in two populations of C. renifolia. In addition, we measured the stigma longevity in unpollinated and open pollinated capitula, and pollinator visitation rates in the field. We found low levels of self-compatibility and significant levels of pollen limitation in C. renifolia. Pollinator visitation rates were moderate (0.047-0.079 visits per capitulum per 30 min). Although pollinator visitation rate significantly differed between populations, they were not translated into differences in achene output. Finally, C. renifolia stigma longevity of unpollinated plants was extremely long and significantly higher than that of open pollinated plants (26.3±2.8 days vs. 10.1±2.2, respectively), which gives support to the increased pollination probability hypothesis for high-elevation flowering plants. Our results add to a growing number of studies that show that xenogamous breeding systems and mechanisms to increase pollination opportunities can be selected in high-elevation ecosystems.

Patterns of genetic diversity in colonizing plant species: Nassauvia lagascae var. lanata (Asteraceae: Mutisieae) on Volcan Lonquimay, Chile.

The effect of colonization on the distribution of genetic diversity within and among populations in relation to species characteristics remains an open empirical question. The objective of this study was to contrast genetic diversity within and among established and colonizing populations of Nassauvia lagascae var. lanata on Volcán Lonquimay (Araucanía Region, Chile), which erupted on 25 December 1988, and relate genetic diversity to biological characteristics of the populations. We analyzed a total of 240 individuals from 15 populations distributed along the Andes Cordillera using AFLP and obtained a total of 307 AFLP bands, of which 97.7% are polymorphic. Values of population differentiation (F(ST)) did not differ significantly among established and colonizing populations, but colonizing populations did have reduced levels of genetic divergence (as indicated by private and rare bands) and genetic variation (e.g., Shannon index). We conclude that a founder effect through limited numbers of founding propagules derived from nearby source populations has not yet been compensated for by subsequent population growth and migration. Low rates of secondary dispersal via running water, kin-structure within populations, and slow population growth seem to contribute to the slow recovery of genetic diversity.

Positive interactions between alpine plant species and the nurse cushion plant Laretia acaulis do not increase with elevation in the Andes of central Chile.

In alpine habitats, positive interactions among plants tend to increase with elevation as a result of altitudinal increase in environmental harshness. However, in mountains located in arid zones, lower elevations are also stressful because of scarce availability of water, suggesting that positive interactions may not necessarily increase with elevation. Here we analysed the spatial association of plant species with the nurse cushion plant Laretia acaulis at two contrasting elevations, and monitored the survival of seedlings of two species experimentally planted within and outside cushions in the semiarid Andes of central Chile. Positive spatial associations with cushions were more frequent at lower elevations. Species growing at the two elevations changed the nature of their association with cushions from neutral or negative at higher elevations to positive at lower elevations. Survival of seedlings was higher within cushions, particularly at lower elevations. The increased facilitation by cushions at lower elevations seems to be related to provision of moisture. This result suggests that cushion plants play a critical role in structuring alpine plant communities at lower elevations, and that climatic changes in rainfall could be very relevant for persistence of plant communities.