Interpopulation Variation Research Articles

Genetic Differentiation of Budburst Timing in Fagus crenata Populations along a Spatial Gradient in Late Frost Timing in the Hakkoda Mountains, Northern Japan

We studied the genetic differentiation in budburst timing among Fagus crenata populations along spatial gradients in late frost timing in the Hakkoda Mountains, northern Japan, by focusing on last fatal frost day and topography. For budburst timing, we analyzed interpopulation variations in habitats, genetic variations in a nursery, and the relationships between these variations and environmental conditions in the habitats. Analyses of interpopulation variation showed that the day and the temperature sum of budburst positively correlated with the last fatal frost day in the habitats. Analyses of genetic variation showed significant genetic variations among provenances and families for both traits. For all provenances, the heritability for these traits were 0.7–0.8. The genetic variations were significantly associated with variations in the last fatal frost day among the provenances, suggesting that natural selection due to late fatal frost causes genetic differentiation in the traits along the spatial gradient in late frost timing. These results demonstrate that late frost is a key factor driving genetic differentiation of leaf-out phenology within a regional tree population.

Interpopulation variation in seed traits of five Polygonaceae

Interpopulation variability in seed traits may drive the regeneration capacity of a species to colonize different environments. In the present study, we evaluated the variation in seed physical traits (mass / size, water imbibition, shape index) and physiological traits (germination) of five Polygonaceae species. Seeds of Polygonum lapathifolium var. salicifolium, P. lapathifolium, Reynoutria japonica, Rumex trisetifer, and R. obtusifolius were collected from two or three populations in Jiujiang, China. Physical seed traits were measured before germination tests conducted under different combinations of light and temperatures. Most species had a significant variation in seed physical and physiological traits, although populations are geographically close. Interpopulation variation in seed traits appeared to be species-specific, with the highest variation for R. japonica and lowest for R. trisetifer seeds. Germination response to temperature and light conditions also varied among species and populations, being mostly inhibited in the dark treatments. The light dependence of germination can be related to the small seed size, except for the round-seeded Rumex, depending on the temperature regime. Optimal temperature ranges mainly varied from 10/20°C to 25/35°C, with significant decreases in germination percentage at both coolest and warmest extremes. Germination requirements seem to be related to altitudinal gradients in populations of P. lapathifolium and R. japonica seeds.

Body size and body condition in the nose-horned viper (Vipera ammodytes): effects of sex and populations

Snakes are ecologically and morphologically plastic organisms that exhibit extensive variations in body size and body condition in response to environmental factors. Documenting inter-population variations is important to describe species comprehensively across their distribution range and to monitor trends over time (e.g. decreasing body condition due to alteration of habitat). Thus, we analyzed the influence of population and sex on body size and body condition in three populations of nose-horned vipers (Vipera ammodytes) in Serbia. In one population, males were larger than females (F1, 39=4.802, p=0.034), but not in the two other populations (F1, 36=0.075, p=0.786; F1, 21=0.018, p=0.893). Females exhibited higher body condition (residual values from the regression of log-body mass against log-body size) than males (F1, 90=10.444, p=0.002); this sex difference was not found in one population when analyzed separately (F1, 35=1.834, p=0.184). Moreover, we found strong inter-population differences in mean body size and mean body condition (F2, 96=8.822, p<0.001 and F2, 90=10.319, p=0.001, respectively). While inter-population difference in body size was driven by males, inter-population difference in body condition was driven by females. These results suggest that, in this species, body size might be an important determinant of mating success in males, while body condition may play a major role in female fecundity.

Conservation Genetics of Lake Sturgeon (Acipenser fulvescens): Nuclear Phylogeography Drives Contemporary Patterns of Genetic Structure and Diversity

Sustainable management of exploited and endangered species is facilitated by knowledge of their geographic genetic structure. Lake sturgeon (Acipenser fulvescens) epitomizes both categories, but genetic information has largely been limited to the Laurentian Great Lakes basin. We assessed the hierarchical geographic genetic structure of lake sturgeon across their Canadian range using a variation at 14 microsatellite loci. Observed patterns showed evidence of two ancestral groups which originated from Mississippian and Missourian glacial refugia. Coalescent analysis indicates the two lineages most recently shared common ancestry during the late Pleistocene and were likely isolated by the late Wisconsinan ice advance, with subsequent interpopulation divergences within each lineage reflecting their reciprocal isolation as glacial meltwaters receded. Hierarchical patterns of genetic relationships among contemporary populations largely reflect colonization histories and connections within primary and secondary watersheds. Populations in western Canada showed strong similarities based on their shared Missourian origins and colonization from glacial Lake Agassiz. By contrast, populations in the Great Lakes–St. Lawrence River drainage were largely founded from a Mississippian source. Sturgeon populations in northern parts of Ontario and Quebec showed evidence of mixed ancestry from secondary contact between the two refugial groups through Holocene meltwater lakes. Within major watersheds, the strong similarity among geographically separate populations reflects their shared ancestry during postglacial colonization. The general lack of structure within major river systems highlights historically continuous habitat (connectivity) and gene flow rather than contemporary barriers (dams). These data highlight the importance of Quaternary and prehistoric events on patterns of genetic diversity and divergence within and among contemporary populations, as well as the importance of these populations for conserving the species’ evolutionary legacy.

Echolocation clicks of free-ranging Indo-Pacific finless porpoises (Neophocaena phocaenoides) in Hainan waters.

The echolocation clicks of free-ranging Indo-Pacific finless porpoises (IPFPs, Neophocaena phocaenoides) have been rarely studied in the wild. This paper aims at describing the echolocation-click characteristics of IPFPs and examining whether IPFPs adapt their sonar system to the habitats in Hainan waters, China. The echolocation clicks were recorded using a 13 elements star-shaped array of hydrophones. A total of 65 on-axis clicks were identified and analyzed. IPFPs use echolocation clicks with a source level (SL) of 158 ± 9 dB re: 1 μPa peak-peak, mean peak, and centroid frequency of 134 ± 3 kHz, -3 dB bandwidth of 14 ± 2 kHz and produce at inter-click intervals of 104 ± 51 ms. The results relative to other porpoises show that finless porpoises in Hainan waters produce clicks with moderate SLs and high peak frequency. These results could be useful in detecting the presence and estimating the density of IPFPs during passive acoustic monitoring in the study area and serve to shed light on the interpopulation variation of click characteristics of finless porpoises as well.

Seven Years of Monitoring Susceptibility to Cry1Ab and Cry1F in Asian Corn Borer.

Resistance monitoring in the Asian corn borer, Ostrinia furnacalis, is necessary to accommodate the commercial introduction and stewardship of Bt maize in China. The susceptibility of 56 O. furnacalis field populations, collected between 2015 and 2021 from the corn belt regions of China, to Cry1Ab and Cry1F toxins was determined. Neonate larvae (within 12 h after hatching) were placed on the surface of semi-artificial agar-free diet incorporating a series of concentrations of purified toxins, and mortality was evaluated after 7d. The median lethal concentration (LC50) values of Cry1Ab and Cry1F were 0.05 to 0.37 µg/g (protein/diet) and 0.10 to 1.22 µg/g, respectively. Although interpopulation variation in susceptibility to the toxins was observed, the magnitude of the differences was 5.8-fold and 8.3-fold for Cry1Ab and Cry1F, respectively. These results suggested that the observed susceptibility differences reflect natural geographical variation in response and not variation caused by prior exposure to selection pressures. Therefore, the O. furnacalis populations were apparently still susceptible to Cry1Ab and Cry1F across their range within China. The monitoring data established here will serve as a comparative reference for early warning signs of field-evolved resistance after the cultivation of Bt maize in China.

Validation of discriminant functions from the rib necks in two Portuguese adult identified populations.

Sexual dimorphism is the basis for sex estimation research in skeletal remains, helping the positive identification of individuals in forensic backgrounds. In this regard, it has been proved that the metrical analysis of the costal neck of the first four ribs in Spanish contemporary adult skeletons shows high sexual dimorphism, especially in the first rib. However, the validation of any method developed in identified skeletal collections must be compulsorily reproduced in other skeletonized sets to verify either its potential application in individuals from other locations, or the existence of possible biases associated with inter-population variation. Due to the geographical and socioeconomic proximity between Spain and Portugal, this paper aims to check the utility of the discriminant functions designed by Partido-Navadijo et al. (2021) in the two skeletal collections of the University of Coimbra (Portugal). Results show the utility of these discriminant functions in Portuguese population, with frequencies of cases correctly assigned reaching up to 93.6% in the Coimbra Identified Skeletal Collection (CISC); and up to 92.6% in the 21st Century Identified Skeletal Collection (CEI/XXI). However, two particularities between the Spanish and Portuguese osteological assemblages can be highlighted: the possible existence of secular changes in relation to the CISC collection (1904-1938); and a reversal in the degree of costal dimorphism, being the third and fourth ribs of the CEI/XXI collection more dimorphic than the first ones.

The potential climatic range of spotted lanternfly may be broader than previously predicted.

Spotted lanternfly (Lycorma delicatula White) is an invasive planthopper that was introduced to the United States from Asia and readily spreads via human aided means. Three geographically separated populations in the United States (NJ, PA, and WV) were collected and used to assess the effects of fluctuating thermal regimes that included temperatures above or below the upper (Tmax) and lower (Tmin) developmental thresholds, respectively, on nymphal survival and development, and to determine if there was within- and among-population variation in hatch timing and temperature responses of nymphs. Nymphs exposed to temperatures > Tmax and <Tmin were able to develop when those temperatures were part of an alternating regime, even though development took longer, and the average survival was lower than that of the corresponding constant temperature. When individuals from different geographically separated populations were exposed to the same temperature regimes, there was intra- and inter-population variation in time to hatch, instar duration, and estimated Tmin values. The NJ population on average hatched earlier than the PA populations. There was 1-4°C difference in estimates of the Tmin for the first through third instars for individuals from different populations. In addition, the time in instar estimates for constant 15 and 25°C from this study were 26 and 7 days faster, respectively, than estimates from previous studies. The variability in thermal responses documented in this study is large enough to have impacts on predicted phenology and potential risk of establishment especially in areas previously considered too cold to be at risk. This new information should be incorporated into phenology and risk models to improve their predictive ability.

Infraspecific Anatomical Study of Salvia limbata C. A. Mey. (Lamiaceae) in Iran

Salvia limbata is a medicinal plant of the Lamiaceae family that is naturally distributed in various regions of Iran and neighboring countries. In the current evaluation, the leaf blade and petiole anatomical variables were examined in eight Iranian S. limbata populations to explore their taxonomic significance and interpopulation variations. The evaluated populations were harvested from three subprovinces of the Irano-Turanian province. The plant samples were fixed in formaldehyde 90%, ethanol 5%, acetic acid 5% solution, and the hand cross sections of the blade and petiole were double stained with carmine and methylene blue. Data were analyzed using PAST ver. 2.1 and findings revealed that all qualitative variables were invariable between populations, except for the shape of the leaf blade and the epidermal cells of the petiole. Most quantitative traits varied among the considered populations by principal component analysis (PCA) and divided the investigated characteristics into seven components, where two first components had more than 80% of the total variation. In PCA loading, most of the characteristics assessed were negatively correlated. According to UPGMA dendrogram and PCA plot, the populations were clustered into three groups. The PCA biplot revealed the distinct characteristic(s) for each classified group. The clustering patterns of these populations were not in agreement with the geographical distance and phytogeographic similarity between the populations. Several anatomical characteristics were found similar to those recorded in some Lamiaceae genera and lacked taxonomic value, whereas others had taxonomic importance at the infraspecific level. According to a phytogeographic survey and a previous study of molecular genetic diversity, it can be suggested that genetic background can create enough anatomical adaption in populations of S. limbata to establish itself in a wide range of habitats. Meanwhile, the microhabitat has a powerful influence on the anatomical structure.

Past history shapes evolution of reproductive success in a global warming scenario

Adaptive evolution is critical for animal populations to thrive in the fast-changing natural environments. Ectotherms are particularly vulnerable to global warming and, although their limited coping ability has been suggested, few real-time evolution experiments have directly accessed their evolutionary potential. Here, we report a long-term experimental evolution study addressing the evolution of Drosophila thermal reaction norms, after ∼30 generations under different dynamic thermal regimes: fluctuating (daily variation between 15 and 21 °C) or warming (daily fluctuation with increases in both thermal mean and variance across generations). We analyzed the evolutionary dynamics of Drosophila subobscura populations as a function of the thermally variable environments in which they evolved and their distinct background. Our results showed clear differences between the historically differentiated populations: high latitude D. subobscura populations responded to selection, improving their reproductive success at higher temperatures whereas their low latitude counterparts did not. This suggests population variation in the amount of genetic variation available for thermal adaptation, an aspect that needs to be considered to allow for better predictions of future climate change responses. Our results highlight the complex nature of thermal responses in face of environmental heterogeneity and emphasize the importance of considering inter-population variation in thermal evolution studies.

Exploring the Ecological Preferences and Essential Oil Variability in Wild-Growing Populations of the Endangered Local Greek Endemic Thymus holosericeus (Lamiaceae).

Thymus holosericeus Čelak. (Lamiaceae) is a taxonomically isolated and endangered local endemic thyme species which is geographically isolated in four Ionian Islands (West Greece). The present study investigated the essential oil (EO) composition, the ecological preferences, and their correlations in three T. holosericeus wild-growing populations from Zakynthos (ΤH-Z), Cephalonia (ΤH-C) and Lefkada (ΤH-L). The variations in essential oil yield and the composition of T. holosericeus populations were evaluated using hydrodistillation, GC/MS, TLC and NMR analysis. The climatic conditions of each sample were organized and analyzed in RStudio with the raster package and in SPSS with Pearson's Canonical Correlation Analysis (CCA), respectively. The aerial parts of the plants varied in EO yields from 1.92 to 2.28% w/v. The analysis of EO constituents revealed noteworthy qualitative and quantitative inter-population variation. The composition of EOs revealed the presence of linalool (82.77%) and borneol (5.95%) as major compounds in ΤH-Z, while carvacrol (35.34%), geraniol (23.98%), linalool (14.37%), borneol (5.66%), thymol (4.27%) and p-cymene (4.08%) were the main compounds in ΤH-C and linalool (40.37%), geraniol (39.42%) and borneol (5.20%) were dominant components in ΤH-L. The results of the gas chromatography procedure have also been confirmed by 1H and 13C-NMR and TLC analysis. The ecological profile showed an average annual precipitation of 942 ± 18.33 mm and the temperature limits in which T. holosericeus seems to adapt to are 6.80± 1.08 °C 27.70 ± 0.70 °C. Regarding the examined samples, TH-C was adapted to the driest summer and coldest winter conditions, TH-Z was adapted to the lowest annual precipitation with the most complex climatic conditions, and TH-L was adapted to the highest summer temperatures with the lowest precipitation in the wettest period of the year. For each sampled population, the CCA identified the association of the samples' EOs composition with the prevailing local environmental conditions.

Heat stress and recovery effects on the physiology and biochemistry of Castanea sativa Mill.

Chestnut forests are undergoing increasing heat stress due to the current global warming, but little is known about the physiology and biochemistry responses of Castanea sativa Mill. to heat or whether differences exist between populations. Six-month-old seedlings from three climatically contrasting populations of C. sativa (from the north, centre, and south of Spain) were subjected to control and heat stress conditions for 7 days. The effects of heat stress on seedlings and their recovery (10 days after heat stress) were described by assessment of visible symptoms, growth, mortality, and leaf gas exchange of plants, quantification of compounds involved in the primary and secondary metabolism, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. In response to stress, plant biomass decreased, and plant biochemistry altered depending on the tissue and the population. Major alterations in the primary metabolism of stressed plants occurred in leaves, characterized by increased levels of soluble sugars, nitrogen, and proline, and depletion of starch. Increased levels of soluble sugars and starch depletion occurred mostly in seedlings from the southern population, while proline increase occurred only in the northern population. Secondary metabolism of seedlings experienced the highest variation below ground, and roots of heat-stressed plants increased the content of phenolic compounds. LC-MS analysis permitted identification and quantification of six compounds induced by heat, five of which were detected in the roots. Differential biochemistry responses to heat stress were observed among populations. At recovery, most of the altered parameters had returned to control conditions, suggesting high resilience to heat stress in this Mediterranean tree species. This is the first study to address the effects of heat stress on the physiology and biochemistry of C. sativa and their interpopulation variability. Most parameters were significantly influenced by the interaction of population and heat treatment, indicating that genetic differentiation controlled the phenotypic differences of C. sativa in response to heat stress. Extensive genetic variation in plasticity in physiological and biochemical parameters in response to heat stress reveals an opportunity for chestnut for global warming-mediated selection.

Intraspecific variation among Chinook Salmon populations indicates physiological adaptation to local environmental conditions.

Understanding interpopulation variation is important to predicting species responses to climate change. Recent research has revealed interpopulation variation among several species of Pacific salmonids; however, the environmental drivers of population differences remain elusive. We tested for local adaptation and countergradient variation by assessing interpopulation variation among six populations of fall-run Chinook Salmon from the western United States. Juvenile fish were reared at three temperatures (11, 16 and 20°C), and five physiological metrics were measured (routine and maximum metabolic rate, aerobic scope, growth rate and critical thermal maximum). We then tested associations between these physiological metrics and 15 environmental characteristics (e.g. rearing temperature, latitude, migration distance, etc.). Statistical associations between the five physiological metrics and 15 environmental characteristics supported our hypotheses of local adaptation. Notably, latitude was a poor predictor of population physiology. Instead, our results demonstrate that populations from warmer habitats exhibit higher thermal tolerance (i.e. critical thermal maxima), faster growth when warm acclimated and greater aerobic capacity at high temperatures. Additionally, populations with longer migrations exhibit higher metabolic capacity. However, overall metabolic capacity declined with warm acclimation, indicating that future climate change may reduce metabolic capacity, negatively affecting long-migrating populations. Linking physiological traits to environmental characteristics enables flexible, population-specific management of disparate populations in response to local conditions.

Life History Traits and Metabolic Pool Variation in Neotropical Species of Drosophila (Diptera, Drosophilidae).

The differential exploration of natural resources by Drosophila species has effects on fitness, with changes in life history and metabolic traits. There is a lack of research on the variation in these characters in different environments in Neotropical species of Drosophila. The purpose of this study was to evaluate the profile of life history traits, including viability, development time, and dry weight (as a measure of size), as well as the metabolic pools of triglyceride, glycogen, and protein, in populations from the southern and southeastern regions of Brazil of four Neotropical Drosophila species: D. willistoni, of the Sophophora subgenus, and D. mercatorum, D. maculifrons, and D. ornatifrons, which belong to the Drosophila subgenus. Life history and metabolic traits showed interpopulational variation in at least one species. When significant differences in life history parameters occurred, species of the same subgenus presented similar profiles, i.e., southern populations were larger, less viable, and showed longer development time. This was also observed for triglyceride. However, for the other two metabolic pools (glycogen and total proteins), D. maculifrons and D. ornatifrons presented inverse patterns to the other two species, with the highest values in southeastern populations and the lowest in southern populations. These populational variations indicate plasticity of the examined life history traits, which allows distinctive responses to different environmental conditions shared by speciesof the same subgenus. Nevertheless, interspecific comparisons did not reflect phylogenetic relationships, with the highest viability being found for D. willistoni and D. mercatorum, which is probably correlated to the ability of these species to explore a broader variety of habitats. On the other hand, the storage capability of metabolic pools seems to be species specific, determined by the adaptive history to the quality and availability of resources, with D. mercatorum (low) and D. ornatifrons (high) having opposing capacities to store metabolites from their diets.

Variability of morphological features of Dracocephalum multicaule (Lamiaceae) in natural populations of Dagestan

The structure of intra- and inter-population variability of Dracocephalum multicaule Montbr. et Auch. ex Benth. along the altitude gradient was studied on the basis of a complex of morphological features of plants. Two populations of D. multicaule were collected from different altitude levels (800 and 1130 m above sea level). Differences between populations by place of growth (microclimatic conditions), communities in which the species grows, age composition, as well as morphological features were revealed. A decrease in the average values of quantitative and dimensional traits with the increase in altitude has been recorded, with the exception of two (the length of the inflorescence and the number of verticils). Intra- and inter-population variability of traits are at medium and high levels. Variability of the number of flowers in the inflorescence (43.5–51.5) and weight characteristics (36.1–50.0) are high. The interpopulation variability of species traits is the result of the influence of a complex of factors of the altitude gradient and the population age. The areas differ in ecological habitat conditions and the degree of anthropogenic load. The increasing anthropogenic impact in the places where the species grows disrupts the stability of natural populations and affects plant reproduction. In order to preserve the species of D. multicaule in natural habitats, it is necessary to reduce anthropogenic pressure, as well as to introduce the species into culture.

Interpopulation variation in leaf out phenology of Fagus crenata along topographic variation associated with the late frost regime in the Hakkoda Mountains, northern Japan

AbstractWe studied local variations in temperature from winter to spring, and interpopulation variations in leaf out phenology (the day and the temperature sum for budburst and leaf expansion) of Siebold's beech (Fagus crenata) canopy trees. We focused on local topographic variation associated with the late frost regime for the canopy trees using 5–10 years of in situ observation of the temperature at 12 sites and leaf out phenology of two populations inhabiting a basin (basin populations) and 4 populations inhabiting hillside slopes (hillside slope populations) in the Hakkoda Mountains, northern Japan. The late frost regime differed between topographies; late frosts occurred during warmer periods in the basin compared to hillside slopes. The basin populations exhibited a larger temperature sum for leaf out than the hillside slope populations, regardless of altitude, suggesting that local variation in the late frost regime is an abiotic factor causing local variations in leaf out phenology. The six studied populations exhibited earlier days and smaller temperature sum of budburst in years with longer chilling duration. However, the extent of phenotypic plasticity in the temperature sum was small for the basin compared to hillside slopes. The temperature sum of leaf expansion in the hillside slope populations also negatively correlated with chilling duration, whereas that of the basin populations responded in the opposite direction. The safety margin from the last frost differed between the topographies, but not that from the last fatal frost, suggesting local adaptation to the late frost regime in each habitat.

Interpopulation variation in inbreeding is primarily driven by tolerance of mating with relatives in a spermcasting invertebrate.

The degree to which individuals inbreed is a fundamental aspect of population biology shaped by both passive and active processes. Yet, the relative influences of random and non-random mating on the overall magnitude of inbreeding are not well characterized for many taxa. We quantified variation in inbreeding among qualitatively accessible and isolated populations of a sessile marine invertebrate (the colonial ascidian Lissoclinum verrilli) in which hermaphroditic colonies cast sperm into the water column for subsequent uptake and internal fertilization. We compared estimates of inbreeding to simulations predicting random mating within sites to evaluate if levels of inbreeding were (1) less than expected because of active attempts to limit inbreeding, (2) as predicted by genetic subdivision and passive inbreeding tolerance, or (3) greater than simulations due to active attempts to promote inbreeding via self-fertilization or a preference for related mates. We found evidence of restricted gene flow and significant differences in the genetic diversity of L. verrilli colonies among sites, indicating that on average colonies were weakly related in accessible locations, but their levels of relatedness matched that of first cousins or half-siblings on isolated substrates. Irrespective of population size, progeny arrays revealed variation in the magnitude of inbreeding across sites that tracked with the mean relatedness of conspecifics. Biparental reproduction was confirmed in most offspring (86%) and estimates of total inbreeding largely overlapped with simulations of random mating, suggesting that interpopulation variation in mother-offspring resemblance was primarily due to genetic subdivision and passive tolerance of related mates. Our results highlight the influence of demographic isolation on the genetic composition of populations, and support theory predicting that tolerance of biparental inbreeding, even when mates are closely related, may be favoured under a broad set of ecological and evolutionary conditions.

Gene expression in the female tree swallow brain is associated with inter- and intra-population variation in glucocorticoid levels

Studies of the evolutionary causes and consequences of variation in circulating glucocorticoids (GCs) have begun to reveal how they are shaped by selection. Yet the extent to which variation in circulating hormones reflects variation in other important regulators of the hypothalamic-pituitary-adrenal (HPA) axis, and whether these relationships vary among populations inhabiting different environments, remain poorly studied. Here, we compare gene expression in the brain of female tree swallows (Tachycineta bicolor) from populations that breed in environments that differ in their unpredictability. We find evidence of inter-population variation in the expression of glucocorticoid and mineralocorticoid receptors in the hypothalamus, with the highest gene expression in a population from an extreme environment, and lower expression in a population from a more consistent environment as well as in birds breeding at an environmentally variable high-altitude site that are part of a population that inhabits a mixture of high and low altitude habitats. Within some populations, variation in circulating GCs predicted differences in gene expression, particularly in the hypothalamus. However, some patterns were present in all populations, whereas others were not. These results are consistent with the idea that some combination of local adaptation and phenotypic plasticity may modify components of the HPA axis affecting stress resilience. Our results also underscore that a comprehensive understanding of the function and evolution of the stress response cannot be gained from measuring circulating hormones alone, and that future studies that apply a more explicitly evolutionary approach to important regulatory traits are likely to provide significant insights.

Estimation of Age-at-Death Using Cortical Bone Histomorphometry of the Rib and Femur: A Validation Study on a British Population.

Histomorphometry constitutes a valuable tool for age estimation. Histological interpopulation variability has been shown to affect the accuracy of age estimation techniques and therefore validation studies are required to test the accuracy of the pre-existing methodologies. The present research constitutes a validation study of widely known histological methods on the sixth rib and the femoral midshaft of a 19th century British population originating from Blackburn, England. An evaluation of the histomorphometric features of eleven ribs and five femora was performed and used to test the accuracy of selected methods. Results indicated that osteon area and circularity were the only histomorphometric variables that presented significant interpopulation variability. Cho et al.'s method for the ribs and the average value produced using Kerley and Ubelaker's method for intact osteon and percentage of lamellar bone equations for femur were considered the only reliable markers for estimating the age on the Blackburn sample. In the case of old individuals, Goliath et al.'s method provided more satisfactory results. Overall, the present study provides evidence on the applicability of the aging histomorphometric methods on a British sample and highlights the limitations of applying histomorphometric methods developed on different reference populations than the one under investigation.

What Is the Role of Body Composition Assessment in HCC Management?

In the last decade, body composition (BC) assessment has emerged as an innovative tool that can offer valuable data concerning nutritional status in addition to the information provided by the classical parameters (i.e., body mass index, albumin). Furthermore, published data have revealed that different types of body composition are associated with different outcomes. For example, abnormalities of skeletal muscle, a common finding in cirrhotic and oncologic patients, are associated with poor outcome (i.e., high morbidity and high mortality). The disposition (visceral/subcutaneous adipose tissue) and radiodensity of adipose tissue proved to also be determinant factors for HCC outcome. Despite all the advantages, BC assessment is not part of the standard pre-therapeutic workup. The main reasons are the high heterogeneity of data, the paucity of prospective studies, the lack of a standard assessment method, and the interpopulation variation of BC. This paper aims to review the available evidence regarding the role of BC as a prognostic tool in the HCC population undergoing various therapies.