Cytochrome b sequences of ancient cattle and wild ox support phylogenetic complexity in the ancient and modern bovine populations

Mitochondrial DNA has been the traditional marker for the study of animal domestication, as its high mutation rate allows for the accumulation of molecular diversity within the time frame of domestic history. Additionally, it is exclusively maternally inherited and haplotypes become part of the domestic gene pool via actual capture of a female animal rather than by interbreeding with wild populations. Initial studies of British aurochs identified a haplogroup, designated P, which was found to be highly divergent from all known domestic haplotypes over the most variable portion of the D-loop. Additional analysis of a large and geographically representative sample of aurochs from northern and central Europe found an additional, separate aurochs haplotype, E. Until recently, the European aurochs appeared to have no matrilinear descendants among the publicly available modern cattle control regions sequenced; if aurochs mtDNA was incorporated into the domestic population, aurochs either formed a very small proportion of modern diversity or had been subsequently lost. However, a haplogroup P sequence has recently been found in a modern sample, along with a new divergent haplogroup called Q. Here we confirm the outlying status of the novel Q and E haplogroups and the modern P haplogroup sequence as a descendent of European aurochs, by retrieval and analysis of cytochrome b sequence data from twenty ancient wild and domesticated cattle archaeological samples.     

Clinicopathological and prognostic value of lncRNA PANDAR expression in solid tumors: Evidence from a systematic review and meta-analysis

PANDAR (promoter of CDKN1A antisense DNA damage activated RNA) has been shown to be aberrantly expressed in many types of cancer. Considering conflicting data, the current study was aimed to assess its potential role as a prognostic marker in malignant tumors. A comprehensive literature search of PubMed, Medline, and Web of Science was performed to identify all eligible studies describing the use of PANDAR as a prognostic factor for different types of cancer. Data related to overall survival (OS) and clinicopathologic features were collected and analyzed. The pooled hazard ratio (HR) and odds radio (OR) with a 95% confidence interval (CI) were used to estimate associations. Ten original studies containing 1,231 patients were included. The results showed that in patients with cancer, high PANDAR expression is correlated with lymph node metastasis (LNM; OR = 2.57; 95% CI, 1.76–3.81; p < 0.001), tumor stage (OR = 2.90; 95% CI, 1.25–6.75; p = 0.013), and tumor size (OR = 1.79; 95% CI, 1.11–2.91; p = 0.018). However, sensitivity analysis further demonstrated a significant association between high PANDAR expression and OS, both in multivariate and univariate analysis models (pooled HR 2.01; 95% CI, 1.17–3.44 and pooled HR 2.62; 95% CI, 1.98–3.47, respectively), after omitting one study. These results suggested that PANDAR expression might be indicative of advanced disease and poor prognosis in patients with cancer. Further studies are necessary to determine the value of this risk stratification biomarker in clinical management of patients with cancer.     

Impact of intrasexual selection on sexual dimorphism and testes size in the Mexican howler monkeys Alouatta palliata and A. pigra

One of the goals of physical anthropology and primatology is to understand how primate social systems influence the evolution of sexually selected traits. Howler monkeys provide a good model for studying sexual selection due to differences in social systems between related species. Here, we examine data from the sister howler monkey species Alouatta palliata and A. pigra inhabiting southeastern Mexico and northern Guatemala. We use a resampling approach to analyze differences in sexual dimorphism of body and canine size. In addition, we compare testes size as a way of gauging the intensity of sperm competition in both species. Morphometric data were collected from wild-caught individuals, including body mass and length, and dental data were obtained from casts from wild individuals and from museum specimens. Although A. pigra individuals are larger than their A. palliata counterparts, we find that both species exhibit similar levels of sexual dimorphism for all of the variables considered. Testicular volume results indicate that A. palliata male testes are on average twice as large as those of A. pigra males, suggesting more intense sperm competition in the former species. Our study shows that A. pigra is not highly sexually dimorphic as was once thought, and testes size differences suggest the need for a clearer understanding of howler monkey social systems.     

Natural selection on body size traits in a long‐lived bird,the snow petrel Pagodroma nivea

I consider the possibility of selection favouring large body size in a population of snow petrels (Pagodroma nivea), a long‐lived seabird species. I measured natural selection on body size traits in a population from 1987 to 1998. There was evidence of selection on body size associated with fecundity and survival. Directional selection on bill length and stabilizing selection on tarsus length associated with reproductive success were detected among males. Selection associated with survival favoured males with longer bills. However, selection was weak in all cases. No evidence of selection acting on female body size traits was detected. Offspring–parents regression suggested that bill length and tarsus length were heritable. Although I was able to identify the targets of selection in this population, I could not demonstrate the ecological implications of both tarsus length and bill length variation. The selection on male, but not on female, body size traits suggests factors such as intrasexual competition for nests and/or mates rather than factors such as feeding efficiency as mechanisms of selection on bill size.     

Contrasting selection pressure on body and weapon size in a polygynous megaherbivore

Sexual size dimorphism (SSD) is a common morphological trait in ungulates, with polygyny considered the leading driver of larger male body mass and weapon size. However, not all polygynous species exhibit SSD, while molecular evidence has revealed a more complex relationship between paternity and mating system than originally predicted. SSD is, therefore, likely to be shaped by a range of social, ecological and physiological factors. We present the first definitive analysis of SSD in the common hippopotamus (Hippopotamus amphibius) using a unique morphological dataset collected from 2994 aged individuals. The results confirm that hippos exhibit SSD, but the mean body mass differed by only 5% between the sexes, which is rather limited compared with many other polygynous ungulates. However, jaw and canine mass are significantly greater in males than females (44% and 81% heavier, respectively), highlighting the considerable selection pressure for acquiring larger weapons. A predominantly aquatic lifestyle coupled with the physiological limitations of their foregut fermenting morphology likely restricts body size differences between the sexes. Indeed, hippos appear to be a rare example among ungulates whereby sexual selection favours increased weapon size over body mass, underlining the important role that species-specific ecology and physiology have in shaping SSD.     

Natural selection on body size is mediated by multiple interacting factors: a comparison of beetle populations varying naturally and experimentally in body size

Body size varies considerably among species and among populations within species, exhibiting many repeatable patterns. However, which sources of selection generate geographic patterns, and which components of fitness mediate evolution of body size, are not well understood. For many animals, resource quality and intraspecific competition may mediate selection on body size producing large-scale geographic patterns. In two sequential experiments, we examine how variation in larval competition and resource quality (seed size) affects the fitness consequences of variation in body size in a scramble-competing seed-feeding beetle, Stator limbatus. Specifically, we compared fitness components among three natural populations of S. limbatus that vary in body size, and then among three lineages of beetles derived from a single base population artificially selected to vary in size, all reared on three sizes of seeds at variable larval density. The effects of larval competition and seed size on larval survival and development time were similar for larger versus smaller beetles. However, larger-bodied beetles suffered a greater reduction in adult body mass with decreasing seed size and increasing larval density; the relative advantage of being large decreased with decreasing seed size and increasing larval density. There were highly significant interactions between the effects of seed size and larval density on body size, and a significant three-way interaction (population-by-density-by-seed size), indicating that environmental effects on the fitness consequences of being large are nonadditive. Our study demonstrates how multiple ecological variables (resource availability and resource competition) interact to affect organismal fitness components, and that such interactions can mediate natural selection on body size. Studying individual factors influencing selection on body size may lead to misleading results given the potential for nonlinear interactions among selective agents.     

Patterns of maximum body size evolution in Cenozoic land mammals: eco-evolutionary processes and abiotic forcing

There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal diversity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to sampling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal diversity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing.     

Sexual size dimorphism and selection in the wild in the waterstrider Aquarius remigis: Body size,components of body size and male mating success

Sexual size dimorphism is assumed to be adaptive and is expected to evolve in response to a difference in the net selection pressures on the sexes. Although a demonstration of sexual selection is neither necessary nor sufficient to explain the evolution of sexual size dimorphism, sexual selection is generally assumed to be a major evolutionary force. If contemporary sexual selection is important in the evolution and maintenance of sexual size dimorphism then we expect to see concordance between patterns of sexual selection and patterns of sexual dimorphism. We examined sexual selection in the wild, acting on male body size, and components of body size, in the waterstrider Aquarius remigis, as part of a long term study examining net selection pressures on the two sexes in this species. Selection was estimated on both a daily and annual basis. Since our measure of fitness (mating success) was behavioral, we estimated reliabilities to determine if males perform consistently. Reliabilities were measured as ? statistics and range from fair to perfect agreement with substantial agreement overall. We found significant univariate sexual selection favoring larger total length in the first year of our study but not in the second. Multivariate analysis of components of body size revealed that sexual selection for larger males was not acting directly on total length but on genital length. Sexual selection for larger male body size was opposed by direct selection favoring smaller midfemoral lengths. While males of this species are smaller than females, they have longer genital segments and wider forefemora. Patterns of contemporary sexual selection and sexual size dimorphism agree only for genital length. For total length, and all other components of body size examined, contemporary sexual selection was either nonsignificant or opposed the pattern of size dimporhism. Thus, while the net pressures of contemporary selection for the species may still act to maintain sexual size dimorphism, sexual selection alone does not.     

HOXD-AS1 is a predictor of clinical progression and functions as an oncogenic lncRNAs in papillary thyroid cancer

Long noncoding RNA HOXD cluster antisense RNA 1 (HOXD-AS1) has been found to play a crucial role in the tumorigenesis and progression of human cancer. However, the role of HOXD-AS1 in papillary thyroid cancer is still unknown. The purpose of this study was to investigate the clinical value and biological function of HOXD-AS1 in papillary thyroid cancer. The results showed HOXD-AS1 is overexpressed in papillary thyroid cancer tissues and cell lines compared with matching nontumor tissue specimens and normal thyroid cell line, respectively. High expression of HOXD-AS1 was associated with elderly people, advanced clinical stage, large tumor size, present lymph node metastasis, and distant metastasis. There was no significant correlation between HOXD-AS1 expression and disease-free survival or overall survival in this cohort from the TCGA database. The study in vitro suggested reduced HOXD-AS1 expression inhibited papillary thyroid cancer cell proliferation, migration, and invasion, and promoted cell-cycle arrest. In conclusion, HOXD-AS1 is a biomarker for predicting clinical progression in papillary thyroid cancer.     

Correlated evolution of conspicuous coloration and body size in poison frogs (Dendrobatidae)

Conspicuous coloration is often used in combination with chemical defenses to deter predators from attacking. Experimental studies have shown that the avoidance inducing effect of conspicuous prey coloration increases with increasing size of pattern elements and with increasing body size. Here we use a comparative approach to test the prediction from these findings, namely that conspicuous coloration will evolve in tandem with body size. In our analysis, we use a previously published mitochondrial DNA-based phylogeny and comparative analysis of independent contrasts to examine if evolutionary shifts in color pattern have been associated with evolutionary changes in body size in aposematic poison frogs (Anura: Dendrobatidae). Information on body size (snout to vent length) and coloration were obtained from the literature. Two different measures of conspicuousness were used, one based on rankings by human observers and the other based on computer analysis of digitized photographs. The results from comparative analyses using either measure of coloration indicated that avoidance inducing coloration and body size have evolved in concert in poison frogs. Results from reconstruction of character change further indicate that the correlated evolution of size and coloration has involved changes in both directions within each of the different clades of the phylogenetic tree. This finding is consistent with the hypothesis that selection imposed by visually guided predators has promoted the evolution of larger body size in species with conspicuous coloration, or enhanced evolution of conspicuous coloration in larger species.     

Functional role of a long non-coding RNA LIFR-AS1/miR-29a/TNFAIP3 axis in colorectal cancer resistance to pohotodynamic therapy

Colorectal Cancer (CRC) is one of the most common digestive system malignant tumors. Recently, PDT has been used as a first-line treatment for colon cancer; however, limited curative effect was obtained due to resistance of CRC to PDT. During the past decades, accumulating CRC-related long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs have been reported to exert diverse functions through various biological processes; their dysregulation might trigger and/or promote the pathological changes. Herein, we performed microarrays analysis to identify dysregulated lncRNAs, miRNAs and mRNAs in PDT-treated HCT116 cells to figure out the lncRNA-miRNA interactions related to the resistance of CRC to PDT treatment, and the downstream mRNA target, as well as the molecular mechanism. We found a total of 1096 lncRNAs dysregulated in PDT-treated CRC HCT116 cells; among them, LIFR-AS1 negatively interacted with miR-29a, one of the dysregulated miRNAs in PDT-treated CRC cells, to affect the resistance of CRC to PDT. LIFR-AS1 knockdown attenuated, whereas miR-29a inhibition enhanced the cellular effect of PDT on HCT116 cell proliferation and apoptosis. Furthermore, among the dysregulated mRNAs, TNFAIP3 was confirmed to be a direct target of miR-29a and exerted a similar effect to LIFR-AS1 on the cellular effects of PDT. In summary, LIFR-AS1 serves as a competitive endogenous RNA (ceRNA) for miR-29a to inhibit its expression and up-regulate downstream target TNFAIP3 expression, finally modulating the resistance of CRC to PDT. We provide an experimental basis for this lncRNA/miRNA/mRNA network being a promising target in CRC resistance to PDT treatment.     

Sexual and lifetime selection on body size in a marine fish: the importance of life-history trade-offs

Many field measurements of viability and sexual selection on body size indicate that large size is favoured. However, life-history theory predicts that body size may be optimized and that patterns of selection may often be stabilizing rather than directional. One reason for this discrepancy may be that field estimates of selection tend to focus on limited components of fitness and may not fully measure life-history trade-offs. We use an 8-year, demographic field study to examine both sexual selection and lifetime selection on body size of a coral reef fish (the bicolour damselfish, Stegastes partitus). Selection via reproductive success of adults was very strong (standardized selection differential=1.04). However, this effect was balanced by trade-offs between large adult size and reduced cumulative survival during the juvenile phase. When we measured lifetime fitness (net reproductive rate), selection was strongly stabilizing and only weakly directional, consistent with predictions from life-history theory.     

Intraspecific variation in body size and sexual size dimorphism,and a test of Rensch's rule in bats

The magnitude and direction of sexual size dimorphism (SSD) may vary considerably within and among taxa, and the primary causes of such variation have not been thoroughly elucidated. For example, the effect of abiotic factors is frequently attributed to explain intra‐ and interspecific variation in SSD. Rensch's rule, which states that males vary more in size than females when body size increases, has rarely been tested in bats. Therefore, whether bats follow Rensch's rule remains unclear, particularly when females are larger than males. We investigated whether four bat species presented SSD, as well as whether their body sizes varied within each sex across localities, testing the hypothesis that intraspecific SSD varies substantially depending of sampling localities. We finally examined whether bats followed Rensch's rule by simultaneously using intraspecific and interspecific approaches. Although SSD was not observed for most bat species within each locality, the females of three of the four captured species exhibited differences in body size between particular localities. Usually the females varied more in size than did males across localities, mostly exhibiting a female‐biased SSD. Significant differences in SSD were observed (i.e. mean values of the sexual dimorphism index), even though Rensch's rule was not followed.     

Subtle but ubiquitous selection on body size in a natural population of collared flycatchers over 33 years

Understanding the magnitude and long‐term patterns of selection in natural populations is of importance, for example, when analysing the evolutionary impact of climate change. We estimated univariate and multivariate directional, quadratic and correlational selection on four morphological traits (adult wing, tarsus and tail length, body mass) over a time period of 33 years (≈ 19 000 observations) in a nest‐box breeding population of collared flycatchers (Ficedula albicollis). In general, selection was weak in both males and females over the years regardless of fitness measure (fledged young, recruits and survival) with only few cases with statistically significant selection. When data were analysed in a multivariate context and as time series, a number of patterns emerged; there was a consistent, but weak, selection for longer wings in both sexes, selection was stronger on females when the number of fledged young was used as a fitness measure, there were no indications of sexually antagonistic selection, and we found a negative correlation between selection on tarsus and wing length in both sexes but using different fitness measures. Uni‐ and multivariate selection gradients were correlated only for wing length and mass. Multivariate selection gradient vectors were longer than corresponding vector of univariate gradients and had more constrained direction. Correlational selection had little importance. Overall, the fitness surface was more or less flat with few cases of significant curvature, indicating that the adaptive peak with regard to body size in this species is broader than the phenotypic distribution, which has resulted in weak estimates of selection.     

The evolution of island gigantism and body size variation in tortoises and turtles

Extant chelonians (turtles and tortoises) span almost four orders of magnitude of body size, including the startling examples of gigantism seen in the tortoises of the Galapagos and Seychelles islands. However, the evolutionary determinants of size diversity in chelonians are poorly understood. We present a comparative analysis of body size evolution in turtles and tortoises within a phylogenetic framework. Our results reveal a pronounced relationship between habitat and optimal body size in chelonians. We found strong evidence for separate, larger optimal body sizes for sea turtles and island tortoises, the latter showing support for the rule of island gigantism in non-mammalian amniotes. Optimal sizes for freshwater and mainland terrestrial turtles are similar and smaller, although the range of body size variation in these forms is qualitatively greater. The greater number of potential niches in freshwater and terrestrial environments may mean that body size relationships are more complicated in these habitats.     

Coevolution of body size and metabolic rate in vertebrates: a life‐history perspective

Despite many decades of research, the allometric scaling of metabolic rates (MRs) remains poorly understood. Here, we argue that scaling exponents of these allometries do not themselves mirror one universal law of nature but instead statistically approximate the non‐linearity of the relationship between MR and body mass. This ‘statistical’ view must be replaced with the life‐history perspective that ‘allows’ organisms to evolve myriad different life strategies with distinct physiological features. We posit that the hypoallometric allometry of MRs (mass scaling with an exponent smaller than 1) is an indirect outcome of the selective pressure of ecological mortality on allocation ‘decisions’ that divide resources among growth, reproduction, and the basic metabolic costs of repair and maintenance reflected in the standard or basal metabolic rate (SMR or BMR), which are customarily subjected to allometric analyses. Those ‘decisions’ form a wealth of life‐history variation that can be defined based on the axis dictated by ecological mortality and the axis governed by the efficiency of energy use. We link this variation as well as hypoallometric scaling to the mechanistic determinants of MR, such as metabolically inert component proportions, internal organ relative size and activity, cell size and cell membrane composition, and muscle contributions to dramatic metabolic shifts between the resting and active states. The multitude of mechanisms determining MR leads us to conclude that the quest for a single‐cause explanation of the mass scaling of MRs is futile. We argue that an explanation based on the theory of life‐history evolution is the best way forward.