Broad Comparative Analysis Research Articles

Not all fine-branch locomotion is equal: Grasping morphology determines locomotor performance on narrow supports

Fine-branch models have long played a central role in primate evolutionary research. Nevertheless, recent studies of positional behavior in nonprimate arboreal mammals have challenged the idea that synapomorphic primate features, such as grasping extremities, uniquely facilitated access to the fine-branch zone. We test the alternative hypothesis that grasping extremities specifically improve locomotor performance in a fine-branch environment by examining how support diameter influences locomotor mechanics in one sciurid rodent (Sciurus carolinensis) and two platyrrhine primates (Callithrix jacchus and Saimiri boliviensis). These species were chosen to broadly model different stages in the evolution of primate grasping morphology. The results showed that transitioning from broad to narrower supports required the greatest kinematic adjustment in squirrels and the least adjustment in squirrel monkeys, with marmosets displaying an intermediate level of adjustment. Moreover, on any given support, squirrels' locomotor mechanics differed from marmosets' in a manner consistent with a greater need for stability, despite superficial ecomorphological similarities between sciurid rodents and callitrichine primates. Morphological analyses of autopodial size and proportions suggest that variation in locomotor performance more closely tracked variation in overall hand and foot size rather than digit length per se. Indeed, a broad comparative analysis revealed that for their body mass, primates have longer hands than similarly sized arboreal rodents and marsupials (although only the primate-rodent comparison was significant after incorporating phylogenetic relatedness). Inclusion of fossil stem primates (plesiadapiforms) and euprimates (adapiforms) in these analyses suggests that this primate-wide grade shift in relative autopodial size must have occurred early in the evolutionary history of the group. Overall, our findings show that basal primate morphological adaptations may have specifically facilitated improved locomotor performance in a fine-branch niche, rather than merely permitting access to the environment. As such, future adaptive hypotheses of primate origins should incorporate the import of primate-like morphology on locomotor performance as well.

Toxins from scratch? Diverse, multimodal gene origins in the predatory robber fly Dasypogon diadema indicate a dynamic venom evolution in dipteran insects.

BackgroundVenoms and the toxins they contain represent molecular adaptations that have evolved on numerous occasions throughout the animal kingdom. However, the processes that shape venom protein evolution are poorly understood because of the scarcity of whole-genome data available for comparative analyses of venomous species.ResultsWe performed a broad comparative toxicogenomic analysis to gain insight into the genomic mechanisms of venom evolution in robber flies (Asilidae). We first sequenced a high-quality draft genome of the hymenopteran hunting robber fly Dasypogon diadema, analysed its venom by a combined proteotranscriptomic approach, and compared our results with recently described robber fly venoms to assess the general composition and major components of asilid venom. We then applied a comparative genomics approach, based on 1 additional asilid genome, 10 high-quality dipteran genomes, and 2 lepidopteran outgroup genomes, to reveal the evolutionary mechanisms and origins of identified venom proteins in robber flies.ConclusionsWhile homologues were identified for 15 of 30 predominant venom protein in the non-asilid genomes, the remaining 15 highly expressed venom proteins appear to be unique to robber flies. Our results reveal that the venom of D. diadema likely evolves in a multimodal fashion comprising (i) neofunctionalization after gene duplication, (ii) expression-dependent co-option of proteins, and (iii) asilid lineage-specific orphan genes with enigmatic origin. The role of such orphan genes is currently being disputed in evolutionary genomics but has not been discussed in the context of toxin evolution. Our results display an unexpected dynamic venom evolution in asilid insects, which contrasts the findings of the only other insect toxicogenomic evolutionary analysis, in parasitoid wasps (Hymenoptera), where toxin evolution is dominated by single gene co-option. These findings underpin the significance of further genomic studies to cover more neglected lineages of venomous taxa and to understand the importance of orphan genes as possible drivers for venom evolution.

Prayers for fossil mantis unfulfilled: Prochaeradodis enigmaticus Piton, 1940 is a cockroach (Blattodea)

The fossil species Prochaeradodis enigmaticusPiton, 1940, from Menat (France, Paleocene) has been regarded as a crown-Mantodea (praying mantis) and was subsequently used as one of the very few temporal calibration points relevant for the order. Ambiguities in previous descriptions prompted us to re-examine the type material. Based on our new observations and a broad comparative analysis across Dictyoptera, we recognized three independent morphological character states supporting an unequivocal placement of the fossil within Blattodea (cockroaches and termites). These states are: 1) in forewing, the AA area has intercalary veins; 2) in forewing, ScP is short and oblique; and 3) in hind wing, CuA has many posterior branches not reaching the posterior wing margin but the cubital furrow. This new placement discounts the use of this fossil as a Mantodea tree calibration point.

Escherichia coli B2 strains prevalent in inflammatory bowel disease patients have distinct metabolic capabilities that enable colonization of intestinal mucosa

BackgroundEscherichia coli is considered a leading bacterial trigger of inflammatory bowel disease (IBD). E. coli isolates from IBD patients primarily belong to phylogroup B2. Previous studies have focused on broad comparative genomic analysis of E. coli B2 isolates, and identified virulence factors that allow B2 strains to reside within human intestinal mucosa. Metabolic capabilities of E. coli strains have been shown to be related to their colonization site, but remain unexplored in IBD-associated strains.ResultsIn this study, we utilized pan-genome analysis and genome-scale models (GEMs) of metabolism to study metabolic capabilities of IBD-associated E. coli B2 strains. The study yielded three results: i) Pan-genome analysis of 110 E. coli strains (including 53 isolates from IBD studies) revealed discriminating metabolic genes between B2 strains and other strains; ii) Both comparative genomic analysis and GEMs suggested that B2 strains have an advantage in degrading and utilizing sugars derived from mucus glycan, and iii) GEMs revealed distinct metabolic features in B2 strains that potentially allow them to utilize energy more efficiently. For example, B2 strains lack the enzymes to degrade amadori products, but instead rely on neighboring bacteria to convert these substrates into a more readily usable and potentially less sought after product.ConclusionsTaken together, these results suggest that the metabolic capabilities of B2 strains vary significantly from those of other strains, enabling B2 strains to colonize intestinal mucosa.The results from this study motivate a broad experimental assessment of the nutritional effects on E. coli B2 pathophysiology in IBD patients.

A novel Multiple Attribute Decision Making approach based on interval data using U2P-Miner algorithm

This paper aims to introduce a technique for order of preference using pattern mining based on Decision Makers (DMs) level of risk aversion. However, the model is essentially defined on the problem of supplier selection, it can be used to deal with almost any similar decision making problem. This novel Multiple Attribute Decision Making (MADM) model takes the advantages of the U2P-Miner algorithm, the interval data weighting method, and the Linear Assignment Method (LAM). The key idea behind the method is to consider the attribute with more frequent patterns as the common attribute and to assign a smaller weight to it. Since, the model handles interval data as input, it can be guaranteed that the model uses the detailed information and, therefore, the resulting weight factors are more realistic. The DMs risk aversion level is also addressed in the model, which is necessary in real-life situations. Accordingly, the proposed decision making process depends directly on DMs attitude toward risk. It gives DM the opportunity to make a decision in two ways: 1) based on the specified risk aversion level, 2) based on an integrated approach using LAM. The linearity of the LAM, by itself, enhances the scalability of the model. Moreover, the necessity of providing pairwise comparison judgments is completely eliminated in the model and, therefore, the reliability of the decision making is enhanced. The effectiveness of the model is finally demonstrated through a numerical example while the broad comparative and sensitivity analysis further proves its validity and superiority.

Interpretable and accurate medical data classification – a multi-objective genetic-fuzzy optimization approach

In medical decision support systems, both the accuracy (i.e., the ability to adequately represent the decision making processes) as well as the transparency and interpretability (i.e., the ability to provide a domain user with compact and understandable explanation and justification of the proposed decisions) play essential roles. This paper presents an approach for automatic design of fuzzy rule-based classification systems (FRBCSs) from medical data using multi-objective evolutionary optimization algorithms (MOEOAs). Our approach generates, in a single run, a collection of solutions (medical FRBCSs) characterized by various levels of accuracy-interpretability trade-off. We propose a new complexity-related interpretability measure and we address the semantics-related interpretability issue by means of efficient implementation of the so-called strong fuzzy partitions of attribute domains. We also introduce a special-coding-free representation of the rule base and original genetic operators for its processing as well as we implement our ideas in the context of well-known and one of the presently most advanced MOEOAs, i.e., Non-dominated Sorting Genetic Algorithm II (NSGA-II). An important part of the paper is devoted to a broad comparative analysis of our approach and as many as 26 alternative techniques arranged in 32 experimental set-ups and applied to three well-known benchmark medical data sets (Breast Cancer Wisconsin (Original), Pima Indians Diabetes, and Heart Disease (Cleveland)) available from the UCI repository of machine learning databases (http://archive.ics.uci.edu/ml). A number of useful in medical applications performance measures including accuracy, sensitivity, specificity, and several interpretability measures are employed. The results of such a broad comparative analysis demonstrate that our approach significantly outperforms the alternative methods in terms of the interpretability of the obtained FRBCSs while remaining either competitive or superior in terms of their accuracy. It is worth stressing that the overwhelming majority of the existing medical classification methods concentrate almost exclusively on the accuracy issues.

Do method and species lifestyle affect measures of maximum metabolic rate in fishes?

The rate at which active animals can expend energy is limited by their maximum aerobic metabolic rate (MMR). Two methods are commonly used to estimate MMR as oxygen uptake in fishes, namely during prolonged swimming or immediately following brief exhaustive exercise, but it is unclear whether they return different estimates of MMR or whether their effectiveness for estimating MMR varies among species with different lifestyles. A broad comparative analysis of MMR data from 121 fish species revealed little evidence of different results between the two methods, either for fishes in general or for species of benthic, benthopelagic or pelagic lifestyles.

Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae.

Broad-based species comparisons across mammalian orders suggest a number of factors that might influence the evolution of large brains. However, the relationship between these factors and total and regional brain size remains unclear. This study investigated the relationship between relative brain size and regional brain volumes and sociality in 13 felid species in hopes of revealing relationships that are not detected in more inclusive comparative studies. In addition, a more detailed analysis was conducted of four focal species: lions (Panthera leo), leopards (Panthera pardus), cougars (Puma concolor), and cheetahs (Acinonyx jubatus). These species differ markedly in sociality and behavioral flexibility, factors hypothesized to contribute to increased relative brain size and/or frontal cortex size. Lions are the only truly social species, living in prides. Although cheetahs are largely solitary, males often form small groups. Both leopards and cougars are solitary. Of the four species, leopards exhibit the most behavioral flexibility, readily adapting to changing circumstances. Regional brain volumes were analyzed using computed tomography. Skulls (n = 75) were scanned to create three-dimensional virtual endocasts, and regional brain volumes were measured using either sulcal or bony landmarks obtained from the endocasts or skulls. Phylogenetic least squares regression analyses found that sociality does not correspond with larger relative brain size in these species. However, the sociality/solitary variable significantly predicted anterior cerebrum (AC) volume, a region that includes frontal cortex. This latter finding is despite the fact that the two social species in our sample, lions and cheetahs, possess the largest and smallest relative AC volumes, respectively. Additionally, an ANOVA comparing regional brain volumes in four focal species revealed that lions and leopards, while not significantly different from one another, have relatively larger AC volumes than are found in cheetahs or cougars. Further, female lions possess a significantly larger AC volume than conspecific males; female lion values were also larger than those of the other three species (regardless of sex). These results may reflect greater complexity in a female lion’s social world, but additional studies are necessary. These data suggest that within family comparisons may reveal variations not easily detected by broad comparative analyses.

Spectroscopic and laser characterization of Yb0.15:(LuxY1-x)3Al5O12 ceramics with different Lu/Y balance.

We report a broad comparative analysis of the spectroscopic and laser properties of solid solution Lutetium-Yttrium Aluminum Garnet (LuYAG, (LuxY1-x)3Al5O12) ceramics doped with Yb. The investigation was mainly aimed to assess the impact of the Lu/Y ratio on the Yb optical and laser properties. Therefore we analyzed a set of samples with different Y/Lu balance, namely 25/75, 50/50 and 75/25, with 15% Yb doping. We found that the Yb absorption and emission spectra changed from YAG to LuAG when gradually increasing in Lu content. Regarding the laser emission, remarkable results were achieved with all samples. Maximum output power was 8.2 W, 7.3 W and 8.7 W for Y/Lu balance 25/75, 50/50 and 75/25 respectively, at 1030 nm; the slope efficiency and the optical-to-optical efficiencies approached or exceeded 60% and 50% respectively. The tuning range was investigated using an intracavity ZnSe prism. The broadest tuning range (998 nm to 1063 nm) was obtained with Y/Lu balance 75/25, whereas the emission of the other two samples extended from 1000 nm to 1058 nm. To the best of our knowledge, this is the first comparative analysis of Yb:LuYAG ceramics or crystals as laser host across such a broad range of Y/Lu ratios.

Russian Exceptionalism: a Comparative Perspective

Abstract This article seeks to define a certain form of exceptionalism - missionist exceptionalism - and ask to what extent it applies to Russia. The method will be a broad comparative analysis. The core argument is that missionist exceptionalism is fundamentally paradoxical; that polities make largely similar claims about themselves while pleading sui generis uniqueness. This hypothesis is asserted by examining the exceptionalism of other polities. These are two rivals of Russia; the United States and Poland, a “sentimental ally” of Russia, Serbia, and a country with a deep and interesting relationship with Russia, Israel.

Mapping the Profit Motive: A Comparative Analysis of For-­Profit and Non-­Profit Charter Schools

For-profit charter schools represent a controversial new market-based education reform (Garcia, Barber, & Molnar, 2009; Conn, 2002). This essay explores how schools operated by for-profit corporations differ from those operated by non-profit organizations. Specifically, do for-profit charter schools locate in demographically distinct areas and serve different student populations than similar schools operated by non-profit providers? Research suggests that charter school operators in some districts appear to strategically locate their schools in an effort to exclude certain student populations (Lubienski, Gulosino, & Weitzel, 2009). If charter schools seek to exclude certain students, as these schools proliferate in a district or region there may be an intensifying stratification effect detrimental to the most disadvantaged students (Bifulco, Ladd, & Ross, 2009). This essay undertakes a broad comparative analysis of the neighborhood demographic and student population characteristics of charter schools operated by for-profit corporations and nonprofit organizations, using multilevel modeling and geographic information systems, to compare the two school types across dissimilar state contexts. In so doing, the study seeks to isolate the impact of a school being operated by a for-profit corporation and illuminate what impact the proliferation of for-profit schools might have on the distribution of student populations across regions.

Expatriates as voters? The new dynamics of external voting in Sub-Saharan Africa

Expatriate voting has gained in importance over the last decade in Sub-Saharan Africa. This article gives an empirical overview of existing regulations in all independent states of the continent and examines some explanatory approaches in the African context. One approach claims that expatriate enfranchisement is a functional response to the increasing importance of migrants and their remittances. A second explanation refers to the role of domestic political structures and regime types. A third cluster of explanatory factors links external voting to the interests of political parties. Both in the broader comparative analysis and by looking more specifically at the cases of Ghana, South Africa, Cape Verde and Nigeria, all three approaches specifically contribute to understanding variation of external voting rights in Sub-Saharan Africa.

Fiscal Policy Issues in the Aging Societies

Aging may be one of the most far-reaching processes defining the economic, fiscal, and social changes societies are likely to experience over the next 40 years. The demographic consequences of aging will have a dramatic impact on labor markets, economic growth, social structures — and government budgets. These issues have gained urgency after the second largest global recession in the past 100 years. Based on a broad comparative analysis of countries that include the EU and non-EU European and Central Asian countries, as well as several case studies and model simulations, the paper seeks to provide broad answers — tailored in part to distinct groups of countries according to their aging-fiscal profiles –– to major questions facing governments’ budgets in aging societies: What are the fiscal-aging profiles of Western European, emerging European, and Central Asian countries? In other words, how good or bad is their fiscal situation — “initial conditions” — in view of their emerging aging-related problems? What kind of public spending pressures are likely to emerge in the coming decades, and what will be their relative importance? How do countries compare in terms of the possible impacts of aging on growth and long-term debt sustainability? What can be learned from in-depth and comparative case studies of aging, fiscal sustainability, and fiscal reform? Are there good-practice examples — countries doing things right at the right time — that may offer lessons for the others? And, perhaps most important, given the need for long-term fiscal consolidation for many countries, what kind of revenue and expenditure policy agendas are likely to emerge to mitigate the effects of aging? A key policy conclusion is that countries should aim for early rather than delayed reforms dealing with long-term aging pressures. The urgency is accentuated by the debt situations and/or adverse debt and demographic dynamics in almost all countries but also by the evolving voter preferences. As societies age and voting preferences increasingly reflect the political will of the older population, it will become more difficult to enact the necessary reforms ensuring social and fiscal sustainability.

A geometric morphometrics comparative analysis of Neandertal humeri (epiphyses-fused) from the El Sidrón cave site (Asturias, Spain)

A new collection of 49,000 year old Neandertal fossil humeri from the El Sidrón cave site (Asturias, Spain) is presented. A total of 49 humeral remains were recovered, representing 10 left and 8 right humeri from adults, adolescents, and a juvenile (not included in the analyses). 3D geometric morphometric (GM) methods as well as classic anthropological variables were employed to conduct a broad comparative analysis by means of mean centroid size and shape comparisons, principal components analysis, and cluster studies. Due to the fragmentary nature of the fossils, comparisons were organized in independent analyses according to different humeral portions: distal epiphysis, diaphysis, proximal epiphysis, and the complete humerus. From a multivariate viewpoint, 3D-GM analyses revealed major differences among taxonomic groups, supporting the value of the humerus in systematic classification. Notably, the Australopithecus anamensis (KP-271) and Homo ergaster Nariokotome (KNM-WT 15000) distal humerus consistently clusters close to those of modern humans, which may imply a primitive condition for Homo sapiens morphology. Australopithecus specimens show a high degree of dispersion in the morphospace. The El Sidrón sample perfectly fits into the classic Neandertal pattern, previously described as having a relatively wide olecranon fossa, as well as thin lateral and medial distodorsal pillars. These characteristics were also typical of the Sima de los Huesos (Atapuerca) sample, African mid-Pleistocene Bodo specimen, and Lower Pleistocene TD6-Atapuerca remains and may be considered as a derived state. Finally, we hypothesize that most of the features thought to be different between Neandertals and modern humans might be associated with structural differences in the pectoral girdle and shoulder joint.

Comparative TKI Profiling Analyses to Explore Potential Mechanisms of Ponatinib-Associated Arterial Thrombotic Events

Abstract Background: Ponatinib is a potent pan-BCR-ABL tyrosine kinase inhibitor (TKI) indicated for patients with T315I positive or treatment-refractory CML and Ph+ ALL. To develop hypotheses regarding molecular and cellular targets of ponatinib that could contribute to arterial thrombotic events observed in some patients we are undertaking a broad comparative profiling analysis of ponatinib and other TKIs. Methods: Cellular activities of ponatinib and additional BCR-ABL (imatinib, nilotinib, dasatinib, bosutinib) and VEGFR2/multi-targeted (sunitinib, regorafenib) TKIs were examined in panels of Ba/F3 cell lines expressing activated kinase variants (N=61), tumor cell lines (N=246), and primary lines derived from human vasculature (aortic smooth muscle cells [ASMC] and umbilical vein [HUVEC], aortic [HAEC] and pulmonary artery [HPAEC] endothelial cells). Human steady-state Cave concentrations of 45 mg ponatinib (101 nM) were corrected for the functional effects of protein binding (3.6-fold) to derive the clinically-effective concentration. Results: Ponatinib inhibits the in vitro activity of multiple kinases with IC50s within 10-fold of ABL, including members of the VEGFR, PDGFR, FGFR, EPH receptor and SRC families of kinases, KIT, RET, TIE2, and FLT3. This profile was largely recapitulated in cellular assays using engineered Ba/F3 cells, with ponatinib demonstrating substantially greater potency against VEGFRs, FGFRs, TIE2, RET and FLT3 than other ABL TKIs. Across a broad panel of tumor cell lines, ponatinib inhibited viability with a median IC50 of 598 nM. Ponatinib only inhibited 16 cell lines (6.5%) with IC50s below its clinically effective concentration (28 nM) with the 5 most sensitive lines (IC50 <1 nM) all being BCR-ABL positive. Within the vasculature-derived cell panel, ponatinib inhibited viability of HUVECs grown in full serum with an IC50 of 261 nM, with all of the other ABL and non-ABL TKIs tested having IC50s >2000 nM. Effects of ponatinib on HAECs, HPAECs and ASMCs were more modest (IC50s 1533, 490 and 750 nM, respectively). Finally, ponatinib (IC50 20 nM) and other VEGFR2 inhibitors potently inhibited survival of HUVECs grown in VEGF-dependent conditions, while other BCR-ABL inhibitors, except dasatinib (IC50 14 nM), did not. Conclusions: Ponatinib is a potent BCR-ABL inhibitor that also inhibits VEGFR2 and other kinases at clinically achievable concentrations in vitro. Modest effects of ponatinib on endothelial cells have been observed that warrant further exploration in vivo. Developing a precise understanding of the mechanism by which ponatinib contributes to arterial thrombotic events should facilitate development of strategies to optimize its benefit/risk in patients. Disclosures Rivera: ARIAD Pharmaceuticals Inc: Employment, Equity Ownership. Pritchard:ARIAD Pharmaceuticals, Inc.: Employment, Equity Ownership. Gonzalvez:ARIAD Pharmaceuticals, Inc.: Employment, Equity Ownership. Baker:ARIAD Pharmaceuticals, Inc.: Employment, Equity Ownership. Gozgit:ARIAD Pharmaceuticals, Inc.: Employment, Equity Ownership. Hodgson:ARIAD Pharmaceuticals, Inc.: Employment, Equity Ownership.

Polyploid formation shapes flowering plant diversity.

Polyploidy, or whole genome duplication, has been an important feature of eukaryotic evolution. This is especially true in flowering plants, where all extant angiosperms have descended from polyploid species. Here we present a broad comparative analysis of the effect of polyploidy on flowering plant diversity. We examine the widely held hypothesis that polyploid flowering plants generate more diversity than their diploid counterparts, by fitting stochastic birth/death models to observed ploidal frequency data from 60 extant angiosperm genera. Our results suggest the opposite, that diploids speciate at higher rates than polyploids, through a combination of simple diploid speciation and tetraploidy. Importantly, the estimated diploid advantage stemmed primarily from a higher rate of polyploidization in diploids than polyploids. Our model is also able to account for the empirically observed correlation between polyploidy and species richness without assuming that polyploids have a speciation advantage over diploids.

Nymphalid eyespot serial homologues originate as a few individualized modules.

Serial homologues are repeated traits that share similar development but occur in different parts of the body. Variation in number of repeats accounts for substantial diversity in animal form and considerable work has focused on identifying the factors accounting for this variation. Little is known, however, about how serial homologues originally become repeated, or about the relative timing of repeat individuation relative to repeat origin. Here, we show that the serially repeated eyespots on nymphalid butterfly wings most likely arose as a small cluster of units on the ventral hindwing that were later co-opted to the dorsal and anterior wing surfaces. Based on comparative analyses of over 400 species, we found support for a model of eyespot origin followed by redeployment, rather than by the conventional model, where eyespots arose as a complete row of undifferentiated units that later gained individuation. In addition, eyespots most likely evolved from simpler pattern elements, single-coloured spots, which were already individuated among different wing sectors. Finally, the late appearance of eyespots on the dorsal, hidden wing surface further suggests that these novel complex traits originally evolved for one function (thwarting predator attacks) and acquired a second function (sexual signalling) when moved to a different body location. This broad comparative analysis illustrates how serial homologues may initially evolve as a few units serving a particular function and subsequently become repeated in novel body locations with new functions.

The Key Factors to Promote LNG-Powered Vessels in Inland Waterway Transport of China

Using LNG as ship fuel is one of the most important measures applied to reduce shipping emission and green development in recent years. This paper aims to study on the feasibility of applying LNG to inland waterway vessels in China. A broad investigation, data analysis and comparative analysis are conducted in this paper to get insightful conclusions regarding to the feasibility of technology, the effect of emission reduction, the economic feasibility and bunkering pathway. It is found that it is practicable to apply LNG in inland waterway vessels from the technical and secure perspective, the emission of CO2、NOX and SOX can be reduced. However, the cost will increase significantly, in particular for the vessels in small sizes.

Visual Acuity in Mammals: Effects of Eye Size and Ecology

Previous comparative research has attributed interspecific variation in eye size among mammals to selection related to visual acuity. Mammalian species have also been hypothesized to differ in visual acuity partly as a result of differences in ecology. While a number of prior studies have explored ecological and phylogenetic effects on eye shape, a broad comparative analysis of the relationships between visual acuity, eye size and ecology in mammals is currently lacking. Here we use phylogenetic comparative methods to explore these relationships in a taxonomically and ecologically diverse sample of 91 mammal species. These data confirm that axial eye length and visual acuity are significantly positively correlated in mammals. This relationship conforms to expectations based on theoretical optics and prior analyses of smaller comparative samples. Our data also demonstrate that higher visual acuity in mammals is associated with: (1) diurnality and (2) predatory habits once the effects of eye size and phylogeny have been statistically controlled. These results suggest that interspecific variation in mammalian visual acuity is the result of a complex interplay between phylogenetic history, visual anatomy and ecology.

Stone cairns across eastern Africa: a critical review

This paper collates and synthesises a wide range of reports concerning stone cairns and related structures from across eastern Africa. These features often enclose human burials and are common in many areas, but they have only ever been sporadically investigated. I attempt to arrange them into a preliminary typology and make the first steps towards a broader comparative analysis. While these features have often been referred to as monuments and in some instances ‘megaliths’ I urge caution in such labelling. We should first evaluate the social context of their construction before we equate them with concepts derived from other parts of the world. Understanding the construction of eastern African landscapes through features such as these may provide a broader context for studying some of the region's larger and more commonly investigated monuments.