451 research outputs found

    Modularity for Mathematica

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    Morphological integration is correlation of parts, the integration of morphological traits or features that must function, grow, or be passed to offspring on as working units. Individual integrated units are modules, a group of traits that are highly correlated among themselves but only loosely correlated with traits in other modules. The study of integration and modularity was first developed by Olson and Miller (1958) and expanded on by Cheverud (1982), Zelditch (1988), Wagner (1995), Raff (1996), Klingenberg (2000), Mitteroecker (2007) and many others. The basic component of studying modularity and integration is identifying packages of intercorrelated traits that behave independently of other such packages, whether through ontogeny, across individuals within a population, or during the course of evolution. This package performs a simple analysis of modularity on geometric morphometric landmark data. This package accompanies the review by Goswami and Polly (2010). Users are referred to that paper for a discussion of the methods embedded in this package, including their strengths and weaknesses, and for elaboration of other methods that address broader problems

    Morphometric Analysis of Cranial Shape in Fossil and Recent Euprimates

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    Quantitative analysis of morphology allows for identification of subtle evolutionary patterns or convergences in anatomy that can aid ecological reconstructions of extinct taxa. This study explores diversity and convergence in cranial morphology across living and fossil primates using geometric morphometrics. 33 3D landmarks were gathered from 34 genera of euprimates (382 specimens), including the Eocene adapiforms Adapis and Leptadapis and Quaternary lemurs Archaeolemur, Palaeopropithecus, and Megaladapis. Landmark data was treated with Procrustes superimposition to remove all nonshape differences and then subjected to principal components analysis and linear discriminant function analysis. Haplorhines and strepsirrhines were well separated in morphospace along the major components of variation, largely reflecting differences in relative skull length and width and facial depth. Most adapiforms fell within or close to strepsirrhine space, while Quaternary lemurs deviated from extant strepsirrhines, either exploring new regions of morphospace or converging on haplorhines. Fossil taxa significantly increased the area of morphospace occupied by strepsirrhines. However, recent haplorhines showed significantly greater cranial disparity than strepsirrhines, even with the inclusion of the unusual Quaternary lemurs, demonstrating that differences in primate cranial disparity are likely real and not simply an artefact of recent megafaunal extinctions

    Academic Career Development Stress and Mental Health of Higher Secondary Students- an Indian Perspective

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    The authors explored the mental health of students with their academic career-related stressors collecting data from 400 students of different schools of Eastern part of India by using; namely GIS, theGeneral Health Questionnaire (GHQ) and theAcademic Career Development Stress Scale. The data was subjected to t tests and ANOVA. Results indicated (i) academic career development stress along with its ten components reveal dissimilarities with respect to gender and streams of study, (ii) significant relationship were indicated between the mental health status of students and various aspects of academic stress and demographic factors, (iii) qualitative analyses highlighted the complex of association among academic stress, mental health and other variables.

    Complex macroevolutionary dynamics underly the evolution of the crocodyliform skull

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    All modern crocodyliforms (alligators, crocodiles and the gharial) are semi-aquatic generalist carnivores that are relatively similar in cranial form and function. However, this homogeneity represents just a fraction of the variation that once existed in the clade, which includes extinct herbivorous and marine forms with divergent skull structure and function. Here, we use high-dimensional three-dimensional geometric morphometrics to quantify whole-skull morphology across modern and fossil crocodyliforms to untangle the factors that shaped the macroevolutionary history and relatively low phenotypic variation of this clade through time. Evolutionary modelling demonstrates that the pace of crocodyliform cranial evolution is initially high, particularly in the extinct Notosuchia, but slows near the base of Neosuchia, with a late burst of rapid evolution in crown-group crocodiles. Surprisingly, modern crocodiles, especially Australian, southeast Asian, Indo-Pacific species, have high rates of evolution, despite exhibiting low variation. Thus, extant lineages are not in evolutionary stasis but rather have rapidly fluctuated within a limited region of morphospace, resulting in significant convergence. The structures related to jaw closing and bite force production (e.g. pterygoid flange and quadrate) are highly variable, reinforcing the importance of function in driving phenotypic variation. Together, these findings illustrate that the apparent conservativeness of crocodyliform skulls betrays unappreciated complexity in their macroevolutionary dynamics.Fil: Felice, Ryan N.. Colegio Universitario de Londres; Reino Unido. Natural History Museum; Reino UnidoFil: Pol, Diego. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Goswami, Anjali. Natural History Museum; Reino Unid

    Analysis and Prediction of Alerts in Perimeter Intrusion Detection System

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    Perimeter surveillance systems play an important role in the safety and security of the armed forces. These systems tend to generate alerts in advent of anomalous situations, which require human intervention. The challenge is the generation of false alerts or alert flooding which makes these systems inefficient. In this paper, we focus on short-term as well as long-term prediction of alerts in the perimeter intrusion detection system. We have explored the dependent and independent aspects of the alert data generated over a period of time. Short-term prediction is realized by exploiting the independent aspect of data by narrowing it down to a time-series problem. Time-series analysis is performed by extracting the statistical information from the historical alert data. A dual-stage approach is employed for analyzing the time-series data and support vector regression is used as the regression technique. It is helpful to predict the number of alerts for the nth hour. Additionally, to understand the dependent aspect, we have investigated that the deployment environment has an impact on the alerts generated. Long-term predictions are made by extracting the features based on the deployment environment and training the dataset using different regression models. Also, we have compared the predicted and expected alerts to recognize anomalous behaviour. This will help in realizing the situations of alert flooding over the potential threat

    The fossil record of phenotypic integration and modularity: A deep-time perspective on developmental and evolutionary dynamics

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    Variation is the raw material for natural selection, but the factors shaping variation are still poorly understood. Genetic and developmental interactions can direct variation, but there has been little synthesis of these effects with the extrinsic factors that can shape biodiversity over large scales. The study of phenotypic integration and modularity has the capacity to unify these aspects of evolutionary study by estimating genetic and developmental interactions through the quantitative analysis of morphology, allowing for combined assessment of intrinsic and extrinsic effects. Data from the fossil record in particular are central to our understanding of phenotypic integration and modularity because they provide the only information on deep-time developmental and evolutionary dynamics, including trends in trait relationships and their role in shaping organismal diversity. Here, we demonstrate the important perspective on phenotypic integration provided by the fossil record with a study of Smilodon fatalis (saber-toothed cats) and Canis dirus (dire wolves). We quantified temporal trends in size, variance, phenotypic integration, and direct developmental integration (fluctuating asymmetry) through 27,000 y of Late Pleistocene climate change. Both S. fatalis and C. dirus showed a gradual decrease in magnitude of phenotypic integration and an increase in variance and the correlation between fluctuating asymmetry and overall integration through time, suggesting that developmental integration mediated morphological response to environmental change in the later populations of these species. These results are consistent with experimental studies and represent, to our knowledge, the first deep-time validation of the importance of developmental integration in stabilizing morphological evolution through periods of environmental change

    Ecological and life-history drivers of avian skull evolution

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    One of the most famous examples of adaptive radiation is that of the Galápagos finches, where skull morphology, particularly the beak, varies with feeding ecology. Yet increasingly studies are questioning the strength of this correlation between feeding ecology and morphology in relation to the entire neornithine radiation, suggesting that other factors also significantly affect skull evolution. Here, we broaden this debate to assess the influence of a range of ecological and life history factors, specifically habitat density, migration, and developmental mode, in shaping avian skull evolution. Using 3D geometric morphometric data to robustly quantify skull shape for 354 extant species spanning avian diversity, we fitted flexible phylogenetic regressions and estimated evolutionary rates for each of these factors across the full dataset. The results support a highly significant relationship between skull shape and both habitat density and migration, but not developmental mode. We further found heterogenous rates of evolution between different character states within habitat density, migration, and developmental mode, with rapid skull evolution in species which occupy dense habitats, are migratory, or are precocial. These patterns demonstrate that diverse factors impact the tempo and mode of avian phenotypic evolution, and that skull evolution in birds is not simply a reflection of feeding ecology
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