Threatened Neotropical mollusks: Analysis of shape differences in three endemic snails from High Paraná River by geometric morphometrics

Variation in shape among a living and 2 extinct aquatic snails of the genus Aylacostoma, using a geometric morphometric method of thin plate splines and multivariate analysis was investigated. The analysis was performed to evaluate the diagnostic capability of this method and to explore shell shape differences, due to the lack of other data, in an attempt to answer why only 1 of the species persisted in the wild. Sixteen landmarks in a bi-dimensional space for 32 shells of type, paratype and reference specimens deposited in museums of Argentina were defined. Analysis was successful in assigning individual specimens to particular species. Statistically significant differences in last whorl, aperture, and spire were found for the first 4 non-uniform components explaining an 85% of local variation observed. Differences could be related to a differential use of habitat and/or to the degree of exposure to water current. More globose shell found in the extinct species could be associated to habitats and substrata with the highest water currents, whereas the more stylized shell in the third species could be related to a preference for more protected habitats, like those where it presently occurs.Facultad de Ciencias Naturales y Muse

Threatened Neotropical mollusks: Analysis of shape differences in three endemic snails from High Paraná River by geometric morphometrics

Variation in shape among a living and 2 extinct aquatic snails of the genus Aylacostoma, using a geometric morphometric method of thin plate splines and multivariate analysis was investigated. The analysis was performed to evaluate the diagnostic capability of this method and to explore shell shape differences, due to the lack of other data, in an attempt to answer why only 1 of the species persisted in the wild. Sixteen landmarks in a bi-dimensional space for 32 shells of type, paratype and reference specimens deposited in museums of Argentina were defined. Analysis was successful in assigning individual specimens to particular species. Statistically significant differences in last whorl, aperture, and spire were found for the first 4 non-uniform components explaining an 85% of local variation observed. Differences could be related to a differential use of habitat and/or to the degree of exposure to water current. More globose shell found in the extinct species could be associated to habitats and substrata with the highest water currents, whereas the more stylized shell in the third species could be related to a preference for more protected habitats, like those where it presently occurs.Facultad de Ciencias Naturales y Muse

Associations Between Genetic Data and Quantitative Assessment of Normal Facial Asymmetry

Human facial asymmetry is due to a complex interaction of genetic and environmental factors. To identify genetic influences on facial asymmetry, we developed a method for automated scoring that summarizes local morphology features and their spatial distribution. A genome-wide association study using asymmetry scores from two local symmetry features was conducted and significant genetic associations were identified for one asymmetry feature, including genes thought to play a role in craniofacial disorders and development: NFATC1, SOX5, NBAS, and TCF7L1. These results provide evidence that normal variation in facial asymmetry may be impacted by common genetic variants and further motivate the development of automated summaries of complex phenotypes

Threatened Neotropical mollusks: Analysis of shape differences in three endemic snails from High Paraná River by geometric morphometrics

Variation in shape among a living and 2 extinct aquatic snails of the genus Aylacostoma, using a geometric morphometric method of thin plate splines and multivariate analysis was investigated. The analysis was performed to evaluate the diagnostic capability of this method and to explore shell shape differences, due to the lack of other data, in an attempt to answer why only 1 of the species persisted in the wild. Sixteen landmarks in a bi-dimensional space for 32 shells of type, paratype and reference specimens deposited in museums of Argentina were defined. Analysis was successful in assigning individual specimens to particular species. Statistically significant differences in last whorl, aperture, and spire were found for the first 4 non-uniform components explaining an 85% of local variation observed. Differences could be related to a differential use of habitat and/or to the degree of exposure to water current. More globose shell found in the extinct species could be associated to habitats and substrata with the highest water currents, whereas the more stylized shell in the third species could be related to a preference for more protected habitats, like those where it presently occurs.Facultad de Ciencias Naturales y Muse

Revealing the vectors of cellular identity with single-cell genomics

Single-cell genomics has now made it possible to create a comprehensive atlas of human cells. At the same time, it has reopened definitions of a cell's identity and of the ways in which identity is regulated by the cell's molecular circuitry. Emerging computational analysis methods, especially in single-cell RNA sequencing (scRNA-seq), have already begun to reveal, in a data-driven way, the diverse simultaneous facets of a cell's identity, from discrete cell types to continuous dynamic transitions and spatial locations. These developments will eventually allow a cell to be represented as a superposition of 'basis vectors', each determining a different (but possibly dependent) aspect of cellular organization and function. However, computational methods must also overcome considerable challenges-from handling technical noise and data scale to forming new abstractions of biology. As the scale of single-cell experiments continues to increase, new computational approaches will be essential for constructing and characterizing a reference map of cell identities.National Institutes of Health (U.S.) (grant P50 HG006193)BRAIN Initiative (grant U01 MH105979)National Institutes of Health (U.S.) (BRAIN grant 1U01MH105960-01)National Cancer Institute (U.S.) (grant 1U24CA180922)National Institute of Allergy and Infectious Diseases (U.S.) (grant 1U24AI118672-01

The Role of Hydrologic Regimes in Driving Morphologic Divergence and the Trait Compositions of Fish Assemblages

The hydrologic regime is an important determinant of the ecological integrity of a stream. Hydrologic regimes are defined by the magnitude, timing, frequency, rate of change, and duration of high and low flow events and capture long term patterns of variability and predictability of water movement in a stream. Flow regimes influence many aspects of the biophysical environment in lotic systems; therefore organisms have adapted to natural flow patterns. We investigated how fish have adapted to flow regimes at both a population and community level. In the first study presented in this thesis, we hypothesized fish exhibit phenotypic divergence to allow them to persist across gradients of hydrologic variability. We combined a comparative field study and mesocosm experiment to investigate the morphological divergence of Campostoma anomalom (central stonerollers) between streams characterized by highly variable, intermittent flow regimes and streams characterized by relatively stable, groundwater flow regimes and assessed the plastic effects of one component of flow regimes, magnitude (water velocity), on fish morphology. We observed differences in shape between flow regimes likely driven by differences in allometric growth patterns, but observed no morphologic plasticity. The second study included in this thesis investigated the relationships between fish traits and hydrologic metrics and determined how traits are spatially auto-correlated within a stream network. We observed complex relationships between fish traits and hydrology; some traits exhibited different responses in different flow regimes. Trait-hydrology relationships were the strongest in groundwater and runoff streams, but very weak in intermittent streams. Spatial factors described more variability in the distribution of fish traits than hydrologic metrics within and between flow regimes and different types of spatial auto-correlation structured trait patterns across flow regimes. Overall, the results of these studies support the implementation of environmental-flow standards and contribute new considerations to include in the development of ecological-flow relationships

Quantitative analysis of suture lines in Carboniferous ammonoids

Two morphometric methods are applied and compared for the analysis of suture lines in Early Carboniferous ammonoids of the superfamilies Pericycloidea, Girtyoceratoidea and Goniatitoidea. We analysed (1) classic metric data (proportions of the width and depths or heights of lobes and saddles) using multivariate statistic methods and (2) outline data of the external lobe and the ventrolateral saddle of the same ammonoid taxa using the elliptic Fourier analysis. Both methods lead to similar results and simultaneously demonstrate ontogenetic and phylogenetic trends of these ammonoids. Our results are consistent with three previously suggested evolutionary patterns: (1) a general decrease of the amplitude of lobes and saddles, (2) a proportional widening of the external lobe and (3) a heightening of the median saddle.</p

A Predictive Model of "Favorable" Versus "Unfavorable" Growth For Orthodontic Treatment Planning

. Purpose The purpose of this study was to use longitudinal cephalometric data to identify cephalometric characteristics associated with “favorable” and “unfavorable” craniofacial growth patterns in adolescents. Materials and Methods This retrospective longitudinal study included 226 untreated adolescent subjects, ages 10-15. Subjects were grouped as “favorable” and “unfavorable” based on the horizontal relationships of the maxillary and mandibular skeletal bases, defined by ANS and Pg. They were grouped based on these relations at 10 and 15, as well as on the changes that occurred between 10 and 15. Statistical analyses, including paired t-tests, bivariate correlations, and multiple regressions, were used to determine the associations. Discriminant analysis was used to predict group membership at age 15. Results Horizontal maxillomandibular relationships of females, but not males, worsened between 10 and 15 years of age. The majority (58%) of the subjects with favorable horizontal relationships at 10 maintained their favorable horizontal relationships. Relationships at 15 were most closely associated with changes or relationships between T1 and T2. Multiple regression showed that the Y-axis, ANS-N-Pg and symphysial angle explained approximately 60% of the variation in horizontal relationships at age 15. Discriminant function, using these three variables, correctly predicted “favorable” or “unfavorable” relations at age 15 77.4% of the time. Conclusions While most horizontal relationships are stable, individual variability is great. To determine an individual’s relationship at 15, information about their relationships at 10 and the changes between 10 and 15 are needed, with the changes beting the most important. Horizontal relations at age 15 are able to be predicted using the variables of Y-axis, ANS-N-Pg, and symphysial angle. Using these variables it is possible to predict if a subject will have favorable or unfavorable relations with over 75% accuracy

Statistical Shape and Intensity Modeling of the Shoulder

Anatomical variability in the shoulder is inherently present and can influence healthy and pathologic biomechanics and ultimately clinical decision-making. Characterizing variation in bony morphology and material properties in the population can support treatment and specifically the design, via shape and sizing, of shoulder implants. Total Shoulder Arthroplasty (TSA) is the treatment of choice for glenohumeral osteoarthritis as well as bone fracture. Complications and poor outcomes in TSA are generally influenced by the inability of the implant to replicate the natural joint biomechanics and by the bone quality around the fixation features. For this reason, knowledge of bony morphology and mechanical properties can support optimal implant design and sizing, and thus improve TSA results. Statistical shape and intensity modeling is a powerful tool to represent the shape and mechanical properties variation in a training set. Accordingly, the objectives of this thesis were: 1) to develop a statistical shape model (SSM) of the proximal humeral cortical and cancellous bone; 2) to develop an SSM and a statistical intensity model (SIM) of the scapular bone. A training set of 85 humeri and 53 scapulae were reconstructed from CT scans and registered to common templates. Principal Component Analysis (PCA) was applied to the registered geometries to quantify morphological and bone properties variation in the population. For both the humerus and the scapula SSM, the first mode of variation accounted for most of the variation and described scaling. Subsequent modes described changes in the scapular plate, acromion process and scapular notch for the scapula, and in the neck angle, head inclination, greater and lesser tubercles for the humerus. Variation in cortical thickness of the humeral diaphysis was largely independent of size and statistically significant differences with ethnicity were noted. Asian subjects showed higher humeral cortical thickness with respect to Caucasians, regardless of gender. The first mode of variation in the scapular SIM described scaling in material properties distribution, with higher bone density located centrally and anteriorly in the glenoid region. The bone property maps developed for the scapular training set realistically captured inter-subject variability and they represent a valuable tool to assess fixation features and screw location and trajectories for TSA glenoid component. The SSMs and SIM developed in this thesis represent a useful infrastructure to support population-based evaluations and assess possible anatomical differences with gender and ethnicity, SSM and SIM can also provide anatomical relationship in support of implant design and sizing