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Morphological Variables (morphological + variable)
Selected AbstractsIncreased Behavioral Variation and the Calculation of Release Numbers for Reintroduction ProgramsCONSERVATION BIOLOGY, Issue 3 2004M. ELSBETH McPHEE This increased variation can translate into decreased survivorship upon reintroduction to native habitats. Data show that captive populations of oldfield mice (Peromyscus polionotus subgriseus) exhibit such an increase in variation. Motivated by these results, we developed a series of calculations for a "release ratio" that can be used to determine the number of captive-bred animals needed to compensate for the increased variance. We present calculations of release ratios for behavioral and morphological variables with different distributions and illustrate the functional relationship between release numbers, increased variation, and change in average behavior and morphology. Our calculations indicated that the release of 130,150 captive-bred oldfield mice is equivalent to the release of 100 wildlike animals. Release ratios will vary among species, however, and perhaps among different populations of the same species and should be calculated separately for each situation. Development of the release ratio is the first rigorous effort to incorporate behavioral and morphological changes due to captivity into reintroduction planning. Release ratios will help conservation biologists ensure that the appropriate number of animals is released, thus increasing the success of reintroduction programs. Resumen:,Las poblaciones cautivas pueden exhibir mayor variación conductual que sus contrapartes silvestres como resultado del relajamiento de presiones selectivas en el ambiente de cautiverio. Esta variación incrementada puede traducirse en una disminución de la supervivencia en la reintroducción a hábitats nativos. Hay datos que muestran que poblaciones cautivas de ratones Peromyscus polionotus subgriseus exhiben tal incremento en la variación. Motivados por estos resultados, desarrollamos una serie de cálculos para un "índice de liberación" que pueda utilizarse para determinar el número de animales criados en cautiverio requerido para compensar la variación incrementada. Presentamos los cálculos de 2 índices de liberación para variables conductuales y morfológicas con distribuciones diferentes e ilustramos la relación funcional entre el número de liberaciones, la variación incrementada y el cambio en la conducta promedio y la morfología. Nuestros cálculos indicaron que la liberación de 130 a 150 ratones es equivalente a la liberación de 100 animales silvestres. Sin embargo, los índices de liberación varían entre especies y quizás entre poblaciones diferentes de la misma especie y deben calcularse por separado en cada situación. El desarrollo de índices de liberación es el primer esfuerzo riguroso para incorporar cambios conductuales y morfológicos debido al cautiverio en la planificación de reintroducciones. Los índices de liberación ayudarán a que los biólogos de la conservación se aseguren que el número de animales liberados es el apropiado, incrementando con ello el éxito de los programas de reintroducción. [source] Pleomorphic adenoma: Cytologic variations and potential diagnostic pitfallsDIAGNOSTIC CYTOPATHOLOGY, Issue 1 2009Uma Handa M.D. Abstract The diverse morphological features encountered in pleomorphic adenoma (PA) may cause diagnostic errors in fine needle aspiration cytology (FNAC). The present study was performed to evaluate the variations in the cytological features of pleomorphic adenoma and to assess the efficacy of FNAC in its diagnosis. Fifty cases diagnosed as PA on FNAC were retrieved from the records of the Pathology Department. Cytologic smears and sections were reviewed and the cytologic diagnoses were compared with the definitive histologic diagnoses. In cases correctly diagnosed on aspiration, morphological variables like patterns of the epithelial component, type and extent of the mesenchymal matrix, metaplastic cells, hyaline globules, cystic change, giant cells, crystalline deposits, nuclear inclusions/grooves, and nuclear atypia were evaluated. The extreme diversity in morphologic features seen in histologic sections was reflected in the smears of PA. Metaplastic changes were observed more frequently in sections, while nuclear changes like inclusions/grooves were more commonly seen in smears. Other morphological features like cylindromatous pattern, giant cells and crystalline deposits were observed with equal frequency in smears and sections. Cytohistologic agreement was present in 45 of the 50 cases (90%). In 5 cases diagnosed as pleomorphic adenoma on FNAC, the histology revealed 1 case each of schwannoma, perineurioma, ectomesenchymal chondromyxoid tumor of tongue, adenoid cystic carcinoma and mucoepidermoid carcinoma. FNAC is a fairly accurate pre-operative procedure for the diagnosis of PA. The cytopathologist needs to be aware of the cytologic variations in pleomorphic adenoma so as to avoid diagnostic errors. Diagn. Cytopathol. 2009. © 2008 Wiley-Liss, Inc. [source] Effects of size and morphology on swimming performance in juvenile brown trout (Salmo trutta L.)ECOLOGY OF FRESHWATER FISH, Issue 4 2003A. F. Ojanguren Abstract,,, Our study assesses swimming capacity (speed and stamina) and possible morphometric determinants of locomotor performance of juvenile brown trout (Salmo trutta L.). We addressed these issues at the individual level to have an approach of the functional significance of intraspecific variation in morphological design. Both swimming speed and endurance time showed significant positive relationships with fish length. Size-corrected values of speed and endurance time were negatively correlated suggesting a phenotypic trade-off between burst and prolonged swimming. Size was also highly correlated with all the morphological variables measured. Therefore, we used the residuals of the regressions of those variables on fish length to remove the effect of body size. A principal components analysis (PCA) summarised the 12 morphological variables into two factors, which accounted for 44.3% of the variance. PC1 combined several measures of body depth and width, whereas PC2 represented mainly postanal length relative to abdomen length. Relationships between the scores of the two factors and size-corrected values of maximum swimming speed and endurance time were weak. PC2 showed a significant positive relationship with endurance time; that is, individuals with longer caudal regions were able to swim against water flow for longer periods of time. Stoutness (PC1) showed a marginally significant negative correlation with endurance time. The lack of stronger relationships could be because of the low morphometric variability among the test individuals, all proceeding from the same population, reared in a common environment, and measured at the same ontogenetic stage. [source] POSTMATING SEXUAL SELECTION: ALLOPATRIC EVOLUTION OF SPERM COMPETITION MECHANISMS AND GENITAL MORPHOLOGY IN CALOPTERYGID DAMSELFLIES (INSECTA: ODONATA)EVOLUTION, Issue 2 2004A. Cordero Rivera Abstract Postmating sexual selection theory predicts that in allopatry reproductive traits diverge rapidly and that the resulting differentiation in these traits may lead to restrictions to gene flow between populations and, eventually, reproductive isolation. In this paper we explore the potential for this premise in a group of damselflies of the family Calopterygidae, in which postmating sexual mechanisms are especially well understood. Particularly, we tested if in allopatric populations the sperm competition mechanisms and genitalic traits involved in these mechanisms have indeed diverged as sexual selection theory predicts. We did so in two different steps. First, we compared the sperm competition mechanisms of two allopatric populations of Calopteryx haemorrhoidalis (one Italian population studied here and one Spanish population previously studied). Our results indicate that in both populations males are able to displace spermathecal sperm, but the mechanism used for sperm removal between both populations is strikingly different. In the Spanish population males seem to empty the spermathecae by stimulating females, whereas in the Italian population males physically remove sperm from the spermathecae. Both populations also exhibit differences in genital morphometry that explain the use of different mechanisms: the male lateral processes are narrower than the spermathecal ducts in the Italian population, which is the reverse in the Spanish population. The estimated degree of phenotypic differentiation between these populations based on the genitalic traits involved in sperm removal was much greater than the differentiation based on a set of other seven morphological variables, suggesting that strong directional postmating sexual selection is indeed the main evolutionary force behind the reproductive differentiation between the studied populations. In a second step, we examined if a similar pattern in genital morphometry emerge in allopatric populations of this and other three species of the same family (Calopteryx splendens, C. virgo and Hetaerina cruentata). Our results suggest that there is geographic variation in the sperm competition mechanisms in all four studied species. Furthermore, genitalic morphology was significantly divergent between populations within species even when different populations were using the same copulatory mechanism. These results can be explained by probable local coadaptation processes that have given rise to an ability or inability to reach and displace spermathecal sperm in different populations. This set of results provides the first direct evidence of intraspecific evolution of genitalic traits shaped by postmating sexual selection. [source] Energetic trade-off between maintenance costs and flight capacity in the sand cricket (Gryllus firmus)FUNCTIONAL ECOLOGY, Issue 4 2008R. F. Nespolo Summary 1Energetic trade-offs are those compromises that appear when the energy budget of an individual's life history closely matches or exceeds the net available energy in the environment in a given moment. In these situations, two or more functions can compete and organisms face physiological decisions in order to survive and reproduce. 2In insects, one of the most costly investments is flight capacity, which increases dispersal capacity but is energetically expensive. Adult sand crickets (Gryllus firmus) can vary drastically in this capacity, being macropterous or micropterous depending on whether they exhibit flight-capable wings. However, this binary phenotype has a continuous subjacent determinant in the macropterous morph which is the mass of the muscles that power flight, the dorso-longitudinal muscles (DLM). 3Using respirometric measurements, we studied a potential trade-off between body parts, the mass of the DLM and energy metabolism (including both maximum and average metabolism). By recording the metabolic rate of c. 180 crickets and then dissecting and weighing their body parts, we took advantage of the correlational structure to infer associations between energetic and morphological variables. We found that the residual mass of the DLM shows a quadratic relationship with residual resting and average metabolism: at low DLM mass there is a negative relationship, which becomes positive at higher DLM mass. 4We suggest that this pattern of covariance is a consequence of the negative correlation between DLM mass and gonad mass, and the relative contribution of functional vs. non-functional DLM. Then, by using energetics and a combination of multivariate and correlational statistics we were able to show how two important life-history functions (i.e. Dispersal and fecundity) compete for the same resources in an insect species. [source] Seedling growth and morphology of three oak species along field resource gradients and seed mass variation: a seedling age-dependent responseJOURNAL OF VEGETATION SCIENCE, Issue 3 2010Ignacio M. Pérez-Ramos Abstract Question: What is the relative importance of seed mass and abiotic factors in species-specific seedling growth and morphology during the first and the second growing season? How do oak species respond along gradients of these factors? Location: Mediterranean oak forest in southern Spain. Methods: We analysed seedling growth components and morphology of three co-occurring Quercus species (two deciduous and one evergreen). Oak seeds with a wide variety of sizes were sown along broad gradients of abiotic conditions. Intra- and inter-specific differences were evaluated by calibrating maximum likelihood estimators of seedling growth during the first two years of life. Results: We found multiple resources and conditions affecting seedling morphology and biomass allocation. However, the integrative variables of seedling growth , total aboveground biomass and relative growth rate (RGR) , were affected by two main factors: seed mass and light conditions. The relative contribution of these two factors depended strongly on seedling age. Seed mass explained most of the growth and morphological variables during the first year, while light conditions were the best predictor in the second growing season. In contrast, soil factors did not play an important role in seedling growth. We found some evidence of regeneration niche partitioning between oak species along the light gradient, a reflection of their distribution patterns as adults at the study site. Conclusions: We conclude that inter-specific differences in seedling growth, arising from seed size variability and microsite heterogeneity, could be of paramount importance in oak species niche segregation, driving stand dynamics and composition along environmental gradients. [source] Body size and joint posture in primatesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009John D. Polk Abstract Body mass has been shown in experimental and comparative morphological studies to have a significant effect on joint posture in major limb joints. The generalizability of experimental studies is limited by their use of small sample sizes and limited size ranges. In contrast, while comparative morphological studies often have increased sample sizes, the connection between joint posture and morphological variables is often indirect. The current study infers joint postures for a large sample of primates using an experimentally validated method, and tests whether larger primates use more extended joint postures than smaller species. Postures are inferred through the analysis of patterns of subchondral bone apparent density on the medial femoral condyle. Femora from 94 adult wild-shot individuals of 28 species were included. Apparent density measurements were obtained from CT scans using AMIRA software, and the angular position of the anterior-most extent of the region of maximum apparent density on the medial femoral condyle was recorded. In general, the hypothesis that larger-bodied primates use more extended knee posture was supported, but it should be noted that considerable variation exists, particularly at small body sizes. This indicates that smaller species are less constrained by their body size, and their patterns of apparent density are consistent with a wide range of knee postures. The size-related increase in inferred joint posture was observed in most major groups of primates, and this observation attests to the generalizability of Biewener's model that relates body size and joint posture. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] Scaling of chew cycle duration in primatesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Callum F. Ross Abstract The biomechanical determinants of the scaling of chew cycle duration are important components of models of primate feeding systems at all levels, from the neuromechanical to the ecological. Chew cycle durations were estimated in 35 species of primates and analyzed in conjunction with data on morphological variables of the feeding system estimating moment of inertia of the mandible and force production capacity of the chewing muscles. Data on scaling of primate chew cycle duration were compared with the predictions of simple pendulum and forced mass,spring system models of the feeding system. The gravity-driven pendulum model best predicts the observed cycle duration scaling but isrejected as biomechanically unrealistic. The forced mass,spring model predicts larger increases in chew cycle duration with size than observed, but provides reasonable predictions of cycle duration scaling. We hypothesize that intrinsic properties of the muscles predict spring-like behavior of the jaw elevator muscles during opening and fast close phases of the jaw cycle and that modulation of stiffness by the central nervous system leads to spring-like properties during the slow close/power stroke phase. Strepsirrhines show no predictable relationship between chew cycle duration and jaw length. Anthropoids have longer chew cycle durations than nonprimate mammals with similar mandible lengths, possibly due to their enlarged symphyses, which increase the moment of inertia of the mandible. Deviations from general scaling trends suggest that both scaling of the jaw muscles and the inertial properties of the mandible are important in determining the scaling of chew cycle duration in primates. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Prognostic significance of tumour angiogenesis in schistosoma-associated adenocarcinoma of the urinary bladderBJU INTERNATIONAL, Issue 1 2002E. El Sobky Objective To report on tumour angiogenesis and its relationship with morphological variables and prognosis in adenocarcinoma of the urinary bladder associated with schistosomiasis. Patients and methods Fifty-five vesical adenocarcinomas were evaluated from 30 men and 25 women (mean age 47.2 years, sd 8.7, range 30,65) who were followed up after radical cystectomy and urinary diversion for a mean (sd, range) of 61 (43.5, 2.7,159.5) months. Vessels were stained immunohistochemically using an antibody to the platelet endothelial cell-adhesion molecule CD31. Microvessels were counted in active areas of angiogenesis within the tumours (at ×,250) and the microvessel density (MVD) quantified using the mean of three counts. Treatment failure was defined as death from cancer or the development of local recurrence or distant metastasis. Kaplan-Meier survival curves and Cox's proportional hazard model were used to assess survival. Results The overall 5- and 10-year survival rates were 57% and 51%, respectively. The presence of lymph node metastasis and high mean vascular density (> 26) were significantly associated with a poor prognosis. The 5-year survival for patients with negative lymph nodes was 66% while no patients with positive nodes survived for 5 years (P < 0.001); the survival was 72% for patients with a low MVD and 33% for those with a high MVD (P = 0.0016). From individual results plotted against vascularity in lymph node-negative patients, there was a significantly better outcome for those with a low MVD ( 26; P = 0.0099); this significance was maintained on multivariate analysis. However, there was no significant relationship between angiogenesis and the different clinicopathological factors apart from the grade (P = 0.03); tumour stage, grade and DNA profile had no significant effect on survival in these patients. Conclusions These findings suggest that assessing angiogenesis using the MVD provides an independent predictor of survival in patients with adenocarcinoma of the urinary bladder. [source] | |||||||||||||