Individual Morphological Traits Research Articles

Extreme dietary specialisation in adult male southern elephant seals: determining variation between individual trophic diets

Although dietary studies have provided important insights into the causes and ramifications of diet variation for the southern elephant seal (SES) (Mirounga leonina), adult males are comparatively underrepresented within that literature. Individual males can vary morphologically as well as behaviourally, leading to differences in their life history trajectories and outcomes. Therefore, to improve our understanding of the male diet, we sought to determine the degree of dietary variation between as well as within individuals from the West Antarctic Peninsula. Secondly, we investigated whether individual morphological traits, seasonality, and year influenced their dietary variation. Whiskers were sampled from 31 adult male seals and used to measure the bulk stable isotope nitrogen (δ15N). We sequentially segmented each whisker to create a time series of datapoints for each individual, allowing us to compare δ15N variation within each seal as well as assess variation between the seals. We then investigated the relationships between male dietary variation and body length, girth, season, and year. We found that adult male SESs maintained an extremely specialised diet. Variation between individuals was strongly correlated with their body size, with larger seals feeding higher up the trophic web. Interestingly, seasonality and year both influenced variation within the seals’ diets, but only year was seen to influence the variability between seals. We discuss the possible causes and ramifications of dietary specialisation for the SES and highlight the need for combined tracking and stable isotope investigations to improve our understanding of the ontogeny of the seals’ dietary specialisation.

Cultural transmission and perception of vessel shapes among Hebron potters

While craft apprenticeship can be understood as socially mediated individual learning, the ensuing prediction of individual and cultural object traits within craft communities has not been investigated. Here we provide an assessment of vessel shape variations occurring through cultural transmission and their visual perception by the craftsmen. To this end, 26 Hebron potters distributed through nine familial transmission units were asked to produce vessels of three different pottery types, then 21 of the participants were invited to visually identify their proper vessels and those of five other potters. We used the Elliptical Fourier method to analyze vessel shape variation among the productions. Our findings demonstrated that the learning process modified the ceramic shape, the cultural morphological traits being combined with new individual traits. Moreover, the individual morphological traits overtook the cultural ones, which is supposed to lead to divergence of vessel shapes within the transmission chain. If certain cultural morphological traits perpetuate through generations, this certainly does not result from fidelity copying occurring through learning but from stabilizing mechanisms such as consumer demand. Our results showed that potters do perceive the subtle same-type vessel shape variations and thereby could select the individual variant they prefer to produce.

Reproductive Output, Synchrony across Depth and Influence of Source Depth in the Development of Early Life stages of Kelp.

Ecklonia radiata is the main foundation species in Australian temperate reefs, yet little has been published on its reproduction and how this may change across its depth range (1-50+m). In this study, we examined differences in sporophyte morphology and zoospore production during a reproductive season and across four depths (7, 15, 25, and 40m). Additionally, we examined differences in germination rate, survival, and morphological traits of gametophytes obtained from these four depths, cultured under the same light and temperature conditions. Multivariate morphology of sporophytes differed significantly between deep (~40m) and shallow sites (7 and 15m), but individual morphological traits were not significantly different across depths. Total spore production was similar across depths but the peak of zoospore release was observed in February at 15m of depth (6,154zoospores · mm-2 of tissue) and the minimum observed in January at 7, 25, and 40m (1,141, 987, and 214zoospores · mm-2 of tissue, respectively). The source depth of zoospores did not have an influence in the germination rate or the survival of gametophytes, and only gametophytes sourced from 40m sites presented significantly less surface area and number of branches. Overall, these results indicate that E. radiata's reproductive performance does not change across its depth range and that kelp beds reproducing in deeper areas may contribute to the replenishment of their shallow counterparts. We propose that deep kelps may constitute a mechanism of resilience against climate change and anthropogenic disturbances.

Phylogenetic and ecological correlates of pollen morphological diversity in a Neotropical rainforest

AbstractMorphology varies enormously across clades, and the morphology of a trait may reflect ecological function or the retention of ancestral features. We examine the tension between ecological and phylogenetic correlates of morphological diversity through a case study of pollen grains produced by angiosperms in Barro Colorado Island, Panama (BCI). Using a molecular phylogeny of 730 taxa, we demonstrate a statistically significant association between morphological and genetic distance for these plants. However, the relationship is non‐linear, and while close relatives share more morphological features than distant relatives, above a genetic distance of ~ 0.7 increasingly distant relatives are not more divergent in phenotype. The pollen grains of biotically pollinated and abiotically pollinated plants overlap in morphological space, but certain pollen morphotypes and individual morphological traits are unique to these pollination ecologies. Our data show that the pollen grains of biotically pollinated plants are significantly more morphologically diverse than those of abiotically pollinated plants.Abstract in Spanish is available with online material.

Conflicting functional effects of xylem pit structure relate to the growth-longevity trade-off in a conifer species

Consistent with a ubiquitous life history trade-off, trees exhibit a negative relationship between growth and longevity both among and within species. However, the mechanistic basis of this life history trade-off is not well understood. In addition to resource allocation conflicts among multiple traits, functional conflicts arising from individual morphological traits may also contribute to life history trade-offs. We hypothesized that conflicting functional effects of xylem structural traits contribute to the growth-longevity trade-off in trees. We tested this hypothesis by examining the extent to which xylem morphological traits (i.e., wood density, tracheid diameters, and pit structure) relate to growth rates and longevity in two natural populations of the conifer species Pinus ponderosa Hydraulic constraints arise as trees grow larger and xylem anatomical traits adjust to compensate. We disentangled the effects of size through ontogeny in individual trees and growth rates among trees on xylem traits by sampling each tree at multiple trunk diameters. We found that the oldest trees had slower lifetime growth rates compared with younger trees in the studied populations, indicating a growth-longevity trade-off. We further provide evidence that a single xylem trait, pit structure, with conflicting effects on xylem function (hydraulic safety and efficiency) relates to the growth-longevity trade-off in a conifer species. This study highlights that, in addition to trade-offs among multiple traits, functional constraints based on individual morphological traits like that of pit structure provide mechanistic insight into how and when life history trade-offs arise.

A transient microtubule-based structure uncovers a new intrinsic asymmetry between the mother centrioles in the early Drosophila spermatocytes.

Parent centrioles are characterized in most organisms by individual morphological traits and have distinct asymmetries that provide different functional properties. By contrast, mother and daughter centrioles are morphologically undistinguishable during Drosophila male gametogenesis. Here we report the presence of previously unrecognized microtubule-based structures that extend into the peripheral cytoplasm of the Drosophila polar spermatocytes at the onset of the first meiosis and are positive for the typical centriolar protein Sas-4 and for the kinesin-like protein Klp10A. These structures have a short lifespan and are no longer found in early apolar spermatocytes. Remarkably, each polar spermatocyte holds only one microtubule-based structure that is associated with one of the sister centriole pairs and specifically with the mother centriole. These findings reveal an inherent asymmetry between the parent centrioles at the onset of male meiosis and also uncover unexpected functional properties between the mother centrioles of the same cells.

Computer‐aided photographic identification of Rosalia alpina (Coleoptera: Cerambycidae) applied to a mark‐recapture study

Abstract Assessing the conservation status of protected species needs quantitative population data, generally obtained using Capture‐Mark‐Recapture methods (CMR). The exploitation of natural marking (e.g. individual morphological traits) offers an interesting alternative, based on image analyses, which may result in a less manipulation of protected species compared to the typical artificial marking method. In our 2‐year CMR study, we tested for the first time in the natural setting the feasibility and the application of the computer‐aided photographic identification method of Rosalia alpina using the individual elytral spots as the natural marking. The I3SC software was used for the photographic analysis. Data were collected from populations of two National Parks of central Italy during July–August in 2014 and 2015. We developed a standard procedure in order to optimise the image acquisition in the field and to acquire clear and comparable images, facilitating the I3SC screening process. The results demonstrated that the computer‐aided photographic identification of natural markings can be implemented in a CMR population study of R. alpina. Our image processing approach showed that using only the elytral central spot contours made the tracing contour process less time‐consuming obtaining reliable results. Furthermore, I3SC output scores were used to identify a threshold value for the identification of new individuals or recaptures, facilitating the final identification proposed by operators. Finally, we assessed the possibility of performing the methodology using a Citizen Science approach.

Natural selection on morphology varies among years and by sex in Magellanic Penguins (Spheniscus magellanicus)

ABSTRACT The evolution of morphology in a population reflects several factors, including the influence of environmental variability on natural selection. We estimated natural selection on, and heritability of, 4 individual morphological traits (bill length, bill depth, flipper length, and foot length) and 2 multivariate morphological traits in adult Magellanic Penguins (Spheniscus magellanicus) at Punta Tombo, Argentina, from 1983 to 2010. We estimated heritability of morphology with parent–offspring regression and animal models, conditioning on sex because the species is sexually dimorphic. For the analysis of selection on each trait, we estimated both linear and quadratic selection gradients, based on the number of fledglings produced, for breeding males and females in each year. Estimates from animal models indicated that all 6 traits were heritable; in parent–offspring regressions, corresponding heritabilities were significantly higher in sons than in daughters in 100% of tests. Over 28 yr, we detecte...

Covarying variances: more morphologically variable populations also exhibit more diet variation.

Many ecologically generalized populations are composed of relatively specialized individuals that selectively consume a subset of their population's diet, a phenomenon known as 'individual specialization'. The Niche Variation Hypothesis posits that this individual specialization can arise during ecological release if niche expansion occurs mainly through diet divergence among individuals, leading to greater morphological variation. Most tests of this hypothesis have searched for correlations between niche width and morphological variance, but this approach rests on the untested assumption that within-population morphological diversity is highly correlated with ecological diversity. Here, we test whether intrapopulation diet variation is correlated with intrapopulation morphological variation, across 12 lacustrine populations of three-spine stickleback. First, we use behavioral observations, isotopes, and gut contents to show that, within populations, individuals differ in microhabitat use and diet. Second, we show that some populations exhibit more diet variation than others, as evidenced by differences in both isotopic and gut content variation among individuals. Finally, we confirm that populations with greater dietary variation are more morphologically variable. However, this relationship is only significant when total morphological variance is examined, not for individual morphological traits. This discordance may reflect among-population differences in the relationship between individual morphology and diet. Because morphology-diet relationships can differ among populations, morphological variance may be a poor predictor of actual diet variation when diverse populations are being compared.

Population structure of the widespread species, Anogeissus leiocarpa (DC.) Guill. & Perr. across the climatic gradient in West Africa semi-arid area

In the climate change context, widely distributed plant species can serve as relevant barometers of ecosystems' sensitivity or resilience to disturbances. This study aimed at assessing the population structure and individual morphological traits of Anogeissus leiocarpa, a widespread tree species, across a broad strip of land, from the north to the south of Burkina Faso. We compared stands in four phytogeographical zones in order to analyze morphological variations in trees and recruits density, individual size and their spatial structure. Our results showed significant increase of tree density from the Sahel (77.1 trees/ha) to the South-Sudanian (166 trees/ha) while diameter, height and basal area had an opposite trend. No recruits were found in the Sahel stands, while their density increased from the Sub-Sahel (5.17 individuals/ha) to the South-Sudanian (6.46 individuals/ha). Tree diameters revealed positive asymmetric distributions in the Sudanian and Sub-Sahel whereas the Sahel stands showed a symmetric distribution. Height structure of saplings revealed “J reverse” shape in Sudanian stands while Sub-Sahelian ones exhibited Gaussian shape. Height–diameter relationships revealed thin trees towards the south-Sudanian. The spatial structure of trees indicated random distributions in all zones whereas recruits presented aggregative distribution trend in the Sudanian zones. A. leiocarpa's trees have a good ability to support broad climatic fluctuations but the populations' rejuvenation is unpredictable in the extreme harsh conditions. The species is fairly resilient to anthropogenic disturbances in Sub-Sahel and Sudanian zones. However, managing issues should pay attention to the species communities by considering its demographic behavior in the health state appreciation of ecosystems.

Recent and Widespread Rapid Morphological Change in Rodents

In general, rapid morphological change in mammals has been infrequently documented. Examples that do exist are almost exclusively of rodents on islands. Such changes are usually attributed to selective release or founder events related to restricted gene flow in island settings. Here we document rapid morphological changes in rodents in 20 of 28 museum series collected on four continents, including 15 of 23 mainland sites. Approximately 17,000 measurements were taken of 1302 rodents. Trends included both increases and decreases in the 15 morphological traits measured, but slightly more trends were towards larger size. Generalized linear models indicated that changes in several of the individual morphological traits were associated with changes in human population density, current temperature gradients, and/or trends in temperature and precipitation. When we restricted these analyses to samples taken in the US (where data on human population trends were presumed to be more accurate), we found changes in two additional traits to be positively correlated with changes in human population density. Principle component analysis revealed general trends in cranial and external size, but these general trends were uncorrelated with climate or human population density. Our results indicate that over the last 100+ years, rapid morphological change in rodents has occurred quite frequently, and that these changes have taken place on the mainland as well as on islands. Our results also suggest that these changes may be driven, at least in part, by human population growth and climate change.

Geographic divergence in floral morphology and scent in Linanthus dichotomus (Polemoniaceae)

Floral reproductive morphology and scent are of primary importance to pollinators in guiding foraging decisions. We compared the floral scent and reproductive morphology between two subspecies of Linanthus dichotomus (Polemoniaceae) that are taxonomically distinguished by geography and flowering time: the vespertine L. dichotomus subsp. dichotomus and the diurnal L. dichotomus subsp. meridianus. Disparity in flowering time between the two subspecies is accompanied by differences in flower visitors. We collected floral volatiles using dynamic headspace methods and analyzed them using gas chromatography and mass spectroscopy. Together, the subspecies produced a total of 39 floral scent compounds. Subspecies differ in the quantitative pattern of volatiles that attract noctuid moths (e.g., lilac aldehydes) vs. a more general suite of visitors (e.g., phenylacetaldehyde), but not in overall scent emission rates. A discriminant function analysis correctly distinguished between the two subspecies based on scent samples 86% of the time. We measured seven reproductive morphological traits; a discriminant function analysis distinguished between the two subspecies based on morphological samples 81% of the time. We found significant differences between subspecies in scent but not in individual morphological traits. The evidence presented here is most consistent with a hypothesis of pollinator-mediated selection.

Diet-morphology relationship in a fish assemblage from a medium-sized river of French Guiana: the effect of species taxonomic proximity

We investigated the global relationship between diet and morphology for 42 fish species from a medium-sized river in French Guiana and checked the influence of the species taxonomic proximity on the implication of individual morphological traits in that relation. The 42 species were classified in eight trophic guilds based on analysis of more than 4000 stomach contents. Taxonomic proximity between species was accounted for by an autoregressive model applied to original data of diet and morphology. Original and taxonomic-free data were then submitted to a Canonical Correspondence Analysis in order to detect the relationship between diet and morphology. We compared the results obtained by analyzing the original data and the corrected data. The results confirm the existence of a significant global relationship between diet and morphology. However, morphological traits responsible for that relation were different when considering the taxonomic-free data. Particularly the well known relationship between gut length and detritivory was not observed on the taxonomic free analysis. It is concluded that controlling for phylogeny is essential to the detection of relationships between diet and morphology. It is also concluded that, despite the robustness of some relationships between morphology and diet, many diets cannot be inferred by a ecomorphological approach.

Parallel Lasers for Remote Measurements of Morphological Traits

Abstract: Animal ecology research could benefit from the measurement of individual morphological traits. In bovids, male horn size often correlates with annual reproductive success, is sensitive to resource abundance, and could be a predictor of survival. However, live captures are costly, involve some risk of injury or substantial disturbance to the animals, and are impossible in many situations. To remotely measure horn growth of free‐ranging Alpine ibex (Capra ibex), I designed an aluminum frame that holds parallel laser pointers and a digital camera. I took digital pictures of ibex horns and calculated horn growth based on the fixed distance between the 2 laser points. This simple and accurate technique could benefit many ecological studies that require linear measurements, such as shoulder height, body length, leg length, or fin length. It could also help measure body features (e.g., fur or skin patterns, scars), increasing the reliability of individual photographic identification.

Quantifying the Spiral Leaf Trait of Arabidopsis from the 3D Shape Model Towards Computational Phenomics

Computational phenomics becomes more important in the recently remarkable advance of functionalgenomics. In the RIKEN Genomic Sciences Center, more than 50,000 mutant lines of the modelplant Arabidopsis thaliana have been produced for the saturated mutagenesis of the genome[3]. Forthe research of functional genomics, to establish the high-throughput phenotypic screening systemis a matter of vital importance[1]. Towards the high-throughput system, we have proposed a novelmethodology of the phenotypic analysis which is based on 3-dimensional(3D) model reconstruction viasurface measurement by the laser range nder(LRF)[5] and the computational screens of morphologi-cal traits on the 3D reconstructed model[2]. However, conventional description of morphological traitsof Arabidopsis is mostly qualitative due to subjective human observations. Thus we need to de nequantitatively individual morphological traits to be handled as objectively digital parameters. In thisreport, we focus on the spiral leaf trait[3, 4] as one of 3D-speci c traits at rosette leaves, and proposea quantitative de nition of the spiral leaf trait. Through an experiment to extract the quantitativespiral leaf trait at a wild-type and a mutant line, we exhibit the importance for quantifying traitsprecisely towards computational screens based on the 3D reconstructed model.

Sexually dimorphic pelvic morphology in South African whites and blacks

It is well known that there is metric and morphologic variation in the expression of sexual dimorphism between racial phenotypes and populations. Therefore, the purpose of this research is to assess morphologic sex differences in the pelves of South African whites and blacks. Results will be used to improve the identification of human skeletal remains by producing group specific standards. Morphologic features of both left and right os coxae were studied in a sample of 400 known sex/race individuals from the Pretoria and Dart collections. Bones that were clearly pathologic or visibly deformed were excluded from the study. Data were subjected to SPSS analysis. Results indicated that overall, public bone shape was the easiest to assess and was the most consistently reliable morphological indicator of sex in both sexes and population groups. At 88% average accuracy, the most discriminating traits in whites were pubic bone shape and subpubic concavity form. In blacks, greater sciatic notch form allowed the highest separation, averaging 87.5%, followed by pubic shape at 84.5%. Important findings included the fact that there were significant differences in the accuracy of sex determination from pelvic morphology between both males and females and whites and blacks. In conclusion, this study provides quantification of individual morphological traits in the os coxae of white and black South Africans that will be of value in forensic and archaeological analyses, especially when dealing with fragmentary remains. It also demonstrates that population differences affect the expression of sexual dimorphism and must be accounted for to develop the most effective methods of analysis.

Accuracy of sex determination using morphological traits of the human pelvis

This study assesses the accuracy and reliability of 17 individual morphological traits of the pelvis frequently used to determine the sex of human skeletal remains. A sample of 49 right and left adult hip bones and sacra of documented individuals were available from an historic church cemetery dating from the 19th century. A hypothetical ranking of the accuracy of traits was drawn from the literature. Next, individual traits were evaluated for precision and accuracy of observations, and combinations of two and three traits were evaluated for their collective effectiveness as sex indicators. The effect of age on the accuracy of traits for sex determination was also examined. Precision of traits was generally good. Several combinations of three criteria produced higher levels of accuracy than the trait list as a whole. A total of six traits was judged to be most effective as sex discriminators because of low intraobserver error levels and better than 83% accuracy rats. There was no indication of an age effect on the precision or accuracy of these traits although sample sizes are small.

Accuracy of Sex Determination Using Morphological Traits of the Human Pelvis

This study assesses the accuracy and reliability of 17 individual morphological traits of the pelvis frequently used to determine the sex of human skeletal remains. A sample of 49 right and left adult hip bones and sacra of documented individuals were available from an historic church cemetery dating from the 19th century. A hypothetical ranking of the accuracy of traits was drawn from the literature. Next, individual traits were evaluated for precision and accuracy of observations, and combinations of two and three traits were evaluated for their collective effectiveness as sex indicators. The effect of age on the accuracy of traits for sex determination was also examined. Precision of traits was generally good. Several combinations of three criteria produced higher levels of accuracy than the trait list as a whole. A total of six traits was judged to be most effective as sex discriminators because of low intraobserver error levels and better than 83% accuracy rats. There was no indication of an age effect on the precision or accuracy of these traits although sample sizes are small.

Evapotranspiration Rates of Eleven Zoysia Genotypes

We compared evapotranspiration (ET) rates for 11 Zoysia genotypes, encompassing two species and their hybrid, maintained at nonlimiting soil moisture under field conditions and in an environmental chamber of high evaporative potential. ET rate relationships to leaf area [leaf extension rate (LER)], canopy resistance [shoot density (SHD)], and internal resistance [abaxial (AB) and adaxial (AD) leaf blade stomatal densities] characteristics were determined. Three-year ET rate means were not significantly different among genotypes in the field study, but ET rates among genotypes differed significantly under the higher evaporative potential of an environmental-chamber study. ET rate was not significantly correlated with LER for either the data from the field or the chamber. ET rates of both types of tests also were not significantly correlated with SHD or AB or AD leaf blade stomatal density. Data from field and environmental-chamber research suggest that differences of individual morphological traits among the 11 zoysiagrasses do not influence the ET rate when measured from minilysimeters maintained at nonlimiting soil moisture.

Morphological Changes Associated with Three Cycles of Recurrent Selection for Grain Yield Improvement in Oat1

To assess the potential for improving grain yield via indirect morphological trait selection, the original and third cycle parents from a recurrent selection program for grain yield in oat (Avena sativa L.) were compared. Evaluation was based on hill plots grown in three field environments. This selection increased grain yield 13.5% and total dry matter 15.9%; thus, there was no increase in harvest index. All morphological structures measured increased in size. Grain yield was not closely or consistently related to any individual morphological trait, nor to the photosynthetic area of the flag leaf and panicle. Analysis of allometric relationships (the size of one plant structure relative to another) indicated that the size of morphological structures within a genotype tended to be proportional, but variability in allometric relationships was present. Therefore, selection for altered allometric relationships may be successful, but construction of an ideotype based on certain levels of expression of individual morphological traits, or photosynthetic areas, is not likely to be effective in increasing grain yield.