Standardized Major Axis Research Articles

Light Environment Has Little Effect on Heteroblastic Development of the Temperate Rain Forest Tree Gevuina avellana Mol. (Proteaceae)

Premise of research. Heteroblastic species are those that show an abrupt change in shape and/or size among individual metamers during ontogeny. Gevuina avellana Mol. (Proteaceae) is a typical tree species in the temperate rain forests of Chile and Argentina. This tree shows drastic heteroblasty, changing from simple leaves at the seedling stage to pinnate leaves during development. It regenerates mostly in shady understories, but juveniles can be found growing under a wide range of light conditions (5%–50% canopy openness). Thus, considering that light has been proposed as a driver of the heteroblastic strategy, G. avellana is an interesting model to study the potential environmental modulation of its ontogenetically programmed heteroblasty. Therefore, the aim of this study was to determine the effect of light availability on G. avellana’s heteroblastic trajectory. We postulated that G. avellana’s ontogenetic changes in leaf complexity (i.e., heteroblasty) increase under high light availability.Methodology. Saplings along most of the light availability gradient were sampled. Plant height was used as a proxy for ontogeny. We measured several leaf traits (leaf area), shape (aspect ratio), pinnation (leaf dissection index), and complexity (fractal dimension index). First, we evaluated the change in each leaf trait with height by means of Pearson’s correlation. Then we tested for differences in leaf traits along the ontogeny between two light environments (higher and lower than 10% canopy openness) by the line-fitting standardized major axis method.Pivotal results. We found positive correlations between each leaf trait and plant height (P < 0.001), while only leaf size and complexity showed higher ontogenetic increases under high light.Conclusions. Light environment has a small but significant effect on the heteroblastic trajectory of G. avellana. In particular, saplings inhabiting microsites with high light availability have larger and more complex leaves. While allometry would explain the ontogenetic trajectory of leaf size, the increased complexity could reflect functional advantages for large leaves in tall plants, especially under high light conditions.

Slope-related variations in twig and leaf traits of Robinia pseudoacacia in the northern mountains of Lanzhou

Aims The growth relationship between twigs and leaves is a strategy that plants enhance the ability to use space resources under environmental stresses, and elucidation of this characteristics is important for understanding the phenotypic plasticity of plants in coping with environmental heterogeneity. Our objective was to examine how Robinia pseudoacacia would vary in twig and leaf configuration in response to changes in slope aspect. Methods In the northern mountains of Lanzhou in Gansu Province, China, 20 transects were laid out horizontally along the contour at intervals of 50 m from an elevation of 1 550 m upward in four different slope aspects, and 12 plots were set up along each transect at intervals of 5 m. A handheld GPS was used to measure latitude, longitude and altitude of each plot. Community traits were investigated and all individuals of R. pseudoacacia were used for measurements of the cross-sectional area of twigs, total leaf area, leafing intensity, and average area of a single leaf on each twig. Arc GIS was used to construct the digital elevation model(DEM). The 240 plots were categorized into groups of northern, eastern, western and southern aspects, and the standardized major axis(SMA) estimation method was then used to examine the allometric relationship between the cross-sectional area of twigs, total leaf area, leafing intensity and average area of a single leaf. Important findings With changes in the slope aspect from north to east, south and west, the crown density, average tree height and soil moisture of the plant community displayed a pattern of decrease—increase, and the cross-sectional area of twigs, total leaf area and average area of a single leaf of R. pseudoacacia displayed a pattern of decrease—increase and the leafing intensity displayed a pattern of increase—decrease. Significant positive relationships between the cross-sectional area of twigs and total leaf area were found in R. pseudoacacia in all slope aspects(p 0.05), and the common slope of the regressions was significantly greater than 1; significant negative relationships between leafing intensity and average area of a single leaf were found in all slope aspects(p 0.05), and the common slope of the regressions was significantly close to –1. In addition, when the slope aspect changed from north to east, south and west, the y-intercepts in the scaling relationships of the cross-sectional area of twigs vs. total leaf area and the leafing intensity vs. individual leaf area both displayed a pattern of decrease—increase. The allometric relationship between twig and leaf with changes in slope aspect of the habitat reflected the response and adaption of plant functional traits to their biotic and abiotic environments and the investment balance mechanism of plant architecture construction.

Relationship between leaf traits of Melica przewalskyi and slope aspects in alpine grassland of Qilian Mountains, China

Aims Variations in leaf characteristics can reflect plant acclimation to environments. We aimed to examine the relationship between leaf traits of Melica przewalskyi and slope aspect. Methods In alpine grassland of Qilian Mountains, Gansu Province, China, 80 plots were sampled at intervals of 20 m along eight aspects. Latitude, longitude and altitude of each plot were recorded by GPS. At each plot, 10 individuals of M. przewalskyi were random selected and harvested for measurements of leaf mass, leaf area, and leaf volume. A digital elevation model (DEM) was constructed to extract elevation, aspect, and slope for each plot by ArcGIS. The 80 plots were divided into groups of north, east, west and south aspect. Values for leaf traits were log-transformed. the standardized major axis (SMA) estimation method, was used to examine the covariation among leaf traits. Important findings Leaf area and leaf volume decreased significantly as aspect turns from north to east, from east to west, and from west to south, but not so for leaf mass, suggesting that leaf thickness increased as slope aspect changes, and thus led to the smaller and thicker leaves on the south-facing slope than that on north-facing slope. A clear allometric relationship between leaf mass and leaf area was found only on the south-facing slope where increase in leaf mass was greater than that in leaf area. While on other slope aspects, an isometric relationships between them was observed. The allometric relationship between leaf mass and leaf volume was found on all four aspects, with the growing speed of leaf volume greater than that of leaf mass, and a rising SMA slope. We can conclude that variations in leaf traits of M. przewalskyi with slope aspect could reflect plant acclimation.

Evaluating indices of body condition in two cricket species.

Body mass components (dry mass, lean dry mass, water mass, fat mass) in each sex correlate strongly with body mass and pronotum length in Gryllus texensis and Acheta domesticus. Ordinary least squares (OLS) regression underestimates the scaling relationship between body mass and structural size (i.e., pronotum length) in both cricket species compared with standard major axis (SMA) regression. Standardized mass components correlate more strongly with scaled mass index () than with residual body mass (R i). R i represents the residuals from an OLS regression of log body mass against log pronotum length. Neither condition index predicts energy stores (i.e., fat content) in G. texensis. R i is not correlated with energy stores in A. domesticus whereas is negatively correlated. A comparison of condition index methods using published data showed that neither sex nor diet quality affected body condition at adulthood in G. texensis when using the scaled mass index. However, the residual index suggested that sex had a significant effect on body condition. Further, analysis of covariance (ANCOVA) suggested that diet quality significantly affects body mass while statistically controlling for body size (i.e., body condition). We conclude that the statistical assumptions of condition index methods must be met prior to use and urge caution when using methods that are based on least squares in the y -plane (i.e., residual index ANCOVA).

Effects of fertilization on the relations of diameter at breast height between different-aged ramets of Phyllostachys edulis population

Aims Clonal plants are physiologically integrated, allowing translocation of photosynthates, water, nutrients and other substances between connected ramets within a clone. This suggests that the sizes of ramets of different ages may be correlated. So far, however, little is known about the effects of fertilization on the size relationships between ramets of different ages. In this study, we aim to examine how fertilization affects the relations of diameter at breast height(DBH) between ramets of different ages in the giant clonal bamboo Phyllostachys edulis. Methods We established 112 20 m × 30 m plots of P. edulis in Longquan City, Zhejiang Province, China. Among them, 46 plots were fertilized only in 2008, 49 fertilized in five consecutive years from 2004 to 2008, and 17 unfertilized(the control). We measured DBH of ramets of one, three and five years old in each plot in 2009. The relations of DBH between ramets of different ages in different fertilization treatments were examined using allometric scaling by the standardized major axis(SMA) analysis, and that were also analyzed by multiple linear regression. Important findings The DBH of the 1-year-old ramets was significantly greater than that of the 5-year-old ones in the 5-year fertilization plots, while no significant difference was found in the 1-year fertilization plots. Under different fertilization treatments, the slopes of SMA(0.88–1.10) for the relations of DBH between ramets of one, three and five years old were not significantly different from 1.00(p 0.05), suggesting isomeric growth relationships. Compared to the control(unfertilization), fertilization in one or five years did not change the slope of SMA. However, fertilization in five years increased the intercept of SMA, indicating that continuous fertilization could result in greater DBH increment in the 1-year-old ramets. The multiple linear stepwise regression analysis indicated that 3-year-old ramets could greatly influence DBH of the newly produced ramets, and that the effect of DBH of the 5-year-old ramets on that of the 1-year-old ramets increased after five years of continuous fertilization.

Variations with slope in stem and leaf traits of Melica przewalskyi in alpine grassland

Aims The relationship between stem and leaf growth is a strategy that plant canopy enhances photosynthetic efficiency and competitiveness through configuration adjustments; this relationship indicates the ratio between xylem and photosynthetic area in a heterogeneous environment. Our objective was to examine how Melica przewalskyi modulated leaf and stem traits in adaptation to changes in slope. Methods In the alpine grassland of Qilian Mountains, Gansu Province, China, 80 plots were set up along four transects corresponding to contrasting aspects with 20 m distance between adjacent plots. A GPS was used to record latitude, longitude and altitude of each plot and Arc GIS software was used for constructing a digital elevation model(DEM) and extracting information on elevation, aspect, and slope. Community characteristics were investigated and 10 random individuals of M. przewalskyi were cut at the soil surface in each plot, and leaf mass, leaf area and stem mass were measured in laboratory. The 80 plots were grouped into 0°–10°, 10°–20°, 20°–30° slope gradients. Stem and leaf traits were log-transformed and then standardized major axis(SMA) estimation method was used to examine the allometric relationships of stem mass with leaf area or leaf mass. Important findings The stem mass, leaf mass and leaf area of M. przewalskyi gradually decreased, but the leaf number increased, with slope gradient. An isometric relationship was found between stem mass and leaf area in plots within each slope gradient, whereas an allometric relationship was found between stem mass and leaf mass. Melica przewalskyi grown on steeper slopes tended to have smaller leaf area and greater leaf number at a given stem mass, and leaves with greater stem mass had greater leaf mass. A significant difference in the SMA slope among the three slope gradients of the plots suggested that the slope of the growth site constrained leaf area and leaf mass by stem mass, reflecting plant adaptation to heterogeneous environment.

Thermodynamics constrains allometric scaling of optimal development time in insects.

Development time is a critical life-history trait that has profound effects on organism fitness and on population growth rates. For ectotherms, development time is strongly influenced by temperature and is predicted to scale with body mass to the quarter power based on 1) the ontogenetic growth model of the metabolic theory of ecology which describes a bioenergetic balance between tissue maintenance and growth given the scaling relationship between metabolism and body size, and 2) numerous studies, primarily of vertebrate endotherms, that largely support this prediction. However, few studies have investigated the allometry of development time among invertebrates, including insects. Abundant data on development of diverse insects provides an ideal opportunity to better understand the scaling of development time in this ecologically and economically important group. Insects develop more quickly at warmer temperatures until reaching a minimum development time at some optimal temperature, after which development slows. We evaluated the allometry of insect development time by compiling estimates of minimum development time and optimal developmental temperature for 361 insect species from 16 orders with body mass varying over nearly 6 orders of magnitude. Allometric scaling exponents varied with the statistical approach: standardized major axis regression supported the predicted quarter-power scaling relationship, but ordinary and phylogenetic generalized least squares did not. Regardless of the statistical approach, body size alone explained less than 28% of the variation in development time. Models that also included optimal temperature explained over 50% of the variation in development time. Warm-adapted insects developed more quickly, regardless of body size, supporting the “hotter is better” hypothesis that posits that ectotherms have a limited ability to evolutionarily compensate for the depressing effects of low temperatures on rates of biological processes. The remaining unexplained variation in development time likely reflects additional ecological and evolutionary differences among insect species.

Biomass Partitioning and Its Relationship with the Environmental Factors at the Alpine Steppe in Northern Tibet

Alpine steppe is considered to be the largest grassland type on the Tibetan Plateau. This grassland contributes to the global carbon cycle and is sensitive to climate changes. The allocation of biomass in an ecosystem affects plant growth and the overall functioning of the ecosystem. However, the mechanism by which plant biomass is allocated on the alpine steppe remains unclear. In this study, biomass allocation and its relationship to environmental factors on the alpine grassland were studied by a meta-analysis of 32 field sites across the alpine steppe of the northern Tibetan Plateau. We found that there is less above-ground biomass (MA) and below-ground biomass (MB) in the alpine steppe than there is in alpine meadows and temperate grasslands. By contrast, the root-to-shoot ratio (R:S) in the alpine steppe is higher than it is in alpine meadows and temperate grasslands. Although temperature maintained the biomass in the alpine steppe, precipitation was found to considerably influence MA, MB, and R:S, as shown by ordination space partitioning. After standardized major axis (SMA) analysis, we found that allocation of biomass on the alpine steppe is supported by the allometric biomass partitioning hypothesis rather than the isometric allocation hypothesis. Based on these results, we believe that MA and MB will decrease as a result of the increased aridity expected to occur in the future, which will reduce the landscape’s capacity for carbon storage.

Improving provenance studies in migratory birds when using feather hydrogen stable isotopes

Hydrogen stable isotopes (δ2H) in feathers are used to determine the origin and migration strategy of birds. To identify the geographic location of the site of feather synthesis, calibration curves for the relation between feather δ2H and amount‐weighted growing‐season δ2H in precipitation are used to generate feather δ2H isoscapes. Factors like species, age and year might generate isotopic variation in calibration curves, but the extent to which accounting for variation may improve calibration curves and hence provenance determination of birds, is unknown. We compared three European calibration curves: 1) an existing multi‐species curve, uncorrected for age and year variation, and two species‐specific calibration curves, based on mallard Anas platyrhynchos feathers, of 2) varying age and year, and 3) juvenile natal origin, corrected for year variation. Calibration curves using ordinary least square linear regression (OLS) as opposed to standard major axis regression showed least bias in estimation. As expected, we found that a single species (mallard) OLS calibration curve corrected for age and year yielded the highest coefficient of determination, but was still surprisingly similar to the other two calibration curves. Nevertheless, when using feathers of known‐origin to assess provenance accuracy, the calibration curve that accounted for species, age and year variation yielded the best prediction in as many as 59% of the cases. Our study is the first to demonstrate implications of isotopic variation on assessing the origin of individual birds, but also highlights the relatively small gain in precision that is achieved by generating species, age and year specific calibration curves rather than resorting to more general alternatives.

Size relationships of water discharge in rivers: scaling of discharge with catchment area, main‐stem length and precipitation

AbstractScaling relationships between water turnover or discharge and water system size may help to reveal and understand general patterns and processes in regional and global hydrological systems. In the present study, we derived global as well as climate‐specific scaling relationships between average or maximum river discharge and catchment area, main‐stem length and precipitation, based on data from 663 monitoring stations worldwide. Data were retrieved from a Global Runoff Data Centre (GRDC) database. The scaling relationships were established with ordinary least square (OLS) and standard major axis (SMA) regressions. The focus was on the SMA regressions because this method provides better estimates of the slope.The overall empirical regressions derived were highly significant (p &lt; 0.01). Average discharge (Q) and maximum discharge (Qmax) scaled to catchment area (A) with SMA slopes of 1.23 (r2 = 0.40) and 0.99 (r2 = 0.41), respectively. Average discharge (Q) scaled to length (L) with a slope of 2.16 (r2 = 0.40), while catchment area (A) scaled to main‐stem length (L) with a slope of 1.76 (r2 = 0.91). The addition of precipitation (P), yielding a multiple regression of discharge versus catchment area and precipitation, improved the explained variability to r2 = 0.56 and r2 = 0.52 for average and maximum discharge, respectively. Slopes of climate zone‐specific regressions tended to be similar to the slopes of the overall relationships. The uncertainties of the regressions were discussed and, where possible, compared to regressions derived in other studies. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Biomass allocation of branches and leaves in Phyllostachys heterocycla ‘Pubescens’ under different management modes: allometric scaling analysis

Aims Allometric relationship between branch and leaf is limited by plant ontogeny and affected by environmental conditions,which is not well investigated in giant clone species such as Phyllostachys heterocycla ‘Pubescens'.Our objectives were to study the effects of different management modes(obtruncation and fertilization) on branch and leaf biomass allocations of P.heterocycla ‘Pubescens' and to discuss the effects within canopy.Methods Obtruncation is a particular pruning operation cutting off the top(about 40%–70% canopy) of P.heterocycla ‘Pubescens'.This management methods used in north Zhejiang of China to reduce trees falling from strong wind or heavy snow.A replicated 2 × 2 factorial experiment(obtruncation and fertilization) was established in Zhejiang Province in 2004.In 2010 and 2011,a total of 50 plants were cut down to investigate branch and leaf biomass,as well as leaf area of selected leaves within the canopy.Allometric scaling was applied to analyze the relation of branch and leaf biomass.Important findings Averaged branch and leaf biomass for individual plant were decreased 40.23% and 41.01%,respectively,following obtruncation and increased 20.18% and 30.23%,respectively,following fertilization.Obtruncation severely changed the growth trajectory and resulted in a greater standardized major axis(SMA) slope,which indicated relatively more biomass was allocated to leaves.This was more significant under non-fertilization treatments.When compared to non-fertilization,fertilization significantly decreased SMA slope in unobtruncated trees,which was attributed to relatively larger leaf photosynthetic products partitioning to branches after fertilization.In addition,allocation patterns of branch and leaf biomass at different canopy parts were affected by light availability that was different in different fertilization treatments.Obtruncation changed SMA slope by nearly 50% and 10% for fertilization,which indicated that direct interference(obtruncation) easily changed the grown trajectory and indirect effects(fertilization) were more limited by plant ontogeny.

Response of leaf morphometric traits of Quercus species to climate in the temperate zone of the North-South Transect of Eastern China

Aims Plant leaf morphological traits can effectively reflect changes of plant living environments and affect the behaviors and function of plants. Our objective was to reveal the response of leaf morphometric traits of Quercus species to climate in the temperate zone of the North-South Transect of Eastern China (NSTEC). Methods We obtained leaf morphometric information by measuring plants in herbariums. We used mathematical methods of correlation analysis and standardized major axis to investigate relationships between leaf morphology and climate factors, as well as correlations among leaf morphological traits. Important findings With changing climate conditions in the temperate zone of NSTEC, leaf morphological traits of Quercus species changed significantly. Leaf area of Quercus species increased with decreased annual tem- perature and increased annual sunlight, which helps leaves to absorb more light radiation and reduce the loss of heat. The degree of leaf division can not only decrease heat dissipation from leaves, but can also enhance the fluctuation of sap flow to improve the physiological activities of leaves. Vein density increased with increased temperature and light intensity, improving the water transportation capacity, and increased with increased precipi- tation, improving the supporting ability of leaves. In addition, in order to adapt to the changed climate conditions, Quercus species built a combination of leaf morphological traits, with increased leaf area, petiole length and de- gree of leaf division, while vein density decreased. Petiole length and vein density also increased with the leaves tending toward an elongated shape.

Twig and leaf trait differences in Stellera chamaejasme with slope in alpine grassland

Aims The growth relationship between twig and leaf is a strategy that plant canopy structure employs to space resources and enhance photosynthetic efficiency and competitiveness through configuration adjustments.Our objective was to examine how Stellara chamaejasme exploited twig and leaf configuration to explore the effects of slope change.Methods In the upper reaches of Shiyang river,Gansu Province,China,80 plots were set up at intervals of 20 m from the foot of a mountain along eight aspects.GPS was used to record latitude,longitude and altitude of each plot.Community traits were investigated and five S.chamaejasme were cut randomly on each plot for measurement of twig length,twig number,leaf area and leaf number.ArcGIS was used to set up digital elevation model(DEM) and abstract slope data of the study site.The 80 plots were divided into 0°-10°,10°-20° and 20°-30° slope gradients.Values for twig and leaf traits were logarithmically converted,and then the standardized major axis(SMA) estimation method was used to examine the allometric relationship between twig number,twig length,leaf number and leaf length.Important findings Twig length,twig number and leaf area of S.chamaejasme gradually decreased along the slope gradient.Significant allometric relationships between leaf number and twig length and between twig number and twig length were found to be consistent in all three slope gradients.Growing speed of twig length was greater than the speed of leaf number,and the growing speed of twig number was greater than the speed of twig length.However,there were significant differences in SMA slope in the three slope gradients,suggesting that slope constrains the leaf number and twig number that can be supported by a given twig length.

Can Body Condition and Somatic Indices be Used to Evaluate Metal-Induced Stress in Wild Small Mammals?

Wildlife is exposed to natural (e.g., food availability and quality, parasitism) and anthropogenic stressors (e.g., habitat fragmentation, toxicants). Individual variables (e.g., age, gender) affect behaviour and physiology of animals. Together, these parameters can create both great inter-individual variations in health indicators and interpretation difficulties. We investigated the relevance of body condition and somatic indices (liver, kidneys) as indicators of health status in wood mice (Apodemus sylvaticus, n = 560) captured along a metal pollution gradient in four landscape types (30 sampling squares 500-m sided). The indices were calculated using a recently proposed standard major axis regression instead of an ordinary least square regression. After considering age and gender for the body condition index, no landscape type influence was detected in the indices. However, important index variability was observed between sampling squares; this effect was included as a random effect in linear models. After integrating all individual and environmental variables that may affect the indices, cadmium (Cd) concentrations in both the liver and kidneys were negatively related to body condition and liver indices only for individuals from highly contaminated sites. Lead in the liver was negatively related to the liver index, and Cd in kidneys was positively linked to the kidney index, potentially suggesting metal-induced stress. However, interpretation of these indices as a wildlife ecotoxicology tool should be performed with caution due to the sensitivity of potentially confounding variables (e.g., individual factors and environmental parameters).

Leaf functional traits vary with the adult height of plant species in forest communities

Aims Within-community variation accounts for a remarkable proportion of the variation in leaf functional traits. Plant height may be used to explain within-community variances of leaf traits because different microenvironments, especially light intensity, may occur at differ ent heights. This study determines whether or not leaf nitrogen (N) and phosphorus (P) contents as well as leaf mass per area (LMA) are interspecifically correlated with the adult height of forest woody species. We also discuss these relationships with respect to community structure and functions of the ecosystem. Methods A total of 136 dicotyledonous woody species from 6 natural forests (3 evergreen and 3 deciduous ones) in East China (latitude: 18°44′ – 45°25′ N, longitude: 108°50′–128°05′ E) were investigated. For each of the 157 species–site combinations, 6 traits were measured: plant adult height relative to the forest canopy (H R), leaf N and P contents per unit area (N area and P area), N and P contents per unit dry mass (N mass and Pmass) and LMA. The total variances of each leaf trait across sites were partitioned in a hierarchical manner. The relationships between leaf traits and H R within forest communities were then analyzed using both standardized major axis regression and Felsenstein’s phylogenetic independent contrasts. Relationships between evergreen and deciduous forests were compared by linear mixed models. Important Findings HR is a robust predictor of leaf N area, Parea and LMA, explaining 36.7, 39.4 and 12.0% of their total variations across forests, respectively. Leaf Narea, Parea and LMA increased with H R in all of the studied forests, with slopes that were steeper in evergreen forests than in deciduous ones. Leaf N mass and Pmass showed no significant relationship with H R generally. The increase in leaf Narea, Parea and LMA with HR across species is assumed to maximize community photosynthesis and may favor species with larger H R.

Length–Weight Relations of Eight Fish Species from a Small Caribbean Coastal Lagoon, Mexico

Due to the importance of the estuarine fish fauna in Mexico and the implications of length&#8211;weight relation (LWR) for management and conservation, we present the estimates of the LWR for eight fish species from Rio Huach, a small estuarine system of the Mexican Caribbean. Fishes were caught in five sampling points during an annual cycle (1998) and in November of 2000, were measured with a digital calliper and weighed with a digital balance to obtain the standard length (SL) and weight (W). The LWR were obtained with two estimation methods: standardized major axis (SMA) and ordinary least squares (OLS). A total of 678 specimens were suitable for analysis. The estimates of LWR for Bathygobius soporator (Valenciennes, 1837) and Cyprinodon artifrons Hubbs, 1936 are presented here for first time, and for four species statistical differences with previous estimations of LWR were found (considering one or both estimation methods). With these results, the knowledge of LWR for tropical fish species is increasing and the importance of considering the estimation of LWR parameters using the standardized major axis method is discussed.

Sex‐Related Shape Dimorphism in the Human Radiocarpal and Midcarpal Joints

Previous research has revealed significant size differences between human male and female carpal bones but it is unknown if there are significant shape differences as well. This study investigated sex-related shape variation and allometric patterns in five carpal bones that make up the radiocarpal and midcarpal joints in modern humans. We found that many aspects of carpal shape (76% of all variables quantified) were similar between males and females, despite variation in size. However, 10 of the shape ratios were significantly different between males and females, with at least one significant shape difference observed in each carpal bone. Within-sex standard major axis regressions (SMA) of the numerator (i.e., the linear variables) on the denominator (i.e., the geometric mean) for each significantly different shape ratio indicated that most linear variables scaled with positive allometry in both males and females, and that for eight of the shape ratios, sex-related shape variation is associated with statistically similar sex-specific scaling relationships. Only the length of the scaphoid body and the height of the lunate triquetrum facet showed a significantly higher SMA slope in females compared with males. These findings indicate that the significant differences in the majority of the shape ratios are a function of subtle (i.e., not statistically significant) scaling differences between males and females. There are a number of potential developmental, functional, and evolutionary factors that may cause sex-related shape differences in the human carpus. The results highlight the potential for subtle differences in scaling to result in functionally significant differences in shape.

Assessment of remotely-sensed sea-surface temperature and chlorophyll-a concentration in San Matías Gulf (Patagonia, Argentina)

Field measurements of surface temperature and chlorophyll-a concentration were used to evaluate for the first time the performance of the standard sea surface temperature and chlorophyll-a algorithms of the Moderate Resolution Imaging Spectroradiometer (MODIS) in San Matías Gulf, northern of the Argentine Patagonian Continental Shelf (between 40°47′S and 42°13′S). The fit of the temperature data to a Standard Major Axis (SMA) type II regression model indicated that a high proportion of the total variance (r2≥0.80) was explained by the model. For chlorophyll-a, the low correlation (r2=0.15) and high dispersion indicated a poor performance and a general overestimation of Chl-a by the OC3Mv5 algorithm as indicated by the Relative Percent Difference (RPD=113%). However, for stations located in the northern area of the gulf the result showed a higher correlation (r2=0.76) and less dispersion (RPD=31%). The feasible reasons and explanations for the performance of NLSST and OC3Mv5 algorithms are discussed. The results of the temporal variability analysis of SST and Chl-a in different areas of the gulf agreed with previous studies.

δ15N values of macroalgae as an indicator of the potential presence of waste disposal from land-based marine fish farms

The nitrogen isotope ratio (δ15N) in tissues of native macroalgae was evaluated as a means of indicating the intensity and spatial extent of organic contamination due to disposal of waste from land-based marine fish farms (LBMFFs). Three species of macroalgae from the genus Fucus and the green macroalgae Codium tomentosum were selected for study. The study was carried out at seven flat marine fish farms located in Galicia (NW Spain). Tests were carried out to determine the intra-annual variation in δ15N values and any differences between selected macroalgae. The δ15N values enrichment was observed close to the disposal point, and δ15N values varied more widely throughout the year (±5.57 ‰) at sites affected by the marine fish farm effluent compared to natural conditions (±2 ‰). No significant differences in the isotopic signals were observed in the different species studied (standard major axis). The δ15N values of macroalgae may be an ideal means of detecting the presence of LBMFFs effluents.

Rare species drive local trait diversity in two geographically disjunct examples of a naturally rare alpine ecosystem in New Zealand

AbstractQuestionIs there evidence for similar community assembly processes in two geographically disjunct examples of a rare alpine ecosystem?LocationTwo alpine granite gravel fields 610 km apart along a fault line in western South Island, New Zealand – the Lookout Range and Mt Titiroa.MethodsPlot‐based vascular plant composition and traits for 86 species (height, seed length, leaf size and nutrient concentrations) were used to examine community structure reflecting assembly processes. We examined species richness, trait values averaged across species and plots, relationships between trait pairs using standardized major axis (SMA) regression and phylogenetically independent contrasts (PIC), relationships between abundance and trait values, and functional diversity indices against null models. Lastly, we partitioned taxonomic, functional and phylogenetic diversity within and across alpine ranges.ResultsFunctional and phylogenetic turnover of diversity between the two locations was low (2.9% and 6.3%, respectively) relative to turnover of taxonomic diversity (75%). Species‐level traits were similar between the two locations, except leaf P, which was higher at Mt Titiroa. Plot‐level average traits were all significantly higher on Mt Titiroa. Relationships between species‐level traits were typically non‐significant at both locations, or significant only at a single location. In contrast, relationships between plot‐level trait values were frequently significant and consistent across the two locations. At both locations, dominant species had a narrow range of similar trait values, while rare species had a wide range of values. Within plots, we found both trait convergence and divergence. Associations of trait values among dominant and rare species were largely non‐random but inconsistent between the two locations.ConclusionsThe two locations had a similar pool of trait values but often differed in how those traits were assembled. Results demonstrate that dominant species are subject to rigorous filters during community assembly leading to trait convergence, but rare species contributed to trait diversity and trait divergence. Models of community assembly can often predict traits of dominant species but must consider the importance of rare species as a source of local trait diversity, even in species‐poor communities under severe environmental conditions.