Measurements Of Morphological Traits Research Articles

Environmental filtering mediates desert ant community assembly at two spatial scales.

Understanding the mechanisms that maintain species coexistence and determine patterns of community assembly are fundamental goals of ecology. Quantifying the relationship between species traits and stress gradients is a necessary step to disentangle assembly processes and to be able to predict the outcome of environmental change. We examined the hypothesis that desert ant communities are assembled by niche-based processes i.e., environmental filtering and limiting similarity. First, we used population-level morphological trait measurements to study the functional structure of ant communities along a dryland environmental stress gradient. Second, we developed species distribution models for each species to quantify large-scale climatic niche overlap between species. Body, femur, antennal scape, and head lengths were correlated with environmental gradients. Regionally, the ant community was significantly and functionally overdispersed in terms of morphological traits which suggests the importance of competition to ant community structure. Ant community assembly was also strongly influenced by environmental factors as the degree of functional trait divergence, but not phylogenetic divergence, decreased with increasing environmental stress. Thus, environmental stress likely mediates limiting similarity in these desert ecosystems. Species with lower climatic niche overlap were more dissimilar in morphological traits. This suggests that environmental filtering on ant functional traits is important at the scale of species distributions in addition to regional scales. This study shows that environmental and biotic filtering (i.e., niche-based assembly mechanisms) are jointly and non-independently structuring the ant community.

Size spectra of the edaphic fauna of typical Argiudol soils of the Rolling Pampa Region, Argentina.

Soil-dwelling organisms populate the spaces-referred to as interstices-between the litter on the soil surface and the pores in the soil's organo-mineral matrix. These organisms have pivotal roles in soil ecosystem functions, such as the breakdown and decomposition of organic matter, the dispersal of bacterial and fungal spores and biological habitat transformation. These functions, in turn, contribute to broader ecosystem services like carbon and nutrient cycling, soil organic matter regulation and both chemical and physical soil fertility.This study provides morphological data pertaining to a range of soil organism sizes, specifically in Argiudol soils subjected to varying levels of agricultural activity in the Rolling Pampas Region, one of the world's most extensive and fertile plains.The primary focus is on soil microarthropods-namely, Acari (mites) and Collembola (springtails)-with a body width of less than 2 mm. These organisms constitute the majority of life in the intricate soil pore network. Additionally, the study documents species of earthworms (Oligochaeta, Crassiclitelata), recognised as ecosystem engineers for their ability to create physical channels in the soil matrix and to distribute organic matter. Moreover, the study includes measurements of morphological traits of soil-dwelling "macrofauna" (organisms with a body width greater than 2 mm), which are also implicated in various soil ecosystem functions. These include population regulation by apex predators, organic matter decomposition, biogenic structure formation, nutrient mobilisation and herbivory. In this paper, we report both the geographical locations and individual measurements of key morphological traits for over 7,000 specimens, covering a range of soil-dwelling organisms. These include springtails (Entognatha, Collembola), mites (Arachnida, Acari), earthworms (Oligochaeta, Crassiclitellata) and additional soil macrofauna. All specimens were collected from typical Argiudol soils located in three distinct agricultural systems characterised by varying levels of land-use intensity. To our knowledge, no other dataset exists providing this information for the Argentinian Pampas.

Participatory definition of breeding objectives and breeding practice for goat population in northeastern Ethiopia: An input for in-situ conservation and genetic improvement program

Knowing the production system and breeding objectives is a prerequisite for designing in-situ conservation and genetic improvement programs. This study aimed to characterize goats' breeding practices and relative importance and identify goat keepers' breeding objectives. Data were collected through three approaches: formal personal interviews, measurement of morphological traits of live animals, and own flock ranking methods. Several SAS procedures were used to analyze the data. The result revealed that goats were the second most economically important livestock species next to cattle. Income generation and home meat consumption were the major reasons for keeping goats. The mating method was an uncontrolled natural mating method. Most (90–100%) goat keepers select male and female goats to be a parent for the next generation. Coat color, physical appearance, twinning ability, milk yield, and kid growth were identified as breeding objectives for breeding females through the personal interview method. Similarly, the most crucial traits for selecting a buck were growth, physical appearance, and coat color. Based on own animal ranking method, coat color, physical appearance, milk yield, twining ability, and mothering ability were the most important traits. The rank of animals was in line with the phenotype of morphological traits and market price. In conclusion, coat color, physical appearance, milk yield, and twining ability were identified to be the most important traits. Therefore, these breeding objectives can be used as input for designing a genetic improvement program for this goat population.

Flower morphology and nectar quality traits in faba bean affect attraction to bees

AbstractLegumes provide nutritious floral resources for bees thus are commonly considered for use in schemes to enhance pollinators in agroecosystems. In particular, legume landraces are important elements in practices towards sustainable agriculture. Differences in flower morphology and nectar may affect the attraction of pollinators. The aim of the present study was to investigate possible differences in pollinator attraction between a Vicia faba L. landrace and a commercial variety and to indicate differences in floral characteristics and nectar quality traits which can be associated with bee visits. To assess this, floral morphological trait measurements and chemical analysis using high‐resolution mass spectrometry‐based non‐targeted screening of the flower nectar were carried out and bee visits on faba bean flowers were recorded. Floral traits that contributed to the separation of the two accessions were ‘intensity of streaks’ and ‘extent of anthocyanin colouration’ on standard petal which were more pronounced in the landrace. All nectar traits examined contributed to the separation of the two V. faba accessions. Chemical substances such as amino acids and sugars which are important for bee nutrition are differentially increased in the landrace compared with the commercial variety. The landrace attracted more bee genera (Apis, Anthophora, Eucera) and bee visits compared with the commercial variety (only Eucera) supporting that the floral and nectar differences between the accessions of the same plant species are important to bees. The well‐fitting interrelation of the landrace flowers and bee visits can have possible implications in agricultural practices such as crop breeding for pollinator friendly varieties through selecting floral traits, improvement of foraging resources for pollinators in agroecosystems and subsequently food production. Exploitation of the V. faba landrace in agroecological schemes to support conservation of flora and fauna genetic resources in situ should be considered also for the benefit of future food stability and security.

Towards understanding the type and function of indigenous goats: input for genetic improvement and conservation programme

ABSTRACT This study aimed to provide a better understanding of the type, function, and production potential of Central Highland goats. Morphometric measurements were collected from 510 heads of goats. About 17 biologically important structural indices were computed using morphological trait measurements. The data were analyzed using SAS’s general linear model, principal component analysis, and stepwise multiple regression techniques. Body index value indicate that the Central Highland goat’s shape is rectangular, which is good conformation for meat production. The dactyl thorax, transverse pelvic, longitudinal pelvic, relative depth of thorax, and width indices suggest their suitability for meat production. However, proportionality and length indices showed an aptitude for milk production. Besides, the body ratio and depth indices indicate less susceptibility of this goat breed to dust infestation and arthritis, good walking ability, good foraging capability, and move easily in sloppy areas. In conclusion, structural indices showed that Central Highland goats could be classified as having a dual purpose and better aptitude for meat production. The results of this study could be an input for designing genetic improvement and conservation programmes for the sustainable utilization of indigenous goats.

Isotopic niches do not follow the expectations of niche conservatism in the bird genus Cinclodes.

Phenotypic traits are expected to be more similar among closely related species than among species that diverged long ago (all else being equal). This pattern, known as phylogenetic niche conservatism, also applies to traits that are important to determine the niche of species. To test this hypothesis on ecological niches, we analysed isotopic data from 254 museum study skins from 12 of the 16 species of the bird genus Cinclodes and measured stable isotope ratios for four different elements: carbon, nitrogen, hydrogen and oxygen. We find that all traits, measured individually, or as a composite measurement, lack any phylogenetic signal, which in turn suggests a high level of lability in ecological niches. We compared these metrics to the measurements of morphological traits in the same genus and found that isotopic niches are uniquely evolutionarily labile compared to other traits. Our results suggest that, in Cinclodes, the realized niche evolves much faster than expected by the constraints of phylogenetic history and poses the question of whether this is a general pattern across the tree of life.

Study of Productive, Reproductive and Morphological Traits of Bucks in Different Eco-zones of Lumbini Province, Nepal

Goat is a domesticated small ruminant, primarily reared by small farmers for meat production, across the country. The productivity of goat is often low, which could be related to several genetic and non-genetic factors. A field study was carried out to characterize, evaluate and estimate the effect of non-genetic factors on the productive and reproductive performance of hill goats in different eco- zones at Rolpa district of Lumbini province. Altogether 43 bucks of different age groups were identified for this study. Morphological attributes, productive, and reproductive performance were collected based on field monitoring and measurements within different altitudes of Rolpa district. Least square analysis was performed using Harvey (1990) computer software package, and means were compared using DMRT. The measurements of morphological traits were higher in male as compared to females. Results revealed the age at first service of bucks (336 days), the average body weight of buck was (38.76 kg), the overall body length of buck from one to four year was 78.01±0.35 cm, overall heart girth of one to four years’ age buck was 77.57±1.65 cm, average wither height from one to four-year-old buck was 71.88±2.13 cm, overall average Scrotal circumference of bucks (1-4 years) were 24.38±0.71 cm respectively. The results of this study suggest that the performance of low altitude goat flocks was better than mid and high-altitude goat flocks in the Rolpa district in terms of production and reproduction traits. The selection of the best performance of buck could be done on the basis of their traits for breeding. This result could be attributed to superior genotype along with better management practices followed by the farmers in Rolpa district.

TiP-Leaf: a dataset of leaf traits across vegetation types on the Tibetan Plateau

Abstract. Functional trait databases are emerging as a crucial tool for a wide range of ecological studies, including next-generation vegetation modelling across the world. However, few large-scale studies have been reported on plant traits in the Tibetan Plateau (TP), the cradle of East Asian flora and fauna with specific alpine ecosystems, and no report on plant trait databases could be found. In this work, an extensive dataset of 11 leaf functional traits (TiP-Leaf), mainly for herbs and shrubs and a few trees on the TP, was compiled through field surveys. The TiP-Leaf dataset, which was compiled from 336 sites distributed mainly on the plateau surface and the northern margin of the TP across alpine and temperate vegetation regions and sampled from 2018 to 2021, contained 1692 morphological trait measurements of leaf thickness, leaf fresh weight, leaf dry weight, leaf dry-matter content, leaf water content, leaf area, specific leaf area and leaf mass per area and 1645 chemical element trait measurements of leaf carbon, nitrogen and phosphorus contents. Thus, 468 species that belong to 184 genera and 51 families were obtained and measured. In addition to leaf trait measurements, the geographic coordinates, bioclimate variables, disturbance intensities and vegetation types of each site were also recorded. The dataset could provide solid data support to effectively quantify the modern ecological features of alpine ecosystems, thereby further evaluating the response of alpine ecosystems to climate change and human disturbances and improving the next-generation vegetation model. The dataset, which is available from the National Tibetan Plateau Data Center (TPDC; Jin et al., 2022a; https://doi.org/10.11888/Terre.tpdc.272516), can make a great contribution to the regional and global plant trait databases.

Artemisia pollen dataset for exploring the potential ecological indicators in deep time

Abstract. Artemisia, along with Chenopodiaceae, is the dominant component growing in the desert and dry grassland of the Northern Hemisphere. Artemisia pollen with its high productivity, wide distribution, and easy identification is usually regarded as an eco-indicator for assessing aridity and distinguishing grassland from desert vegetation in terms of the pollen relative abundance ratio of Chenopodiaceae/Artemisia (C/A). Nevertheless, divergent opinions on the degree of aridity evaluated by Artemisia pollen have been circulating in the palynological community for a long time. To solve the confusion, we first selected 36 species from nine clades and three outgroups of Artemisia based on the phylogenetic framework, which attempts to cover the maximum range of pollen morphological variation. Then, sampling, experiments, photography, and measurements were taken using standard methods. Here, we present pollen datasets containing 4018 original pollen photographs, 9360 pollen morphological trait measurements, information on 30 858 source plant occurrences, and corresponding environmental factors. Hierarchical cluster analysis on pollen morphological traits was carried out to subdivide Artemisia pollen into three types. When plotting the three pollen types of Artemisia onto the global terrestrial biomes, different pollen types of Artemisia were found to have different habitat ranges. These findings change the traditional concept of Artemisia being restricted to arid and semi-arid environments. The data framework that we designed is open and expandable for new pollen data of Artemisia worldwide. In the future, linking pollen morphology with habitat via these pollen datasets will create additional knowledge that will increase the resolution of the ecological environment in the geological past. The Artemisia pollen datasets are freely available at Zenodo (https://doi.org/10.5281/zenodo.6900308; Lu et al., 2022).

English

Interesting morphological traits in tree organs are essential for selecting the best plant germplasm. Variation in morphometric traits of leaf, fruit and seed of multipurpose tree Diospyros mespiliformis were studied in two climatic zones in Benin using 735 trees from 4 major habitats (provenances) in each climatic zone. Morphological trait measurements were combined with architectural parameters and analyzed using two-way ANOVA, principal components analysis and hierarchical clustering. Results indicated that significant differences were observed between leaves, fruits and seed morphological traits within climatic zones and habitats in terms of dimensions across the study area. Compared to the other three habitats (low dimensions), leaves from woodland showed large dimensions (µL_leaf=130 mm, µl_leaf=50 mm). Soudano Guinean zone recorded the highest fruits morphological traits values (µd_fruit= 36 mm µl_fruit=30 mm) while Soudanian zone had the lowest (µd_fruit= 12 mm, µl_fruit=8 mm). More seeds per fruit were recorded in woodlands and parklands. Out of these, hierarchical analysis grouped ebony morphotypes into four clusters. There was no significant correlation between the number of seeds per fruits and other fruit traits. However, significant and strong positive correlations were found between morphometric characters, bearing and architectural parameters (R = 0.96). The provenance significantly affected variations in organ-related traits.  Correlation relationships suggested morphotypes for breeding improvement. Interesting and desired characteristics delineating individuals and populations can guide future selection of targeted ebony trees with the aim of improving high-value species in agroforestry domestication program.   Key words: Diversity, domestication, environmental factors, morphological descriptors, multivariate analysis.

Assessing taxonomic and functional change in British breeding bird assemblages over time

AbstractAimThe aim was to identify the primary drivers of compositional change in breeding bird assemblages over a 40‐year period.LocationBritain.Time periodFrom 1970 to 2010.Major taxa studiedBirds.MethodsUsing morphological trait measurements and a dataset of presence–absence data for British breeding birds surveyed in 10 km × 10 km hectads during two time periods, we calculated temporal taxonomic and functional beta diversity for each hectad alongside the change in species richness, mean nearest taxon distance (MNTD) and mean pairwise distance (MPD). We also estimated potential drivers of beta diversity, including climatic and land‐use and land‐cover (LULC) change variables, elevation and assemblage species richness in 1970 (1970rich). We used random forest regressions to test which variables best explained compositional change in the assemblages. We also assessed spatial taxonomic and functional change by analysing multiple‐site beta diversity and pairwise dissimilarities between time periods.ResultsInitial (1970) species richness was the most important predictor (highest importance score) across all models, with areas characterized by higher initial richness experiencing less assemblage change overall. The coordinates included to capture spatial autocorrelation in the data were also important predictors of change. Most climate and LULC variables had relatively low explanatory power; elevation and average temperature were the most influential. All metrics increased slightly with increasing elevation, except for species richness change and MPD, which decreased.Main conclusionsThe composition of British breeding bird assemblages changed substantially between 1970 and 2010. Spatial heterogeneity increased, both taxonomically and functionally. We show evidence that hectads with larger assemblages have been buffered from temporal diversity change and that those at higher elevations changed more in composition than those at lower elevations. Overall, coarse‐resolution climate and LULC explained only small to moderate amounts of variation, suggesting that stochastic assembly change or finer‐scale drivers might be drivers of temporal changes in assemblage composition.

Mycorrhizal Fungi Inoculation Improves Capparis spinosa’s Yield, Nutrient Uptake and Photosynthetic Efficiency under Water Deficit

Agricultural yields are under constant jeopardy as climate change and abiotic pressures spread worldwide. Using rhizospheric microbes as biostimulants/biofertilizers is one of the best ways to improve agro-agriculture in the face of these things. The purpose of this experiment was to investigate whether a native arbuscular mycorrhizal fungi inoculum (AMF-complex) might improve caper (Capparis spinosa) seedlings’ nutritional status, their morphological/growth performance and photosynthetic efficiency under water-deficit stress (WDS). Thus, caper plantlets inoculated with or without an AMF complex (+AMF and −AMF, respectively) were grown under three gradually increasing WDS regimes, i.e., 75, 50 and 25% of field capacity (FC). Overall, measurements of morphological traits, biomass production and nutrient uptake (particularly P, K+, Mg2+, Fe2+ and Zn2+) showed that mycorrhizal fungi inoculation increased these variables significantly, notably in moderate and severe WDS conditions. The increased WDS levels reduced the photochemical efficiency indices (Fv/Fm and Fv/Fo) in −AMF plants, while AMF-complex application significantly augmented these parameters. Furthermore, the photosynthetic pigments content was substantially higher in +AMF seedlings than −AMF controls at all the WDS levels. Favorably, at 25% FC, AMF-colonized plants produce approximately twice as many carotenoids as non-colonized ones. In conclusion, AMF inoculation seems to be a powerful eco-engineering strategy for improving the caper seedling growth rate and drought tolerance in harsh environments.

What does a threatened saproxylic beetle look like? Modelling extinction risk using a new morphological trait database.

The extinction of species is a non-random process, and understanding why some species are more likely to go extinct than others is critical for conservation efforts. Functional trait-based approaches offer a promising tool to achieve this goal. In forests, deadwood-dependent (saproxylic) beetles comprise a major part of threatened species, but analyses of their extinction risk have been hindered by the availability of suitable morphological traits. To better understand the mechanisms underlying extinction in insects, we investigated the relationships between morphological features and the extinction risk of saproxylic beetles. Specifically, we hypothesised that species darker in colour, with a larger and rounder body, a lower mobility, lower sensory perception and more robust mandibles are at higher risk. We first developed a protocol for morphological trait measurements and present a database of 37 traits for 1,157 European saproxylic beetle species. Based on 13 selected, independent traits characterising aspects of colour, body shape, locomotion, sensory perception and foraging, we used a proportional-odds multiple linear mixed-effects model to model the German Red List categories of 744 species as an ordinal index of extinction risk. Six out of 13 traits correlated significantly with extinction risk. Larger species as well as species with a broad and round body had a higher extinction risk than small, slim and flattened species. Species with short wings had a higher extinction risk than those with long wings. On the contrary, extinction risk increased with decreasing wing load and with higher mandibular aspect ratio (shorter and more robust mandibles). Our study provides new insights into how morphological traits, beyond the widely used body size, determine the extinction risk of saproxylic beetles. Moreover, our approach shows that the morphological characteristics of beetles can be comprehensively represented by a selection of 13 traits. We recommend them as a starting point for functional analyses in the rapidly growing field of ecological and conservation studies of deadwood.

Can multitrophic interactions shape morphometry, allometry, and fluctuating asymmetry of seed-feeding insects?

Body size is commonly associated with biological features such as reproductive capacity, competition, and resource acquisition. Many studies have tried to understand how these isolated factors can affect the body pattern of individuals. However, little is known about how interactions among species in multitrophic communities determine the body shape of individuals exploiting the same resource. Here, we evaluate the effect of fruit infestation, parasitism rate, and seed biomass on size, allometric and asymmetric patterns of morphological structures of insects that exploit the same resource. To test it, we measured 750 individuals associated with the plant Senegalia tenuifolia (Fabaceae), previously collected over three consecutive years. Negative allometry was maintained for all species, suggesting that with increasing body size the body structure did not grow proportionally. Despite this, some variations in allometric slopes suggest that interactions in a multitrophic food web can shape the development of these species. Also, we observed a higher confidence interval at higher categories of infestation and parasitism rate, suggesting a great variability in the allometric scaling. We did not observe fluctuating asymmetry for any category or species, but we found some changes in morphological structures, depending on the variables tested. These findings show that both allometry and morphological trait measurements are the most indicated in studies focused on interactions and morphometry. Finally, we show that, except for the fluctuating asymmetry, each species and morphological structure respond differently to interactions, even if the individuals play the same functional role within the food web.

A simple use of camera traps for photogrammetric estimation of wild animal traits

AbstractThe measurement of physical traits of animals is an important topic in animal ecology and wildlife management, but it is quite difficult to achieve an acceptable level of accuracy, especially for free‐ranging wild animals. As a non‐invasive method, camera trapping has become a common tool for detecting and monitoring wild animals. In this study, we combined camera‐trapping images and a photogrammetry technique to present a camera trap‐based photogrammetric estimation (CTPE) approach for robust measurement of morphological traits of animals. We first tested our method in a captive population of fallow deer (Dama dama) and compared the estimated shoulder heights by CTPE with corresponding hand measurements. The results revealed a remarkable accuracy, with an expected measurement error within ± 5 cm. Second, we mainly demonstrated a field application of CTPE in a wild population of Altai wapiti (Cervus elaphus sibiricus) in the Kanas National Nature Reserve, Xinjiang, China. For wapiti, we found that the average shoulder height of males was 135 ± 9 cm (mean ± sd, n = 30) and that of females was 125 ± 6 cm (n = 37), with all data significantly fitting a normal distribution. We did not find any differences in CTPE results among cameras, between photograph types (colour vs. black and white) or temperatures. No significant difference existed between our results and the hand‐measured shoulder heights of wapiti from deer farms. Finally, we discussed the strengths, limitations and potential extensions of the method. We suggest that the combination of camera trapping and the photogrammetry technique is quite promising and that CTPE has great potential in wildlife field investigations.

Biometry of the large dragonfly Anax imperator (Odonata: Aeshnidae): A study of traits from larval development to adults

Insect larval development affects adult traits but the biometric relationships are usually poorly understood, including large odonates. In this study, measurements of morphological traits of larvae, exuviae and adults of Anax imperator were recorded. They were used to investigate the effects of early development on adult morphology. Results showed an increase in larval length during the final instar and the length of its exuviae significantly exceeded that of the larva. Length and body mass of teneral adults were strongly related to the length of their exuviae. Adult males were significantly longer than adult females, while both had the same body mass at emergence. Length of teneral adults was negatively related to the date of emergence in both sexes. During maturation, body mass of males only increased slightly whereas that of females increased greatly. Mature specimens were also significantly longer than teneral individuals. Body mass of mature males and length of mature females were both associated with the date of capture. Wing length did not differ between sexes or from data available from Great Britain. This study underscores the importance of taking into account larval growth in order to better understand the adult traits of odonates.

Relationship between swimming capacities and morphological traits of fish larvae at settlement stage: a study of several coastal Mediterranean species.

Experimental measurements were made in the laboratory to determine the swimming capacities of settlement-stage fish larvae of several Mediterranean coastal species collected from the nearshore waters of Corsica, France. Critical swimming speed (Ucrit , cm s-1 ) was measured to provide a realistic laboratory estimate of in situ swimming speed. Morphometric traits were measured to assess potential predictors of a species' swimming ability and, when possible, daily otolith increments were used to estimate age. Observed swimming speeds were consistent with other temperate species and demonstrated that the tested species are competent swimmers and not passive components of their environment. Morphological traits varied in their correlation with Ucrit across groups and species. Direct measurements of morphological traits were better predictors than calculated ratios. Pelagic larval duration had little relationship with swimming speed among species for which daily otolith increments were counted. In addition to expanding the database on swimming capacities of settlement-stage fish larvae in the Mediterranean Sea, this study also developed methods that simplify the assessment of larval fish swimming ability. Swimming speed data are essential for improving larval dispersal models and for predicting recruitment rates in coastal fish populations.

A Low‐Cost Automated System for High‐Throughput Phenotyping of Single Oat Seeds

Efforts focused on the genetic improvement of seed morphometric and color traits would greatly benefit from efficient and reliable quantitative phenotypic assessment in a nondestructive manner. Although several seed phenotyping systems exist, none of them combine the cost effectiveness, identity preservation, throughput, and accuracy needed for implementation in plant breeding. We integrated an image analysis component into a single‐seed analyzer (SSA) system that also captures near‐infrared reflectance (NIR) and weight data. Through the development and utilization of an open‐source computational image analysis pipeline, image data acquired by two cameras mounted on the SSA machine were automatically processed to derive estimates of length, width, height, volume, and color for 96 individual dehulled groats (seeds) of five oat (Avena sativa L.) genotypes replicated across days. With the exception of color, the four traits were found to be strongly correlated with and have repeatability comparable to manual measurements. The seed color values had moderately strong correlation with those measured by a colorimeter, but further improvements to the SSA system are needed to increase measurement accuracy. These results demonstrate that the SSA system has the potential to provide a low‐cost solution for the rapid, accurate measurement of morphological traits on individual seeds of oat and potentially other crop species, allowing the screening of seeds from numerous genotypes in breeding programs.

Using path analysis to predict bodyweight from body measurements of goats and sheep of communal rangelands in Botswana

The objective of this study was to determine the practicality of using linear body measurement traits to predict live weight of goats and sheep under communal grazing in three districts of Botswana, namely Central, Kweneng, and Kgalagadi. Pairwise (Pearson) correlations were estimated using bodyweight (BW) and morphological trait measurements, namely heart girth (HG), shoulder height (SH), and body condition score (BCS) for a sample of 1447 goats and 588 sheep. These ranged from 0.19 to 0.94 for goats and 0.44 to 0.94 for sheep, and were statistically significant. In both animals, regardless of sex, the highest positive correlations were found between BW and HG, followed by BW and SH, then BW and BCS. The direct and indirect relationship between BW and morphological traits using a path analysis approach were also estimated. This analysis suggested that the direct effect of HG on BW was higher at 0.761 for male and 0.662 for female goats, respectively. Similarly, the direct effect of HG on BW was higher among sheep at 0.764 for males and 0.882 for females. The direct effects of SH in all the animals were also positively influenced by BW. It was concluded that among these three morphological traits, the most valuable for estimating the BW for goats and sheep in Botswana is HG, followed by SH. BCS was found non-significant. Path analysis therefore has an advantage over previous empirical studies by providing more detailed information on the relationships (direct and indirect) between these variables. A further implication of this study is that a conversion table could be constructed to help smallholder farmers to estimate the live weight of their sheep and goats from linear measurements. This would aid in the management and marketing of their livestock. Keywords : Body condition score, heart girth measurement, live weight, shoulder height measurement, small ruminants

Understanding ecological transitions under recurrent wildfire: A case study in the seasonally dry tropical forests of the Chiquitania, Bolivia

Wildfires in tropical forests are likely to become a more dominant disturbance due to future increasing feedbacks between rapid frontier expansion and more frequent droughts. This study evaluates the effects of fire recurrence on seasonally dry tropical forests of the Chiquitania region, located in the southern rim of Amazonia, eastern lowlands of Bolivia. Effects were assessed in terms of changes in biomass, forest structure, species diversity and composition. Forest plots were established in well-conserved study sites to compare unburnt forests with forests burned once, twice and three times in the period 2000–2012. Inventories were collected for trees, palms and lianas, including identification of species and measurement of morphological traits related to fire tolerance. Biomass was estimated using different allometric equations, and species composition, richness, abundance and dominance were compared. We found a significant loss in biomass, and putative effects on small and large trees after recurrent burns. The observed patterns in this study suggest that Chiquitano forests respond to recurrent fires through a shift in tree species composition with already-present fire-tolerant species becoming more dominant. This transition presented losses in biomass but increases in species richness. Insights into a possible transition to a more fire-adapted state is of great relevance for forest and fire management strategies in the region, as this transition may become irreversible in a future regime of more frequent wildfires, expected due to drier climatic conditions with increasing patterns of forest fragmentation and spreading use of fire into new forest frontiers.