scholarly journals Morphological structure of ant assemblages in tropical and temperate forests

2016 ◽  
Author(s):  
Rogério R. Silva ◽  
Israel Del Toro ◽  
Carlos Roberto F. Brandão ◽  
Aaron M. Ellison
Keyword(s):  
Nearest Neighbor ◽  
Temperate Forests ◽  
Environmental Gradients ◽  
Morphological Structure ◽  
Morphological Diversity ◽  
Habitat Characteristics ◽  
Latitudinal Gradients ◽  
Eastern United States ◽  
Ant Assemblages ◽  
Species Packing

AbstractMorphological variation in co-occurring species often is used to infer species assembly rules and other processes structuring ecological assemblages. We compared the morphological structure of ant assemblages in two biogeographic regions along two extensive latitudinal gradients to examine common patterns and unique characteristics of trait distribution. We sampled ant assemblages along extensive latitudinal gradients in Tropical Atlantic Forest in eastern Brazil and temperate forests in the eastern United States. We quantified 14 morphological traits related to the ecology and life history of each of 599 ant species and defined the morphological space occupied by different ant assemblages. Null models were used to test whether tropical and temperate ant assemblages differed from random expectation in morphological structure. Correlations between traits and climate were used to infer associations between habitat characteristics and morphological space occupied by ant assemblages. Tropical ant assemblages had higher morphological diversity and variation in the space of occupied morphospace, whereas temperate assemblages had higher variance in size. Although tropical ant assemblages had smaller morphological distances among species, species packing (i.e., mean nearest-neighbor distance) did not differ between regions. Null model analysis revealed scant evidence of habitat filtering or niche differentiation within assemblages. Different traits had different means, variances, skewness, and kurtosis values along each environmental gradient. Mean trait values within assemblages were associated mainly with region and correlated with temperature but trait variances had more complex responses to climate, including interactions between temperature and precipitation in the models. The higher functional diversity in tropical ant assemblages occurs by expansion of the morphospace rather than through an increase in species packing. Different traits vary independently along environmental gradients. Analysis of individual traits together with categorization of the moments of trait distributions (statistical central tendencies) provide new directions for quantifying morphological diversity in ant assemblages.

scholarly journals Reef fish community structure on three islands of Itaipu, Southeast Brazil

2008 ◽  
Vol 6 (2) ◽  
pp. 267-274 ◽  
Author(s):  
José Policarpo de Mendonça-Neto ◽  
Cassiano Monteiro-Neto ◽  
Luiz Eduardo Moraes
Keyword(s):  
Environmental Gradients ◽  
Seasonal Pattern ◽  
Reef Fishes ◽  
Habitat Characteristics ◽  
Brazilian Coast ◽  
Rocky Reef ◽  
Fish Community Structure ◽  
Rocky Reefs ◽  
Chain Link ◽  
One Year

We provide here the first assessment of the composition, abundance and distribution of rocky reef fishes of Itaipu Sound, Rio de Janeiro, off the southeastern Brazilian coast. Monthly visual censuses, benthic quadrats and chain link transects were conducted over one year on rocky reefs at three islands (Menina, Mãe and Pai). A total of 2466 individual fish, belonging to 29 families and 42 species were recorded. The most abundant fish species were Parablennius pilicornis, Haemulon steindachneri, Orthopristis ruber and Diplodus argenteus. Sheltered and complex habitats showed the most abundant and diverse fish populations. There was a major significant separation between sampling sites and a secondary seasonal pattern. The three sites showed similar fish communities with locally structured environmental gradients according to their inherent habitat characteristics.

scholarly journals Genome-wide sequence-based genotyping supports a nonhybrid origin of Castanea alabamensis

2019 ◽  
Author(s):  
M. Taylor Perkins ◽  
Tetyana Zhebentyayeva ◽  
Paul H. Sisco ◽  
J. Hill Craddock
Keyword(s):  
North American ◽  
Distinct Group ◽  
Morphological Diversity ◽  
Hybrid Origin ◽  
Putative Hybrid ◽  
Eastern United States ◽  
The North ◽  
Snp Data ◽  
Genome Wide ◽  
Conservation Concern

AbstractThe genus Castanea in North America contains multiple tree and shrub taxa of conservation concern. The two species within the group, American chestnut (Castanea dentata) and chinquapin (C. pumila sensu lato), display remarkable morphological diversity across their distributions in the eastern United States and southern Ontario. Previous investigators have hypothesized that hybridization between C. dentata and C. pumila has played an important role in generating morphological variation in wild populations. A putative hybrid taxon, Castanea alabamensis, was identified in northern Alabama in the early 20th century; however, the question of its hybridity has been unresolved. We tested the hypothesized hybrid origin of C. alabamensis using genome-wide sequence-based genotyping of C. alabamensis, all currently recognized North American Castanea taxa, and two Asian Castanea species at >100,000 single-nucleotide polymorphism (SNP) loci. With these data, we generated a high-resolution phylogeny, tested for admixture among taxa, and analyzed population genetic structure of the study taxa. Bayesian clustering and principal components analysis provided no evidence of admixture between C. dentata and C. pumila in C. alabamensis genomes. Phylogenetic analysis of genome-wide SNP data indicated that C. alabamensis forms a distinct group within C. pumila sensu lato. Our results are consistent with the model of a nonhybrid origin for C. alabamensis. Our finding of C. alabamensis as a genetically and morphologically distinct group within the North American chinquapin complex provides further impetus for the study and conservation of the North American Castanea species.

scholarly journals Chimpanzee (Pan troglodytes verus) density and environmental gradients at their biogeographical range edge

2020 ◽  
Author(s):  
Erin G. Wessling ◽  
Paula Dieguez ◽  
Manuel Llana ◽  
Liliana Pacheco ◽  
Jill D. Pruetz ◽  
...  
Keyword(s):  
Pan Troglodytes ◽  
Habitat Heterogeneity ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Habitat Characteristics ◽  
Pan Troglodytes Verus ◽  
Range Limit ◽  
Range Edge ◽  
Food Species ◽  
Underlying Mechanisms

ABSTRACTIdentifying ecological gradients at the range edge of a species is an essential step in revealing the underlying mechanisms and constraints that limit the species’ geographic range. We aimed to describe the patterns of variation in chimpanzee (Pan troglodytes verus) density and habitat characteristics perpendicular to the northern edge of their range and to investigate potential environmental mechanisms underlying chimpanzee distribution in a savanna-mosaic habitat. We estimated chimpanzee densities at six sites forming a 126 km latitudinal gradient at the biogeographical range edge of the western chimpanzee in the savanna-mosaic habitats of southeastern Senegal. To accompany these data, we used systematically placed vegetation plots to characterize the habitats at each site for habitat heterogeneity, tree density and size, floral assemblages, among other variables. We found that both biotic and abiotic factors are potential determinants of the chimpanzee range limit in this ecoregion. Specifically, chimpanzee-occupied landscapes at the limit had smaller available floral assemblages, less habitat heterogeneity, and contained fewer closed canopy habitats in which chimpanzees could seek refuge from high temperatures than landscapes farther from the range limit. This pattern was accompanied by a decline in chimpanzee density with increasing proximity to the range limit. Our results provide several indications of the potential limits of food species diversity, thermal refuge, and water availability to the chimpanzee niche and the implications of these limits for chimpanzee biogeography, especially in the face of climate change predictions, as well as to species distributional modeling more generally.

Shell variations in the gastropod, Monodonta labio, in the North-western Pacific: the important role of temperature in the evolution process

2019 ◽  
Vol 99 (7) ◽  
pp. 1591-1599
Author(s):  
Dan Zhao ◽  
Ling-Feng Kong ◽  
Takenori Sasaki ◽  
Qi Li
Keyword(s):  
Environmental Gradients ◽  
Ecological Factors ◽  
Local Maximum ◽  
Morphological Diversity ◽  
Shell Shape ◽  
Shape Variation ◽  
Genetic Structuring ◽  
Morphological Variations ◽  
China Sea

AbstractMolluscan shells showing phenotypic variations are ideal models for studying evolution and plasticity. In north-eastern Asia, genetic and morphological diversity of the gastropod, Monodonta labio, were assumed to be influenced by both palaeoclimatic changes and current ecological factors. In this study, we examined spatial variations in shell shape of M. labio using general measurement and geometric morphometric analysis. We also investigated whether shell shape variation is best explained by environmental gradients or by genetic structuring, based on our prior molecular phylogeographic study. Two common morphological forms were observed among Chinese populations and in the adjacent Asian areas. Both the analyses revealed separation patterns in morphological variations of shell shape among the clades and populations. Environmental modelling analysis showed a significant correlation between shape variations and local maximum temperatures of the warmest month, indicating the role of natural selection in the evolution of this species. Data obtained in this study, combined with the cytochrome oxidase subunit I (COI) molecular phylogenetic data from the prior study, showed that morphological variations in M. labio were constrained by both local adaptation and phenotypic plasticity. We hypothesized that geographic separation by the Dongshan Landbridge was the first step towards its diversification, and that the temperature gradient between the East China Sea and South China Sea probably was the selective force driving the divergence of its morphological variations.

scholarly journals Forest stratification shapes allometry and flight morphology of tropical butterflies

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201071
Author(s):  
Sebastián Mena ◽  
Krzysztof M. Kozak ◽  
Rafael E. Cárdenas ◽  
María F. Checa
Keyword(s):  
Insect Flight ◽  
Morphological Diversity ◽  
Vertical Gradient ◽  
Latitudinal Gradients ◽  
Butterfly Species ◽  
Forest Stratification ◽  
Aspect Ratios ◽  
Flight Morphology ◽  
Study Selection ◽  
Key Factor

Studies of altitudinal and latitudinal gradients have identified links between the evolution of insect flight morphology, landscape structure and microclimate. Although lowland tropical rainforests offer steeper shifts in conditions between the canopy and the understorey, this vertical gradient has received far less attention. Butterflies, because of their great phenotypic plasticity, are excellent models to study selection pressures that mould flight morphology. We examined data collected over 5 years on 64 Nymphalidae butterflies in the Ecuadorian Chocó rainforest. We used phylogenetic methods to control for similarity resulting from common ancestry, and explore the relationships between species stratification and flight morphology. We hypothesized that species should show morphological adaptations related to differing micro-environments, associated with canopy and understorey. We found that butterfly species living in each stratum presented significantly different allometric slopes. Furthermore, a preference for the canopy was significantly associated with low wing area to thoracic volume ratios and high wing aspect ratios, but not with the relative distance to the wing centroid, consistent with extended use of fast flapping flight for canopy butterflies and slow gliding for the understorey. Our results suggest that microclimate differences in vertical gradients are a key factor in generating morphological diversity in flying insects.

scholarly journals Downscaling of ERA-Interim Temperature in the Contiguous United States and Its Implications for Rain–Snow Partitioning

2018 ◽  
Vol 19 (7) ◽  
pp. 1215-1233 ◽  
Author(s):  
Guoqiang Tang ◽  
Ali Behrangi ◽  
Ziqiang Ma ◽  
Di Long ◽  
Yang Hong
Keyword(s):  
United States ◽  
Air Temperature ◽  
Nearest Neighbor ◽  
Reanalysis Data ◽  
Lapse Rate ◽  
Critical Threshold ◽  
Eastern United States ◽  
Temperature Lapse Rate ◽  
Mountainous Regions ◽  
Precipitation Phase

Abstract Precipitation phase has an important influence on hydrological processes. The Integrated Multisatellite Retrievals for Global Precipitation Measurement (IMERG) uses temperature data from reanalysis products to implement rain–snow classification. However, the coarse resolution of reanalysis data may not reveal the spatiotemporal variabilities of temperature, necessitating appropriate downscaling methods. This study compares the performance of eight air temperature Ta downscaling methods in the contiguous United States and six mountain ranges using temperature from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) as the benchmark. ERA-Interim Ta is downscaled from the original 0.75° to 0.1°. The results suggest that the two purely statistical downscaling methods [nearest neighbor (NN) and bilinear interpolation (BI)] show similar performance with each other. The five downscaling methods based on the free-air temperature lapse rate (TLR), which is calculated using temperature and geopotential heights at different pressure levels, notably improves the accuracy of Ta. The improvement is particularly obvious in mountainous regions. We further calculated wet-bulb temperature Tw, for rain–snow classification, using Ta and dewpoint temperature from ERA-Interim and PRISM. TLR-based downscaling methods result in more accurate Tw compared to NN and BI in the western United States, whereas the improvement is limited in the eastern United States. Rain–snow partitioning is conducted using a critical threshold of Tw with Snow Data Assimilation System (SNODAS) snowfall data serving as the benchmark. ERA-Interim-based Tw using TLR downscaling methods is better than that using NN/BI and IMERG precipitation phase. In conclusion, TLR-based downscaling methods show promising prospects in acquiring high-quality Ta and Tw with high resolution and improving rain–snow partitioning, particularly in mountainous regions.

scholarly journals Optimal fishing samplers to reveal the morphological structure of a fish assemblage in a subtropical tidal flat

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Carolina C. Siliprandi ◽  
Víctor M. Tuset ◽  
Antoni Lombarte ◽  
Marc Farré ◽  
Carmen L. D. B. Rossi-Wongtschowski
Keyword(s):  
Tidal Flat ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Morphological Variability ◽  
Morphological Structure ◽  
Morphological Diversity ◽  
Morphological Characters ◽  
Otter Trawl ◽  
Brazilian Coast ◽  
Geometric Morphometric

ABSTRACT Morphological characters of species are essential for assessing the functional structure of a fish assemblage, since differences between them, for example in body shape, are related to many functional and ecological traits (e.g., swimming, search for food, striking and capturing prey, evading predators, spawning). Globally, tidal flats are relevant to fish assemblages by offering feeding, refuge, and reproduction grounds. To analyze the morphofunctional structure of the fish assemblage from a tidal flat on the Brazilian coast, we conducted standardized sampling using nine different fishing gears. The geometric morphometric method was applied to describe the fish shapes and verify the morphological structure of the assemblage. Here, we present the influence/susceptibility of each gear type on the morphological diversity of the fish assemblage. The results indicated that beach seine, otter trawl, marginal encircling gillnet, and fish traps, together, were the most effective gears to represent the maximum morphological variability of fish inhabiting that tidal flat. Moreover, the assemblage showed high morphological redundancy considered as a resistance of the ecosystem for avoiding functional diversity loss, emphasizing the importance of complementary gear use when determining fish assemblages in a conservation context.

scholarly journals Environmental and ecological factors mediate taxonomic composition and body size of polyplacophoran assemblages along the Peruvian Province

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Christian M. Ibáñez ◽  
Melany Waldisperg ◽  
Felipe I. Torres ◽  
Sergio A. Carrasco ◽  
Javier Sellanes ◽  
...  
Keyword(s):  
Body Size ◽  
Species Composition ◽  
Size Structure ◽  
Environmental Gradients ◽  
Ecological Factors ◽  
Taxonomic Composition ◽  
Latitudinal Gradients ◽  
Size Segregation ◽  
Biogeographic Patterns ◽  
Diversity Gradient

Abstract Intertidal communities’ composition and diversity usually exhibit strong changes in relation to environmental gradients at different biogeographical scales. This study represents the first comprehensive diversity and composition description of polyplacophoran assemblages along the Peruvian Province (SE Pacific, 12°S–39°S), as a model system for ecological latitudinal gradients. A total of 4,775 chitons from 21 species were collected on twelve localities along the Peruvian Province. This sampling allowed us to quantitatively estimate the relative abundance of the species in this assemblage, and to test whether chitons conform to elementary predictions of major biogeographic patterns such as a latitudinal diversity gradient. We found that the species composition supported the division of the province into three ecoregional faunal groups (i.e. Humboldtian, Central Chile, and Araucanian). Though chiton diversity did not follow a clear latitudinal gradient, changes in species composition were dominated by smaller scale variability in salinity and temperature. Body size significantly differed by ecoregions and species, indicating latitudinal size-structure assamblages. In some localities body size ratios differed from a random assemblage, evidencing competition at local scale. Changes in composition between ecoregions influence body size structure, and their overlapping produce vertical size segregation, suggesting that competition coupled with environmental conditions structure these assemblages.

From continua to patches: examining stream community structure over large environmental gradients

2002 ◽  
Vol 59 (8) ◽  
pp. 1404-1417 ◽  
Author(s):  
Kristopher K Wright ◽  
Judith L Li
Keyword(s):  
Conceptual Framework ◽  
Algal Biomass ◽  
Environmental Gradients ◽  
Spatial Scales ◽  
Habitat Characteristics ◽  
Physical Habitat ◽  
Macroinvertebrate Communities ◽  
Order Stream ◽  
Longitudinal Gradients ◽  
Individual Variables

We present an approach that integrates a conceptual framework with multivariate ordination techniques and traditional parametric analyses to examine biotic and abiotic gradients in stream ecosystems. Ordinations were used to examine multivariate patterns along an environmental gradient, with individual variables used to interpret those patterns across spatial scales. The conceptual framework provides a consistent context to compare community distributions and consequently allows for hypothesis testing using ordinations. To illustrate the approach, we examined the physical template, fish and benthic macroinvertebrate communities, and algal biomass and production along a 1st- through 5th-order stream gradient in eastern Oregon. We hypothesized that longitudinal distributions of physical habitat characteristics, fishes, macroinvertebrates, and periphyton would reflect highly variable, discontinuous gradients. Multivariate patterns were determined by rotating nonparametric ordinations to a common set of variables and comparing them to conceptual models of (i) an ideal continuum, (ii) a random distribution, and (iii) discrete patches. Physical habitat and fishes reflected strong longitudinal gradients, macroinvertebrates were the most patchy, and algal biomass and production were highly variable. Distributions of individual variables from site and stream-order perspectives revealed how different factors, potentially influencing stream communities, may be continuous or patchy depending on spatial scale.

scholarly journals Fire Regimes and Environmental Gradients Shape Bird, Mammal and Plant Distributions in Temperate Forests

2017 ◽  
Vol 98 (3) ◽  
pp. 227-230
Author(s):  
Luke T. Kelly ◽  
Angie Haslem ◽  
Greg J. Holland ◽  
Steven W. J. Leonard ◽  
Josephine MacHunter ◽  
...  
Keyword(s):  
Temperate Forests ◽  
Environmental Gradients ◽  
Fire Regimes ◽  
Plant Distributions
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