scholarly journals Redescription of two poorly known Arctic Hilaira species (Aranei: Linyphiidae) with notes on species grouping

rej ◽  
2020 ◽  
Vol 29 (1) ◽  
pp. 133-140
Author(s):  
Yu. M. Marusik ◽  
A. A. Nekhaeva
Keyword(s):  
Species Grouping

scholarly journals Individuals from different-looking animal species may group together to confuse shared predators: simulations with artificial neural networks

2006 ◽  
Vol 274 (1611) ◽  
pp. 827-832 ◽  
Author(s):  
Colin R Tosh ◽  
Andrew L Jackson ◽  
Graeme D Ruxton
Keyword(s):  
Animal Species ◽  
Empirical Work ◽  
Species Group ◽  
Mixed Species ◽  
Retinotopic Maps ◽  
Species Groups ◽  
Artificial Neural ◽  
Mixed Species Groups ◽  
Species Grouping ◽  
Prey Items

Individuals of many quite distantly related animal species find each other attractive and stay together for long periods in groups. We present a mechanism for mixed-species grouping in which individuals from different-looking prey species come together because the appearance of the mixed-species group is visually confusing to shared predators. Using an artificial neural network model of retinotopic mapping in predators, we train networks on random projections of single- and mixed-species prey groups and then test the ability of networks to reconstruct individual prey items from mixed-species groups in a retinotopic map. Over the majority of parameter space, cryptic prey items benefit from association with conspicuous prey because this particular visual combination worsens predator targeting of cryptic individuals. However, this benefit is not mutual as conspicuous prey tends to be targeted most poorly when in same-species groups. Many real mixed-species groups show the asymmetry in willingness to initiate and maintain the relationship predicted by our study. The agreement of model predictions with published empirical work, the efficacy of our modelling approach in previous studies, and the taxonomic ubiquity of retinotopic maps indicate that we may have uncovered an important, generic selective agent in the evolution of mixed-species grouping.

scholarly journals ECOLOGICAL AND FUNCTIONAL CLUSTERING OF FORESTAL SPECIES IN THE SOUTH WESTERN AMAZONIA

2016 ◽  
Vol 40 (6) ◽  
pp. 1083-1090
Author(s):  
Elias Lourenço Vasconcelos Neto ◽  
Celso Azevedo ◽  
Luciano Ribas ◽  
Marcus Neves d'Oliveira
Keyword(s):  
Cluster Analysis ◽  
Discriminant Analysis ◽  
Tree Species ◽  
Permanent Plots ◽  
Cumulative Frequency ◽  
Cumulative Frequency Distribution ◽  
Functional Clustering ◽  
Breast Height ◽  
Three Stages ◽  
Species Grouping

ABSTRACT The aim of this study was to perform ecological and functional clustering of tree species in southwestern Amazon. Developed from data from 95 permanent plots of 1 ha each, all individuals with diameter at breast height (DBH) ≥10 cm were measured. The species grouping was performed in three stages: (1) cluster analysis, using the variables: diameter annual periodic increment -(IPADAP) considering three competition levels (high, medium and low) and the 95th percentile of the diameters (P95) cumulative frequency distribution (Ward hierarchical method); (2) Discriminant analysis, using the variables P95 and IPADAP by Fisher's method and (3) subjective stage, considering the species ecological characteristics. The Ward and Fisher methods used for discriminant and cluster analyses were effective for species grouping resulting on the formation of 10 groups. Variables: IPADAP and and P95 were efficient on the formed groups discrimination.. Variations in the growth rates for the overall mean data were reduced wen calculated for each group of species.

scholarly journals Effect of species grouping and site variables on aboveground biomass models for lowland tropical forests of the Indo-Malay region

2017 ◽  
Vol 74 (1) ◽  
Author(s):  
Solichin Manuri ◽  
Cris Brack ◽  
Teddy Rusolono ◽  
Fatmi Noor’an ◽  
Louis Verchot ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Aboveground Biomass ◽  
Biomass Models ◽  
Species Grouping

Adaptive Implications of Mixed-Species Grouping

2017 ◽  
pp. 81-103
Author(s):  
Eben Goodale ◽  
Guy Beauchamp ◽  
Graeme D. Ruxton
Keyword(s):  
Mixed Species ◽  
Species Grouping

Baetis zdenkae sp. nov., a new representative of the Baetis buceratus species-group (Ephemeroptera: Baetidae) from Rhodos (Greece) with notes to species-grouping of the subgenus Baetis Leach, 1815 s. str.

Zootaxa ◽  
2009 ◽  
Vol 1972 (1) ◽  
pp. 1-19 ◽  
Author(s):  
TOMÁŠ SOLDÁN ◽  
ROMAN J. GODUNKO
Keyword(s):  
New Species ◽  
Life Cycle ◽  
Vertical Distribution ◽  
Species Group ◽  
Basic Data ◽  
Male And Female ◽  
European Species ◽  
Species Groups ◽  
A New Species ◽  
Species Grouping

The male and female imago (subimago of both sexes unknown), and larva of a new species belonging to the Baetis buceratus species-group, namely Baetis (Baetis) zdenkae sp. nov. from Rhodos Island are described and illustrated in detail. Substantial diagnostic characters of males and larvae of the whole B. buceratus species-group are summarized and its position relative to other species groups is discussed. Critical characters distinguishing B. zdenkae sp. nov. from all other representatives of the B. buceratus species-group are emphasized and a discussion of 22 characters of the remaining 6 European species-groups of the subgenus Baetis Leach, 1815 s. str. and their relationships is offered. Available data on the biology of B. zdenkae sp. nov. (vertical distribution, habitat, current and substrate preference, abundance and density, possible life cycle type, and mating flight and oviposition patterns) and distribution with respect to possible endemism are given. Basic data on biology and area of distribution of Westpalaearctic species Baetis (Baetis) buceratus Eaton, 1870, B. (B.) nexus Navás, 1918 and B. (B.) spei Thomas & Dia, 1985 known only from Lebanon are summarized and compared to those of B. zdenkae sp. nov.

scholarly journals Diet and ecomorphological relationships of four cichlid species from the Cuiabá River basin

2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Gisele C. Novakowski ◽  
Fernanda A. S. Cassemiro ◽  
Norma S. Hahn
Keyword(s):  
River Basin ◽  
Gill Rakers ◽  
Cichlid Species ◽  
The Third ◽  
Food Size ◽  
Generalist Diet ◽  
Species Grouping

ABSTRACT Relationship between diet and morphology of cichlid were analyzed considering that the trophic apparatus determines differential food use among species. Cichlasoma dimerus and Satanoperca pappaterra showed a generalist diet, while Chaetobranchopsis australis and Crenicichla vittata consumed zooplankton and fish, respectively. Significant correlation between morphology and diet was not found, but C. australis differed from the others species in the upper mouth and longer gill rakers. The morphology data and food size segregated the cichlids into three groups. The first was comprised by C. australis, which has many and longer gill rakers and a more protractile mouth, the second by C. vittata, which have a larger and more-protruded mouth and the third by S. pappaterra and C. dimerus, with a smaller and lower mouth. The latter two groups have more widely spaced gill rakers and consumed larger food. Overall, our results showed different patterns of species grouping when considering morphological or diet data. However, to C. australis the gill rakers determine both the type and size of food.

scholarly journals Effect of Small-Scale Variations in Environmental Factors on the Distribution of Woody Species in Tropical Deciduous Forests of Vindhyan Highlands, India

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
R. K. Chaturvedi ◽  
A. S. Raghubanshi ◽  
J. S. Singh
Keyword(s):  
Environmental Factors ◽  
Native Species ◽  
Light Attenuation ◽  
Woody Species ◽  
Small Scale ◽  
Total N ◽  
Organic C ◽  
Group 2 ◽  
Choice Of Species ◽  
Species Grouping

The aim of this study is to investigate the changes in the composition of mature, naturally established and unmanaged TDF in response to small-scale variations in environmental factors. All woody species with a minimum circumference of 10 cm at 1.37 m height were surveyed in forty-five 20×50 m plots distributed over 5 sites in the TDF of Vindhyan highlands, India. Cluster analysis identified two distinct groups of plots. Group 1 plots had higher soil moisture content (SMC), clay, organic C, total N, total P, and light attenuation than group 2 plots. A total of 48 native species belonging to 25 families were encountered in the sampled area. High eigenvalues for the first two Canonical Correspondence Analysis (CCA) axes indicated the occurrence of species in distinct groups, and significant correlations of the axes with environmental variables indicated the effect of these variables on species grouping. In conclusion, patchiness in the soil resources needs to be considered in restoration efforts. The results of this study are expected to facilitate the decision regarding choice of species in afforestation programmes for restoring the TDF.

scholarly journals Fixed or mixed? Variation in tree functional types and vegetation structure in a forest-savanna ecotone in West Africa

2020 ◽  
Vol 36 (4) ◽  
pp. 133-149
Author(s):  
George K.D Ametsitsi ◽  
Frank Van Langevelde ◽  
Vincent Logah ◽  
Thomas Janssen ◽  
Jose A Medina-Vega ◽  
...  
Keyword(s):  
West Africa ◽  
Vegetation Structure ◽  
Basal Area ◽  
Fire Frequency ◽  
Soil Water Storage ◽  
Vegetation Types ◽  
Above Ground Biomass ◽  
Area Index ◽  
Tropical Vegetation ◽  
Species Grouping

AbstractWe analysed thirty-five 400-m2 plots encompassing forest, savanna and intermediate vegetation types in an ecotonal area in Ghana, West Africa. Across all plots, fire frequency was over a period of 15 years relatively uniform (once in 2–4 years). Although woodlands were dominated by species typically associated with savanna-type formations, and with forest formations dominated by species usually associated with closed canopies, these associations were non-obligatory and with a discrete non-specialized species grouping also identified. Across all plots, crown area index, stem basal area and above-ground biomass were positively associated with higher soil exchangeable potassium and silt contents: this supporting recent suggestions of interplays between potassium and soil water storage potential as a significant influence on tropical vegetation structure. We also found an average NDVI cover increase of ~0.15% year−1 (1984–2011) with plots dominated by non-specialized species increasing more than those dominated by either forest- or savanna-affiliated species. Our results challenge the traditional view of a simple forest vs. savanna dichotomy controlled by fire, and with our newly identified third non-specialized species grouping also potentially important in understanding ecotonal responses to climate change.

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