scholarly journals Large-scale assessment of commensalistic–mutualistic associations between African birds and herbivorous mammals using internet photos

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4520 ◽  
Author(s):  
Peter Mikula ◽  
Jiří Hadrava ◽  
Tomáš Albrecht ◽  
Piotr Tryjanowski
Keyword(s):  
Species Richness ◽  
Body Mass ◽  
Information Technologies ◽  
Large Scale ◽  
Bird Species ◽  
Null Model ◽  
Herd Size ◽  
Mammal Species ◽  
African Mammals ◽  
Herbivorous Mammals

Birds sitting or feeding on live large African herbivorous mammals are a visible, yet quite neglected, type of commensalistic–mutualistic association. Here, we investigate general patterns in such relationships at large spatial and taxonomic scales. To obtain large-scale data, an extensive internet-based search for photos was carried out on Google Images. To characterize patterns of the structural organization of commensalistic–mutualistic associations between African birds and herbivorous mammals, we used a network analysis approach. We then employed phylogenetically-informed comparative analysis to explore whether features of bird visitation of mammals, i.e., their mean number, mass and species richness per mammal species, are shaped by a combination of host mammal (body mass and herd size) and environmental (habitat openness) characteristics. We found that the association web structure was only weakly nested for commensalistic as well as for mutualistic birds (oxpeckers Buphagus spp.) and African mammals. Moreover, except for oxpeckers, nestedness did not differ significantly from a null model indicating that birds do not prefer mammal species which are visited by a large number of bird species. In oxpeckers, however, a nested structure suggests a non-random assignment of birds to their mammal hosts. We also identified some new or rare associations between birds and mammals, but we failed to find several previously described associations. Furthermore, we found that mammal body mass positively influenced the number and mass of birds observed sitting on them in the full set of species (i.e., taking oxpeckers together with other bird species). We also found a positive correlation between mammal body mass and mass of non-oxpecker species as well as oxpeckers. Mammal herd size was associated with a higher mass of birds in the full set of species as well as in non-oxpecker species, and mammal species living in larger herds also attracted more bird species in the full set of species. Habitat openness influenced the mass of birds sitting on mammals as well as the number of species recorded sitting on mammals in the full set of species. In non-oxpecker species habitat openness was correlated with the bird number, mass and species richness. Our results provide evidence that patterns of bird–mammal associations can be linked to mammal and environmental characteristics and highlight the potential role of information technologies and new media in further studies of ecology and evolution. However, further study is needed to get a proper insight into the biological and methodological processes underlying the observed patterns.

scholarly journals Testing biodiversity theory using species richness of reef-building corals across a depth gradient

2019 ◽  
Vol 15 (10) ◽  
pp. 20190493 ◽  
Author(s):  
T. Edward Roberts ◽  
Sally A. Keith ◽  
Carsten Rahbek ◽  
Tom C. L. Bridge ◽  
M. Julian Caley ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Coral Species ◽  
Environmental Gradients ◽  
Abiotic Factors ◽  
Empirical Support ◽  
Null Model ◽  
Local Scale ◽  
Small Scale ◽  
Energy Availability

Natural environmental gradients encompass systematic variation in abiotic factors that can be exploited to test competing explanations of biodiversity patterns. The species–energy (SE) hypothesis attempts to explain species richness gradients as a function of energy availability. However, limited empirical support for SE is often attributed to idiosyncratic, local-scale processes distorting the underlying SE relationship. Meanwhile, studies are also often confounded by factors such as sampling biases, dispersal boundaries and unclear definitions of energy availability. Here, we used spatially structured observations of 8460 colonies of photo-symbiotic reef-building corals and a null-model to test whether energy can explain observed coral species richness over depth. Species richness was left-skewed, hump-shaped and unrelated to energy availability. While local-scale processes were evident, their influence on species richness was insufficient to reconcile observations with model predictions. Therefore, energy availability, either in isolation or in combination with local deterministic processes, was unable to explain coral species richness across depth. Our results demonstrate that local-scale processes do not necessarily explain deviations in species richness from theoretical models, and that the use of idiosyncratic small-scale factors to explain large-scale ecological patterns requires the utmost caution.

Vegetation on and around large-scale buildings positively influences native tropical bird abundance and bird species richness

2018 ◽  
Vol 22 (2) ◽  
pp. 213-225 ◽  
Author(s):  
Richard N. Belcher ◽  
Keren R. Sadanandan ◽  
Emmanuel R. Goh ◽  
Jie Yi Chan ◽  
Sacha Menz ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Bird Species ◽  
Bird Abundance ◽  
Bird Species Richness ◽  
Tropical Bird

Evidence for bottom-up effects in the boreal forest: Do passerine birds respond to large-scale experimental fertilization?

1995 ◽  
Vol 73 (12) ◽  
pp. 2231-2237 ◽  
Author(s):  
Nicholas F. G. Folkard ◽  
James N. M. Smith
Keyword(s):  
Species Richness ◽  
Boreal Forest ◽  
Large Scale ◽  
Bird Species ◽  
Passerine Bird ◽  
Spatial And Temporal Variation ◽  
Bottom Up ◽  
Bird Species Richness ◽  
Point Counts ◽  
The Impact

Boreal plant communities are strongly nutrient limited, and the animals of the boreal forest may therefore experience bottom-up nutrient limitation. We conducted a 5-year experimental study of the impact of aerial nitrogen fertilization on birds of the boreal forest near Kluane Lake, southwestern Yukon, to test for such bottom-up effects. Specifically, we tested if avian abundance and species richness increased after fertilization. Variable circular-plot point counts were made to estimate bird numbers and species richness each summer from 1988 to 1992. Fertilization had no effect on abundance for the first two summers, but total abundances of the seven commonest passerine bird species increased by an average of 46% over the final 3 years. Fertilization had no effect on bird species richness. Population densities and species richness were both low at Kluane compared with patterns seen in temperate forest. Yellow-rumped warblers (Dendroica coronata), dark-eyed juncos (Junco hyemalis), and Swainson's thrushes (Catharus ustulatus) dominated the passerine community at Kluane. There was only moderate spatial and temporal variation in songbird numbers on control plots over the 5-year study period.

scholarly journals Body size affects immune cell proportions in birds and non-volant mammals, but not bats

2020 ◽  
Author(s):  
Emily Cornelius Ruhs ◽  
Daniel J. Becker ◽  
Samantha J. Oakey ◽  
Ololade Ogunsina ◽  
M. Brock Fenton ◽  
...  
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Immune Cell ◽  
White Blood Cells ◽  
Bird Species ◽  
Immune Defense ◽  
Mammal Species ◽  
Scaling Relationships ◽  
Neotropical Bats ◽  
Similar Body

AbstractPowered flight has evolved several times in vertebrates and constrains morphology and physiology in ways that likely have shaped how organisms cope with infections. Some of these constraints likely have impacts on aspects of immunology, such that larger fliers might prioritize risk reduction and safety. Addressing how the evolution of flight may have driven relationships between body size and immunity could be particularly informative for understanding the propensity of some taxa to harbor many virulent and sometimes zoonotic pathogens without showing clinical disease. Here, we used a scaling framework to quantify scaling relationships between body mass and the proportions of two types of white blood cells--lymphocytes, and granulocytes (neutr-/heterophils)--across 60 bat species, 414 bird species, and 256 non-volant mammal species. By using phylogenetically-informed statistical models on field-collected data from wild Neotropical bats, data gleaned from other wild bats available in the literature, and data from captive non-volant mammals and birds, we show that lymphocyte and neutrophil proportions do not vary systematically with body mass among bats. In contrast, larger birds and non-volant mammals have disproportionately higher granulocyte proportions than expected for their body size. Future comparative studies of wild bats, birds, and non-volant mammals of similar body mass should aim to further differentiate evolutionary effects and other aspects of life history on immune defense.Summary statementPowered flight might constrain morphology such that certain immunological features are prioritized. We show that bats largely have similar cell proportions across body mass compared to strong allometric scaling relationships in birds and non-flying mammals.

scholarly journals Body size affects immune cell proportions in birds and non-volant mammals, but not bats

2021 ◽  
Author(s):  
Emily Cornelius Ruhs ◽  
Daniel J. Becker ◽  
Samantha J. Oakey ◽  
Ololade Ogunsina ◽  
M. Brock Fenton ◽  
...  
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Immune Cell ◽  
White Blood Cells ◽  
Bird Species ◽  
Immune Defense ◽  
Mammal Species ◽  
Zoonotic Infections ◽  
Neotropical Bats ◽  
Similar Body

Powered flight has evolved several times in vertebrates and constrains morphology and physiology in ways that likely have shaped how organisms cope with infections. Some of these constraints likely have impacts on aspects of immunology, such that larger fliers might prioritize risk reduction and safety. Addressing how the evolution of flight may have driven relationships between body size and immunity could be particularly informative for understanding the propensity of some taxa to harbor many virulent and sometimes zoonotic pathogens without showing clinical disease. Here, we used a comparative framework to quantify scaling relationships between body mass and the proportions of two types of white blood cells--lymphocytes, and granulocytes (neutr-/heterophils)--across 63 bat species, 400 bird species, and 251 non-volant mammal species. By using phylogenetically-informed statistical models on field-collected data from wild Neotropical bats and from captive bats, non-volant mammals and birds, we show that lymphocyte and neutrophil proportions do not vary systematically with body mass among bats. In contrast, larger birds and non-volant mammals have disproportionately higher granulocyte proportions than expected for their body size. Our inability to distinguish bat lymphocyte scaling from birds and bat granulocyte scaling from all other taxa suggest there may be other ecological explanations (i.e. not flight-related) for the cell proportion scaling patterns. Future comparative studies of wild bats, birds, and non-volant mammals of similar body mass should aim to further differentiate evolutionary effects and other aspects of life history on immune defense and its role in tolerance of (zoonotic) infections.

scholarly journals Longleaf Pine Restoration: Implications for Landscape-Level Effects on Bird Communities in the Lower Gulf Coastal Plain

2003 ◽  
Vol 27 (2) ◽  
pp. 107-121 ◽  
Author(s):  
James W. Tucker ◽  
Geoffrey E. Hill ◽  
Nicholas R. Holler
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Longleaf Pine ◽  
Bird Species ◽  
Pinus Palustris ◽  
Bird Communities ◽  
Selective Logging ◽  
Neotropical Migrants ◽  
Individual Species ◽  
Riparian Habitats

Abstract The longleaf pine (Pinus palustris) ecosystem of the southeastern United States is among the most heavily degraded of all ecosystems. Less than 1% of the original longleaf pine forests remain as old-growth stands. Eglin Air Force Base (Eglin) in northwest Florida contains the largest remaining extent of longleaf pine, but much of this habitat has been degraded through fire suppression, selective logging, and planting off-site species of pines. We examined the distribution of bird species among habitats during spring and fall 1994–1995 to assess the influence of large-scale habitat restoration on bird communities across the landscape. During both spring and fall, species richness and relative abundance of neotropical migrants were greatest in oak hammocks and riparian habitats. During spring, the abundance of resident species was greatest in barrier island scrub and flatwoods, but species richness of residents also was high in oak hammocks. During fall, both species richness and abundance of residents were greatest in oak hammocks and flatwoods. Analyses of abundance for individual species (both neotropical migrants and residents) suggested that each habitat examined was important for ≥1 species. An analysis examining the importance of habitats for conservation found that oak hammocks and riparian habitats were important for species of high management concern, but burned sandhills along with oak hammocks and riparian habitats were very important for species of the greatest management concern. Our results suggest that habitat modifications resulting from restoration of the longleaf pine ecosystem will benefit many species of management concern. Bird species negatively affected by habitat modifications for longleaf pine restoration were abundant in other habitats. South. J. Appl. For. 27(2):107–121.

scholarly journals Generating and testing ecological hypotheses at the pondscape with environmental DNA metabarcoding: a case study on a threatened amphibian

2018 ◽  
Author(s):  
Lynsey R. Harper ◽  
Lori Lawson Handley ◽  
Christoph Hahn ◽  
Neil Boonham ◽  
Helen C. Rees ◽  
...  
Keyword(s):  
Species Richness ◽  
Large Scale ◽  
Gasterosteus Aculeatus ◽  
Abiotic Factors ◽  
Environmental Dna ◽  
Hypothesis Generation ◽  
Vertebrate Species ◽  
Mammal Species ◽  
Negatively Associated ◽  
Fulica Atra

AbstractEnvironmental DNA (eDNA) metabarcoding is revolutionising biodiversity monitoring, but has unrealised potential for ecological hypothesis generation and testing. Here, we validate this potential in a large-scale analysis of vertebrate community data generated by eDNA metabarcoding of 532 UK ponds. We test biotic associations between the threatened great crested newt (Triturus cristatus) and other vertebrates as well as abiotic factors influencing T. cristatus detection at the pondscape. Furthermore, we test the status of T. cristatus as an umbrella species for pond conservation by assessing whether vertebrate species richness is greater in ponds with T. cristatus and higher T. cristatus Habitat Suitability Index (HSI) scores. T. cristatus detection was positively correlated with amphibian and waterfowl species richness. Specifically, T. cristatus was positively associated with smooth newt (Lissotriton vulgaris), common coot (Fulica atra), and common moorhen (Gallinula chloropus), but negatively associated with common toad (Bufo bufo). T. cristatus detection did not significantly decrease as fish species richness increased, but negative associations with common carp (Cyprinus carpio), three-spined stickleback (Gasterosteus aculeatus) and ninespine stickleback (Pungitius pungitius) were identified. T. cristatus detection was negatively correlated with mammal species richness, and T. cristatus was negatively associated with grey squirrel (Sciurus carolinensis). T. cristatus detection was negatively correlated with larger pond area, presence of inflow, and higher percentage of shading, but positively correlated with HSI score, supporting its application to T. cristatus survey. Vertebrate species richness was significantly higher in T. cristatus ponds and broadly increased as T. cristatus HSI scores increased. We reaffirm reported associations (e.g. T. cristatus preference for smaller ponds) but also provide novel insights, including a negative effect of pond inflow on T. cristatus. Our findings demonstrate the prospects of eDNA metabarcoding for ecological hypothesis generation and testing at landscape scale, and dramatic enhancement of freshwater conservation, management, monitoring and research.

Functional evenness of bird communities varies along the elevational gradient in Europe: Conservation implications

2019 ◽  
Author(s):  
Federico Morelli ◽  
Yanina
Keyword(s):  
Species Richness ◽  
Elevation Gradient ◽  
Bird Species ◽  
Elevational Gradient ◽  
Negative Association ◽  
Bird Communities ◽  
Breeding Bird ◽  
Bird Species Richness ◽  
Large Spatial Scale ◽  
Functional Evenness

ContextThe negative association between elevation and species richness is a well-recognized pattern in macro-ecology. ObjectivesThe aim of this study was to investigate changes in functional evenness of breeding bird communities along an elevation gradient in Europe. MethodsUsing the bird data from the EBCC Atlas of European Breeding Birds we estimated an index of functional evenness which can be assumed as a measure of the potential resilience of communities.ResultsOur findings confirm the existence of a negative association between elevation and bird species richness in all European eco regions. However, we also explored a novel aspect of this relationship, important for conservation: Our findings provide evidence at large spatial scale of a negative association between the functional evenness (potential community resilience) and elevation, independent of the eco region. We also found that the Natura2000 protected areas covers the territory most in need of protection, those characterized by bird communities with low potential resilience, in hilly and mountainous areas.ConclusionsThese results draw attention to European areas occupied by bird communities characterized by a potential lower capacity to respond to strong ecological changes, and, therefore, potentially more exposed to risks for conservation.

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