scholarly journals The origin of species richness patterns along environmental gradients: uniting explanations based on time, diversification rate and carrying capacity

2016 ◽  
Vol 44 (4) ◽  
pp. 722-735 ◽  
Author(s):  
Mikael Pontarp ◽  
John J. Wiens
Keyword(s):  
Species Richness ◽  
Carrying Capacity ◽  
Environmental Gradients ◽  
Diversification Rate ◽  
Origin Of Species ◽  
Time Diversification ◽  
Richness Patterns

scholarly journals Can net diversification rates account for spatial patterns of species richness?

2017 ◽  
Author(s):  
Camilo Sanín ◽  
Iván Jiménez ◽  
Jon Fjeldså ◽  
Carsten Rahbek ◽  
Carlos Daniel Cadena
Keyword(s):  
Species Richness ◽  
Spatial Variation ◽  
Spatial Patterns ◽  
Explanatory Power ◽  
Large Family ◽  
Diversification Rate ◽  
Diversification Rates ◽  
Grain Sizes ◽  
Time Period ◽  
Richness Patterns

ABSTRACTThe diversification rate hypothesis (DRH) proposes that spatial patterns of species richness result from spatial variation in net diversification rates. We developed an approach using a time-calibrated phylogeny and distributional data to estimate the maximum explanatory power of the DRH, over a given time period, to current species richness in an area. We used this approach to study species richness patterns of a large family of suboscine birds across South America. The maximum explanatory power of the DRH increased with the duration of the time period considered and grain size; it ranged from 13 – 37 fold local increases in species richness for T = 33 Ma to less than 2-fold increases for T ≤ 10 Ma. For large grain sizes (≤ 8° × 8°) diversification rate over the last 10 Ma could account for all the spatial variance in species richness, but for smaller grain sizes commonly used in biogeographical studies (1° × 1°), it could only explain < 16% of this variance. Thus, diversification since the Late Miocene, often thought to be a major determinant of Neotropical diversity, had a limited imprint on spatial richness patterns at small grain sizes. Further application of our approach will help determine the role of the DRH in explaining current spatial patterns of species richness.Note to readersThis manuscript has been seen by a few researchers, some of whom suggested that before publishing our work in a peer-reviewed journal we should conduct simulations to demonstrate that our methods properly estimate the contribution of variance in diversification rates to spatial variation in species richness. Although we believe that our approach derives logically from theory and statistics and is therefore valid, we understand that it is rather unique and see why some readers would think that an independent validation is necessary. Unable to complete such validation in the near future, however, we decided to make this manuscript available as a preprint to share our ideas and hopefully stimulate discussion on what we believe is a most interesting topic. We also hope to receive feedback that may enable us to improve our work for publication in a journal at a later date.

Relative importance of available energy, environmental heterogeneity, and seed availability for seedling emergence on a limestone pavement

Botany ◽  
2010 ◽  
Vol 88 (12) ◽  
pp. 1045-1056 ◽  
Author(s):  
J. T. Lundholm
Keyword(s):  
Species Richness ◽  
Environmental Heterogeneity ◽  
Environmental Control ◽  
Environmental Gradients ◽  
Spatial Scales ◽  
Elevation Gradient ◽  
Experimental Studies ◽  
Relative Increase ◽  
Available Energy ◽  
Richness Patterns

Environmental heterogeneity at fine spatial scales is expected to be especially important in determining community patterns at seed germination and establishment stages. I compared seedling and adult species richness patterns in relation to environmental gradients by adding seeds from 39 species across an elevation gradient, unimodally related to species richness on a limestone pavement. Environmental variables linked to habitat fertility (“available energy”), within-plot spatial or temporal variability (“environmental heterogeneity”), and spatial coordinates were evaluated as contributors to richness patterns using variance partitioning. Variables related to available energy explained most of the variance in species richness for adults and seedlings in sown plots; pure spatial variation, shared variation between energy and heterogeneity variables, and other shared fractions explained more of the variance in seedling richness in unsown plots. Seedling density and richness increased with sowing, but the relative increase differed along the elevation gradient; relative increase in richness was greatest at the lowest and highest elevations. Limited seed dispersal from parent plants may result in seedlings colonizing less favorable microsites in unsown plots, whereas sowing resulted in greater explained variance owing to environmental factors, and lower variance attributable to space alone, indicating that appropriate species are more able to reach suitable microsites. While many experimental studies have revealed associations between microsite characteristics and species-specific recruitment responses, seed limitations in natural communities can contribute to the spatial structure of seedling communities and mask environmental control of seedling species richness.

scholarly journals The Effect of Climate and Human Pressures on Functional Diversity and Species Richness Patterns of Amphibians, Reptiles and Mammals in Europe

Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 275
Author(s):  
Mariana A. Tsianou ◽  
Maria Lazarina ◽  
Danai-Eleni Michailidou ◽  
Aristi Andrikou-Charitidou ◽  
Stefanos P. Sgardelis ◽  
...  
Keyword(s):  
Species Richness ◽  
Functional Diversity ◽  
Agricultural Land ◽  
Influential Factor ◽  
Climatic Variables ◽  
Quadratic Entropy ◽  
Functional Richness ◽  
Precipitation Seasonality ◽  
Rao’S Quadratic Entropy ◽  
Richness Patterns

The ongoing biodiversity crisis reinforces the urgent need to unravel diversity patterns and the underlying processes shaping them. Although taxonomic diversity has been extensively studied and is considered the common currency, simultaneously conserving other facets of diversity (e.g., functional diversity) is critical to ensure ecosystem functioning and the provision of ecosystem services. Here, we explored the effect of key climatic factors (temperature, precipitation, temperature seasonality, and precipitation seasonality) and factors reflecting human pressures (agricultural land, urban land, land-cover diversity, and human population density) on the functional diversity (functional richness and Rao’s quadratic entropy) and species richness of amphibians (68 species), reptiles (107 species), and mammals (176 species) in Europe. We explored the relationship between different predictors and diversity metrics using generalized additive mixed model analysis, to capture non-linear relationships and to account for spatial autocorrelation. We found that at this broad continental spatial scale, climatic variables exerted a significant effect on the functional diversity and species richness of all taxa. On the other hand, variables reflecting human pressures contributed significantly in the models even though their explanatory power was lower compared to climatic variables. In most cases, functional richness and Rao’s quadratic entropy responded similarly to climate and human pressures. In conclusion, climate is the most influential factor in shaping both the functional diversity and species richness patterns of amphibians, reptiles, and mammals in Europe. However, incorporating factors reflecting human pressures complementary to climate could be conducive to us understanding the drivers of functional diversity and richness patterns.

Lack of congruence between terrestrial and epiphytic lichen strata in boreal forests

2021 ◽  
Vol 53 (1) ◽  
pp. 149-158
Author(s):  
Robert J. Smith ◽  
Sarah Jovan ◽  
Susan Will-Wolf
Keyword(s):  
Species Richness ◽  
Boreal Forests ◽  
Environmental Gradients ◽  
Ground Layer ◽  
Global Changes ◽  
Layer Versus ◽  
Epiphytic Lichen ◽  
Incremental Change ◽  
Compositional Gradients ◽  
Environmental Responses

AbstractLichens occupy diverse substrates across tremendous ranges of environmental variation. In boreal forests, lichen communities co-occur in ‘strata’ defined by terrestrial or arboreal substrates, but these strata may or may not be interchangeable as bioindicators. Do co-occurring lichen strata have similar community structures and environmental responses? Could one stratum serve as a proxy for the other? We assessed variation in species richness and community compositions between ground-layer versus epiphyte-layer lichen strata in boreal forests and peatlands of interior Alaska. Species richness was lower and more spatially structured in the ground layer than the epiphyte layer. Richness of strata was not correlated. The most compositionally unique ground-layer communities were species-poor but contained regionally rare species not common in other plots. Variation in community compositions (ordination scores) were not congruent between strata (Procrustes congruence < 0.16 on 0–1 scale); the largest departures from congruence occurred where ground layers were species-poor. The best predictors of ground-layer community compositions were hydrological and topographic, whereas epiphytes were most associated with macroclimate and tree abundances. We conclude that lichens on different substrates ‘move in different circles’: compositional gradients did not agree and the environmental gradients most important to each lichen stratum were not the same. The conditions which strongly influence one vegetation stratum may have little bearing upon another. As global changes modify habitats, an incremental change in environment may lead community trajectories to diverge among lichen strata.

scholarly journals Arthropod community structure in pastures of an island archipelago (Azores): looking for local–regional species richness patterns at fine-scales

2004 ◽  
Vol 94 (2) ◽  
pp. 111-121 ◽  
Author(s):  
P.A.V. Borges ◽  
V.K. Brown
Keyword(s):  
Species Richness ◽  
Regional Scale ◽  
Local Scale ◽  
Local Species Richness ◽  
Β Diversity ◽  
Arthropod Species ◽  
Α Diversity ◽  
Local Species ◽  
Richness Patterns

AbstractThe arthropod species richness of pastures in three Azorean islands was used to examine the relationship between local and regional species richness over two years. Two groups of arthropods, spiders and sucking insects, representing two functionally different but common groups of pasture invertebrates were investigated. The local–regional species richness relationship was assessed over relatively fine scales: quadrats (= local scale) and within pastures (= regional scale). Mean plot species richness was used as a measure of local species richness (= α diversity) and regional species richness was estimated at the pasture level (= γ diversity) with the ‘first-order-Jackknife’ estimator. Three related issues were addressed: (i) the role of estimated regional species richness and variables operating at the local scale (vegetation structure and diversity) in determining local species richness; (ii) quantification of the relative contributions of α and β diversity to regional diversity using additive partitioning; and (iii) the occurrence of consistent patterns in different years by analysing independently between-year data. Species assemblages of spiders were saturated at the local scale (similar local species richness and increasing β-diversity in richer regions) and were more dependent on vegetational structure than regional species richness. Sucking insect herbivores, by contrast, exhibited a linear relationship between local and regional species richness, consistent with the proportional sampling model. The patterns were consistent between years. These results imply that for spiders local processes are important, with assemblages in a particular patch being constrained by habitat structure. In contrast, for sucking insects, local processes may be insignificant in structuring communities.

From Forest to Farmland: Species Richness Patterns of Trees and Understorey Plants along a Gradient of Forest Conversion in Southwestern Cameroon

2006 ◽  
Vol 15 (13) ◽  
pp. 4097-4117 ◽  
Author(s):  
K. Serge Bobo ◽  
Matthias Waltert ◽  
N. Moses Sainge ◽  
John Njokagbor ◽  
Heleen Fermon ◽  
...  
Keyword(s):  
Species Richness ◽  
Forest Conversion ◽  
Richness Patterns ◽  
Understorey Plants
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