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1. Differential organization of taxonomic and functional diversity in an urban woody plant metacommunity

   https://doi.org/10.1111/avsc.12266  

   Swan, Christopher M. ; Johnson, Anna ; Nowak, David J. ; Acosta, ed., Alicia ( October 2016 , Applied Vegetation Science)

   Urban ecosystems present an opportunity to study ecological communities in the context of unprecedented environmental change. In the face of urban land conversion, ecologists observe new patterns of species composition, dominance, behaviour and dispersal. We propose a hypothetical socioeconomic template that describes a gradient in human investment in community composition to aid in organizing the human role in shaping urban biodiversity. We asked: (1) what is the relative magnitude of taxonomic and functional turnover of urban woody plant communities across different land‐use types; and (2) do land uses exhibiting higher intensity of human management of biodiversity support higher turnover over those with less human influence?

   Baltimore,MD,USA(39°17′ N, 76°38′ W).

   We examined patterns in woody plant biodiversity across 209 plots of different urban land uses. Six land‐use types were arranged along a gradient in the intensity through which humans are hypothesized to manage species composition at the plot scale. We calculated local, or α‐diversity, and compositional turnover, or β‐diversity, of taxonomic and functional diversity across plots within each land‐use type. We compared the magnitude of these biodiversity measures between land uses to test our conceptual template for how the intensity of human management can predict urban woody plant biodiversity.

   We observed high taxonomic turnover in residential and commercial plots compared with vacant or open space land‐use areas. This was associated with a weaker, but similar, pattern in functional diversity. This was associated with low total abundance in residential and commercial plots. Furthermore, the number of unique species was extremely high in the same land‐use types.

   Our observations help explain why turnover can be high in heavily managed plots relative to vacant land. In patches without heavy human management, we found low levels of turnover. This highlights the importance of assessing diversity both locally and at the level of turnover between patches. Management and policy can benefit from the perspective embodied in the conceptual approach tested here.

    

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2. Mammals on mountainsides revisited: Trait‐based tests of assembly reveal the importance of abiotic filters

   https://doi.org/10.1111/jbi.14099  

   Kohli, Brooks A. ; Stevens, Richard D. ; Rickart, Eric A. ; Rowe, Rebecca J. ( March 2021 , Journal of Biogeography)

   Mountains provide uniquely informative systems for examining how biodiversity is distributed and identifying the causes of those patterns. Elevational patterns of species richness are well‐documented for many taxa but comparatively few studies have investigated patterns in multiple dimensions of biodiversity along mountainsides, which can reveal the underlying processes at play. Here, we use trait‐based diversity patterns to determine the role of abiotic filters and competition in the assembly of communities of small mammals across elevation and evaluate the surrogacy of taxonomic, functional, and phylogenetic dimensions of diversity.

   Great Basin ecoregion, western North America.

   Rodents and shrews.

   The elevational distributions of 34 species were determined from comprehensive field surveys conducted in three arid, temperate mountain ranges. Elevation–diversity relationships and community assembly processes were inferred from phylogenetic (PD) and functional diversity (FD) patterns of mean pairwise and mean nearest‐neighbor distances while accounting for differences in species richness. FD indices were calculated separately for traits related to either abiotic filtering (β‐niche traits) or biotic interactions (α‐niche traits) to test explicit predictions of the role of each across elevation.

   Trait‐based tests of processes indicated that abiotic filtering tied to a strong aridity gradient drives the assembly of both low‐ and high‐elevation communities. Support for competition was not consistent with theoretical expectations under the stress‐dominance hypothesis, species interactions‐abiotic stress hypothesis, or guild assembly rule. Mid‐elevation peaks in species richness contrasted with overall FD and PD, which generally increased with elevation. PD and total FD were correlated on two of three mountains.

   The functional diversity of small mammal communities in these arid, temperate mountains is most consistent with abiotic filters, whereas support for competition is weak. Decomposing FD into traits related to separate assembly processes and examining ecoregional variation in diversity were critical for uncovering the generality of mechanisms. Divergent patterns among dimensions revealed species richness to be a poor surrogate for PD and FD across elevation and reflect the effect of biogeographic and evolutionary history. This first analysis of elevational multidimensional diversity gradients for temperate mammals provides a versatile framework for future comparative studies.

    

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3. Mexico ants: incidence and abundance along the Nearctic–Neotropical interface

   https://doi.org/10.1002/ecy.2944  

   Dáttilo, Wesley ; Vásquez‐Bolaños, Miguel ; Ahuatzin, Diana A. ; Antoniazzi, Reuber ; Chávez‐González, Edgar ; Corro, Erick ; Luna, Pedro ; Guevara, Roger ; Villalobos, Fabricio ; Madrigal‐Chavero, Ricardo ; et al ( March 2020 , Ecology)

   Mexico is one of the most biodiverse countries in the world, with an important proportion of endemism mainly because of the convergence of the Nearctic and Neotropical biogeographic regions, which generate great diversity and species turnover at different spatial scales. However, most of our knowledge of the Mexican ant biota is limited to a few well‐studied taxa, and we lack a comprehensive synthesis of ant biodiversity information. For instance, most of the knowledge available in the literature on Mexican ant fauna refers only to species lists by states, or is focused on only a few regions of the country, which prevents the study of several basic and applied aspects of ants, from diversity and distribution to conservation. Our aims in this data paper are therefore (1) to compile all the information available regarding ants across the Mexican territory, and (2) to identify major patterns in the gathered data set and geographic gaps in order to direct future sampling efforts. All records were obtained from raw data, including both unpublished and published information. After exhaustive filtering and updating information and synonyms, we compiled a total of 21,731 records for 887 ant species distributed throughout Mexico from 1894 to 2018. These records were concentrated mainly in the states of Chiapas (n = 6,902, 32.76%) and Veracruz de Ignacio de la Llave (n = 4,329, 19.92%), which together comprise half the records. The subfamily with the highest number of records was Myrmicinae (n = 10,458 records, 48.12%), followed by Formicinae (n = 3,284, 15.11%) and Ponerinae (n = 1,914, 8.8%). Most ant records were collected in the Neotropical region of the country (n = 12,646, 58.19%), followed by the Mexican transition zone (n = 5,237, 24.09%) and the Nearctic region (n = 3,848, 17.72%). Native species comprised 95.46% of the records (n = 20,745). To the best of our knowledge, this is the most complete data set available to date in the literature for the country. We hope that this compilation will encourage researchers to explore different aspects of the population and community research of ants at different spatial scales, and to aid in the establishment of conservation policies and actions. There are no copyright restrictions. Please cite this data paper when using its data for publications or teaching events.

    

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4. The spatial configuration of taxonomic biodiversity along a tropical elevational gradient: α‐, β‐, and γ‐partitions

   https://doi.org/10.1111/btp.12632  

   Willig, Michael R. ; Presley, Steven J. ( February 2019 , Biotropica)

   Biodiversity at larger spatial scales (γ) can be driven by within‐site partitions (α), with little variation in composition among locations, or can be driven by among‐site partitions (β) that signal the importance of spatial heterogeneity. For tropical elevational gradients, we determined the (a) extent to which variation in γ is driven by α‐ or β‐partitions; (b) elevational form of the relationship for each partition; and (c) extent to which elevational gradients are molded by zonation in vegetation or by gradual variation in climatic or abiotic characteristics. We sampled terrestrial gastropods along two transects in the Luquillo Mountains. One passed through multiple vegetation zones (tabonuco, palo colorado, and elfin forests), and one passed through only palm forest. We quantified variation in hierarchical partitions (α, β, and γ) of species richness, evenness, diversity, and dominance, as well as in the content and quality of litter. Total gastropod abundance linearly decreased with increasing elevation along both transects, but was consistently higher in palm than in other forest types. The gradual linear decline in γ‐richness was a consequence of opposing patterns with regard to α‐richness (monotonic decrease) and β‐richness (monotonic increase). For evenness, diversity, and dominance, α‐partitions and γ‐partitions evinced mid‐elevational peaks. The spatial organization of gastropod biodiversity did not mirror the zonation of vegetation. Rather, it was molded by: (a) elevational variation in productivity or nutrient characteristics, (b) the interspersion of palm forest within other forest types, and (c) the cloud condensation point acting as a transition between low and high elevation faunas.

   Abstract in Spanish is available with online material.

    

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5. Evaluating the influences of floral traits and pollinator generalism on α and β diversity of heterospecific pollen on stigmas

   https://doi.org/10.1111/1365-2435.14465  

   Ashman, Tia‐Lynn ; Wei, Na ( November 2023 , Functional Ecology)

   Pollinator sharing often leads to receipt of heterospecific pollen (HP) along with conspecific pollen. As a result, flowering plants can accumulate diverse communities of HP on stigmas. While variation in HP diversity is an important selective force contributing to flowering plant fitness, evolution and community assembly, our understanding of the extent and drivers of heterogeneity of HP diversity is limited.

   In this study, we examined the species compositions and abundances of ~1000 HP communities across 59 co‐flowering plant species in three serpentine seep communities in California, USA. We evaluated the variation in HP diversity (γ diversity) across plant species in each seep and asked whether the variation in HP γ diversity was caused by variation in HP diversity within stigmas (α diversity) or HP compositional variation among stigmas (β diversity) due to the replacement of HP species (turnover) or their loss (nestedness) from one stigma to another. We further evaluated the potential drivers of variation in HP α and β diversity using phylogenetic structural equation models.

   We found that variation in HP γ diversity across plant species was driven strongly by differences among species in HP α diversity and to a lesser extent by HP β diversity. HP community turnover contributed more to HP β diversity than nestedness consistently across plant species and seeps, suggesting a general pattern of HP compositional heterogeneity from stigma to stigma. The phylogenetic structural equation models further revealed that floral traits (e.g., stigma area, stigma‐anther distance, stigma exposure) and floral abundance were key in determining HP α diversity by influencing HP abundance (load size), while floral traits and abundance showed variable impact on HP β diversity (turnover and nestedness). Pollination generalism contributed relatively less to HP‐α and β diversity.

   These findings disentangle the heterogeneity in HP diversity at different levels, which is essential for understanding the process underlying patterns of HP receipt in plant communities. That floral traits drive the heterogeneity in HP diversity points to additional avenues by which HP receipt may contribute to plant evolution.

   Read the freePlain Language Summaryfor this article on the Journal blog.

    

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