Consistency in bird community assembly over medium-term along rural-urban gradients in Argentina

Lucas M. Leveau

doi:10.1186/s13717-021-00302-8

Abstract

BackgroundThe analysis of bird community assembly rules is fundamental to understand which mechanisms determine the composition of bird species in urban areas. However, the long-term variation of community assembly rules has not been analyzed yet. The objectives of this study are (1) to analyze the variation of community assembly rules along rural-urban gradients of three cities in central Argentina and (2) to compare the patterns of community assembly between two periods separated by 6 years. Bird surveys were performed along transects in urban, suburban, and rural habitats during 2011 and 2017. Departures from null models that took into account differences in species richness (standardized effect size, SES) were calculated for functional and phylogenetic diversities.ResultsA total of 57 species were recorded. Bird species richness was higher in suburban than in urban and rural habitats. SES of functional diversity increased over the years and was significantly lower in urban habitats than in rural habitats, showing a pattern of functional clustering in the most urbanized areas and functional randomness in rural ones. Phylogenetic diversity was higher in both suburban and urban habitats than rural ones, and the phylogenetic clustering in rural bird assemblages changed to randomness in suburban and urban habitats.ConclusionsBird communities in urban habitats were phylogenetically random and functionally clustered, evidencing environmental filtering by urbanization. In contrast, bird communities in rural areas tended to be phylogenetically clustered, evidencing that certain clades are adapted to rural areas. The processes structuring bird communities along rural-urban gradients were consistent between the 2 years compared.

Highlights

Urban areas are expanding continuously, causing declines of bird diversity mainly through habitat loss and fragmentation, pollution, and altered resource flows (Grimm et al 2008; Aronson et al 2014; Shanahan et al 2014; Beninde et al 2015)
Two aspects during the last decade have allowed to analyze community assembly rules along urbanization gradients (Moreno-Contreras et al 2019, Weideman et al, 2020): (1) the availability of information regarding phylogenetic relationships among coexisting bird species and their functional characteristics (Jetz et al 2014, Wilman et al 2014) and (2) the possibility to compare the observed phylogenetic and functional diversity against null models that take into account differences in species richness (Swenson 2014)
Discussion the mean sample coverage of transects was high, there was a variation among transects that was significantly related to bird species richness and phylogenetic diversity

Summary

Introduction

Urban areas are expanding continuously, causing declines of bird diversity mainly through habitat loss and fragmentation, pollution, and altered resource flows (Grimm et al 2008; Aronson et al 2014; Shanahan et al 2014; Beninde et al 2015). This diversity decline is reflected in the taxonomic, functional, and phylogenetic diversity (Devictor et al 2010; Morelli et al 2017; Liu et al 2019; Leveau and Leveau 2020). Departures from null models that took into account differences in species richness (standardized effect size, SES) were calculated for functional and phylogenetic diversities

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Discussion

Conclusion