A near half‐century of temporal change in different facets of avian diversity

Abstract

Assessments of spatial patterns of biodiversity change are essential to detect a signature of anthropogenic impacts, inform monitoring and conservation programs, and evaluate implications of biodiversity loss to humans. While taxonomic diversity (TD) is the most commonly assessed attribute of biodiversity, it misses the potential functional or phylogenetic implications of species losses or gains for ecosystems. Functional diversity (FD) and phylogenetic diversity (PD) are able to capture these important trait-based and phylogenetic attributes of species, but their changes have to date only been evaluated over limited spatial and temporal extents. Employing a novel framework for addressing detectability, we here comprehensively assess a near half-century of changes in local TD, FD, and PD of breeding birds across much of North America to examine levels of congruency in changes among these biodiversity facets and their variation across spatial and environmental gradients. Time-series analysis showed significant and continuous increases in all three biodiversity attributes until ca. 2000, followed by a slow decline since. Comparison of avian diversity at the beginning and end of the temporal series revealed net increase in TD, FD, and PD, but changes in TD were larger than those in FD and PD, suggesting increasing biotic homogenization of avian assemblages throughout the United States. Changes were greatest at high elevations and latitudes - consistent with purported effects of ongoing climate change on biodiversity. Our findings highlight the potential of combining new types of data with novel statistical models to enable a more integrative monitoring and assessment of the multiple facets of biodiversity.

Beyond counts and averages: Relating geodiversity to dimensions of biodiversity

“…We documented a positive association between temperature and beta diversity for all dimensions, but we found lower phylogenetic and functional diversity in topographically diverse regions (Figure ). This result echoes the temporal pattern documented by Jarzyna and Jetz (), suggesting that bird communities at high elevations and in cold regions might be relatively homogeneous and thus relatively more vulnerable to changing climate. In the case of breeding birds in the USA, topographically diverse regions might, in fact, be the most sensitive to environmental change.…”

“…Although our study does not address change over time, the discrepancy between taxonomic and functional/phylogenetic diversity patterns with topographical variability and with temperature is notable. Jarzyna and Jetz () also observed that the greatest temporal changes in diversity occurred at higher elevations and latitudes, ascribing this pattern to climate change. We documented a positive association between temperature and beta diversity for all dimensions, but we found lower phylogenetic and functional diversity in topographically diverse regions (Figure ).…”

“…The discrepancy in relationships we observed among the dimensions of biodiversity we examined mirrors that of a previous study examining change in biodiversity over time. Increases in taxonomic diversity without corresponding changes in phylogenetic or functional diversity might indicate biotic homogenization of assemblages; 40 years of BBS surveys show a homogenizing trend over time (Jarzyna & Jetz, ). Although our study does not address change over time, the discrepancy between taxonomic and functional/phylogenetic diversity patterns with topographical variability and with temperature is notable.…”

Agriculture erases climate constraints on soil nematode communities across large spatial scales

“…To assess the congruence between changes in taxonomic, functional, and phylogenetic aspects at both alpha and beta diversity levels, we used a permutation procedure with 999 iterations to test the difference in slopes between the regression line of any two changes and the 1:1 line. In addition, we disentangled the cross‐associations of changes in TD, FD, and PD ([agricultural diversity − natural diversity]/natural diversity) or similarity (agricultural similarity − natural similarity) into different scenarios to gain a better understanding of the underlying processes of biodiversity changes (Figure ; Baiser & Lockwood, ; Jarzyna & Jetz, ). For example, a larger increase in TD compared to the increase in FD (or PD) could come from a gain in functionally (or phylogenetically) redundant taxa (Figure a, region II); while a larger increase in FD (or PD) could be explained by a gain in functionally (or phylogenetically) distinct taxa (Figure a, region I; Jarzyna & Jetz, ).…”

Contrasting diversity patterns of breeding Anatidae in the Northern and Southern Hemispheres

“…Integrated measurement of TD, PD, and FD can provide a comprehensive representation of biodiversity patterns and ecological functions (Calba, Maris, & Devictor, 2014;Pollock et al, 2017). This approach has been applied to the mapping of global biodiversity patterns of certain taxa (Safi et al, 2011), elucidating linkages between biodiversity and ecosystem functions and services (Cadotte, Dinnage, & Tilman, 2012;Flynn et al, 2009;Jarzyna & Jetz, 2017) for conservation policy (Pollock et al, 2017), and to provide insights on how ecological communities are shaped by evolutionary history and the environment (Calba et al, 2014;Jarzyna & Jetz, 2017;Ricklefs, 2007). For example, a community with high PD relative to TD indicates phylogenetic overdispersion; the community consists of mostly unrelated lineages, perhaps due to competitive exclusion as a long history of competitive interactions can cause evolutionary divergence in species niches (Violle, Nemergut, Pu, & Jiang, 2011).…”