Patterns of Beta Diversity of Vascular Plants and Their Correspondence With Biome Boundaries Across North America

Abstract

Understanding why species composition and diversity varies spatially and with environmental variation is a long-standing theme in macroecological research. Numerous hypotheses have been generated to explain species and phylogenetic diversity gradients. Much less attention has been invested in explaining patterns of beta diversity. Biomes boundaries are thought to represent major shifts in abiotic variables accompanied by vegetation patterns and composition as a consequence of long-term interactions between the environment and the diversification and sorting of species. Using North American plant distribution data, phylogenetic information and three functional traits (SLA, seed mass, and plant height), we explicitly tested whether beta diversity is associated with biome boundaries and the extent to which two components of beta diversity-turnover and nestedness-for three dimensions of biodiversity (taxonomic, phylogenetic, and functional)-are associated with contrasting environments and linked to different patterns of historical climatic stability. We found that dimensions of vascular plant beta diversity are strongly coupled and vary considerably across North America, with turnover more influential in biomes with higher species richness and greater environmental stability and nestedness more influential in species-poor biomes characterized by high environmental variability. These results can be interpreted to indicate that in harsher climates with less stability explain beta diversity, while in warmer, wetter more stable climates, patterns of endemism associated with speciation processes, as well as local environmental sorting processes, contribute to beta diversity. Similar to prior studies, we conclude that patterns of similarity among communities and biomes reflects biogeographic legacies of how vascular plant diversity arose and was shaped by historical and ecological processes.

Geographic patterns and environmental correlates of taxonomic and phylogenetic beta diversity for large‐scale angiosperm assemblages in China

“…For both taxonomic and phylogenetic β‐diversity, we calculated the ratio of β nes to β sor (i.e. β ratio = β nes /β sor ; Dobrovolski et al 2012; see also Peixoto et al 2017, Pinto‐Ledezma et al 2018). β ratio indicates the relative influence of turnover and nestedness on total β‐diversity (Dobrovolski et al 2012, Peixoto et al 2017).…”

“…This pattern has been observed in previous studies (Meynard et al 2011, Qian et al 2013, Guevara et al 2016, McFadden et al 2019). Assessing patterns of deviations of phylogenetic β‐diversity from taxonomic β‐diversity across different geographic areas can provide insights into the mechanisms that generate phylogenetic β‐diversity across a broad region (Peixoto et al 2017, Pinto‐Ledezma et al 2018). We therefore calculated phylogenetic β‐diversity deviation (β dev ) from taxonomic β‐diversity using the following formula: β dev = (β sor.tax − β sor.phy )/β sor.tax .…”

“…Accordingly, a smaller value of β dev indicates a greater turnover of phylogenetic lineages and thus a greater effect of phylogenetic β‐diversity between sites. β dev reflects the degree of lineage exchanges between areas over time (Peixoto et al 2017, Pinto‐Ledezma et al 2018).…”

“…In the present study, we simultaneously explore these aspects of β‐diversity using two complementary approaches, namely the neighborhood approach (Peixoto et al 2017, Pinto‐Ledezma et al 2018) and pairwise approach (Qian and Ricklefs 2007, Qian et al 2013), and we test relevant hypotheses for large‐scale angiosperm (flowering plant) assemblages (in 10 000 km 2 ) across China, which has a broad geographic extent and a great variation in climate. Specifically, we test the ‘dispersal limitation’ and ‘environmental filtering’ hypotheses, which are not mutually exclusive.…”

In transition: Avian biogeographic responses to a century of climate change across desert biomes

“…These shortcomings can be addressed by examining temporal change in metacommunities across biomes in response to recent climate change. Biomes are distinct biotic communities that are characterized by sharp transitions of plant and vertebrate communities and by high levels of species turnover across their ecotones (Pinto‐Ledezma, Larkin, & Cavender‐Bares, ; Smith et al, ). These patterns are maintained by abiotic factors, primarily climate, soils, and disturbance regimes (Delcourt & Delcourt, ; Kark & Rensburg, ).…”