Climatic niche comparisons of eastern North American and eastern Asian disjunct plant genera

Abstract

Aim While the floras of eastern Asia (EA) and eastern North America (ENA) share numerous genera, they have drastically different species richness. Despite an overall similarity in the quality of their temperate climates, the climate of EA is more spatially heterogeneous than that of ENA. Spatial environmental heterogeneity has been found to play a key role in influencing species richness in some regions. Here, we tested the following hypotheses: (a) EA species will occupy larger climatic niches than their ENA congeners, (b) congeners of EA‐ENA disjunct genera will occupy statistically equivalent climatic niches, and (c) congeners of EA‐ENA disjunct genera will occupy more similar climatic niches than expected by their respective physiographic context. Location North America and Asia. Time period Present. Major taxa studied Seed plants. Methods Predictions generated by ecological niche models (ENMs) were compared for 88 species across 31 EA‐ENA disjunct genera. ENM predictions were assessed for geographic and ecological breadth. Tests for niche equivalency and similarity were performed for congeneric species pairs to determine if species of disjunct genera have experienced niche conservatism or divergence. Results EA species tend to occupy greater amounts of climatic niche space than their close relatives in ENA. Over two‐thirds of the conducted niche comparisons show that EA‐ENA congeners either occupy equivalent climatic niche space within these broader climatic regimes or occupy non‐equivalent niches that are as similar as expected given their physiographic contexts. Main conclusions EA species tend to occupy larger climatic niches, and congeners of EA‐ENA disjunct genera tend to occupy equivalent/similar niche space within their respective distributions, with differences in occupied niches possibly due to their respective physiographic contexts, highlighting how niche‐neutral processes and niche conservatism may affect the distributions of disjunct species.

An updated phylogeny, biogeography, and PhyloCode‐based classification of Cornaceae based on three sets of genomic data

“…With better data and methodologies available today, biogeographic studies of individual clades can provide a more accurate picture of their dynamic histories on range expansion and restriction and provide solid baseline data for understanding the origin of disjunctions and the assembly of the Earth's phytogeography. The origin of the floristic disjunction/floristic similarity between eastern Asia and North America has been of interest for the past three decades (e.g., Qian and Ricklefs, 2000; Xiang and Soltis, 2001; Donoghue and Smith, 2004; Ricklefs et al, 2004; Harris et al, 2013; Dong et al, 2019; Melton et al, 2020, 2022; see reviews by Wen, 1999; Wen et al, 2010, 2016). Clearly, detailed biogeographic studies of disjunct clades based on robust, dated, comprehensive phylogenies inferred from genome‐wide data using modern methodology are particularly valuable for evaluating hypotheses derived from previous meta‐analyses or synthesis (e.g., Donoghue and Smith, 2004; Wen et al, 2010) that were based on early methodology.…”

Evolutionary origins of the eastern North American–Mesoamerican floristic disjunction: Current status and future prospects

“…Such shared disjunctions offer an unparalleled opportunity to reconstruct how geologic history has shaped the assembly of modern plant communities. More broadly, they also represent excellent systems for studying myriad fundamental processes in ecology and evolution, including speciation and diversification (Xiang et al, 2004; Yang et al, 2018), niche evolution (Wasof et al, 2015; Melton et al, 2022), biotic interactions (Quiroga et al, 2020), community assembly (Donoghue and Smith, 2004; Donoghue, 2008; Manos and Meireles, 2015; Dick and Pennington, 2019; Jiang et al, 2019), and evolutionary responses to climate change over both small and larger time scales (Qian and Ricklefs, 2004; Hamilton and Eckert, 2007; Kuhn et al, 2016).…”

Niche unfilling dominates the naturalization of species from intercontinentally disjunct genera

“…Naturalized species from genera exhibiting the Eastern Asia (EA)–Eastern North America (ENA) floristic disjunction provide an ideal system for examining these niche change scenarios and further investigating the potential role of niche changes in biological invasions. EA and ENA are two geographically separated land masses with largely overlapping climate space (Guo et al, 2006; Heberling et al, 2017; Melton et al, 2022), thus facilitating the interpretation of unbiased niche changes. Meanwhile, these two areas have a long history of reciprocal anthropogenic floristic exchanges (Guo et al, 2006; Seipel et al, 2012), and genera that span the EA‐ENA floristic disjunction are an important component in these floristic exchanges (e.g.…”

“…First, the native ranges of ENA naturalized species from EA‐ENA disjunct genera are restricted in EA, thus excluding the possibility that niche unfilling is detected due to the naturalized species in ENA having wide home ranges beyond just EA and occupying some climate conditions that are not found in EA and ENA. Second, sister species from EA‐ENA disjunct genera occupy similar niches in their respective native ranges (Melton et al, 2022; Yin et al, 2021). Meanwhile, sister species in these genera also share ancestral functional traits and climatic niches (Qian & Ricklefs, 2004) because they formerly had continuous EA‐ENA distributions across the Bering land bridge until they were separated by the cooling climates in the middle and late Tertiary (Tiffney, 1985; Wen, 1999).…”