Phylogenetic diversity anomaly in angiosperms between eastern Asia and eastern North America

Abstract

Although eastern Asia (EAS) and eastern North America (ENA) have similar climates, plant species richness in EAS greatly exceeds that in ENA. The degree to which this diversity difference reflects the ages of the floras or their rates of evolutionary diversification has not been quantified. Measures of species diversity that do not incorporate the ages of lineages disregard the evolutionary distinctiveness of species. In contrast, phylogenetic diversity integrates both the number of species and their history of evolutionary diversification. Here we compared species diversity and phylogenetic diversity in a large number of flowering plant (angiosperm) floras distributed across EAS and ENA, two regions with similar contemporary environments and broadly shared floristic history. After accounting for climate and sample area, we found both species diversity and phylogenetic diversity to be significantly higher in EAS than in ENA. When we controlled the number of species statistically, we found that phylogenetic diversity remained substantially higher in EAS than in ENA, although it tended to converge at high latitude. This pattern held independently for herbs, shrubs, and trees. The anomaly in species and phylogenetic diversity likely resulted from differences in regional processes, related in part to high climatic and topographic heterogeneity, and a strong monsoon climate, in EAS. The broad connection between tropical and temperate floras in southern Asia also might have played a role in creating the phylogenetic diversity anomaly.

Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau

“…At the same time, climate factors explain only a small amount of the variation in NRI, further indicating that the phylogenetic structure of shrub communities in arid areas is less affected by (at least climate‐driven) abiotic environmental filtering (Dong et al, ). These results are supported by Qian et al () who found that compared to trees, shrubs and herbs showed less sensitivity to climate, and attributed this to their smaller size allowing them to take advantage of microhabitat protection.…”

“…Environmental aridity could either serve as an environmental filter to cluster closely related species, or aggravate niche differentiation in order to use different resources (Cavender-Bares et al, 2009). For example, Qian, Jin, and Ricklefs (2017) found that native communities in California were more phylogenetically clustered in dry areas, while Valiente-Banuet and Verdú (2007) found that significant phylogenetic overdispersion of the communities in semiarid regions of Mexico was chiefly due to facilitation between distant species. Soliveres, Torices, and Maestre (2012) investigated 11 Stipa grassland communities in semiarid regions of Spain and suggested that most were phylogenetically random under the combination of habitat filtering and competitive exclusion, but that interaction between species (i.e., competitive exclusion) had a greater impact on community construction.…”

A consistent species richness–climate relationship for oaks across the Northern Hemisphere

“…This finding suggests that the eastern Asian species richness anomaly is not present in this group. Species anomalies between eastern Asia and eastern North America mainly exist for Tertiary relict lineages, which were extirpated from North America in the late Tertiary due to climate cooling and extensive glaciation but have survived in eastern Asia (Guo & Ricklefs, ; Qian et al, ; Qian & Ricklefs, ; Xiang et al, ). Temperate lineages, such as the subgenus Q uercus , which diversified during this cooling period, have relatively higher species richness in North America than in eastern Asia.…”

The role of adaptive strategies in plant naturalization

“…), long‐lived herbs (perennial graminoids and forbs), shrubs (shrubs and lianas) and trees (as used in FGDC (Federal Geographic Data Committee) ; Qian et al . ).…”

“…liana, herbaceous vine), which could limit statistical power, we created a broader classification of four life forms. These life-form categories largely correspond to those of Raunkiaer (1934), and include short-lived herbs (annual and biennial herbs, which merges the graminoid, forb, herbaceous vine and aquatic categories of Pierce et al 2017), long-lived herbs (perennial graminoids and forbs), shrubs (shrubs and lianas) and trees (as used in FGDC (Federal Geographic Data Committee) 1997; Qian et al 2017).…”