Abstract
China has many threatened plant species, which are exposed to environmental degradation and other anthropogenic pressures. We assessed support for potential extinction pathways in Chinese angiosperm genera and quantified possible threats to phylogenetic diversity. We compiled a database and phylogeny for 27,409 Chinese angiosperm species in 2,453 genera. For each genus, we used the International Union for Conservation of Nature (IUCN) Red List classifications to quantify extinction risk and calculated predictors corresponding to their ecological, evolutionary characteristics and exposure to human pressures. We first tested for phylogenetic clustering in extinction risk among genera and then tested support for direct and indirect causal pathways involving our predictors using piecewise structural equation models. Finally, we quantified the potential loss of phylogenetic diversity under different extinction scenarios. We found that extinction risk is non-randomly distributed among Chinese angiosperm genera, with the proportion of threatened species higher in range-limited and species-rich taxa. Habitat loss had a significant positive effect on threatened species richness. Phylogenetic diversity loss under scenarios: the decreasing habitat loss and relative extinction rate were high. Thus, genera would suffer from high extinction risk, if species in these genera occupy similar niches and overlapping ranges. While diversification or speciation via niche divergence might increase range-limited species vulnerable to stochastic extinction, this could reduce extinction risk of the whole clade by expanding its range and climatic niche tolerance. Endemic genera with higher extinction rates, less climatic niche divergence, and lower range segregation are especially vulnerable to anthropogenic disturbances.
Highlights
Biodiversity loss is among the most serious threats of global change, but the risk of extinction is nonrandomly distributed across the tree of life (Vamosi and Wilson, 2008; Vamosi et al, 2018; Davies, 2019)
As measured by Pagel’s lambda, all the genus-level variables exhibited a significant amount of phylogenetic signal
Twenty of the 88 genera identified as highly threatened according to extinction risk are endemic to China, but none of the 50 genera identified by randomization are endemic
Summary
Biodiversity loss is among the most serious threats of global change, but the risk of extinction is nonrandomly distributed across the tree of life (Vamosi and Wilson, 2008; Vamosi et al, 2018; Davies, 2019). Identifying those species most at risk could, help to inform effective interventions, helping to ameliorate the worst impacts. Extinction Risk in Chinese Angiosperms size as a proxy for risk (Purvis et al, 2000b) or (ii) to use a functional approach, where the relative risk among species is determined via their characteristic traits (Chichorro et al, 2019) Both the geographical ranges and functional traits retain some imprint of evolutionary history. We consider ecological, evolutionary, and anthropogenic predictors to predict extinction risk among Chinese angiosperms
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