Inversion of the latitudinal diversity gradient at high taxonomic level in liverworts revealed by a phylogenetically deconstructive approach.

Background And Aims: Like numerous patterns in ecology and evolution, the Latitudinal Diversity Gradient (LDG) varies across phylogenetic levels. Yet, studies that systematically investigate how patterns and processes change at different phylogenetic levels, from the tips to the root, are still relatively scarce. Here, we test the hypothesis that, despite the high long-distance dispersal capacities of liverworts, which would expectedly result in the homogenization of their distributions, an increase of diversity with latitude persists at increasing phylogenetic level due to macroclimatic niche conservatism since the earliest evolutionary history of the group.

Spatial patterns and climatic drivers of phylogenetic structure of regional liverwort assemblages in China.

Background And Aims: Latitudinal diversity gradients have been intimately linked to the tropical niche conservatism hypothesis, which posits that there has been a strong filter due to the challenges faced by ancestral tropical lineages to adapt to low temperatures and colonize extra-tropical regions. In liverworts, species richness is higher towards the tropics, but the centres of diversity of the basal lineages are distributed across extra-tropical regions, pointing to the colonization of tropical regions by phylogenetically clustered assemblages of species of temperate origin. Here, we test this hypothesis through analyses of the relationship between macroclimatic variation and phylogenetic diversity in Chinese liverworts.