DOI: 10.5061/dryad.t76hdr85j
title: Temperature-dependence of liverwort diversification: Cool origin and hot hotspots

description: The evolutionary history underlying gradients in species richness is still
 subject to discussions, and understanding the past niche evolution might
 be crucial in estimating the potential of taxa to adapt to changing
 environmental conditions. With this study we intend to contribute to
 elucidation of the evolutionary history of liverwort species richness
 distributions along elevational gradients at a global scale. For this
 purpose, we linked a comprehensive data set of genus occurrences on
 mountains worldwide with a time-calibrated phylogeny of liverworts and
 estimated mean diversification rates (DivElev) and mean ages (AgeElev) of
 the respective genera per elevational band. In addition, we reconstructed
 the ancestral temperature preferences of the genera. We found that
 diversification rates increase linearly with temperature, and hence
 decrease with elevation. This pattern is mainly driven by epiphytic
 genera. In contrast, overall genus age is highest at intermediate
 elevations where liverwort species richness peaks and decreases towards
 both ends of the elevational and thermal gradient. Our results further
 indicate that the ancestral lineages from which the extant liverwort
 genera descended had a preference for cool temperatures. Because cool (and
 humid) climates are today prevailing at mid-elevations of the world's
 mountains, we conclude that the extant liverwort species diversity
 accumulated over long time at mid-elevations and subsequently expanded
 towards warm lowland (with high diversification rates) and cold alpine
 regions (with low diversification rates). The conserved preference for
 temperate climates shared by the majority of liverwort lineages gives
 reason to the assumption that they will not be able to cope with the
 conditions induced by rapid climate warming, whereas the current
 low-elevation radiation may be less affected by climate change.
description: # Temperature-dependence of liverwort diversification: Cool origin and hot
 hotspots Files in this archive: Table 1: Data set containing elevational
 gradient ID (according to Table 1 in the article), elevation of the taxon
 record (m), taxon name, and the according genus name used for analyses.
 Table 3: Data set (modified after Maul et al. 2023), containing
 elevational gradient ID (according to Table 1 in main article),
 elevational steps of the gradients (m), relative elevation, species
 richness of elevational step, relative species richness, and predicted
 climate data (Bio1, mean annual temperature (C); Bio5, maximum temperature
 of the warmest month (C); Bio6, minimum temperature of the coldest month
 (C); Bio12, annual precipitation amount (mm); Bio13, precipitation amount
 of the wettest month (mm); Bio14, precipitation amount of the driest month
 (mm); Bio18, precipitation amount of the warmest quarter (mm); Bio19,
 precipitation amount of the coldest quarter (mm). Based on the data set
 Table 1, we calculated mean genus diversification rate per elevational
 band including every record, mean genus age per elevational band including
 every record, mean genus diversification rate per elevational band
 including only one record per genus, mean genus age per elevational band
 including only one record per genus. The last column of the table
 specifies the habitat studied on the elevational transect. ``` Reference:
 Maul, K., Wei, Y., Iskandar, E. A. P., Chantanaorrapint, S., Ho, B.,
 Quandt, D., & Kessler, M. (2023). Liverworts show a globally
 consistent midelevation richness peak. Ecology and Evolution, 13(3),
 e9862. https://doi.org/10.1002/ece3.9862. ```