Mountain building, climate cooling and the richness of cold‐adapted plants in the Northern Hemisphere

Abstract

Aim The summits of mountain ranges at mid‐latitude in the Northern Hemisphere share many ecological properties with the Arctic, including comparable climates and similar flora. We hypothesize that the orogeny during the Oligocene‐Miocene combined with global cooling led to the origin and early diversification of cold‐adapted plant lineages in these regions. Before the establishment of the Arctic cryosphere, adaptation and speciation in high elevation areas of these mountain ranges may have led to higher species richness compared to the Arctic. Subsequent colonization from mid‐latitude mountain ranges to the Arctic may explain similar but poorer flora. Location Arctic‐Alpine regions of the Northern Hemisphere. Methods We mapped the cold climate in the Northern Hemisphere for most of the Cenozoic (60 Ma until present) based on paleoclimate proxies coupled with paleoelevations. We generated species distribution maps from occurrences and regional atlases for 5,464 plant species from 756 genera occupying cold climates. We fitted a generalized linear model to evaluate the association between cold‐adapted plant species richness and environmental, as well as geographic variables. Finally, we performed a meta‐analysis of studies which inferred and dated the ancestral geographic origin of cold‐adapted lineages using phylogenies. Results We found that the subalpine‐alpine areas of the mid‐latitude mountain ranges comprise higher cold‐adapted plant species richness than the Palearctic and Nearctic polar regions. The topo‐climatic reconstructions indicate that the cold climatic niche appeared in mid‐latitude mountain ranges (42–38 Ma), specifically in the Himalayan region, and only later in the Arctic (22–18 Ma). The meta‐analysis of the dating of the origin of cold‐adapted lineages indicates that most clades originated in central Asia between 39–7 Ma. Main conclusions Our results support the hypothesis that the orogeny and progressive cooling in the Oligocene‐Miocene generated cold climates in mid‐latitude mountain ranges before the appearance of cold climates in most of the Arctic. Early cold mountainous regions likely allowed for the evolution and diversification of cold‐adapted plant lineages followed by the subsequent colonization of the Arctic. Our results follow Humboldt's vision of integrating biological and geological context in order to better understand the processes underlying the origin of arctic‐alpine plant assemblages.

Reptile species richness associated to ecological and historical variables in Iran

“…This study took in to account both historical and ecological factors effects on the distribution patterns of 171 lizard species in Iran. Our findings support the fact that there is no single driver for biodiversity distribution and there is always a set of ecological and historical factors shaping species richness 3 , 11 , 12 , 74 . Since lizard richness is strongly associated with climate we speculate that lizard diversity and distribution will be affected by future climatic changes.…”

Cenozoic evolution of the steppe-desert biome in Central Asia

“…1 ) in particular serving as a center for plant diversification since at least the early Miocene [e.g., ( 3 , 117 )]. Molecular phylogenetic analyses reveal that diversification in both the alpine biome [e.g., ( 3 , 118 )] and steppe-desert lowlands ( 119 – 121 ) occurred during the mid- to late Miocene, which appear to be driven mainly by cooling and progressive aridity, respectively. This may be related to the generalized northward expansion of the Tibetan Highland and mountain ranges in the vicinity, including uplift of the Tian Shan, Pamir, Kunlun, and Qilian Shan-Nan Shan ( 122 , 123 ).…”

gen3sis: the general engine for eco-evolutionary simulations on the origins of biodiversity

“…To account for uncertainties on paleo-reconstructions on the emerging large-scale biodiversity patterns, we used two paleo-elevation reconstructions [116,117] associated with two approaches to estimate the paleo-temperature of sites (Note S1). L1 had temperatures defined by Köppen bands based on the geographic distribution of lithologic indicators of climate [54]. L2 had temperature defined by a composite of benthic foraminifer isotope records over time [118] and along latitude for specific time periods [119][120][121][122][123][124][125].…”

“…L2 had temperature defined by a composite of benthic foraminifer isotope records over time [118] and along latitude for specific time periods [119][120][121][122][123][124][125]. An aridity index ranging from zero to one was computed based on the subtropical arid Köppen zone for both landscapes [54]. For details see Note S1.…”