Speciation across the Earth driven by global cooling in terrestrial orchids

Abstract

Although climate change has been implicated as a major catalyst of diversification, its effects are thought to be inconsistent and much less pervasive than localized climate or the accumulation of species with time. Focused analyses of highly speciose clades are needed in order to disentangle the consequences of climate change, geography, and time. Here, we show that global cooling shapes the biodiversity of terrestrial orchids. Using a phylogeny of 1,475 species of Orchidoideae, the largest terrestrial orchid subfamily, we find that speciation rate is dependent on historic global cooling, not time, tropical distributions, elevation, variation in chromosome number, or other types of historic climate change. Relative to the gradual accumulation of species with time, models specifying speciation driven by historic global cooling are over 700 times more likely. Evidence ratios estimated for 212 other plant and animal groups reveal that terrestrial orchids represent one of the best-supported cases of temperature-spurred speciation yet reported. Employing >2.5 million georeferenced records, we find that global cooling drove contemporaneous diversification in each of the seven major orchid bioregions of the Earth. With current emphasis on understanding and predicting the immediate impacts of global warming, our study provides a clear case study of the long-term impacts of global climate change on biodiversity.

The Origin And Speciation Of Orchids

“…An analysis of species richness per grid cell derived from the curated GBIF-RAINBIO dataset, showed that Central America (especially Costa Rica) and the northern Andean region (particularly Ecuador and Colombia) have the highest levels of species richness. These geographical patterns of species richness patterns are thus in agreement with the species richness distributions independently obtained through the WCVP database and support findings of studies conducted at the family level (Vitt et al, 2023) and in the Orchidoideae (Thompson et al, 2023).…”

Rapid in situ diversification rates in Rhamnaceae explain the parallel evolution of high diversity in temperate biomes from global to local scales

“…This is consistent with H1, namely that the global expansion of temperate biomes from the Oligocene onward (34 Ma) due to strong climate cooling events and drying, provided ecological opportunities for temperate biodiversity to originate and expand. Similar patterns of increased diversification coinciding with the onset of colder and drier climates in the Miocene have been found in some angiosperm lineages, such as Poaceae, Asteraceae, Saxifragales, rosids, and orchids (Folk et al, 2019;Soltis et al, 2019;Sun et al, 2020;Palazzesi et al, 2022;Thompson et al, 2023a).…”

The origin and speciation of orchids

“…An analysis of species richness per grid cell derived from the curated GBIF‐RAINBIO dataset showed that Central America (especially Costa Rica) and the northern Andean region (particularly Ecuador and Colombia) have the highest levels of species richness. These geographical patterns of species richness are in agreement with the species richness distributions independently obtained through the WCVP database and support findings of studies conducted at the family level (Vitt et al ., 2023) and in Orchidoideae (Thompson et al ., 2023).…”