Edaphic specialization onto bare, rocky outcrops as a factor in the evolution of desert angiosperms

Understanding the processes that enable organisms to shift into more arid environments as they emerge is critical for gauging resilience to climate change, yet these forces remain poorly known. In a comprehensive clade-based study, we investigate recent shifts into North American deserts in the rock...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2023-02, Vol.120 (6), p.e2214729120-e2214729120
Main Authors: Lichter-Marck, Isaac H, Baldwin, Bruce G
Format: Article
Language:English
Subjects:
Angiosperms
Arid environments
Aridification
Aridity
Asteraceae
Bayes Theorem
Bayesian analysis
Biological Sciences
Climate change
Deciduous forests
Desert Climate
Deserts
Ecosystem
Endemism
Evolution
Life history
Magnoliopsida
Mathematical models
Microhabitats
Miocene
Outcrops
Phylogeny
Radiation
Rocks
Statistical inference
Tropical forests
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Summary:Understanding the processes that enable organisms to shift into more arid environments as they emerge is critical for gauging resilience to climate change, yet these forces remain poorly known. In a comprehensive clade-based study, we investigate recent shifts into North American deserts in the rock daisies (tribe Perityleae), a diverse tribe of desert sunflowers (Compositae). We sample rock daisies across two separate contact zones between tropical deciduous forest and desert biomes in western North America and infer a time-calibrated phylogeny based on target capture sequence data. We infer biome shifts using Bayesian inference with paleobiome-informed models and find evidence for seven independent shifts into desert habitats since the onset of aridification in the late Miocene. The earliest shift occurred out of tropical deciduous forests and led to an extensive radiation throughout North American deserts that accounts for the majority of extant desert rock daisies. Estimates of life history and micro-habitat in the rock daisies reveal a correlation between a suffrutescent perennial life history and edaphic endemism onto rocky outcrops, an ecological specialization that evolved prior to establishment and diversification in deserts. That the insular radiation of desert rock daisies stemmed from ancestors preadapted for dry conditions as edaphic endemics in otherwise densely vegetated tropical deciduous forests in northwest Mexico underscores the crucial role of exaptation and dispersal for shifts into arid environments.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.2214729120