Fire temperatures and postfire plant community dynamics in Ecuadorian grass páramo

Ramsay, Paul M.; Oxley, E. R. B.

doi:10.1007/bf00045489

Cited by 71 publications

(12 citation statements)

References 28 publications

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“…While infrequently studied in plants, the importance of diurnal temperature range for determining plant distributions has been emphasized in previous studies. Ramsay (2001) and Zhao et al (2018) found diurnal temperature variation to be an important predictor of plant growth form, a result they attributed to physiological stress adaptation; likewise, there are interactions between diurnal temperature and plant germination (Liu et al, 2013) and with plant size (Myster and Moe, 1995). In some investigations, latitudinal diversity patterns have been partly attributed to diurnal temperature variation in plants and microbes, attributed to filtering out species with narrow physiological tolerances within highly variable biomes (Hu et al, 2019;Lancaster and Humphreys, 2020).…”

Section: Discussionmentioning

confidence: 99%

Anatomy of a mega-radiation: Biogeography and niche evolution inAstragalus

Folk

Charboneau

Belitz

et al. 2023

Preprint

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Astragalus (Fabaceae), with more than 3,000 species, represents a successful radiation of morphologically highly similar species found across the Northern Hemisphere. It has attracted attention from systematists and biogeographers, who have asked what factors might be behind the extraordinary diversity of this important arid-adapted clade and what sets it apart from close relatives with far less species richness. Here, for the first time using extensive taxonomic sampling in a phylogenetic analysis, we ask whether (1) Astragalus is uniquely characterized by bursts of radiation or is instead similar to related taxa. Then we test whether the species diversity of Astragalus is attributable specifically to its predilection for (2) cold and arid habitats or (3) particular soils. Finally, we test (4) whether Astragalus originated in central Asia as proposed and (5) whether niche evolutionary shifts were associated with the colonization of other continents. Our results point to the importance of heterogeneity in the diversification of Astragalus, with upshifts associated with the earliest divergences but attributable to no abiotic factor or biogeographic regionalization tested here. The only potential correlate with diversification we identified was chromosome number. We find strong evidence for a central Asian origin and direct dispersals from this region responsible for much of the present-day distribution, highlighting the importance of central Asia as a biogeographic gateway. In contrast to diversification shifts, biogeographic shifts have a strong association with the abiotic environment. Our most important result was a fundamental divide in soil types and diurnal temperature variation between the Eastern and Western Hemisphere species; this divergence does not reflect differences in available habitat among these biogeographic domains but may reflect unique local gains of edaphic and abiotic stress adaptations. While large clades are logistically difficult to tackle, our investigation shows the importance of phylogenetic and evolutionary studies of "mega-radiations." Our findings reject any simple key innovation behind the dominance and richness of Astragalus and underline the often nuanced, multifactorial processes leading to species-rich clades.

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Section: Discussionmentioning

confidence: 99%

Anatomy of a mega-radiation: Biogeography and niche evolution inAstragalus

Folk

Charboneau

Belitz

et al. 2023

Preprint

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show abstract

Section: Discussionmentioning

confidence: 99%

“…This finding suggests that dispersal to the Americas was associated with niche specialization. Second, the primary correlate identified in the literature with diurnal variation is growth form, with high diurnal variation classically associated with low, cushion‐like growth forms (Ramsay, 2001). Astragalus , by contrast, is remarkable for a morphological conservatism that in many cases fails to demark major clades (Sanderson and Wojciechowski, 1996).…”

Section: Discussionmentioning

confidence: 99%

Anatomy of a mega‐radiation: Biogeography and niche evolution in Astragalus

Folk,

Charboneau,

Belitz

et al. 2024

American J of Botany

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PremiseAstragalus (Fabaceae), with more than 3000 species, represents a globally successful radiation of morphologically highly similar species predominant across the northern hemisphere. It has attracted attention from systematists and biogeographers, who have asked what factors might be behind the extraordinary diversity of this important arid‐adapted clade and what sets it apart from close relatives with far less species richness.MethodsHere, for the first time using extensive phylogenetic sampling, we asked whether (1) Astragalus is uniquely characterized by bursts of radiation or whether diversification instead is uniform and no different from closely related taxa. Then we tested whether the species diversity of Astragalus is attributable specifically to its predilection for (2) cold and arid habitats, (3) particular soils, or to (4) chromosome evolution. Finally, we tested (5) whether Astragalus originated in central Asia as proposed and (6) whether niche evolutionary shifts were subsequently associated with the colonization of other continents.ResultsOur results point to the importance of heterogeneity in the diversification of Astragalus, with upshifts associated with the earliest divergences but not strongly tied to any abiotic factor or biogeographic regionalization tested here. The only potential correlate with diversification we identified was chromosome number. Biogeographic shifts have a strong association with the abiotic environment and highlight the importance of central Asia as a biogeographic gateway.ConclusionsOur investigation shows the importance of phylogenetic and evolutionary studies of logistically challenging “mega‐radiations.” Our findings reject any simple key innovation behind high diversity and underline the often nuanced, multifactorial processes leading to species‐rich clades.

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“…Isothermality represents the strength of change in temperature over the course of the day. As discussed by Folk et al (2023a), this variable represents a major physiological challenge for plants in typically arid regions, requiring morphological and physiological adaptations (Myster and Moe, 1995; Ramsay, 2001; Liu et al, 2013) that are still poorly understood (Folk et al, 2023a). Whether isothermality has a direct effect on diversity, or indirectly affects diversity through aridity or other factors, it is clear that Astragalus lineages have become adapted to specialize and thrive in regions with strong diurnal climatic variability.…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic diversity and regionalization in the temperate arid zone

Folk,

Maassoumi,

Siniscalchi

et al. 2023

Preprint

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Astragalus(Fabaceae) is astoundingly diverse in temperate, cold arid regions of Earth, positioning this group as a model clade for investigating the distribution of plant diversity in the face of climatic challenge. Here we identify the spatial distribution of diversity and endemism inAstragalus, using species distribution models for 752 species and a phylogenetic tree comprising 847 species. We integrated these to map centers of species richness (SR) and relative phylogenetic diversity (RPD), and used grid cell randomizations to investigate centers of endemism. We also used clustering methods to identify phylogenetic regionalizations. We then assembled predictor variables of current climate conditions to test environmental factors predicting these phylogenetic diversity results, especially temperature and precipitation seasonality.We find that SR centers are distributed globally at temperate middle latitudes in arid regions, but the Mediterranean Basin is the most important center of RPD. Endemism centers also occur globally, but Iran represents a key endemic area with a concentration of both paleo- and neoendemism. Phylogenetic regionalization recovered an east-west gradient in Eurasia and an amphitropical disjunction across North and South America; American phyloregions are overall most closely related to east and central Asia. SR, RPD, and lineage turnover are driven mostly by precipitation and seasonality, but endemism is driven primarily by diurnal temperature variation. Endemism and regionalization results point to western Asia and especially Iran as a biogeographic gateway between Europe and Asia. RPD and endemism highlight the importance of temperature and drought stress in determining plant diversity and endemism centers.

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Fire temperatures and postfire plant community dynamics in Ecuadorian grass páramo

Cited by 71 publications

References 28 publications

Anatomy of a mega-radiation: Biogeography and niche evolution inAstragalus

Anatomy of a mega-radiation: Biogeography and niche evolution inAstragalus

Anatomy of a mega‐radiation: Biogeography and niche evolution in Astragalus

Phylogenetic diversity and regionalization in the temperate arid zone

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