Edaphic Aridity as a Factor in Angiosperm Evolution

1972 ◽  
Vol 106 (949) ◽  
pp. 311-320 ◽  
Author(s):  
Daniel I. Axelrod
Keyword(s):  
Angiosperm Evolution

scholarly journals Fossil evidence for low gas exchange capacities for Early Cretaceous angiosperm leaves

Paleobiology ◽  
2011 ◽  
Vol 37 (2) ◽  
pp. 195-213 ◽  
Author(s):  
Taylor S. Feild ◽  
Garland R. Upchurch ◽  
David S. Chatelet ◽  
Timothy J. Brodribb ◽  
Kunsiri C. Grubbs ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Early Cretaceous ◽  
Leaf Gas Exchange ◽  
Exchange Capacity ◽  
Basal Angiosperm ◽  
Photosynthetic Gas Exchange ◽  
Angiosperm Evolution ◽  
Early Angiosperm ◽  
Fossil Evidence ◽  
Functional Analyses

The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian—early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.

Oxygen and environmental stress in plants: and evolutionary context

1994 ◽  
Vol 102 ◽  
pp. 155-165 ◽  
Author(s):  
George A. F. Hendry
Keyword(s):  
Oxidative Stress ◽  
Free Radical ◽  
Environmental Stress ◽  
Angiosperm Evolution ◽  
Selective Pressures ◽  
The Past ◽  
Wide Range ◽  
Evolutionary Context ◽  
Radical Processes ◽  
Oxidative Attack

SynopsisContemporary plant species show a wide range of responses to oxidative attack. Much of this variation may reflect the different environmental selective pressures operating at different geological periods over the course of angiosperm evolution. Evidence is provided to show that the wide range of contemporary responses to oxidative stress may directly reflect the persistence of genes controlling free radical processes under environments of the past.

scholarly journals Chemical Basis of Floral Color Signals in Gesneriaceae: The Effect of Alternative Anthocyanin Pathways

2020 ◽  
Vol 11 ◽  
Author(s):  
Ezgi Ogutcen ◽  
Karine Durand ◽  
Marina Wolowski ◽  
Laura Clavijo ◽  
Catherine Graham ◽  
...  
Keyword(s):  
High Performance ◽  
Flower Color ◽  
Pollination Syndromes ◽  
Angiosperm Evolution ◽  
Ecological Diversification ◽  
Floral Color ◽  
Wide Range ◽  
Hummingbird Pollination ◽  
Color Signals ◽  
Physical And Chemical

Changes in floral pigmentation can have dramatic effects on angiosperm evolution by making flowers either attractive or inconspicuous to different pollinator groups. Flower color largely depends on the type and abundance of pigments produced in the petals, but it is still unclear whether similar color signals rely on same biosynthetic pathways and to which extent the activation of certain pathways influences the course of floral color evolution. To address these questions, we investigated the physical and chemical aspects of floral color in the Neotropical Gesnerioideae (ca. 1,200 spp.), in which two types of anthocyanins, hydroxyanthocyanins, and deoxyanthocyanins, have been recorded as floral pigments. Using spectrophotometry, we measured flower reflectance for over 150 species representing different clades and pollination syndromes. We analyzed these reflectance data to estimate how the Gesnerioideae flowers are perceived by bees and hummingbirds using the visual system models of these pollinators. Floral anthocyanins were further identified using high performance liquid chromatography coupled to mass spectrometry. We found that orange/red floral colors in Gesnerioideae are produced either by deoxyanthocyanins (e.g., apigenidin, luteolinidin) or hydroxyanthocyanins (e.g., pelargonidin). The presence of deoxyanthocyanins in several lineages suggests that the activation of the deoxyanthocyanin pathway has evolved multiple times in the Gesnerioideae. The hydroxyanthocyanin-producing flowers span a wide range of colors, which enables them to be discriminated by hummingbirds or bees. By contrast, color diversity among the deoxyanthocyanin-producing species is lower and mainly represented at longer wavelengths, which is in line with the hue discrimination optima for hummingbirds. These results indicate that Gesnerioideae have evolved two different biochemical mechanisms to generate orange/red flowers, which is associated with hummingbird pollination. Our findings also suggest that the activation of the deoxyanthocyanin pathway has restricted flower color diversification to orange/red hues, supporting the potential constraining role of this alternative biosynthetic pathway on the evolutionary outcome of phenotypical and ecological diversification.

scholarly journals Exine stratification, ectexine structure and angiosperm evolution

Grana ◽  
1982 ◽  
Vol 21 (3) ◽  
pp. 161-170 ◽  
Author(s):  
Michel Guédès
Keyword(s):  
Angiosperm Evolution

scholarly journals Transposable Elements: Powerful Contributors to Angiosperm Evolution and Diversity

2013 ◽  
Vol 5 (10) ◽  
pp. 1886-1901 ◽  
Author(s):  
Keith R. Oliver ◽  
Jen A. McComb ◽  
Wayne K. Greene
Keyword(s):  
Transposable Elements ◽  
Angiosperm Evolution
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