Dataset Information

Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America.

ABSTRACT: Because of a dearth of Cenozoic grass fossils, the timing of the taxonomic diversification of modern subclades within the grass family (Poaceae) and the rise to ecological dominance of open-habitat grasses remain obscure. Here, I present data from 99 Eocene to Miocene phytolith assemblages from the North American continental interior (Colorado, Nebraska, Wyoming, and Montana/Idaho), constituting the only high-resolution mid-Cenozoic record of grasses. Analyses of these assemblages show that open-habitat grasses had undergone considerable taxonomic diversification by the earliest Oligocene (34 million years ago) but that they did not become ecologically dominant in North America until 7-11 million years later (Late Oligocene or Early Miocene). This pattern of decoupling suggests that environmental changes (e.g., climate changes), rather than taxonomic radiations within Poaceae, provided the key opportunity for open-habitat grasses to expand in North America.

SUBMITTER: Stromberg CA

PROVIDER: S-EPMC1189350 | biostudies-literature | 2005 Aug

REPOSITORIES: biostudies-literature

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Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America.

Strömberg Caroline A E CA

Proceedings of the National Academy of Sciences of the United States of America 20050811 34

Because of a dearth of Cenozoic grass fossils, the timing of the taxonomic diversification of modern subclades within the grass family (Poaceae) and the rise to ecological dominance of open-habitat grasses remain obscure. Here, I present data from 99 Eocene to Miocene phytolith assemblages from the North American continental interior (Colorado, Nebraska, Wyoming, and Montana/Idaho), constituting the only high-resolution mid-Cenozoic record of grasses. Analyses of these assemblages show that open ...[more]

PMID: 16099827

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Project description:Abstract The ergot diseases of agricultural and nonagricultural grasses are caused by the infection of Claviceps spp. (Hypocreales, Ascomycota) on florets, producing dark spur?like sclerotia on spikes that are toxic to humans and animals, leading to detrimental impacts on agriculture and economy due to the downgrading of cereal grains, import–export barriers, reduced yield, and ecological concerns. At least seven phylogenetic lineages (phylogenetic species) were identified within the premolecular concept of C. purpurea s.l. (sensu lato) in agricultural areas and vicinities in Canada and the Western United States. Claviceps purpurea s.s (sensu stricto) remained as the most prevalent species with a wide host range, including cereal crops, native, invasive, and weedy grasses. The knowledge on genetic diversity and distribution of C. purpurea s.s. in North America is lacking. The objective of the present study was to shed light on genetic differentiation and evolution of the natural populations of C. purpurea s.s. Multilocus DNA sequences of samples from Canada and the Western USA were analyzed using a phylogenetic network approach, and population demographic parameters were investigated. Results showed that three distinct genetically subdivided populations exist, and the subdivision is not correlated with geographic or host differentiations. Potential intrinsic mechanisms that might play roles in leading to the cessation of gene flows among the subpopulations, that is, mating and/or vegetative incompatibility, genomic adaptation, were discussed. The neutrality of two house?keeping genes that are widely used for DNA barcoding, that is, translation elongation factor 1?? (TEF1??) and RNA polymerase II second largest subunit (RPB2), was challenged and discussed. Regardless of the frequent sexuality and multiple modes of dispersal, the population of the toxigenic plant pathogen, Claviceps purpurea, that infects wide range of agricultural and nonagricultural grasses, was subdivided in nature. The population structure shed light on the underline mechanisms that might have led to the cessation of gene flow among subdivided populations. House?keeping gene markers were not neutral in certain circumstances.

Dataset Information

Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America.

Publications

Decoupled taxonomic radiation and ecological expansion of open-habitat grasses in the Cenozoic of North America.

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