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Am J Bot. 2014 Aug;101(8):1350-61. doi: 10.3732/ajb.1400229.

Miocene leaves of Elaeagnus (Elaeagnaceae) from the Qinghai-Tibet Plateau, its modern center of diversity and endemism.

Author information

1
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China.
2
Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania 16802 USA.
3
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China University of the Chinese Academy of Sciences, Beijing 100049, China.
4
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China.

Abstract

PREMISE OF THE STUDY:

The Qinghai-Tibet Plateau is a major center of plant diversity and endemism, but little is known about how this developed due to the region's very scarce paleobotanical record. The silverberry genus Elaeagnus (Elaeagnaceae) reaches its greatest diversity (54 species) and endemism (36 species) in this area. Fossil Elaeagnaceae could provide significant evidence for the phylogeny and biogeography of the family and contribute primary data regarding the evolution of the unique Qinghai-Tibet Plateau flora in its dramatic setting of tectonic and climatic change.•

METHODS:

We describe four fossil leaves with diagnostic features of Elaeagnus from the late Miocene of eastern Tibet, modern altitude of 3910 m a.s.l.. We also review prior fossil records of Elaeagnaceae.•

KEY RESULTS:

The well-preserved, densely packed, stellate scales on fossil leaf surfaces are diagnostic of Elaeagnaceae. We assign these fossil leaves to Elaeagnus tibetensis T. Su et Z.K. Zhou sp. nov., comprising the first confirmed fossil Elaeagnus leaves worldwide.•

CONCLUSIONS:

Elaeagnus was present in eastern Tibet by the late Miocene. Together with previous fossil records, the new species supports a Holarctic history of the family. The diversification of Elaeagnus in the Qinghai-Tibet Plateau and adjacent areas might have been driven by continuous uplift at least since the late Miocene, causing formation of complex topography and climate with high rainfall seasonality. The characteristic scales on leaf surfaces are likely to be an important functional adaptation to seasonal droughts during early spring.

KEYWORDS:

Elaeagnaceae; Elaeagnus; Hippophae; Miocene; Qinghai-Tibet Plateau; Shepherdia; biogeography; climate change; fossil; leaf

PMID:
25156983
DOI:
10.3732/ajb.1400229
[Indexed for MEDLINE]
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