Hagenia from the early Miocene of Ethiopia: Evidence for possible niche evolution?

Author(s)
Fridgeir Grimsson, Silvia Ulrich, Mario Coiro, Shirley A. Graham, Bonnie F. Jacobs, Ellen D. Currano, Alexandros Xafis, Reinhard Zetter
Abstract

Fossil pollen believed to be related to extant Hagenia abyssinica were discovered in the early Miocene (21.73 Ma) Mush Valley paleoflora, Ethiopia, Africa. Both the fossil and extant pollen grains of H. abyssinica were examined with combined light microscopy, scanning electron microscopy, and transmission electron microscopy to compare the pollen and establish their relationships. Based on this, the fossil pollen grains were attributed to Hagenia. The presence of Hagenia in the fossil assemblage raises the questions if its habitat has changed over time, and if the plants are/were wind pollinated. To shed light on these questions, the morphology of extant anthers was also studied, revealing specialized hairs inside the anthers, believed to aid in insect pollination. Pollen and anther morphology are discussed in relation to the age and origin of the genus within a molecular dated phylogenetic framework, the establishment of complex topography in East Africa, other evidence regarding pollination modes,
and the palynological record. The evidence presented herein, and compiled from the literature, suggests that Hagenia was an insect-pollinated lowland rainforest element during the early Miocene of the Mush Valley. The current Afromontane habitat and ambophilous (insect and wind) pollination must have evolved in post-mid-Miocene times.

Organisation(s)
Department of Botany and Biodiversity Research, Department of Palaeontology
External organisation(s)
Universität Zürich (UZH), Missouri Botanical Garden, Southern Methodist University, University of Wyoming
Journal
Ecology and Evolution
Volume
11
Pages
5164-5186
No. of pages
23
ISSN
2045-7758
DOI
https://doi.org/10.1002/ece3.7408
Publication date
2021
Peer reviewed
Yes
Austrian Fields of Science 2012
105117 Palaeobotany, 106049 Ultrastructure research, 106029 Plant morphology
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/hagenia-from-the-early-miocene-of-ethiopia-evidence-for-possible-niche-evolution(64d6d1ee-2e4c-420a-88e3-27ffc1df3d28).html