Abstract Detail

Systematics Section/ASPT

Rydin, Catarina [1], Bolinder, Kristina [1], Norback Ivarsson, Lena [2], Thureborn, Olle [1], Humphreys, Aelys [3], Han, Fang [4], Ickert-Bond, Stefanie [5], Hoorn, Carina [6].

Moonlight pollination and more in gnetalean evolution.

Ephedra is a member of the Gnetales, a small gymnosperm order that is considered odd compared with other extant gymnosperms and has been in focus regarding the longstanding question of seed plant phylogeny. However, Ephedra attracts research attention for several other reasons too. Its pollen is important paleopalynological markers, indicators of steppe vegetation and a dry paleoclimate. The fossil record indicates substantial fluctuation in diversity and abundance of ephedroids over geological time and this is supported by recent analyses of diversification dynamics using molecular phylogenetic data. Recent work has also shown that two distinct pollen types are present among extant species, an ancestral and a derived type. The ancestral type is known from the fossil record at least from the Early Cretaceous, and probably much longer. In contrast, the derived type is first documented from the latest Cretaceous and does not become abundant until the Eocene. This suggests that crown group Ephedra is much older than molecular dating analyses thus far have indicated. Other recent studies on Ephedra, show that while there are a few key differences among species, interspecific variation in the genus is otherwise low at both molecular and morphological levels. Because of the generally limited variation and a relatively distant relationship to outgroups, deep divergences in the genus are difficult to resolve; however, the currently best estimate of phylogeny depicts Ephedra foeminea as sister to the remaining genus. Ephedra foeminea differs from other species of Ephedra in many respects, instead sharing features with Gnetum and Welwitschia. Our field experimentation and aerodynamic studies have shown that this species is insect-pollinated, corroborating findings of insect pollination in the Gnetum-Welwitschia clade, and that its pollen is sticky although the reason for this is unclear since gnetalean pollen lacks pollenkitt. Most importantly, and in accordance with Gnetum and Welwitschia, Ephedra foeminea has sterile ovules in the male cones and attracts pollinators to both male and female plants using pollination drops. We found that pollination in E. foeminea occurs at full moon, probably as a consequence of co-evolution with nocturnal insects that use the moon to navigate. Most other species of Ephedra are thought to be wind-pollinated, and one such species that is sympatric with E. foeminea, E. distachya, does not correlate its pollination with the lunar cycle. Our observations tentatively indicate that E. foeminea is vulnerable, under threat from light pollution and potentially also future climate change.

1 - Stockholm University, Department of Ecology, Environment and Plant Sciences, Stockholm, SE-10691, Sweden
2 - Sodertorn University, School of Natural Sciences, Technology and Environmental Studies, Huddinge, SE-14189, Sweden
3 - Imperial College London, Department of Life Sciences, Silwood Park Campus, Buckhurst Road, Ascot, West Berkshire, SL5 7PY, UK
4 - University of Geosciences, State Key Laboratory of Biogeology and Environmental Geology, Faculty of Earth Science, Wuhan,, 430074, China
5 - University Of Alaska Museum Of The North, Herbarium (ALA) And Dept. Of Biology And Wildlife, University Of Alaska Fairbanks, 907 Yukon Dr., Fairbanks, AK, 99775, USA
6 - University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Science Park 904, Amsterdam, 1098 XH , The Netherlands

Keywords:
Ephedra
fossils
Gnetum
palynology
pollen
pollination drops
Welwitschia.

Presentation Type: Oral Paper:Papers for Sections
Session: 33
Location: Salon 10/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 8:45 AM
Number: 33004
Abstract ID:993
Candidate for Awards:None