Abstract Detail

The rise and fall of photosynthate: Evolution of plant/fungus interactions from paleobotanical and phylogenomic perspectives

Kenrick, Paul [1], Strullu-Derrien, Christine [2], Mitchell, Ria [1].

The origins of land plant communities.

Photosynthetic organisms have been a part of life on Earth for billions of years, and microbial floras were important on land since the Neoproterozoic. Sometime during the late Neoproterozoic or early Palaeozoic the nature of terrestrial ecosystems changed radically with the evolution of higher plants (i.e., embryophytes). The timeframe for the early colonization of the land by plants is still relatively poorly constrained. Molecular phylogenies provide widely differing calibrations with large elements of uncertainty, whereas the fossil evidence is heavily influenced by preservation potential of the organisms and changes in the nature of the rock record that operate at a global scale. Despite these difficulties, multiple lines of evidence (e.g., molecular phylogenetics, molecular developmental biology, sedimentology, geochemistry, palaeontology) inform our understanding of the organisms, their evolution and their interactions with each other and the environment. Evidence of basal embryophytes is sparse, but a growing body of data on dispersed spores and minute charcoalified fossils provides insights into plants at the bryophyte grade, many of which show combinations of characteristics unknown in living species. Life cycles differed too, with greater similarities between gametophyte and sporophyte phases. In vascular plants, roots and shoots evolved iteratively through gradual specialization from simple leafless photosynthetic axial systems. The evolution of lignified tissues (vascular, peripheral sterome) had occurred by the Late Silurian, and wood in small plants by the Early Devonian, leading to arborescent forms by the Mid to Late Devonian. These changes occurred in the context of developing interactions with other eukaryotes, which frequently took place at the interface between plant and soil. The growing recognition of the importance of eukaryotic symbionts in early terrestrial ecosystems combined with developing phylogenetic frameworks and the application of methods such as X-ray Synchrotron Microtomography open up new possibilities to investigate the early evolution of plants and their environments. The emerging paradigm is one of early life on land dominated by communities of cyanobacteria, basal eukaryotes of various sorts as well as more derived forms of fungi, small bryophyte-like organisms and lichens. Collectively called Cryptogamic Ground Covers, these communities are comparable with those that dominate certain ecosystems today.

1 - The Natural History Museum, Department of Earth Sciences, Cromwell Road, London, SW7 5BD, UK
2 - The Natural History Museum, Department of Earth Sciences, Cromwell Road, London, N/A, SW7 5BD, UK

Keywords:
fossil
land plants
cryptogam
community.

Presentation Type: Symposium Presentation
Session: SY12
Location: Hall A/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 1:45 PM
Number: SY12002
Abstract ID:998
Candidate for Awards:None