Genome duplication and angiosperm diversification: combining experimental and fossil evidence.
Lead Research Organisation:
University of Nottingham
Department Name: Sch of Biosciences
Abstract
The flowering plants (angiosperms) are the most diverse and most recently evolved plant group with more than 250 000 species compared to second most diverse group, the ferns (pteridophytes) with ~10 000 species. The angiosperm radiation, diversification and rise to dominance occurred over a very short period of geological time. During this radiation the angiosperms to moved away from there ancestral aquatic/ moist habitat to more arid environments. Explaining the underpinng mechanisms behind this event remains one of the key unanswered questions in the palaeobotanical research.
Advances in our understanding of the genome of living plants shows that many angiosperms may have undergone several episodes of genome duplication (polyploidy) during their history. Duplication of the genome leads to an increase in plant vigour and fitness, when compared to their ancestors. A well known example of this phenomenon is the hybrid vigour of modern crop plants when compared to their wild relatives. Dating of genome duplication events in the model plant Arabidopsis thaliana shows one of these events occurred during the initial angiosperms radiation. This suggests that changes in genome size may have played an important role in driving this diversification. However, to date this hypothesis has only been tested using the genome of one extant plant, furthermore no direct measure of the size of the genome of fossil plants exists. Consequently, although fascinating, this idea remains speculative.
Recent work has shown the length of guard cells (specialised cell on the leaf surface that control gas exchange) are a strong positive predictor of genome size of living plants. Leaves have an excellent fossil record and obtaining the length of guard cells from fossil specimens is straight forward. This suggests that guard cell length could be used as a proxy measure of genome size on fossil plants. I plan to use this relationship to test the hypothesis that increase in genome size accompanied the diversification of the early angiosperms.
A suite of experiments are designed to run along side this fossil plant investigation to assess how polyploidy impacts on plant health when grown in drought conditions at elevated atmospheric CO2 concentrations relevant to when the angiosperms originated. This work is relevance and importance to the wider scientific community given that a large proportion of crop plant are polyploids.
Advances in our understanding of the genome of living plants shows that many angiosperms may have undergone several episodes of genome duplication (polyploidy) during their history. Duplication of the genome leads to an increase in plant vigour and fitness, when compared to their ancestors. A well known example of this phenomenon is the hybrid vigour of modern crop plants when compared to their wild relatives. Dating of genome duplication events in the model plant Arabidopsis thaliana shows one of these events occurred during the initial angiosperms radiation. This suggests that changes in genome size may have played an important role in driving this diversification. However, to date this hypothesis has only been tested using the genome of one extant plant, furthermore no direct measure of the size of the genome of fossil plants exists. Consequently, although fascinating, this idea remains speculative.
Recent work has shown the length of guard cells (specialised cell on the leaf surface that control gas exchange) are a strong positive predictor of genome size of living plants. Leaves have an excellent fossil record and obtaining the length of guard cells from fossil specimens is straight forward. This suggests that guard cell length could be used as a proxy measure of genome size on fossil plants. I plan to use this relationship to test the hypothesis that increase in genome size accompanied the diversification of the early angiosperms.
A suite of experiments are designed to run along side this fossil plant investigation to assess how polyploidy impacts on plant health when grown in drought conditions at elevated atmospheric CO2 concentrations relevant to when the angiosperms originated. This work is relevance and importance to the wider scientific community given that a large proportion of crop plant are polyploids.
Planned Impact
The main beneficiaries of outputs from this work is anticipated to be the academic community, specifically palaeobotanists and plant scientists working in the fields of evolution and genomics. Our study may also be of interest to the general public and popular science media.
To target both of these groups I have developed the following strategy:
Academic community:
I plan to disseminate the finding of this proposal through oral presentations at international conferences targeting both plant sciences and palaeobotanical audiences and will look to publish at least three high impact papers. The papers where possible will be archived on the project website along with presentations.
Public engagement:
Evolution and the analysis of fossils have long held the attention of the general public. Outputs from this study will contribute to our understanding to the evolution of flowering plants, a highly charismatic group of organisms. Hence the successful completion of this proposal is expected to be of interest to the popular science media and through them the general public. To develop my communication and media skills I plan to attend the attend The Royal Society residential communication skills and media training course in 2012.
Using institutional links at the University of Nottingham I will offer a range of talks covering all aspects of the study during national science week, and will offer a talk to the British Science Festival in 2012.
A more targeted approach will also be developed via the Nuffield Schools and Colleges Bursaries scheme. I will apply to host students from the scheme, which provides students interested in a career in science the opportunity to join a research project with practicing scientists.
To target both of these groups I have developed the following strategy:
Academic community:
I plan to disseminate the finding of this proposal through oral presentations at international conferences targeting both plant sciences and palaeobotanical audiences and will look to publish at least three high impact papers. The papers where possible will be archived on the project website along with presentations.
Public engagement:
Evolution and the analysis of fossils have long held the attention of the general public. Outputs from this study will contribute to our understanding to the evolution of flowering plants, a highly charismatic group of organisms. Hence the successful completion of this proposal is expected to be of interest to the popular science media and through them the general public. To develop my communication and media skills I plan to attend the attend The Royal Society residential communication skills and media training course in 2012.
Using institutional links at the University of Nottingham I will offer a range of talks covering all aspects of the study during national science week, and will offer a talk to the British Science Festival in 2012.
A more targeted approach will also be developed via the Nuffield Schools and Colleges Bursaries scheme. I will apply to host students from the scheme, which provides students interested in a career in science the opportunity to join a research project with practicing scientists.
People |
ORCID iD |
| Barry Harvey Lomax (Principal Investigator) |
Publications
Jardine P
(2017)
Is pollen size a robust proxy for moisture availability?
in Review of Palaeobotany and Palynology
Lee AP
(2015)
Leaf energy balance modelling as a tool to infer habitat preference in the early angiosperms.
in Proceedings. Biological sciences
Lomax B
(2019)
An experimental evaluation of the use of ?13C as a proxy for palaeoatmospheric CO2
in Geochimica et Cosmochimica Acta
Lomax BH
(2014)
Reconstructing relative genome size of vascular plants through geological time.
in The New phytologist
| Description | The project has delivered a series of genome estimate for the earliest flowering plants through exploring the relationship between stomatal size and genome size. To achieve this two trips to Texas State University were undertaken to analyse archived samples. Data on fossil plant anatomy (guard cell lengths GCL) was used to determine the genome size of the earliest angiosperms by using the positive relationship between GCL and genome size (GS) previously determined on living plants. This data on the earliest Angiosperms (~120 million years before present) has been supplemented by an extensive literature survey to expand the database on GCL and hence GS to cover the remainder of the Cretaceous. The data is currently being worked up for publication and phylogenetic analysis is currently on-going. This will be completed before the submission of the financial report. Preliminary analysis shows that the earliest angiosperms had a very small genome size when compared to living gymnosperms and the average genome size of living angiosperms. Initial data analysis also suggests an increase in GS accompanied the radiation of the angiosperms. Analysis of the relationships between GCL and GS in living gymnosperms is currently on-going and will be completed before the submission of the financial report. A database of ~90 gymnosperms covering a broad range of families with a known GS has been collected. This database represents approximately 10% of gymnosperm diversity and this data is currently being worked on to determine the relationship between GCL and GS in living gymnosperms. Experimental work to determine the functional significance of polyploidy at geologically elevated levels of CO2 relevant to the evolutionary history of angiosperms has shifted from work on the model plant Arabidopsis thaliana and the development of synthetic polyploids to working on natural polyploids of Ranunculus (buttercups) which are a basal living group of angiosperms with a relatively good fossil record stretching back ~125 million years. |
| Exploitation Route | Findings of use to accademics |
| Sectors | Environment,Other |
| Description | Experiments with the dead |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Undergraduate students |
| Results and Impact | Talk at project partners (Prof Charles Knight) home Institute California Polytechnic State University informed partners students about work being undertaken |
| Year(s) Of Engagement Activity | 2011 |
| Description | Where have all the flowers come from |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | Yes |
| Geographic Reach | Regional |
| Primary Audience | Media (as a channel to the public) |
| Results and Impact | Talk introduced the concepts and current understanding of the evoltion of flowers to the general public I'm not aware of any notable impact |
| Year(s) Of Engagement Activity | 2012 |