Download Genomic Mechanisms Underpinning Gymnosperm

2017_72: Genomic Mechanisms Underpinning
Gymnosperm Diversification
Supervisors: Dr Felix Forest ([email protected]), Dr Ilia Leitch, Dr Lisa Pokorny &
Dr Steven Dodsworth (Royal Botanical Gardens, Kew), and Dr James Rosindell (Life
Sciences)
Department: Royal Botanical Gardens, Kew
The history of life on Earth can be understood as an endless replacement of branches
in the tree of life. Changes in rates of speciation and extinction determine the rise and
demise of such branches. These changes could occur in response to intrinsic factors
such as developmental constraints, or extrinsic factors such as competition and
climate change.
The aim of this project is to focus on the role intrinsic factors may have had in shaping
the extant diversity of gymnosperms. These factors include genome size and genomic
repeat dynamics (e.g. copy number variation of transposable elements). These factors
are placed in the context of polyploidy (whole genomic duplication – WGD) that is
pervasive in most land plants but much rarer in gymnosperms than angiosperms over
recent evolutionary time. Extant gymnosperms form a monophyletic clade comprising
ca. 1000 species (in ca. 80 genera, 12 families, and 8 orders) of plants with relatively
large genomes.
Both polyploidy and the expansion of repetitive elements have played a role in the
evolution of these large genomes, at different timescales, whilst disparities in
diversification rates are also apparent. For example, Southern Hemisphere
Araucariales present an older distribution of divergence ages than Northern
Hemisphere Pinales, and the relatively species-poor Southern Hemisphere subfamily
Callitroideae is sister to the rather species-rich Cupressoideae.
Addressing how intrinsic factors of genome architecture may have shaped the
observed spatio-temporal disparities in diversification rate is the focus of this project.
It will be important to control for extrinsic factors such as biotic “clade competition”
(e.g. from angiosperms) that could have actively driven the replacement of entire
lineages. This project will use a hypothesis-based approach that combines the
gymnosperms’ rich fossil history with high-throughput sequencing techniques to
explore the biodiversity patterns and drivers underlying extant gymnosperm diversity.
For more information on how to apply visit us at www.imperial.ac.uk/changingplanet
Science and Solutions for a Changing Planet
Together such insights will be vital for understanding and predicting how the different
gymnosperm lineages will respond to the diverse environmental challenges (e.g.
climate change, pests and disease), they now face.
For more information on how to apply visit us at www.imperial.ac.uk/changingplanet