Ecological consequences of angiosperm genome size and macronutrient availability
Publisher
Metadata
Show full item recordAbstract
Genome size (GS) is a fundamental trait influencing cellular, developmental and
ecological parameters, and varies c. 2400- fold in angiosperms. This astonishing range
has the potential to influence a plant’s nutrient demands, since nucleic acids are amongst
the most phosphate and nitrogen demanding cellular biomolecules, and hence its ability
to grow and compete in environments where macronutrients are limited. Angiosperm GS
are strongly skewed towards small genomes, despite the prevalence of polyploidy in the
ancestry of most if not all angiosperm lineages.
This thesis examines the hypothesis that large genome sizes are costly to build and
maintain and that angiosperm species with large GS are constrained by nitrogen and
phosphate limitation. It untangles the interactions between GS, polyploidy and
competition in plant communities, and examines how herbivory and GS play a role in
plant productivity, measured as above-ground biomass.
The hypothesis that large GS are costly was approached by analysing: 1) plant
communities growing under different macronutrient conditions at the Park Grass
Experiment (Rothamsted, UK); 2) plant communities under different conditions of
macronutrient limitation and insect, mollusc, and rabbit herbivory at Nash’s Field in
Silwood Park (UK); and, 3) Ellenberg’s indicator values which represent the realised
niche of a species in terms light, water, and soil fertility.
Support for the hypothesis was found in all experiments. The range of analyses show that
angiosperm plants with large genomes (e.g. 1C-value > 5 pg) are indeed under greater
macronutrient limitation in comparison to plants with small genomes, and that it is
polyploid plants with large GS which are the most competitive when macronutrient
resources are plentiful. In terms of herbivory, the key finding is a highly significant
negative association between GS and rabbit herbivory. A species’ realised niche for soil
fertility was found to show a positive association with its GS. Overall the thesis shows
that angiosperm GS plays a central role in plant community composition and responses
to macronutrient conditions, and potentially on higher ecosystem processes through
associations at different trophic levels.
Authors
Guignard, Maite StephanieCollections
- Theses [4222]