Patterns in Diversity

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At larger scales, diversity is the combination of local, within-site diversity and diversity between sites. While within-site (alpha) diversity depends on environmental conditions, diversity among sites, I.E. dissimilarity between communities depends on dissimilarity in environmental conditions, as well as biotic interactions, dispersal, and stochastic forces. Studies of large-scale diversity patterns often can only explain a small proportion of variability among communities from environmental conditions. The relative importance of the different forces shaping diversity patterns remains of immense interest, not least to understand how humans are influencing diversity and what interventions will best conserve biodiversity for future generations. My current research investigates the influence of humans on patterns of insect diversity.

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Plant Reproduction

 

Reproducing is part of what it means to be alive. Reproductive systems in plants are incredibly diverse, featuring cross- versus self-fertilisation, sexual versus clonal reproduction, several alternative distributions of genders among and within individuals, and a great variety of pollination and seed dispersal agents. Reproductive modes evolve in response to their costs and benefits and subject to genetic constraints. In turn, modes of reproduction strongly affect gene-flow patterns and genetic diversity, influencing potential to colonise new habitat, to adapt to new or changing environments, to give rise to new species or to become extinct. Reproduction also affects population growth rate, so plant populations that experience reduced seed production, for instance because their populations become too small to attract pollinators, or because pollinator populations are reduced, may go extinct. Plant communities consist of species that have avoided extinction, so the reproductive traits of species may contain clues about the history of the coum

 

Unlike many dispersing animals, plant seeds can not actively choose where they will end up and once a plant germinates, it remains rooted in place.The diverse reproductive strategies of plants are probably an evolutionary consequence of these limitations. Although plants have little control of movement of seeds and gametes, they can adapt for more efficient use of particular pollinators or seed dispersers, or to become less reliant on them. There are inherent conflicts in relationships between species, even when both partners benefit. In the case of pollination, foraging behaviour of pollinators has evolved to improve their rate of feeding in a way that often results in poor pollination for plants, while plants have evolved features that restrict feeding rate of pollinators in order to improve pollination.

 

My Research Interests

 

I am interested in causes of variation in plant reproductive success, and the evolutionary and ecological consequences.

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There is evidence for declines in the diversity and abundance of animal pollinators from widespread locations. It thus seems that in common with other groups of animals, pollinators may be subject to a global decline. Because plants depend on pollinators to reproduce, pollinator declines may have far-reaching consequences for ecosystems, including eventual extinction of some plant species and changes in the species composition of plant communities. This could lead to further knock-on effects, such as extinction of other animal species and changes in ecosystem function. In my current research, I am investigating the potential ecological consequences of pollinator declines.

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I am especially interested in the consequences of plant abundance for mating. Allee effects occur when small population size or low density results in decreased performance, possibly leading to population declines. When plants are in small and isolated patches, or individuals are very isolated they become less profitable for pollinators and in consequence, are often less well pollinated than plants in large dense patches. While these Allee effects are common, not all studies have detected them. We don’t yet understand what properties of plants, their pollinators and the communities they are part of govern Allee effects. I am fascinated by this question. Understanding the effects of plant abundance on reproduction can also make a major contribution to conservation of rare species and combating invasive species, which are rare when they are expanding into new territory.

 

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For more details on my research projects, go to my current and past research!