Brummitt, Neil Alistair

2018-01-31T11:38:02Z

2018-01-31T11:38:02Z

2005

Regional distributions of all vascular plant genera have been compiled from herbarium specimens at the Royal Botanic Gardens, Kew, and this data has then been analysed for large-scale patterns in the diversity and distribution of flowering plants, at both genus and family levels. A strong latitudinal gradient in diversity is apparent at family, genus and species levels, though while western South America is most diverse at species and genus levels, it is the SW. Pacific which is most diverse at family level. However, the number of families and genera per region is very strongly correlated, irrespective of the region. There is a very strong relationship between area and both family and genus diversity, though not for numbers of endemic genera. Analysing floristic similarity between different regions of the world reveals very strongly supported continental groups, since most genera are confined to particular continents, although the latitudinal difference between regions is a better predictor of floristic similarity than is simply distance between regions. Latitudinal range-size for genera increases towards the equator, although taxon-size in general decreases with increasing latitudinal range-size. For both families and genera, the range-size frequency distribution is highly skewed towards small range sizes (more so for genera than families), which account for the majority of taxa. Distribution patterns show strong regional clustering, with almost 40% of genera single-region endemics, and approximately 20% of world distribution patterns accounting for about 80% of total angiosperm genus diversity. Analysis of these distribution patterns reveals a strong correlation between diversity and the number of floristic elements, which intersect to form the diversity of a region. In general, though with many exceptions, there is a correlation between recency of evolutionary origin and the size (number of taxa) and spread (size of distribution) of flowering plant families. However, while a phylogenetic perspective becomes essential for addressing within-family patterns of distribution, it is argued that over the whole clade of flowering plants the resulting patterns of diversity are constrained more by large-scale ecological processes.

http://hdl.handle.net/1842/27446

The University of Edinburgh

Annexe Thesis Digitisation Project 2017 Block 16

Already catalogued

Patterns in the diversity and distribution of flowering plant genera

Thesis or Dissertation

PhD Doctor of Philosophy