Three explanations for biodiversity hotspots: small range size, geographical overlap and time for species accumulation. An Australian case study

To understand the generation and maintenance of biodiversity hotspots, we tested three major hypotheses: rates of diversification, ecological limits to diversity, and time for species accumulation. Using dated molecular phylogenies, measures of species' range size and geographical clade overlap...

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Bibliographic Details
Published in:The New phytologist 2015-07, Vol.207 (2), p.390-400
Main Authors: Cook, Lyn G., Hardy, Nate B., Crisp, Michael D.
Format: Article
Language:English
Subjects:
Accumulation
Australia
Biodiversity
Biodiversity hot spots
biodiversity hotspot
Biological Evolution
Climate
Ecological effects
Ecology
Evolution, Molecular
Fabaceae
Fabaceae - genetics
Genetic Speciation
geographical range
Geography
Hot spots
Hypotheses
niche limitation
Phylogeny
range overlap
southwest Australia Floristic Region
Speciation
Species
Species diversity
Species Specificity
time for species accumulation
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Summary:To understand the generation and maintenance of biodiversity hotspots, we tested three major hypotheses: rates of diversification, ecological limits to diversity, and time for species accumulation. Using dated molecular phylogenies, measures of species' range size and geographical clade overlap, niche modelling, and lineages-through-time plots of Australian Fabaceae, we compared the southwest Australia Floristic Region (SWAFR; a global biodiversity hotspot) with a latitudinally equivalent non-hotspot, southeast Australia (SEA). Ranges of species (real and simulated) were smaller in the SWAFR than in SEA. Geographical overlap of clades was significantly greater for Daviesia in the SWAFR than in SEA, but the inverse for Bossiaea. Lineage diversification rates over the past 10 Myr did not differ between the SWAFR and SEA in either genus. Interaction of multiple factors probably explains the differences in measured diversity between the two regions. Steeper climatic gradients in the SWAFR probably explain the smaller geographical ranges of both genera there. Greater geographical overlap of clades in the SWAFR, combined with a longer time in the region, can explain why Daviesia is far more species-rich there than in SEA. Our results indicate that the time for speciation and ecological limits hypotheses, in concert, can explain the differences in biodiversity.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.13199