Abstract Detail


Miller, Joe [1].

Phylogenetic Diversity is a Better Measure of Biodiversity than Taxon Counting.

Biodiversity knowledge is essential for agriculture, food security, disease control, climate change and the environment. Most biodiversity assessments are based species richness, a simple count of species; however, species definitions are qualitative and vary. For example, it is common to describe how diverse a genus or a geographic area is by counting the number of species within it. Phylogenetic diversity (PD), a measurement of the branch lengths in a phylogenetic tree, is a better measure of biodiversity that provides a comparable, evolutionary measure of biodiversity not possible with species counts alone. Despite its advantages, PD is rarely used as the primary measure of biodiversity. We demonstrate the utility of PD as quantitative measure of biodiversity in two ways. We show that the relationship between species richness and PD is not linear but is follows a power law. Therefore current estimates of species richness minimize estimates of what we have scientifically discovered about biodiversity. A sample of 20% of the species corresponds to ≈40% of a clade’s PD. We show that total phylogenetic diversity can be estimated for any group, even when only part of a group is known. For instance, currently only 71.3% of vascular plant species are known to science but these species contain 81.1% of the predicted phylogenetic diversity of vascular plants.  Secondly we developed a genus-level phylogeny for nearly 90% of taxonomically described Australian land plants and compared PD to genus richness in multiple clades. The proportion of PD per genera was skewed among clades. Non-angiosperm clades had more PD than expected given the number of genera while angiosperm clades had less PD than expected. For example, ferns comprised only 4.7% of the genera yet 13.0% of the PD, while the angiosperms as a whole comprised 78.9% of the genera but only 62.7% of the PD. It is likely that cultural reasons are more important than methodological and biological phenomena in explaining these discrepancies. Regardless of reasons for the observed results, we conclude that a shift towards the use of PD as the primary descriptor of biodiversity will promote an important conceptual shift in biodiversity studies as a quantitative science.

1 - National Science Foundation, Office of International Science and Engineering, 2415 Eisenhower Avenue, Alexandria, VA, 22314, USA

phylogenetic diversity

Presentation Type: Oral Paper
Abstract ID:347
Candidate for Awards:None

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