Australasian Science: Australia's authority on science since 1938

Balancing Species Numbers and Phylogenetic Diversity

By Joseph Bennett

The current extinction crisis can be thought of as a fire in the genetic library of life. In the scramble to save as much as we can, we want to save as many books (i.e. species) as possible but we also want to save as much total information (i.e. unique genes) as possible.

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The global extinction crisis shows no signs of abating, and conservation funding falls far short of what is necessary to stop declines in biodiversity. Thus, either implicitly or explicitly, conservation agencies engage in prioritisation: they try to use their limited resources to maximise achievable goals.

Traditionally, biodiversity has often been viewed as species diversity. However, other measures of diversity are gaining acceptance. One of the most prominent of these is phylogenetic diversity – the diversity of evolutionary relationships among species. Phylogenetic diversity can also be thought of as the information contained in life’s genetic library, representing the millions of years of evolution that have led to unique species. Losing a species is like losing a book from this genetic library, and the unique information (i.e. genes) associated with it.

The amount of unique genetic information contained in a species is associated with that species’ phylogenetic distinctiveness – the relative isolation of its branch on the tree of life. A species with no close relatives (whose lineage has been isolated on the tree of life for many millions of years) contains more unique information than one with recently evolved close relatives.

The loss of the more distinct species means the loss of these millions of years of evolution, along with unique...

The full text of this article can be purchased from Informit.