Despite recognition that the pressures described in Pressures affecting biodiversity have a key role in shaping biodiversity at the species and community levels, the role of these pressures in shaping patterns and distribution of genetic diversity is poorly understood. This is a major knowledge gap, because genetic diversity has important consequences for all levels of biodiversity, by influencing the (Banks et al. 2013):
- fitness of individuals
- viability of populations
- adaptability of species to environmental change
- evolution of new species
- structure of communities
- function of ecosystems.
New genomic techniques are providing opportunities to fill this knowledge gap (see New technologies, solutions and innovations), but data and synthesis from them remain limited.
In SoE 2011, the distributions of weighted endemism (i.e. the extent to which species are found nowhere else) and species richness were shown for plants, mammals, birds, reptiles and amphibians. The different taxa show variation in the distribution of endemism in Australia, but some areas have high endemism for many species. The south-west of Western Australia, the Wet Tropics and the New South Wales – Queensland border ranges are areas of high endemism and recognised as such in their listings as global biodiversity hotspots (see Global importance).
Since 2011, significant progress has been made in measuring aspects of biodiversity that reflect the evolutionary history of taxa in Australia. Phylogenetic diversity is a measure of the representation of evolutionary history and extends to a family of ‘phylodiversity’ measures (Laity et al. 2015). Different species differ greatly in the amounts of evolutionary history they represent, and this has important implications for conservation. For example, the extinction of a species that does not have any close living relatives, such as the Wollemi pine — the sole living descendent of a 150 million-year-old lineage—would result in a greater loss of phylogenetic diversity than the extinction of a young species with many close relatives. In addition, maintenance of phylogenetic diversity is crucial for maximising the capacity of species to adapt to environmental change. Phylogenetic endemism is a measure of the geographic rarity of phylogenetic lineages.
Figure BIO7 shows the distributions of phylogenetic diversity and phylogenetic endemism for plants, mammals, passerine birds, snakes and lizards, and myobatrachid and hylid frogs across Australia. The distributions vary across taxa, but some patterns are evident. The east coast of Australia has higher levels of phylogenetic diversity for all taxa, particularly in the Wet Tropics. The south-west of Australia is important for plants and birds, whereas the region around Darwin is also important for most taxa. Phylogenetic endemism is concentrated in the Wet Tropics for all taxa; for frogs, the higher elevation areas along the east coast are centres of high phylogenetic endemism. The areas highlighted by the phylogenetic endemism measure are important because they represent the current restricted ranges of long-diverged lineages whose ability to persist and evolve in the future depends on what occurs within their current habitats (Rosauer et al. 2009).