Anthropogenic activities have significantly altered global biodiversity over the past 200 years, drawing attention to the need for conservation biology. Conservation Biology utilizes emerging interdisciplinary techniques to assess and make policies on environmental protection. Traditionally, conservation biology has investigated how ecology is altered by human influences. Recently, phylogenetics has been implemented into this field to include evolutionary value into the calculus of conservation priorities. Phylogenies are instrumental for predicting the impacts of anthropogenic extinctions, because unlike natural extinctions, these are highly non-random. Phylogenetically, mammals are one of the most well studied groups of animals, making them an ideal system for making conservation priorities that reflect evolutionary diversity. California is well known for its robust mammalian diversity and multifarious habitats, making it an ideal setting for this project. We utilized pre-existing data on the phylogenetics and conservation status of California’s mammal species to investigate the relationships between extinction risk and phylogeny using the statistical analysis program R. Specifically, we measured the potential loss of phylogenetic diversity and disparity by calculating the percentage decrease in phylogenetic diversity (PD) and Net Relatedness Index (NRI) when all species and subspecies with elevated extinction risk are pruned from the California mammal tree of life.
Results/Conclusions
In nearly every assessment, the total PD was highly conserved after high risk species were removed. We calculated that 7% of the total number of native terrestrial mammals have elevated extinction risk according to the IUCN. However, when these species are removed from our phylogeny, PD dropped by 2.4%. Comparatively, when we ran 1000 random iterations with the same number of species removed, PD dropped by a significantly greater 3.3%. Alternatively, we observed no significant trend for our NRI assessments.
Our phylogenetic analysis reveals that the potential loss in PD is generally lower than we would expect from a random loss of the same predicted number of species in a phylogeny consisting of California’s native terrestrial mammalian species. Between 9.2 – 38.5 % of California’s terrestrial mammalian species have elevated extinction risk, with an associated loss of 1.9 – 14.3% total PD. However, the loss of total PD was over-dispersed compared to the random loss of the same number of species, suggesting that while not inconsequential, these losses are not exacerbated by phylogenetic clustering. Conversely, our analyses of NRI revealed that the relationship between conservation status and evolutionary history was phylogenetically random, suggesting these losses are not impacted by phylogenetic clustering.