Continental‐scale spatial phylogenetics of Australian angiosperms provides insights into ecology, evolution and conservation

Abstract

Aim Biodiversity studies typically use species, or more recently phylogenetic diversity (PD), as their analysis unit and produce a single map of observed diversity. However, observed biodiversity is not necessarily an indicator of significant biodiversity and therefore should not be used alone. By applying a small number of additional metrics to PD, with associated statistical tests, we can determine whether more or less of the phylogeny occurs in an area, whether branch lengths in an area are longer or shorter, and whether more long or short-branched endemism occurs in an area, than expected under a null model. Location Australian continent.Methods We used a phylogeny sampling 90% of Australia's angiosperm genera, and 3.4 million georeferenced plant specimens downloaded from Australia's Virtual Herbarium (AVH), to calculate PD, relative phylogenetic diversity (RPD) and relative phylogenetic endemism (RPE). Categorical analysis of neo-and palaeo-endemism (CANAPE) and randomization tests were performed to determine statistical significance.Results We identify several combinations of significant PD and endemism across the continent that are not seen using observed diversity patterns alone. Joint interpretation of these combinations complements the previous interpretations of Australia's plant evolutionary history. Of conservation concern, only 42% of the significant endemism cells found here overlap with existing nature reserves.Main conclusions These spatial phylogenetic methods are feasible to apply to a whole flora at the continental scale. Observed richness or PD is inadequate to fully understand the patterns of biodiversity. The combination of statistical tests applied here can be used to better explain biodiversity patterns and the evolutionary and ecological processes that have created them. The spatial phylogenetic methods used in this paper can be also be used to identify conservation priorities at any geographical scale or taxonomic level.

Congruent biogeographical disjunctions at a continent-wide scale: Quantifying and clarifying the role of biogeographic barriers in the Australian tropics

“…Of the 13 common barriers to plant distributions identified here, 11 can be directly compared to biogeographic breaks previously identified in the distributions of birds [4] and subsequently mammals [13], amphibians [82], Crustacea, and insects [12]. We have identified two novel disjunctions (Arnhem Land Plateau and Atherton Tableland) that have been previously noted as locations of high species endemism and turnover, but not as biogeographic barriers per se [64,83,84]. …”

Fern and lycophyte diversity in the Pacific Northwest: Patterns and predictors

“…An alternative way to incorporate the tree of life is through phylogenetic diversity measures, also referred to as phylodiversity measures (Laity et al, ). When applied using a spatial phylogenetics framework (Thornhill et al, ), these measures provide a way to summarize information about the spatial distribution of biodiversity.…”

“…and (v) how may anticipated climate change affect pteridophyte species distributional ranges in the near future? We use spatial phylogenetics (Thornhill et al, ) to map PD and PE across the PNW, compare PD and PE against randomized models to discern areas with higher or lower values than expected, identify centers of PE and determine whether they represent neo‐ or paleo‐endemism. We also explore relationships between environmental variables and the distribution of pteridophytes and significant areas of PD and PE and employ environmental niche modeling to predict suitable habitats during the LGM and for the year 2070.…”

The Hunting of the SNaRC: A Snarky Solution to the Species Problem

“…A related metric has appeared more recently called phylogenetic endemism (PE), which is a measure of how range-restricted lineages are (Rosauer, Laffan, et al 2009). There is a burgeoning school of research called "spatial phylogenetics" that takes advantage of the availability of large-scale phylogenies, and big distributional data sets derived from museum digitization efforts, to look at patterns of PD and PE on the landscape (Gonzalez-Orozco, Pollock, et al 2016;Mishler, Knerr, et al 2014;Nagalingum, Knerr, et al 2015;Schmidt-Lebuhn, Knerr, et al 2015;Thornhill, Baldwin, et al 2017;Thornhill, Mishler, et al 2016). The results from these studies enable rankless phylogenetic evaluations of conservation priorities, as well as studies of evolution, ecology, and biogeography.…”