Fast Evolutionary Distinctiveness in R

Evolutionary distinctiveness is a metric that quantifies how isolated a species is on a phylogenetic tree ā€“ some species have few or no close living relatives.

The standard method for calculating evolutionary distinctiveness is either by using the R package picante or caper. For very large trees, such calculation is a memory-intensive operation and a bottle-neck for these algorithms.

Because of these challenges, we developed a new method in our phyloregion package that speeds up the process significantly to produce results in seconds! Here’s how:

Let’s try computing evolutionary distinctiveness for a tree with 5,000 species:

# packages we benchmark.
tree <- ape::rcoal(5000)

ed_picante <- function(x) picante::evol.distinct(x, type="fair.proportion")
ed_caper <- function(x) caper::ed.calc(x)
ed_phyloregion <- function(x) phyloregion::evol_distinct(x, type="fair.proportion")

res <- bench::mark(picante=ed_picante(tree),
          phyloregion=ed_phyloregion(tree), check=FALSE)
## # A tibble: 3 x 6
##   expression       min   median `itr/sec` mem_alloc `gc/sec`
##   <bch:expr>  <bch:tm> <bch:tm>     <dbl> <bch:byt>    <dbl>
## 1 picante        11.9m    11.9m   0.00140   287.9GB    0.122
## 2 caper          21.1s    21.1s   0.0474     21.6GB    0.284
## 3 phyloregion   64.5ms   67.2ms  14.8       882.2KB    0

Comparing phyloregion against other packages in terms of speed and memory efficiency in computing evolutionary distinctiveness.


Here, phyloregion is several orders of magnitude faster and efficient in memory allocation than the other packages.

The function in phyloregion is called evol_distinct and it is used as follows:

evol_distinct(tree, type = c("equal.splits", "fair.proportion"), ...)

If you find this vignette tutorial useful, please cite in publications as:

Daru, B.H., Karunarathne, P. & Schliep, K. (2020) phyloregion: R package for biogeographic regionalization and macroecology. Methods in Ecology and Evolution 11: 1483-1491. doi: 10.1111/2041-210X.13478.

About Barnabas Daru

Evolutionary Biogeographer
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