Imperilled phylogenetic endemism of Malagasy lemuriformes

Abstract

Aim To highlight where in Madagascar the phylogenetically and spatially rare lemur species at risk of extinction are concentrated. Location Madagascar.Methods Phylogenetic endemism (PE) is a combined measure for apportioning a phylogenetic tree across a landscape used to identify those geographical locations that contain spatially rare phylogenetic diversity (Rosauer et al., 2009). We present a simple extension (imperilled phylogenetic endemism) that scales this phylogenetic diversity by the probability of its loss to extinction. We apply these measures to a composite phylogeny of all confirmed Malagasy lemuriform species using International Union for Conservation of Nature (IUCN) extent of occurrence and threat status data.Results We find that, because nonimperilled species are scattered about the lemuriform tree, interior branches of the tree are still quite secure: this also means that areas of high phylogenetic endemism for Madagascar lemuriformes are often the same areas as those of high imperilled PE (IPE), as both are heavily weighted by branches nearer the tips. However, although the North of Madagascar holds the largest amount of spatially rare evolutionary history using both PE and IPE, there are additional pockets of imperilled history in the south and west.Main Conclusions Correlations of endemism and threat status with phylogenetic isolation are modest across lemurs and so are not substitutable conservation values. They might best be integrated on the landscape using IPE. As illustrated here, IPE successfully highlights areas containing species which are at once threatened with extinction and that are phylogenetically and spatially rare.

The PD Phylogenetic Diversity Framework: Linking Evolutionary History to Feature Diversity for Biodiversity Conservation

“…PE performs well in the example above; however, it shares a weakness of ED, when combined with probabilities and summed-up to provide overall scores. To see this, I consider a recent study of the phylogeny of Malagasy lemuriformes (Gudde et al 2013 ). This study set out to identify places with a concentration of threatened phylogenetic distinctive and rare species.…”

“…Their "imperilled phylogenetic endemism" (IPE) index is the sum over all branches of branch length times its probability of extinction (product of extinction probabilities of all descendents) times the inverse of its range-extent. Gudde et al ( 2013 ) claimed to "quantify where on the landscape at-risk evolutionary history is concentrated." However, their "imperilled phylogenetic endemism" (IPE) index appears to have the weakness that it could highlight places that have no threatened branches at all.…”

“…IPE is supposed to refl ect a concentration of range restricted, threatened species. Gudde et al ( 2013 ) argued that "our mapping does indeed quantify where at risk PD is concentrated". However, IPE, in the example above, actually quantifi ed where not -at -risk PD was concentrated!…”

“…However, they focussed on the "highest accumulation of top mammal species ranked in terms of their EDGE score." Similarly, Gudde et al ( 2013 ) set out to identify places with a concentration of threatened phylogenetically distinctive and rare species. Both studies, while identifying important assessment issues for the future, unfortunately applied methods that do not fully integrate the principle of phylogenetic complementarity.…”

“…On the other hand, we could examine the loss in expected PD if the area was lost (received no protection). This would be useful, in contrast to the IPE measure of Gudde et al ( 2013 ), in revealing areas that have geographically restricted elements of threatened PD. Future work may examine how these basic calculations of expected gains and losses can be used in combination to defi ned priorities for KBAs and other geographic areas as conservation foci.…”