Global conservation prioritization for the Orchidaceae

Abstract

Quantitative assessments of endemism, evolutionary distinctiveness and extinction threat underpin global conservation prioritization for well-studied taxa, such as birds, mammals, and amphibians. However, such information is unavailable for most of the world's taxa. This is the case for the Orchidaceae, a hyperdiverse and cosmopolitan family with incomplete phylogenetic and threat information. To define conservation priorities, we present a framework based on phylogenetic and taxonomic measures of distinctiveness and rarity based on the number of regions and the area of occupancy. For 25,434 orchid species with distribution data (89.3% of the Orchidaceae), we identify the Neotropics as hotspots for richness, New Guinea as a hotspot for evolutionary distinctiveness, and several islands that contain many rare and distinct species. Orchids have a similar proportion of monotypic genera as other Angiosperms, however, more taxonomically distinct orchid species are found in a single region. We identify 278 species in need of immediate conservation actions and find that more than 70% of these do not currently have an IUCN conservation assessment and are not protected in ex-situ collections at Botanical Gardens. Our study highlights locations and orchid species in urgent need of conservation and demonstrates a framework that can be applied to other data-deficient taxa.

Figure 1

World maps highlighting centres of orchid (A) endemic species richness (B) evolutionary distinctness (C) evolutionary distinctness based on the range size of species (D) evolutionary distinctiveness based on the number of regions species occupy. All calculations, maps and other graphics were created using R 3.5.1, R Core Team. R software: Version 3.5.1. R Found. Stat. Comput. (2018) https://doi.org/10.1007/978-3-540-74686-7.

Figure 2

(A) Histogram showing the proportion of orchids and Angiosperm species (excluding orchids) that are located in a given number of geographic regions. (B) Histogram showing the proportion of monotypic orchid genera that are located in a given number of geographic regions. (C) World map highlighting centres of monotypic orchid species richness. All calculations, maps and other graphics were created using R 3.5.1, R Core Team. R software: Version 3.5.1. R Found. Stat. Comput. (2018) https://doi.org/10.1007/978-3-540-74686-7.

Figure 3

World maps highlighting centres of priority species based on several metric scores: (A) evolutionary distinctness rarity based on the number of regions species occupy (ED_Regions), (B) evolutionary distinctness rarity based on the range size of species (ED_Range), (C) monotypic genera and rarity based on the number of regions species occupy, and (D) monotypic genera and rarity based on the range size of species. All calculations, maps and other graphics were created using R 3.5.1, R Core Team. R software: Version 3.5.1. R Found. Stat. Comput. (2018) https://doi.org/10.1007/978-3-540-74686-7.

Figure 4

Overview of the 278 priority orchid species, including growth form, habitat, altitude, and pollination syndrome.

Figure 5

(A) Proportion of orchid species with IUCN assessments. (B) Proportion of orchid species found in botanic garden collections globally.