Are long-distance dispersal syndromes associated with the conservation status of plant species? The Canary Islands as a case study

Alberto J Coello,Pablo Vargas,Yurena Arjona,María Leo

doi:10.5209/mbot.60071

Abstract

Dispersal is the process that allows organisms to reach new suitable territories and expand their area of occupancy. In plants, long-distance dispersal (LDD) of diaspores is related to the presence of morphological structures (dispersal syndromes) that favor mobility by wind (anemochorous), sea currents (thalasochorous) and animals (epizoochorous and endozoochorous). The relationship between these LDD structures and the distribution of plant species is related to characteristics of different archipelagoes. Previous studies in several archipelagoes found that the Canary Islands showed the strongest positive relationship between dispersal syndromes and species distributions. It has been long hypothesized that species without specialized structures for dispersal have more difficulties in expanding their areas of occupancy and consequently these species are more threatened because of limited distribution. Nevertheless, the effect of the dispersal ability of plant species on the degree of threat has never been tested in oceanic archipelagoes. In this study, we selected the 262 lowland endemic plant species of the Canary Islands and evaluated the relationship between the presence/absence of the four LDD syndromes and their threat status. A considerable number of threatened (154 spp.) and non-threatened (108 spp.) species were observed, of which 93 had LDD syndromes and 169 did not. Our analyses failed to find statistically significant differences between the number of threatened species with and without LDD syndromes and their IUCN threatened status. In sum, this study shows a poor contribution of dispersal abilities in the degree of threat of endemic plant species in the Canary Islands.

Highlights

Certain areas of the Earth, known as biodiversity hotspots, hold high levels of biological diversity and are affected by an exceptional loss of habitat
The objectives of the present study are to determine (i) whether plant species without long-distance dispersal (LDD) syndromes have a higher number of threatened species in the Canarian endemic lowland flora than species with LDD syndromes; and (ii) whether species without LDD syndromes have a higher degree of threat regarding to the IUCN categories (LC < NT < VU < EN < CR) than those species with LDD syndromes
After combining the list of IUCN categories (MuñozRodríguez & al., 2016) and the list of LDD syndromes and species distributions (Arjona & al., 2018) we found 108 non-threatened species (51 LC and 57 NT) and 154 threatened species (85 VU, 37 EN and 32 CR) (Figure 1)

Summary

Introduction

Certain areas of the Earth, known as biodiversity hotspots, hold high levels of biological diversity and are affected by an exceptional loss of habitat. (2000) and updates made by Conservation International (www.conservation.org/how/pages/hotspots.aspx), several of these biodiversity hotspots are located on islands, despite their limited surface compared to mainland. The high isolation of islands has implications in speciation processes and leads to higher rates of insular endemisms (Whittaker & FernándezPalacios, 2007). Island isolation, together with their reduced areas, is related to a higher extinction. Mediterranean Botany 39(2) 2018: 105-110 risk compared to the mainland and makes islands a more challenging territory to preserve (Frankham, 1998). The majority of species of vertebrates and plants extinctions recorded have occurred on islands (Sax & Gaines, 2008). Islands are a precious resource for science and should be a conservation priority

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