Micro-Hotspots for Conservation: An Umbrella Tree Species for the Unique Socotran Reptile Fauna

Abstract

Umbrella species are defined as species that can be rare and sensitive to human disturbance, whose protection may confer the protection of other co-occurring species. The dragon’s blood tree Dracaena cinnabari Balf.f. was already considered an umbrella species on Socotra Island (Indic Ocean, Yemen) due to its ecological importance for some native biota. We studied the reptile community living on D. cinnabari from Socotra Island. We sampled reptiles on trees across most D. cinnabari populations and applied co-occurrence and network partition analyses to check if the presence of reptiles on D. cinnabari populations was random or structured. Regardless of its patched and scarce actual distribution, we report the use of this tree as a habitat by more than half of the reptile community (12 endemic reptiles). Co-occurrence and network partition analyses demonstrate that this community is structured across the distribution of dragon’s blood trees, reflecting complex allopatric, vicariant, and biotic interaction processes. Hence, these trees act as micro-hotspots for reptiles, that is, as areas where endemic and rare species that are under threat at the landscape scale co-occur. This Socotra endemic tree is currently threatened by overgrazing, overmaturity, and climate change. Its protection and declaration as an umbrella species are expected to benefit the reptile community and to protect evolutionary processes that are partially driven by the ecological links between reptiles and this tree. To our knowledge, no tree species has been proposed as an umbrella species for island vertebrate endemics so far, highlighting the ecological uniqueness of Socotra Island.

Punica protopunica Balf., the Forgotten Sister of the Common Pomegranate (Punica granatum L.): Features and Medicinal Properties—A Review

“…Socotra Archipelago is known to be a section of what was once the Gondwana Supercontinent [ 52 , 53 ]. The biodiversity and geology of the island of Socotra are living and tangible proof of the historical biogeography of the supercontinent of Gondwana [ 54 ].…”

“…In the early Cretaceous, Gondwana included the continental areas of Africa, South Asia, Polynesia and Central America, which later separated to create the continents as we know them today. Subsequently, the 4 islands of the Socotra archipelago, was isolated from the Indian Ocean approximately 20 million years ago, when the African and Arab plates separated, which resulted in the formation of the Gulf of Aden [ 52 , 55 ]. At some point in that transformation, the Socotra archipelago was left behind, isolating all the living matter contained in that piece of land.…”

Twenty years of biodiversity research and nature conservation in the Socotra Archipelago (Yemen)

“…Image from Google Earth, modified by Kay Van Damme extinction of a single individual or a small population, whether it belongs to a species of plants or animals, matters. For example, the loss of a single individual of the iconic Socotra Dragon's Blood Tree (Dracaena cinnabari) would not only affect the entire vegetation that lives sheltered below the canopy and the animals associated with it (Rejžek et al 2016;Vasconcelos et al 2020), but it may also change the amount of water that is part of the island's hydrological cycle on which human life depends (Kalivodová et al 2020). Often, effects that we see today are the results of trends that have been set in motion over the last decades, and which are accelerated through global warming and other, more direct, human interventions.…”

“…About 90% of the terrestrial reptiles are endemic to the archipelago, and several of those rely on the availability of the trunks and branches of trees or bushes (Fasola et al 2020). The endemic gecko Hemidactylus dracaenacolus, assessed as critically endangered in the IUCN Red List, is even found exclusively on tree trunks of the endemic Dragon's Blood Tree (Vasconcelos et al 2020). Therefore, the declines or the disappearance of vegetation through a combination of factors, may accelerate the direct extinction of associated species in the absence of vegetation cover.…”

Dragon Trees, Tertiary Relicts in Current Reality

“…caboverdeana, species that have an important value for population studies and setting up a framework for conservation et al [34] present the results of an extensive serrulata in Oman and an assessment of its threats. Vasconcelos et al [35] highlight D. cinnabari as an umbrella species providing microhabitats for almost half of the endemic reptile fauna on Socotra. Finally, Maděra et al [36] review the current knowledge of the taxonomy, evolution, anatomy and morphology, physiology and ontogeny of the arborescent Dragon tree species.…”