18 Dec 2013

The riddle of the mystery gazelle (Arabian Gazelle or Mountain Gazelle?) – Farasan Islands

Evidence for the existence of an enigmatic species of Arabian Gazelle Gazella arabica was known only on the basis of museum specimens that was supposedly collected on the Farasan Islands and arrived from Arabia in Berlin in 1825. The museum specimen appears to document a species that disappeared soon after it was discovered and The International Union for Conservation of Nature (IUCN) included G. arabica as an extinct species on its Red List until 2008. Its status was then revised to “data deficient” owing to the lack of genetic data. Various people placed the Arabian Gazelle with the Mountain Gazelle Gazella gazelle a species that ranks among the most critically endangered mammals on the Arabian Peninsula. Past conservation efforts have been plagued by confusion about the phylogenetic relationship among various ‘phenotypically discernable’ populations, and even the question of species boundaries was far from being certain. As a result recent (2010) mtDNA sequences of 126 individuals collected from the wild throughout the Arabian Peninsula and from captive stocks were analysed. Analyses revealed two reciprocally monophyletic genetic lineages within the presumed species Gazella gazella: one ‘northern clade’ on the Golan Heights (Israel/Syrian border) and one genetically diverse larger clade from the rest of the Arabian Peninsula including the Farasan Islands as well as the Arava Valley (Negev, Israel). Applying the Strict Phylogenetic Species Concept allows assigning species status to these two major clades. The name favoured for the Arabian clade was G. arabica, given that molecular analyses would show that the lectotype of G. arabica is included in this group. If the Golan population is assigned species status G. gazella, it raises taxonomic questions as to which species name can be assigned to the populations from the Arabian Peninsula. The two oldest names are Antilope Arabica (Lichtenstein, 1827) and A. cora (Smith, 1827), but there are nomenclatural difficulties with both these names. If molecular evidence from the type material of Gazella Arabica does not confirm a distinct species and the specimens group instead with the Peninsula clade of gazelles, then this would be the appropriate name for all Mountain gazelles of the Arabian Peninsula. This is in fact exactly what happened when trying to clarify the position of Arabian Gazelle and remedy its status; researchers recently examined the DNA of the almost 200-year-old type specimen, as part of a collaborative project between German, UK and Saudi Arabian scientists. The results surprised everyone. “It turned out that the skin and the skull come from different animals” and the specimen was in fact a “composite” made up of parts representing two different lineages of the Mountain gazelle G. gazella found in the Eastern Mediterranean region and on the Arabian Peninsula, respectively. But that’s not all. The new data indicate that the Arabian form, hitherto classified as a subspecies of G. gazella and recently recognized as a species in its own right, is in fact G. arabica, alive and kicking.

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