The mystery of the Arabian miniatures

The Arabian peninsula is bigger than western Europe, and ecologically similar to North Africa. However, an unexplained fact is that most of its species of large terrestrial animals are diminutive.

All of the wild ungulates and the major Carnivora of the Arabian peninsula are smaller than conspecifics, or their closest ecological counterparts, in Africa or mainland Asia. The same was true for the extinct Arabian form of the ostrich (Struthio camelus). This generalisation applies to Gazella saudiya (extinct), Gazella arabica, Gazella marica, Capra nubiana, Oryx leucoryx (which narrowly escaped extinction), Arabitragus jayakari, Panthera pardus, Caracal caracal, Acinonyx jubatus (locally extinct), Canis lupus, Vulpes vulpes and Hyaena hyaena.

One of the reasons why this puzzle is poorly appreciated is that most of the species listed above do not have the body proportions usually associated with miniature varieties of mammals, such as proportionately large heads and eyes and proportionately short legs and horns. The most familiar example is the Arabian oryx, which looks as well-proportioned as its Saharan relative, Oryx dammah, despite being only about half the body mass.

Reduction in body size is a familiar pattern on islands, and is usually explained by the limitation on resources in confined areas. This rationale can theoretically apply to peninsulas too, to the degree that peninsulas produce isolation from mainlands. And a further parallel with islands is the tendency of the fauna to be driven rapidly to extinction by human hunters.

However, isolation is an unsatisfactory explanation for the remarkably consistent diminution in the Arabian fauna, because this peninsula is larger than any island on Earth. Even if it is borne in mind that aridity limits the productivity and reliability of resources, how can the effects have been so different from the Sahara?

The mystery of the Arabian miniatures remains an intriguing puzzle for naturalists to ponder.

פורסם על-ידי milewski milewski, אוקטובר 02, 2020 12:53 אחה"צ

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