Archivos de diario de octubre 2020

02 de octubre de 2020

The mystery of the Arabian miniatures

@sanjoaquinserpents @jorgejuanrueda @chewitt1 @tandala @tfrench @sammyboy2059 @capracornelius @saber_animal @ldacosta @aguilita @maxallen @marcelo_aranda @mr_fab @pelagicgraf @grinnin @jacob12_ @oviscanadensis_connerties @calebcam @galewski @dinofelis

The Arabian Peninsula is bigger than western Europe, and ecologically similar to North Africa. However, an unexplained fact is that most of its terrestrial animals, of body mass 1 kilogram or more, are diminutive.

Not only are the wild ungulates and the major Carnivora of the Arabian peninsula all smaller-bodied than conspecifics (or their closest ecological counterparts) in Africa or mainland Asia, but five of the six wild species of ungulates, and both of the top carnivores, are smaller-bodied than the key deer (https://en.wikipedia.org/wiki/Key_deer) - an extremely diminutive form restricted to small islands off Florida.

The body mass attained by the genus Lepus (https://www.inaturalist.org/journal/milewski/64019-why-has-there-never-been-a-donkey-size-jackrabbit-part-1) on the Arabian Peninsula is only a quarter of that attained by the same genus in semi-arid, subtropical North America.

The pattern applies also to the extinct Arabian form of the ostrich (Struthio camelus syriacus, https://en.wikipedia.org/wiki/Arabian_ostrich), which was smaller-bodied than the various subspecies in Africa.

This means that

  • there has been no wild species of herbivore on the Arabian Peninsula - apart from the mysterious ancestor of a camel - with adult female body mass averaging more than 65 kg, and
  • both of the top predators of the Arabian Peninsula are only about the size of the Eurasian lynx (Lynx lynx).

The lion (Panthera leo) seems to have been naturally absent from the Arabian Peninsula (https://www.researchgate.net/publication/342663553_The_Asiatic_or_Persian_Lion_Panthera_leo_persica_Meyer_1826_in_Palestine_and_the_Arabian_and_Islamic_Region). Far from compensating for this absence by increased body size, the Arabian leopard (Panthera pardus nimr) is the smallest-bodied subspecies: adult females about 20 kg. The Arabian wolf (Canis lupus arabs) likewise weighs only about 20 kg. The lynx-like felid Caracal caracal, too, is relatively small-bodied on the Arabian Peninsula.

The following illustrates the various mammalian species.

ARTIODACTYLA: BOVIDAE

Gazella saudiya is extinct, with no photos of the living animal (https://en.wikipedia.org/wiki/Saudi_gazelle). It was the smallest of all gazelles, with adult female body mass probably less than 13 kg.

Gazella arabica has adult female body mass probably about 15 kg. See https://www.zoochat.com/community/media/arabian-mountain-gazelle-gazella-gazella-cora.421165/ and https://www.shutterstock.com/nb/image-photo/extremely-shy-wild-female-dorcas-gazelle-387163744 and https://www.biolib.cz/en/image/id171988/ and https://www.shutterstock.com/nb/image-photo/male-arabian-mountain-gazelle-gazella-cora-1139195546 and http://shahbazmuhammed.blogspot.com/2015/03/arabian-mountain-gazelle.html.

Gazella marica has adult female body mass probably about 18 kg. See https://1.bp.blogspot.com/-sb9jKDyMmzU/XzaWasrR8gI/AAAAAAAAi3Y/6KJLfUB4qWkauKq96yj0c_XTGKDZG3hIwCLcBGAsYHQ/s1600/Arabian%2BSand%2BGazelle1.jpg and https://4.bp.blogspot.com/-kysR7MF0juA/UzBTOxNvP6I/AAAAAAAAPso/megatJCItzI/s3200/Sand_Gazelle1.jpg and https://calphotos.berkeley.edu/cgi/img_query?enlarge=0000+0000+1115+1312 and http://awwp.alwabra.com/wp-content/uploads/2014/04/Adult_Male_Rheem_Gazelle_01.jpg.

Arabitragus jayakari has adult female body mass about 20 kg (https://www.biorxiv.org/content/10.1101/2021.01.26.428299v1.full.pdf). See https://www.mammalwatching.com/2018/06/12/infos-and-pics-on-arabian-tahr/ and https://www.biolib.cz/en/image/id373892/ and https://www.biolib.cz/en/image/id366322/ and https://colnect.com/en/phonecards/phonecard/32140-Arabian_Tahr-1993_The_Rare_And_The_Beautiful-Omantel-Oman and https://www.alamy.com/arabian-tahr-arabitragus-jayakari-male-captive-oman-october-image357523434.html and https://www.fujairahobserver.com/2021/11/18/fujairahs-fauna-and-flora-3/.

Capra nubiana has adult female body mass about 23.5 kg (https://cdnsciencepub.com/doi/pdf/10.4141/cjas84-204), compared to 56 kg in Capra cylindricornis (https://en.wikipedia.org/wiki/East_Caucasian_tur). The Arabian species is also smaller-bodied than Capra caucasica (https://en.wikipedia.org/wiki/West_Caucasian_tur) and the Ethiopian species Capra walie (https://en.wikipedia.org/wiki/Walia_ibex). See https://en.wikipedia.org/wiki/Capra_(genus)#/media/File:Capra_range_map2.jpg and https://www.dreamstime.com/male-nubian-ibex-walking-along-mountain-rocks-showing-off-large-curved-horns-capra-nubiana-al-ain-zoo-image151878031 and https://www.naturepl.com/stock-photo-nubian-ibex-capra-nubiana--old-male-walking-on-a-rock-negev-desert-nature-image01667947.html and https://stock.adobe.com/search/images?k=ibex+isolated&asset_id=246925501.

Oryx leucoryx (which narrowly escaped extinction) has adult female body mass about 63 kg (https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180269#:~:text=The%20mean%20body%20mass%20of,%3D%206%2C%20range%2048%E2%80%9390). See https://www.alamy.com/arabian-oryx-white-oryx-walking-through-desert-in-yotvata-hai-bar-nature-reserve-breeding-and-reacclimation-center-oryx-leucoryx-image342292900.html and https://www.desicomments.com/animals/white-oryx-on-sand/ and https://www.istockphoto.com/photo/endangered-arabian-or-white-oryx-walks-along-the-desert-in-the-united-arab-emirates-gm1141255843-305683103 and https://www.freeimages.com/premium/arabian-oryx-1601835.

ARTIODACTYLA: CAMELIDAE

Camelus dromedarius, the ancestral dromedary, does not conform to the trend of miniaturisation on the Arabian Peninsula. According to https://www.pnas.org/content/113/24/6707 the wild form last occurred in what is today Dubai. If so, it seems that this ungulate, which is large-bodied for an artiodactyl even by mainland standards, survived in Arabia partly because of the island-like freedom from predation by the lion and the spotted hyena (Crocuta crocuta). Even if the population of the wild dromedary in Arabia was merely relictual, it would depart from the pattern because C. dromedarius, with body mass at least 400 kg, is not small-bodied among the camelids of the Holocene, worldwide.

PERISSODACTYLA: EQUIDAE

Equus hemionus hemippus (https://en.wikipedia.org/wiki/Syrian_wild_ass), a subspecies of the Asian wild ass, was associated mainly with the Levant and Mesopotamia. However, it is thought also to have extended to what is now Saudi Arabia. It was the smallest of all the wild forms of equid of the Holocene, worldwide. I estimate its body mass to have been less than 150 kg (https://www.inaturalist.org/journal/milewski/59035-the-forgotten-domestication-of-the-eurasian-wild-ass). Although only marginally present on the Arabian Peninsula, it conformed somewhat to the general trend of miniaturisation.

HYRACOIDEA: PROCAVIIDAE

Procavia capensis jayakari of the Arabian Peninsula is smaller-bodied (average adult total length 41 cm, skull length 8.1 cm) than P. c. syriaca (49 cm and 9.0 cm, respectively) of Jordan, Lebanon, and Israel (Harrison and Bates 1991), and P. c. capensis (52 cm and 9.1 cm, respectively) of southern Africa (Skinner and Chimimba 2005). Given that the average adult body mass in southern Africa is 3.5 kg, the Arabian subspecies probably weighs only about 2 kg. See https://www.inaturalist.org/observations/35854925.

LAGOMORPHA: LEPORIDAE

Lepus capensis in Syria and Lebanon, as in South Africa, weighs about 2 kg. By contrast, subspecies omanensis (http://www.birdsoman.com/Mammals/132-Hares/CapeHare/CapeHare.htm and https://www.flickr.com/photos/dave_irving/27234084723 and https://www.flickr.com/photos/dave_irving/30205611511 and https://valbum.net/media.details.php?mediaID=4065) of Oman weighs closer to 1 kg. This is based on the fact that its total length averages only 38.5 cm compared to 59.5 cm in South Africa (Harrison and Bates 1991, Skinner and Chimimba 2005). Lepus capensis cheesmani (https://www.inaturalist.org/observations/9692185 and https://www.enature.qa/specie/desert-hare-arabian-hare-cape-hare/ and https://english.alarabiya.net/features/2018/09/14/A-Saudi-photographer-s-insights-on-the-Uruq-Bani-Ma-arid-Saudi-wildlife-protected-area and https://www.inaturalist.org/observations/56510260) of Saudi Arabia is also diminutive.

CARNIVORA: FELIDAE

Panthera pardus nimr: see https://www.dreamstime.com/stock-photo-arabian-leopard-looking-prey-image86330372and https://gulfnews.com/world/gulf/oman/catching-the-endangered-arabian-leopard-on-camera-1.1392145 and https://en.wikipedia.org/wiki/Arabian_leopard#/media/File:PikiWiki_Israel_14861_judean_desert_leopard_cropped.JPG.

Caracal caracal schmitzi (https://www.pumapix.com/wild-cat-profile-arabian-caracal/) of the Arabian Peninsula is smaller-bodied than Caracal caracal caracal of southern Africa. The averages for total length are 91 cm and 112 cm respectively (Harrison and Bates 1991, Skinner and Chimimba 2005).

Acinonyx jubatus (locally extinct) was smaller-bodied on the Arabian Peninsula than in Africa (Harrison and Bates 1991).

CARNIVORA: CANIDAE

Canis lupus arabs: see https://en.wikipedia.org/wiki/Arabian_wolf and https://www.inaturalist.org/observations/40380794.

Vulpes vulpes arabica, with adult body mass about 2.7 kg (https://en.wikipedia.org/wiki/Arabian_red_fox), is far smaller-bodied than the same species in Europe, which has adult body mass about 6 kg (https://academic.oup.com/mspecies/article/doi/10.2307/3504236/2600732?login=false).

CARNIVORA: VIVERRIDAE

Genetta genetta grantii of the Arabian Peninsula is smaller-bodied than G. g. genetta of the Iberian Peninsula, based on the length of the hind foot (7.5cm vs 8.5 cm). My sources are Harrison and Bates (1991) and https://academic.oup.com/mspecies/article/doi/10.2307/0.680.1/2600797?login=false.

CARNIVORA: HYAENIDAE

Hyaena hyaena sultana of the Arabian Peninsula has average adult body mass about 31 kg (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6662563/). "All body measurements averaged smaller in the two southern subspecies, H. h. dubbah and sultana, than in the three northern subspecies, barbara, syriaca, and hyaena (Rieger, 1979a)" (https://academic.oup.com/mspecies/article/doi/10.2307/41353899/2600235?login=false and https://www.researchgate.net/publication/254163197_Hyaena_hyaena/link/5624c66508aea35f2686a9ad/download.). The length of the skull averages 22.5 cm in H. h. sultana, compared with 24 cm in H. h. syriaca of Israel, Jordan, and Lebanon (Harrison and Bates 1991). See https://www.zoochat.com/community/media/arabian-striped-hyena.404031/ and https://www.zoochat.com/community/media/arabian-striped-hyena.172934/ and https://www.researchgate.net/publication/341725041_The_Arabian_Striped_Hyaena_Hyaena_hyaena_sultana_Pocock_1934_Carnivora_Hyaenidae_in_the_Kingdom_of_Saudi_Arabia_aldb_almukhtt_alrby_fy_almmlkt_alrbyt_alswdyt#:~:text=There%20are%205%20subspecies%20of%20Striped%20Hyena%3A&text=Arabian%20Striped%20Hyaena%20(Hyaena%20hyaena%20sultana%20Pocock%2C%201934)%20%E2%80%93,March%202020%2C%20April%202020.

CARNIVORA: MUSTELIDAE

Mellivora capensis pumilio of the Arabian Peninsula is smaller-bodied than both M. c. wilsoni of Israel and M. c. capensis of southern Africa (Harrison and Bates 1991).

PRIMATES: CERCOPITHECIDAE

Papio hamadryas arabicus "appears to average smaller than P. h. hamadryas from Africa, with the teeth especially small" (Harrison and Bates 1991). See https://www.inaturalist.org/observations/1333584 and https://www.inaturalist.org/observations/110994912.

Based on Harrison and Bates (1991), this leaves only the following species as exceptions:


One of the reasons why this remarkably consistent diminution has been overlooked is that some of the species listed above lack the body proportions usually associated with reduction in body size, such as large-looking heads and eyes, and short-looking legs and horns.

For example:

Reduction in body size is a familiar pattern on islands (http://www.tobiaslab.net/wp-content/uploads/2021/04/Benitez-Lopez-et-al.-2021-Island-rule.-NEE.pdf and https://www.jstor.org/stable/2461638 and https://digitalcommons.macalester.edu/cgi/viewcontent.cgi?article=1007&context=biogeography), usually explained by limitation on resources in confined areas.

This can theoretically apply to peninsulas too, inasmuch as 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 pattern of diminution in the Arabian fauna, because this peninsula is larger than any island on Earth (https://www.newsweek.com/true-scale-map-world-shows-how-big-countries-really-are-1183386). Even allowing 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.

Ingresado el 02 de octubre de 2020 por milewski milewski | 14 comentarios | Deja un comentario