Analysis: Corucia ssp. Integrades
Brian L. Schnirel
Leeway Corucia Research Center (LCRC)
Date of submission: March 7, 2008Date of publication: April 10, 2008
This question of subspecies integrades of monkey scincid Corucia zebrata will be discussed in this paper.
◊ An article from Brian L. Schnirel, (2008 April 10). "Analysis: Corucia ssp. Integrades." Biology-Online.org. Retrieved from http://www.biology-online.org/articles/analysis-corucia-ssp-integrades.html.
The Monkey skink Corucia zebrata is known from two documented subspecies. Corucia zebrata zebrata - Gray, 1855. Corucia zebrata alfredschmidti - Kohler, 1997. The following is an excerpt from the introduction of subspecies comparison of the Genus: Corucia - Jones/Schnirel (2006): "Corucia zebrata zebrata described and named (Gray, 1855) and Corucia zebrata alfredschmidti described and named (Kohler, 1997) represent the two subspecies of Corucia zebrata - the prehensile tailed monkey skink. The common monkey skink hails from the larger islands of the Solomon archipelago southeast of Buka and Bougainville. This includes Choiseul, Guadalcanal, Isabel, Malaita, Nggla, New Georgia, Santa Ana, San Cristobal, Shortlands, and Ugi (Balsai, 1995). The North Solomon monkey skink (Corucia zebrata alfredschmidti) hails from the North Solomons which are comprised of Bougainville and Buka (Kohler, 1997). Bougainville is by far the largest island in the archipelago and being on the northeast fringe of these islands, supported the establishment of peripheral isolates evolving into the subspecies alfredschmidti. This is supported by the sheer number and larger distribution of the subspecies zebrata in the southeastern islands. The core population of Corucia zebrata zebrata appears to be from Quadalcanal (Balsai, 1995). The allopathic subspeciation of the Genus: Corucia reveals a larger size of Corucia zebrata alfredschmidti compared to Corucia zebrata zebrata. Indeed, a semi-Wallace line appears to exist between Bougainville and Choiseul. "There is an affinity along the lines of Bougainville - Choiseul, separated by the Bougainville strait, in which the faunal differences are relatively distinct (faunal differences 86%)" (Green/Slade, 1968). Other animals show a size differential with the populations on Bougainville being generally larger than that on Choiseul. The monkey faced flying fox (Pteralopex anceps) on Bougainville is also larger (255-280 mm). On Choiseul, next to Bougainville, the population is smaller (160-275mm) (E. Bowen-Jones 1997). "
The question of intergrades between the main archipelago monkey skink: Corucia zebrata zebrata - (Czz) and the North Solomon monkey skink: Corucia zebrata alfredschmidti - (Cza), has been discussed. The three main tracks of this question are: If Intergrades exist... A). Could this have happened naturally in the original ecosystem between random chance introductions of Cza and Czz through natural means such as rafting episodes? B). Could Wild Corucia been distributed across the Bougainville Strait between Bougainville and Choiseul by the Solomon native human contingent? C). Are the intergrades a result of pairing of Corucia in captivity by human orchestrated introductions, whether planned, by random chance, or in pairing desperation. Track A: As stated in Subspecies comparison of the Genus: Corucia, A semi Wallace line of genetic distinctiveness in size and genetic diversity is clearly evident. If there was free natural exchange across the Bougainville strait, The differences would be much more watered down. A Cza Corucia from Bougainville or a Czz from Choiseul could be conceived as rafting on a log from Bougainville to Choiseul or from Choiseul to Bougainville. Rafting is well known as a means of distributing species and creating new ones. For instance: in the lizard world the common green iguana - Iguana iguana has by rafting, established new populations and species such as in the Galapagos Island archipelago. Evidence of this across the Bougainville strait as of this date, does not reflect this. Another point to consider is the strength and direction of the Bougainville current which further gives credence to this being a natural barrier. The wind and current difficulties in navigation are mentioned in Thirty Years in the South Seas - Richard Parkinson - 1999. Track A Conclusion: Could rafting have occurred to introduce the two species- Highly doubtful. Track B: Solomon native humans do have a market for Corucia for food and shipments from one island to another are possible. Also possible are accidental or deliberate introductions of one island Corucia to another. Again, as of this date, Imports from the Solomons as well as research by Parker, Balsai, Gray and Kohler - shows no evidence of naturally occurring integrades of Corucia. Track B conclusion: Are there man induced integrades of Cza and Czz in the Solomons? Not Likely. Track C: Captive bred integrades of Corucia. As subspecies, it is feasibly possible to breed Cza and Czz. There has been some genetic drift and there is behavior differences noted from the two subspecies. However, a pairing could produce young. The time honored classification of what is the demarcation of two species is that any young produced are considered 'mules' and cannot reproduce. As subspecies: A Cza/Czz offspring should not only be viable but also be able to produce young. The genetic drift as subspecies would make the Czz/Cza hybrid potentially a contributor of possible miscarriages and deformities. A Czz/Cza hybrid would be identified by a mixed combination of features some from one subspecies and some from another such as Scleral color, mixture in parietal scales, body scalation, etc. Track C Conclusion: Could Captive bred subspecies integrades of Corucia exist? A possibility. A documented case remains to be seen.
As much as we know, there is so much we don't know. A greater study of the Solomon archipelago forest canopy is needed similar to the New Caledonian study by De Vosjoli. Proper documentation, measurements and exchange of data between guardians of Corucia can further find the answer to the ultimate question.
Balsai, Michael J.; 1995. Husbandry and breeding of the Solomon islands prehensile- tailed skink (Corucia zebrata). The Vivarium, Escondido, California, U.S.A. pp. 4-11.
Bowens, E.; Jones; 1997. Flying foxes on Choiseul (Solomon islands) - the need for conservation. Oryx, Volume 31, July, Cambridge, U.K. page 309.
Coburn, John; 1996. Prehensile tailed skinks. T.F.H. Publications Inc. Neptune City, New Jersey, U.S.A. 64 pages.
De Vosjoli, Phillippe 1993. The general care and maintenance of prehensile tailed skinks. Advanced Vivarium Systems Inc., Lakeside, California, U.S.A.
Jones/Schnirel; 2006. Subspecies comparison of the Genus: Corucia. Polyphemos, Florence, South Carolina U.S.A., Volume 4, Issue 1. May. pp 1- 25.
Kohler, G.; 1997. Eine neue unterart des wickelshwanz skinkes Corucia zebrata von Bougainville, Papua Neuguinea - Salamandrae, Germany, Volume 33, Issue 1, pp. 61-65.
Green, Slade; 1968. Island patterns in the Solomon islands bird fauna. Evolution, Volume 11-Number 4, December, London, U.K. pp. 751-761.
Langerwerf, Burt; 2003. Agama International; Personal communication.
McCoy, Michael; 1980. Reptiles of the Solomon islands. Wau Ecology Institute, Handbook No. 7:30. Papua New Guinea.
Parker, F.; 1983. The prehensile tailed skink (Corucia zebrata) on Bougainville island, Papua New Guinea. Advances in herpetology and evolutionary biology, Museum of Comparative Zoology, Cambridge, Massachusetts, U.S.A. pp. 435- 440.
Schnirel, Brian L. 2004. Seni biometric analysis on the extinct Scincidae species: Macroscincus coctei. Underlined) Polyphemos, Volume 2, Issue 1,
May, Florence, South Carolina, U.S.A. May pp. 12-22.